User Manual
2715
Spectrum Analyzer
070-9115-05
This document supports
firmware version 2.14.97 and above.
Copyright E T ektronix, Inc. All rights reserved.
T ektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supercedes
that in all previously published material. Specifications and price change privileges reserved.
Printed in the U.S.A.
T ektronix, Inc., P.O. Box 1000, Wilsonville, OR 97070–1000
TEKTRONIX and TEK are registered trademarks of T ektronix, Inc.
WARRANTY
T ektronix warrants that this product will be free from defects in materials and workmanship for a period of one (1) year
from the date of shipment. If any such product proves defective during this warranty period, T ektronix, at its option, either
will repair the defective product without charge for parts and labor, or will provide a replacement in exchange for the
defective product.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration of the
warranty period and make suitable arrangements for the performance of service. Customer shall be responsible for
packaging and shipping the defective product to the service center designated by T ektronix, with shipping charges prepaid.
T ektronix shall pay for the return of the product to Customer if the shipment is to a location within the country in which the
T ektronix service center is located. Customer shall be responsible for paying all shipping charges, duties, taxes, and any
other charges for products returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate
maintenance and care. T ektronix shall not be obligated to furnish service under this warranty a) to repair damage resulting
from attempts by personnel other than T ektronix representatives to install, repair or service the product; b) to repair
damage resulting from improper use or connection to incompatible equipment; or c) to service a product that has been
modified or integrated with other products when the effect of such modification or integration increases the time or
difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX WITH RESPECT TO THIS PRODUCT IN LIEU OF ANY
OTHER WARRANTIES, EXPRESSED OR IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
TEKTRONIX’ RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND
EXCLUSIVE REMEDY PROVIDED TO THE CUST OMER FOR BREACH OF THIS WARRANTY. TEKTRONIX
AND ITS VENDORS WILL NOT BE LIABLE FOR ANY INDIRECT , SPECIAL, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES IRRESPECTIVE OF WHETHER TEKTRONIX OR THE VENDOR HAS
ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.
Table of Contents
Introduction
Getting Started
Operating Basics
General Safety Summary vii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preface xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What is a Spectrum Analyzer? 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What Can You Do With a Spectrum Analyzer? 1–2. . . . . . . . . . . . . . . . . . . . . . . . . .
About the 2715 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Getting Started 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiving and Unpacking 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Packaging and Storing 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Precautions 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Checkout 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Making Your First Measurement 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating Basics 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Screen 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connectors, Controls, and Menus 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SWP/TRG Menu Structure 3–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UTIL Menu Structure
(1 of 2) 3–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UTIL Menu Structure
(2 of 2) 3–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MRK/FREQ Menu Structure 3–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CATV/APPL CATV Measurements Page 1 Menu Structure (1 of 3) 3–14. . . . . . . . .
CATV/APPL CATV Measurements Page 1 Menu Structure (2 of 3) 3–15. . . . . . . . .
CATV/APPL CATV Measurements Page 1 Menu Structure (3 of 3) 3–16. . . . . . . . .
CATV/APPL CATV Measurements Page 2 Menu Structure (1 of 2) 3–17. . . . . . . . .
CATV/APPL CATV Measurements Page 2 Menu Structure (2 of 2) 3–18. . . . . . . . .
CATV/APPL Applications Menu Structure 3–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DEMOD Menu Structure 3–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DSPL Menu Structure 3–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
USER DEF Menu Structure 3–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INPUT Menu Structure 3–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2715 User Manual
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Table of Contents
Dedicated Controls
CATV Measurements
Dedicated Controls 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fundamental Operations 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPAN/DIV 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Entry
(Normal Mode) 4–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Frequency Entry (NonCATV Mode) 4–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
REF LEVEL 4–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Enhanced Versatility 4–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Res BW 4–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Video Filter 4–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vert Scale 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sweep 4–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Level 4–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Storage 4–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Freq/Mkrs 4–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous Controls 4–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CATV Measurements 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CATV Preliminary Information 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General (CATV) 2715 Mode 5–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CARRIER LEVEL and AVERAGED POWER Measurement 5–20. . . . . . . . . . . . . .
CARRIER SUR VEY Measurement 5–25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MODULATION DEPTH Measurement 5–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AURAL (FM) DEVIATION Measurement 5–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CARRIER-TO-NOISE, DESIRED-to-UNDESIRED Measurement 5–35. . . . . . . . .
HUM/LFD Measurement 5–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
FREQUENCY RESPONSE 5–43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ADJACENT CHANNEL LEAKAGE Measurements 5–47. . . . . . . . . . . . . . . . . . . . .
CTB and CSO Measurements 5–49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CROSS MODULATION Measurement 5–60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
In-Channel Response Measurement 5–62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Auxiliary Operations 5–68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spectrum Analyzer Menus
Spectrum Analyzer Menus 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the Menus 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input 6–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MKR/FREQ 6–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DSPL 6–27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ensemble A veraging 6–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
APPL 6–43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DEMOD 6–56. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
UTIL 6–60. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SWP/TRIG 6–83. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
USER DEF 6–89. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The Audio Alert 6–71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2715 User Manual
Appendices
Table of Contents
Appendix A: Specifications A–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Characteristics A–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B: Broadcast AM, FM, and TV Signal Sources B–1. . . . . . . . .
Appendix C: System Messages C–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix D: Global Resets D–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Definitions D–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset Cycle Description D–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reset Categories D–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix E: External Input and Output E–1. . . . . . . . . . . . . . . . . . . . . . .
Mains Power E–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J101 — TV Sideband Analyzer and External Tracking Generator Interface E–1. . .
J102 — External Trigger E–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J103 — Accessory Connector E–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
J104 — Digital Communications Port E–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix F: Accessories and Options F–1. . . . . . . . . . . . . . . . . . . . . . . . . .
Accessories F–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Options F–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glossary and Index
2715 User Manual
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Table of Contents
List of Figures
Figure 2–1: Display with Factory Default Power-Up Settings 2–6. . . . . .
Figure 2–2: Normal On-Screen Data Readouts 2–7. . . . . . . . . . . . . . . . . .
Figure 2–3: Typical Measurement Result Display 2–13. . . . . . . . . . . . . . . .
Figure 2–4: The Primary Controls 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2–5: Calibrator Signal and Harmonics 2–15. . . . . . . . . . . . . . . . . . .
Figure 2–6: Calibrator Signal Fundamental 2–19. . . . . . . . . . . . . . . . . . . . .
Figure 3–1: Layout of the Text Screen in the Spectral Display Mode 3–1
Figure 3–2: Layout of the Text Screen in the Menu Display Mode 3–2. .
Figure 3–3: The Frequency/Marker Function Block 3–3. . . . . . . . . . . . . .
Figure 3–4: Fundamental Analyzer Controls 3–4. . . . . . . . . . . . . . . . . . . .
Figure 3–5: The Keypad 3–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3–6: Display Register Control 3–6. . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3–7: Vertical Scale and Other Controls 3–7. . . . . . . . . . . . . . . . . . .
Figure 3–8: Resolution BW and Sweep Control 3–8. . . . . . . . . . . . . . . . . .
Figure 3–9: The 2715 Back Panel 3–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 4–1: Example of a Waterfall Display 4–25. . . . . . . . . . . . . . . . . . . . .
Figure 4–2: Typical Plotter Output Showing TV Channel Spectrum 4–34
Figure 5–1: CATV MEASUREMENTS Menu 5–4. . . . . . . . . . . . . . . . . . .
Figure 5–2: Channel 2 of the STD channel table selected for edit
with menu set to change SCRAMBLED
(toggles between YES/NO) 5–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–3: Channel with FINISH selected 5–9. . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–4: Carrier Level, Averaged Power Measurement Results 5–24. .
Figure 5–5: Typical Carrier Survey Report Screen 5–27. . . . . . . . . . . . . . .
Figure 5–6: Typical Frequency Response Display Without
Reference 5–45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5–7: Typical Frequency Response Display With Reference 5–46. .
Figure 5–8: Typical CTB (or CSO) Measurement Results Display 5–54. .
Figure 5–9: Typical Continuous Mode Results Display 5–59. . . . . . . . . . . .
Figure 6–1: The INPUT Menu 6–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–2: Sweep/Trigger Menu with SWEEP RATE Selection
Chosen 6–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Figure 6–3: 75/50 W Matching Minimum Loss Pad 6–8. . . . . . . . . . . . . .
Figure 6–4: Equipment Setup for Field Strength Measurements 6–11. . . .
Figure 6–5: Average Signal Plus Noise and Average Signal-Plus-Noise
Subtracted from the Current Sweep 6–33. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–6: Average MEAN Noise and MAX HOLD
Signal-Plus-Noise 6–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–7: B, C Minus A Offset to Center 6–35. . . . . . . . . . . . . . . . . . . . .
Figure 6–8: B, C Minus A Offset to Top 6–35. . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–9: 2715 Plot with Title and Plot Labels 6–40. . . . . . . . . . . . . . . . .
Figure 6–10: The SIGNAL SEARCH Frequency Range 6–49. . . . . . . . . . .
Figure 6–11: Illustration of Occupied BW Measurement 6–51. . . . . . . . . .
Figure 6–12: Portion of U.S. Broadcast FM Band 6–52. . . . . . . . . . . . . . . .
Figure 6–13: OCCUPIED BW Mode with MAX HOLD 6–53. . . . . . . . . . .
Figure 6–14: Instantaneous Frequency Deviation and
Maximum Observed Deviation 6–55. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–15: Video Field Using Internal or TV Field Triggering 6–84. . . .
Figure 6–16: Video Signal Using Continuous Horizontal
Line Triggering 6–86. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6–17: Video Signal Using Knob-Selectable Horizontal
Line Triggering
(VITS Visible) 6–87. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–1: Typical Accuracy Limits for Carrier-to-Noise
Measurement A–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–2: Typical Accuracy Limits for CTB Measurement A–7. . . . . .
Figure A–3: Typical Accuracy Limits for Nongated CSO
Measurement A–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–4: Typical Accuracy Limits for Gated CSO
Measurement A–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–5: Typical ACL Measurement Limits for
2 dB Accuracy A–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–6: Typical D/U Measurement Range Limits for
2 dB Accuracy A–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–7: Typical Digital Signal CSO Measurement Range
Limit for 2 dB Accuracy A–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure A–8: Typical Digital Signal CTB Measurement Range
Limit for 2 dB Accuracy A–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure E–1: Accessory Connector (J103) E–3. . . . . . . . . . . . . . . . . . . . . . .
Figure E–2: Sweep Gate and Ramp Timing E–5. . . . . . . . . . . . . . . . . . . . .
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Figure E–3: IEEE Standard 488 (GPIB) Connector
Pin Assignments E–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure E–4: RS-232-C Connector Pin Assignments E–8. . . . . . . . . . . . . . .
Figure E–5: 9-Pin Female to 9-Pin Female Null-Modem Cable E–9. . . . .
Figure E–6: 9-Pin Female to 25-Pin Female Null-Modem Cable E–10. . . .
Figure E–7: 9-Pin Female to 25-Pin Male Extension Cable E–11. . . . . . . .
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2715 User Manual
List of Tables
Table of Contents
Table 5–1: Safe Maximum Signal Levels 5–2. . . . . . . . . . . . . . . . . . . . . . .
Table 5–2: Signal Type Measurements 5–5. . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–3: Menu Selections 5–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–4: STD 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–5: HRC 5–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–6: IRC 5–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–7: Examples of Cycle Delay/Target Line Duration
Interaction 5–31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 5–8: Locations of Noise Measurement 5–37. . . . . . . . . . . . . . . . . . . .
Table 6–1: Equivalent Decibel — Voltage Values 6–12. . . . . . . . . . . . . . . .
Table 6–2: AUTO Tuning Increment 6–22. . . . . . . . . . . . . . . . . . . . . . . . . .
Table 6–3: The File System 6–76. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 6–4: Additional File System 6–76. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table A–1: CATV Characteristics A–2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table A–2: Frequency-Related Characteristics A–11. . . . . . . . . . . . . . . . . .
Table A–3: Frequency/Amplitude Related Characteristics A–13. . . . . . . .
Table A–4: Amplitude-Related Characteristics A–14. . . . . . . . . . . . . . . . . .
Table A–5: Input/Output Signal Characteristics A–17. . . . . . . . . . . . . . . . .
Table A–6: Power Requirements A–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table A–7: Supplementary Characteristics Due to Options A–19. . . . . . .
Table A–8: General Characteristics A–20. . . . . . . . . . . . . . . . . . . . . . . . . . .
Table A–9: Environmental Characteristics A–21. . . . . . . . . . . . . . . . . . . . .
Table A–10: Physical Characteristics A–22. . . . . . . . . . . . . . . . . . . . . . . . .
Table A–11: Certifications and Compliances A–23. . . . . . . . . . . . . . . . . . . .
Table A–12: Safety Certification Compliance A–24. . . . . . . . . . . . . . . . . . .
Table A–13: Safety Standards A–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table E–1: 9-Pin Female to 9-Pin Female Null-Modem Cable E–9. . . . .
Table E–2: 9-Pin Female to 25-Pin Female Null-Modem Cable E–10. . . .
Table E–3: 9-Pin Female to 25-Pin Male Extension Cable E–11. . . . . . . . .
Table F–1: Standard Accessories F–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table F–2: Optional Accessories F–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table F–3: Power Cord Identification F–2. . . . . . . . . . . . . . . . . . . . . . . . .
2715 User Manual
vii
Table of Contents
viii
2715 User Manual
General Safety Summary
Review the following safety precautions to avoid injury and prevent damage to
this product or any products connected to it. To avoid potential hazards, use this
product only as specified.
Only qualified personnel should perform service procedures.
While using this product, you may need to access other parts of the system. Read
the General Safety Summary in other system manuals for warnings and cautions
related to operating the system.
To Avoid Fire or
Personal Injury
Use Proper Power Cord. Use only the power cord specified for this product and
certified for the country of use.
Connect and Disconnect Properly . Do not connect or disconnect probes or test
leads while they are connected to a voltage source.
Ground the Product. This product is grounded through the grounding conductor
of the power cord. To avoid electric shock, the grounding conductor must be
connected to earth ground. Before making connections to the input or output
terminals of the product, ensure that the product is properly grounded.
Observe All Terminal Ratings. To avoid fire or shock hazard, observe all ratings
and marking on the product. Consult the product manual for further ratings
information before making connections to the product.
The common terminal is at ground potential. Do not connect the common
terminal to elevated voltages.
Do not apply a potential to any terminal, including the common terminal, that
exceeds the maximum rating of that terminal.
Do Not Operate Without Covers. Do not operate this product with covers or panels
removed.
Use Proper Fuse. Use only the fuse type and rating specified for this product.
2715 User Manual
Avoid Exposed Circuitry. Do not touch exposed connections and components
when power is present.
Wear Eye Protection. Wear eye protection if exposure to high-intensity rays or
laser radiation exists.
Do Not Operate With Suspected Failures. If you suspect there is damage to this
product, have it inspected by qualified service personnel.
Do Not Operate in Wet/Damp Conditions.
Do Not Operate in an Explosive Atmosphere.
ix
General Safety Summary
Keep Product Surfaces Clean and Dry .
Provide Proper Ventilation. Refer to the manual’s installation instructions for
details on installing the product so it has proper ventilation.
Symbols and Terms
T erms in this Manual. These terms may appear in this manual:
WARNING. Warning statements identify conditions or practices that could result
in injury or loss of life.
CAUTION. Caution statements identify conditions or practices that could result in
damage to this product or other property.
T erms on the Product. These terms may appear on the product:
DANGER indicates an injury hazard immediately accessible as you read the
marking.
WARNING indicates an injury hazard not immediately accessible as you read the
marking.
CAUTION indicates a hazard to property including the product.
Symbols on the Product. The following symbols may appear on the product:
WARNING
High Voltage
Protective Ground
(Earth) T erminal
x
CAUTION
Refer to Manual
Double
Insulated
2715 User Manual
Preface
This manual contains operating information for the Tektronix 2715 Spectrum
Analyzer and includes menus and operating features. The following manuals also
support the Tektronix 2715 Spectrum Analyzer:
H 2714 & 2715 Spectrum Analyzer Programmer
H 2714 & 2715 Spectrum Analyzer Reference
H 2715 Spectrum Analyzer Service
H Cable TV RF Measurements Software User
For manual ordering information, refer to Appendix F: Accessories & Options or
contact your local Tektronix Field Office or representative.
Who Should Use This Manual?
This manual is intended for electronic technicians with experience in making
cable television-related measurements.
Standards and Conventions Used
Most terminology is consistent with standards adapted by IEEE and IEC.
Abbreviations used in the instrument and in the documentation are consistent
with ANSI Y1.1–1972. Copies of the ANSI and IEEE standards can be ordered
from the Institute of Electrical and Electronic Engineers Inc.
Change/History Information
Changes to the 2715 may occur or manual errors may be found that make some
of the information in the manual inaccurate. When this happens, Manual Change
Information notices containing the corrected information are inserted at the rear
of the manual. This ensures that the manual contains the latest and most accurate
information available when the product is sold.
Contact any Tektronix Service Center for information.
2715 User Manual
xi
Preface
Manual Organization
General
Sections 1 through 3 contain material that enables the beginning or experienced
operator to safely power up and initially normalize the spectrum analyzer.
Sections 4 through 6 provide detailed explanations and some measurement
examples that may be especially useful. The examples should be read while
interactively using the spectrum analyzer and carrying out the instructions. In
this way, you quickly acquire the knowledge and skills necessary to make
accurate measurements. The end of one example and start of the next are
indicated by a settings box that looks like this:
8.75MHZ (AUTO SWEEP) M 11.45 MHZ
23.5DBMV M 13.8 DBMV
600KHZ 10 DB/
300KHZ RBW STD CH 2
The box shows what the control settings of the spectrum analyzer should be to
continue with the example that follows it. The contents of the box resemble the
spectrum analyzer’s on-screen data readouts. Each example begins with the
sweep control in AUTO mode. To remind you of this, (AUTO SWEEP) is shown
in the top center of the box. The parentheses mean the enclosed item is not part
of the normal on-screen readouts.
Specific
Six appendices, a glossary, and an index contain information about a number of
topics useful, but not essential, to spectrum analyzer operation.
Introduction contains a brief description of spectrum analysis and reviews the
characteristics of the Tektronix 2715 Cable TV Spectrum Analyzer.
Getting Started enables you to safely apply power and signals to the spectrum
analyzer. You become acquainted with the fundamental controls of the instrument and make your first measurements using a firmware-based CATV
measurement routine and the built-in calibration signal.
Operating Basics provides most of the information needed for routine operation.
Dedicated Controls explains the features of the spectrum analyzer and the
benefits you gain from each control and menu option as you go through
examples. You learn to easily obtain accurate spectral and time-domain
measurements.
CATV Measurements describes CATV requirements and offers step-by-step
procedures to conduct automated measurement routines.
xii
2715 User Manual
Preface
Spectrum Analyzer Menus describes the 2715 menu-selectable, firmware-driven
features.
Appendix A: Specification lists the 2715 electrical, physical, and environmental
specifications.
Appendix B: Broadcast AM, FM & TV Signal Sources describes connecting the
2715 to various signal sources to do the examples shown in the manual.
Appendix C: System Messages describes abnormal instrument operating
situations and the recommended resolution or correction.
Appendix D: Global Resets provides the definitions, descriptions, and categories
of the various reset procedures for the instrument settings.
Appendix E: External Input and Output explains the procedure to get signals in
and out of the back panel of your spectrum analyzer. Configurations for
interconnect cables are also discussed.
Appendix F: Accessories & Options describes all standard and optional
accessories and options currently available for the 2715.
If you are already familiar with the spectrum analyzer, this manual can serve as a
“how to” reference. Check the index or table of contents for the location of the
subject of interest. Then set the spectrum analyzer according to the corresponding settings box, and refresh your memory by carrying out the example
following the box.
2715 User Manual
xiii
Preface
xiv
2715 User Manual
Introduction
Introduction
This section introduces you to the basic concepts of an RF spectrum analyzer and
its uses. This section also briefly describes the features of the 2715 Cable TV
Spectrum Analyzer.
What is a Spectrum Analyzer?
There are several types of spectrum analyzers, but we will describe only the
heterodyne, or scanning, spectrum analyzer. A scanning RF spectrum analyzer is
essentially a radio receiver.
Tune a conventional FM broadcast receiver from one end of the band to the
other. As you tune, plot the reading of the signal level meter versus frequency.
The graph you produce is a frequency domain representation, or spectrum, of the
FM broadcast band. The graph tells you at which frequencies the signals occur
and how strong they are. If stations are too close together, you will not be able to
get an independent meter reading for each individual station, and you will hear
them simultaneously. This is because the intermediate frequency (IF) filter of the
receiver has a bandwidth that is too wide to separate (resolve) the stations.
What you have just done is tune or scan the FM broadcast band with a resolution
bandwidth equal to the bandwidth of the IF filter in your receiver. If you plot
your measurements on graph paper with one centimeter divisions, making each
division equal 1 MHz, the span/division of the resulting plot is 1 MHz/division.
2715 User Manual
If you stop tuning, the receiver no longer spans a range of frequencies, but is
fixed at the currently selected frequency; it is in zero span mode. The output of
the receiver depends on the signal coming through the IF filter at the selected
frequency. If you plot the amplitude of the signal as a function of time (or view it
on an oscilloscope-type display) you create a time-domain representation (signal
amplitude versus time).
A spectrum analyzer performs similarly to the receiver except that the scanning
is usually performed automatically (and faster than you do it manually) and there
is a selection of IF bandwidths or resolution bandwidths to choose from.
Multiple resolution bandwidths are needed because in some cases you may want
to separate closely-spaced, narrow-band signals, while in others you may want to
examine signals with larger bandwidths. There is a maximum speed at which a
band can be accurately scanned with a resolution bandwidth of a given width
(generally, the smaller the resolution bandwidth, the slower the speed). The
spectrum analyzer can automatically select the fastest speed for you.
You can find additional information about basic spectrum analyzer concepts and
definitions in Tektronix application note 26W-7037-1, Spectrum Analyzer
Fundamentals.
1–1
Introduction
What Can You Do With a Spectrum Analyzer?
Spectrum analyzers measure how the power in an input signal is distributed in
frequency. You can use spectrum analyzers to determine signal amplitudes and
frequencies, noise power, carrier-to-noise ratios, signal or filter bandwidths,
distortion (harmonic and intermodulation), FM deviation, and percent modulation. Also, you can use spectrum analyzers to detect spurious signals, align
transmitters and receivers, and check specifications.
About the 2715
The Tektronix 2715 Cable TV Spectrum Analyzer is a portable, cable TV, radio
frequency (RF), scanning spectrum analyzer for use in the field or in the shop. It
weighs less than 22 lbs (9.5 kg) and can be equipped with a battery and inverter
for use in locations without AC power.
The user interface is simple enough for the beginner but versatile enough to
satisfy an expert. Fundamental cable TV (CATV) measurement parameters, such
as center frequency, span/division, and reference level, are automatically set
when you select a channel table and channel. In nonCATV mode, measurement
parameters can be controlled directly with dedicated keys. You can display a
spectrum by using only three controls. Call-up menus enable you to automate
operations, such as bandwidth or carrier-to-noise ratio measurements, and to
directly enter front-panel control settings. Measurement parameters and results
are displayed on-screen.
To increase measurement flexibility, the 2715 Cable TV Spectrum Analyzer has
the following standard features:
H Automated CATV measurements, including in-service measurements of
carrier-to-noise (C/N), composite second order (CSO), and in-channel
response (ICR)
H Frequency-corrected YIG oscillator for high frequency accuracy; you can
change the default oscillator settling delay time to optimize settling time for
your particular use; the 2715 stores the new value
H True analog display (in addition to digital storage) with 1 ms/div sweep speed
that lets you see beats down in the noise
H Low input signal sensitivity with the built-in preamplifier activated
H Signals as large as 70 dBmV (+20 dBm) can be accommodated
H Automatic selection of both sweep speed and resolution bandwidth
H Digital and time-domain functions
H AM/FM detection
H User-definable modes
H 300 Hz to 5 MHz resolution bandwidths
1–2
2715 User Manual
Introduction
Post-detection digital sampling and storage is used with a unique max/min
display mode that provides a close approximation of analog displays. Peak
detection is also provided. It is possible to display up to four traces simultaneously and to perform ensemble statistics. A continuously updated “waterfall”
display mode can be used to compare the four most recent spectral sweeps.
124 Kbytes of nonvolatile random access memory (NVRAM) is provided to
enable saving front-panel configurations and spectral sweeps for later review or
operation. The exact storage capability depends on what else you are storing in
the instrument (such as user-defined keystroke sequences).
You may improve the center frequency setting time in some applications by
changing the YIG oscillator settling delay time from the factory default value.
The new setting value is saved automatically. See Changing the YIG Settle Delay
on page 6–78 for more information.
NOTE. The stability and frequency accuracy specifications of the spectrum
analyzer are guaranteed only for the factory default YIG settling delay time.
In-service measurement capability includes measurement of C/N, CSO, and ICR
(on NTSC and PAL signals only). Gating hardware in the 2715 Spectrum
Analyzer allows these measurements to be made on normal modulated TV
signals without disruption to the TV program in progress.
Since gated-measurement techniques have advantages and disadvantages, the
2715 Spectrum Analyzer is designed so that you always have a choice of
whether or not you use gated (in-service) measurement techniques. If you follow
the In-Service menu selections for C/N, CSO, or ICR, you will be making a
gated measurement; otherwise you will be making a measurement in the
conventional way without gating. For more information about in-service
measurements refer to In-Service Measurement Capability on page 5–18.
The instrument is very durable, but rough handling, or liquids, dust, or other
contaminants inside the case can cause damage. The optional Travel Line
package provides additional protection during transportation.
Optional capabilities result in even greater performance. Refer to Appendix F:
Accessories and Options, for information on options currently available for the
2715 Cable TV Spectrum Analyzer.
2715 User Manual
1–3
Introduction
1–4
2715 User Manual
Getting Started
Getting Started
This section describes the procedure you should follow when your new 2715
arrives from the factory. Observe the indicated precautions to prevent damage to
the instrument during initial checkout and subsequent use.
Receiving and Unpacking
The spectrum analyzer and its standard accessories are carefully packed at the
factory using a specially designed shipping container to prevent damage during
transit.
If, upon receipt, damage to the shipping container is evident, notify the shipper.
Tektronix, Inc. is not responsible for damage caused during shipping.
If you have not already done so, carefully remove the spectrum analyzer and its
accessories from the shipping container and inspect them for damage. Do not
destroy the shipping container. Test spectrum analyzer operation using the
System Checkout procedure on page 2–4. If damage or defects are discovered,
or if components are missing, notify your local Tektronix field office or
representative.
Packaging and Storing
In the event that the equipment must be returned to a Tektronix Service Center,
carefully package it in the original shipping container. Use the vinyl vapor
barrier, and insert the original foam blocks in the same fashion they were
received. If the original shipping materials are not available, use a container of
equivalent strength and dimensions. Wrap the instrument in a vinyl vapor barrier,
and cushion the instrument on all sides with foam or other suitable packing
material.
Attach a tag to the instrument clearly showing:
H Owner’s name and address
H Name of the person at your location who may be contacted
H Instrument model and serial number
H Description of the problem and service expected
2715 User Manual
2–1
Getting Started
Installation
The 2715 can be stored up to 90 days in an environment that meets the nonoperating specifications. It is suggested that you provide a dust cover. For longer
periods, the 2715 should be enclosed in a vapor barrier containing appropriate
desiccant material and stored in an environment that meets the nonoperating
specifications. The original shipping material can be used and is also useful for
protecting the equipment if it must be moved.
The 2715 is designed for table-top operation in any orientation and requires no
special installation. However, the handle can be positioned at several angles to
serve as a convenient tilt stand. To position the handle, pull out at both pivot
points on the sides of the instrument, and simultaneously rotate the handle to the
desired position.
Tektronix, Inc. provides an optional rackmount adapter kit (Option 30) that
requires 5.25 in (133.4 mm) vertical clearance and a cradle mount adapter
(Option 34) that requires 7 in (177.9 mm). Contact your local Tektronix field
office or representative for additional information.
Precautions
The 2715 is equipped with a plastic front panel cover to protect it from mechanical damage. The cover should always be used when transporting the 2715. To
remove the cover, place the 2715 on its back feet, then simultaneously pull out
and up slightly on each side of the cover.
Regardless of where the spectrum analyzer is used or installed, always provide at
least 50.80 mm (2 in.) clearance adjacent to the cooling vents at the sides,
bottom, and back of the spectrum analyzer.
See Appendix A: Specifications for input power requirements.
NOTE. See the Getting Started section of your 2715 Cable TV System Software
Manual for setup instructions needed to connect the 2715 to a personal
computer.
The spectrum analyzer is tough but not indestructible. It can be damaged unless
the following cautions are observed:
H Do not apply too large a signal to the input
2–2
Never apply signals to the RF INPUT connector if their combined amplitude
is greater than +70 dBmV (+20 dBm), or if there is a DC component greater
than 100 V. If you exceed these input ratings, you can permanently damage
the spectrum analyzer.
2715 User Manual
Getting Started
If necessary, use an external attenuator first. Further, to prevent damage by
transients, use maximum RF attenuation when connecting a signal with a DC
component. Then remove attenuation as needed to make the measurement.
Also, be aware that the 2715 is optimized for a –30 dBm input to the first
mixer. A larger input signal may lead to nonlinear operation and inaccurate
results.
DO NOT connect a CATV trunk carrying AC power directly to the RF
INPUT. The 1
st
mixer can be overloaded making accurate measurements
impossible. Also, a power surge might raise the peak AC voltage above the
maximum safe input level.
CAUTION. The maximum safe RF and DC input levels are clearly printed near
the signal input jack (RF INPUT).
H Do not apply incorrect AC input power
The 2715 will accept mains power up to 250 VAC
(refer to Appendix A:
RMS
Specifications for additional information). It is unlikely that you will apply
incorrect power while using standard plugs and receptacles in the normal
working environment. However, in the field or during abnormal conditions,
you might have to connect temporary power. Be certain that any power
source connected to the 2715 applies less than 250 VAC
RMS
between
conductors or between either conductor and ground. To avoid damage to the
source, ensure that it is rated for at least 120 W operation.
H Do not allow moisture, dust, or other contaminants inside the case
Electronic circuits do not mix well with water, chemicals, dust, or grit. The
case is not water tight or air tight, so avoid exposing your instrument to these
or other contaminants. Do not place liquid containers on or near the
spectrum analyzer where they can be spilled into it. Use the Travel Line rain
cover (Option 33), or other suitable covering, when transporting the
spectrum analyzer outside in inclement weather.
2715 User Manual
H Do not handle the spectrum analyzer with undue roughness
Do not physically abuse the spectrum analyzer. It can withstand a fair amount
of rough handling but dropping it off a workbench or bouncing it around the trunk
of a car or the back of a truck may cause damage. Protect the instrument while
transporting it, and use it where it cannot be accidentally hit, kicked, or dropped.
H Provide proper ventilation
2–3
Getting Started
System Checkout
CAUTION. To prevent damage from over heating, you must ensure that the
clearance provided by the feet is maintained on the bottom and that there are at
least 2 in (50.80 mm) of clearance around the other sides. DO NOT block the air
intake areas on the sides, bottom, or the exhaust area at the rear. Never operate
the instrument inside a carrying case.
After you have observed the foregoing precautions, you are ready to perform the
initial system checkout. Checkout consists of “normalizing” the spectrum
analyzer and then measuring the frequency and amplitude of the built-in
calibration source. In the process, you will become acquainted with the front
panel and the display.
Turning On the Spectrum
Analyzer
Before applying power, make sure there is no signal source connected to the
spectrum analyzer.
1. Plug in the power cord.
2. Press the POWER switch.
The green LED adjacent to the power switch lights indicating that power is
turned on. The LED indicators flash and you hear a few beeps as the 2715
performs its power-up self test.
When power is applied to the 2715, it initializes its front-panel controls to
settings stored in memory. If the instrument has been used before, those settings
may be user-defined (see User-Defined Power-Up Settings on page 6–62). If no
user-defined settings exist, the 2715 defaults to the factory power-up settings that
are permanently stored in initialized RAM (random access memory). The only
exception is that the default channel table and channel are replaced by the last
selected channel table and channel before power-down.
A display appears on screen almost immediately. You may see the following
message:
WARMUP TIME 15 MIN
When the factory-default power-up settings are being used, it is possible to make
general observations immediately after the power is turned on. If user-defined
power-up settings are implemented, the message WAITING FOR USER
DEFINED POWERUP appears briefly. The 2715 front panel is locked out while
the message is displayed. After the message disappears, the factory-default
settings are replaced by the user-defined settings, and you can proceed with your
observations.
2–4
2715 User Manual
Getting Started
Whichever settings are used, the WARMUP message is displayed. It disappears
after a few seconds. Remember, however, that the spectrum analyzer may require
a full 15 minutes to be operating within specification. Consequently, measurement errors and system messages can occur within the warm-up period,
particularly if you switch the spectrum analyzer to a narrow span or resolution
bandwidth (BW) filter.
You may also see the following phrase during warmup:
NORMALIZATION SUGGESTED
Initial Normalization
Normalization is a process by which the 2715 measures and stores its own
calibration parameters using a built-in reference. When this message appears, the
instrument is reporting that its self-test feature has determined that its performance no longer matches that predicted by the previous normalization. It is not
unusual for the message to appear during the warm-up period, especially if a
narrow resolution bandwidth filter is called for by user-defined power-up
settings, or if the ambient temperature is different than that at which the previous
normalization was performed. If the message remains (or reappears) after the
warm-up period, a new normalization should be carried out. Normalization
ensures the utmost accuracy when making measurements. We suggest that,
whenever maximum accuracy is required, you allow your instrument to reach a
stable operating temperature in the environment in which the measurements will
be carried out and then perform a normalization before making the measurements.
Perform a normalization to ensure the calibration of the 2715 and to verify its
operational status. Additional information about normalization may be found in
Normalizing the 2715 on page 6–65.
1. To do an initial normalization of the 2715, ensure that no external signals are
connected to the 2715.
2. Press [UTIL] and [3].
2715 User Manual
This calls up a menu that offers you a choice of normalization processes.
3. Select ALL PARAMETERS by pressing [0].
Normalization should begin immediately and continue without interruption
until it is completed.
Normalizing all parameters requires several minutes. During the process, you
will see various displays and messages which keep you informed of progress, but
do not require action. The process ends with an audible beep and the message
NORMALIZATION COMPLETE, indicating satisfactory operation. If you
receive any other message terminating this initial normalization, repeat the
procedure. If the message persists, contact your Tektronix Service Center.
2–5
Getting Started
Restoring the Factory
Default Settings
The Initial Display
To ensure a common starting point for the calibration signal measurement, you
must restore the factory-default power-up settings.
4. Press [UTIL] [1] [1].
This restores the factory-default settings whenever the 2715 is in normal
spectral display mode (and most other modes). It is a handy method of
returning to a fixed set of conditions if you get lost.
Figure 2–1 shows what the spectrum analyzer screen looks like after initializing
the instrument settings.
Center Frequency
Reference
Level
68.8 dBmV
180 MHz
183 MHz
186 MHz
10 dB
Noise
Floor
600 kHz
Figure 2–1: Display with Factory Default Power-Up Settings
The displayed spectrum represents the noise floor of the spectrum analyzer. The
noise floor is the amplitude of the noise generated internally by the spectrum
analyzer itself and passed through the resolution bandwidth filter. Narrowing the
resolution bandwidth lowers the noise floor, because noise power is directly
proportional to the resolution bandwidth.
The noise appears as a thick, irregular band across the bottom portion of the
screen. To achieve this appearance, digital display storage is used. The unique
max/min display shown here is designed to resemble the analog spectra that the
spectrum analyzer inherently produces.
2–6
2715 User Manual
Getting Started
5. Press [D] to see the analog display.
This turns off the D storage register (the only one currently enabled). When
all registers are turned off, the analog display appears.
6. Repeatedly press [D] to toggle the D register on and off several times. Notice
the similarity between displays.
7. Turn the D register on.
To obtain the max/min display, the maximum and minimum amplitudes of the
analog spectrum are each sampled at 256 points. Plotting the two interleaved sets
of 256 points produces the 512 point graph of the spectrum that you see. This
display not only imitates the analog spectrum, but can also assist in detecting
low-level signals by more effectively showing the characteristic void they
produce under the noise floor.
The spectral display is overlaid by a 32-character wide by 16-character high text
screen. Not all of the text fields are displayed all the time, and you can turn the
text screen on and off by pressing [READOUT].
The top portion of the text screen contains two data readout columns that are
present whenever the text screen is turned on. The readouts show spectrum
analyzer settings or measurement results. Figure 2–2 shows the data normally
displayed in the readout columns.
Center frequency Marker frequency
Reference level Marker amplitude
Horizontal scale factor Vertical scale factor
Resolution bandwidth Channel table and number
(Various messages may appear as needed below the
data readout columns)
Figure 2–2: Normal On-Screen Data Readouts
With the spectrum analyzer in the MAX SPAN mode (indicated by MAX
following the horizontal scale factor), the resulting spectrum spans the entire
input frequency range. In this mode, the first item in the left column lists the
frequency at the location of the frequency marker (the intensified spot on
the display).
2715 User Manual
2–7
Getting Started
The types of information in the right column may change depending on
operating mode. You will learn when to expect alternate information as we
discuss the various modes. Below the readout columns, messages and indicators
appear as warranted, and numeric instrument settings can be entered.
Control Panel Basics
The control panel has several characteristics included to make it easy and
convenient to operate:
H Controls with related functions are generally grouped together — the
groupings (Function Blocks) are defined by the borders or background color
surrounding the controls
H Dedicated controls permit quick selection of important measurement
functions — the controls are defined by background color
H Arrow keys directly increase and decrease critical control settings
H Menu keys located in the MENUS function block call up lists of operator-
selectable features
H A numeric keypad permits selection of menu options and entering of critical
measurement parameters
H Terminator buttons in the keypad block designate the units for numeric
entries with a single keystroke
H An immediate entry mode that enables you to enter arbitrary values for the
channel/frequency, span, and reference level directly from the keypad
H Red LED function status indicators adjacent to certain buttons indicate when
the functions are active
2–8
H Green LED register status indicators illuminate when any storage register
contains a saved waveform
The controls most fundamental to spectrum measurements ([CHAN/FREQ],
[SPAN/DIV], and [REF LEVEL]) are located in a single central function block
with a dark gray background. These controls can be conveniently set using either
the arrow keys or immediate entry mode.
The arrow keys enable you to instantly change control settings. [ b ] and [ y ]
move according to the channel table selection. The arrow keys are active
whenever the spectrum analyzer is in the spectral display mode.
2715 User Manual
Getting Started
In immediate entry mode, you press the key corresponding to the parameter you
wish to set ([CHAN/FREQ], [SPAN/DIV], or [REF LEVEL]), type the
parameter value on the keypad, and press the appropriate terminator key to
complete the entry. The value appears on screen as you type.
Each of the terminators ([W], [X], [Y], and [Z]) can represent more than one unit
as indicated by the legend to the right of each key; however, the keys are context
sensitive. If an entry represents a frequency, the indicated frequency unit is
selected automatically when you press the key. If dBs are required, the indicated
dB unit is selected, and so on for all of the units.
Many keys are toggle-action. The ability to undo an action, including menu
selection, by pushing the same button or sequence of buttons that carried out the
action is typical of operations performed on the 2715.
8. Press [VID FLTR] to observe the toggle action.
The red video filter LED illuminates, and the trace shrinks vertically as the
filter turns on and averages the noise.
Sounds
9. Press [VID FLTR] again.
The noise spectrum expands to its original size as the filter is turned off, and
the LED goes out.
The 2715 can emit tones under the following conditions:
H During power-on self test
H When an abnormal condition occurs
H When a message appears
H When a key is pressed
The instrument emitted self-test beeps when it was powered up. The beep can be
set to sound when an error occurs, when a key is pressed, when either happens,
or it can be set to never sound.
If the error alert is turned on and an abnormal condition exists, such as a request
to extend a measurement parameter beyond its range, the 2715 emits a high-level
beep. A message is simultaneously displayed on-screen describing the abnormal
condition.
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Getting Started
The 2715 is equipped with AM and FM demodulator circuits that extract the
audio signals on amplitude or frequency modulated RF signals. The demodulated
audio is reproduced on the built-in speaker. This feature can be used to identify
most voice channels based on their content or call signs and can help to identify
others by enabling you to determine the type of modulation (frequency shift
keying, pulsed CW). For better quality audio or private listening, use the
headphone jack on the right side of the 2715. The AM/FM demodulators are
discussed in detail in DEMOD on page 6–56.
The Built-In Calibrator
The 2715 is equipped with a built-in calibration source. The calibrator for the
2715 has no external “Cal Signal” output. Instead, the calibrator resides in the
2715 and can be “connected” to the input path without the need for external
cabling by selecting the proper Input Menu option.
10. Press the MAX SPAN key (located below the REF LEVEL key).
11. Press the AUTO RES BW key.
12. Press [INPUT] to call up the Input Menu.
Item 9 specifies a CAL SIG @ 100MHz 18.8DBMV. The calibrator is a CW
signal with a fundamental frequency of 100 MHz at an amplitude of 18.8 dBmV
(–30 dBm). Higher order harmonics at lower levels are also present. Item 9
toggles the calibrator on and off.
13. Press [9] to turn the calibrator on.
The screen reverts immediately to the spectral display. The word CALIBRATOR now appears near the bottom right of the screen signifying that the
calibrator is enabled. You should see a few signal peaks towards the left of
the display. These are the fundamental and harmonics of the calibrator
signal. If you do not see them, it is because the amplitudes of the harmonics
may be lower than the noise floor of the 2715.
NOTE. When the calibrator is enabled, the normal RF input is disconnected
internally from the input attenuator and cannot be viewed.
14. Press [INPUT] [9] to disable the calibrator.
Making Your First Measurement
The following two types of measurements can be made with the 2715:
H CATV measurements
H NonCATV measurements
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2715 User Manual
Getting Started
Selecting a Channel Table
The factory defaults set the 2715 in the normal (CATV) mode.
The resolution bandwidth (RES BW) is set to 300 kHz, allowing you to see most
of the detail in the channel band.
1. Connect a cable TV feed to the RF INPUT.
2. Press [CATV/APPL] [8] [1] to call up a menu of channel tables.
Initially, there are three factory-installed tables in this menu. You may
choose to add other tables to this menu using the PC-based software that
comes with the 2715.
3. Press [0] to select the standard (STD) table.
The reference level is then set so the peak of the visual carrier is approximately one division down from the top graticule line, and the center
frequency and span are set so the channel band is centered on the screen
horizontally.
4. Press any menu button to return to the spectral display.
The abbreviation CHAN appears at left center of the screen. The CHAN
indicator tells you that you can enter the channel number directly from the
keypad. This is done by keying in a permissible number followed by the [W]
terminator key (labeled CHAN).
Select an active channel (channel 8 for this exercise).
5. Press keypad numbers corresponding to the desired channel.
The numbers you press appear on screen to the right of CHAN. If you make
a mistake, you can correct it by repeatedly pressing the backspace key until
the incorrect number disappears and then entering the correct number.
6. Press [W] after the channel number has been entered.
This key can represent units of CHAN, GHz, SEC, or V. Because you
selected an entry mode that requires a channel, the 2715 correctly interprets
the currently displayed entry as STD CH 8.
Direct frequency entry capability is available from the front panel. However, the
1 GHz terminator is not available in the normal mode, because it is reserved for
channel selection.
You are now ready to perform a CATV measurement.
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Getting Started
Typical CATV
Measurement
This example is one of several CATV measurements and allows you to measure
the visual and aural carrier levels over the selected channel. Note that the
following are the only actions needed to make a measurement:
H Select a channel table
H Select a measurement channel
H Select a measurement
H Run the measurement
The channel table and measurement channel selected at power down will be
remembered when power is reapplied to the 2715. Therefore, the only thing that
needs to be selected after that is the type of measurement.
Items 1 through 4 on the second page of the CATV MEASUREMENTS menu
are toggle-type functions. For example, if you select VIEW MODULATION
(LINE) with [CATV/APPL] [9] [2], you get a preselected VITS line. You must
make the same selection or select another measurement to disable the line
display.
7. Press [CATV/APPL] [1] to call up the CARRIER LEVELS menu.
8. Press [0] to select/run the Carrier Levels.
The 2715 starts the measurement routine (much like performing a center
measure on the visual and aural carriers). When the measurement is finished,
the 2715 returns to the spectral display. Two lines near center screen display
the measurement results. One line displays the visual carrier amplitude and
frequency in absolute values, and the second line displays aural carrier
amplitude and frequency as offsets from the visual carrier values.
9. Press [CATV/APPL] to recall the CARRIER LEVELS measurement menu.
10. Press [1] to store the measurement results.
11. Press [2] to display the measurement results. See Figure 2–3 for a typical
display.
12. Press [W] to display the last stored results (if they exist).
13. Press [3] to print the measurement results. (The spectrum analyzer must be
connected to a printer that is capable of printing text.)
14. Press [4] to print the stored measurement results.
15. Press [9] to deselect the CARRIER LEVELS measurement.
16. Disconnect the cable TV feed from the RF INPUT.
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2715 User Manual
CARRIER LEVEL: CURRENT
CHAN 8 24–OCT–91 19:33:08
TEKTRONIX
JOHN SMITH
VISUAL 8.7DBMV @ 181.240072MHZ
AURAL −16.4DBC @ +4.499988MHZ
PRESS ”W” TO CONT, ”Z” TO ABORT
Figure 2–3: Typical Measurement Result Display
Getting Started
Making Your First
NonCATV Measurement
This procedure shows you how to verify the frequency and amplitude of the
calibration signal. Although the calibration signal is used, the measurement
technique is the same for any continuous signal. In the process, you will learn to
use three of the most important controls on the spectrum analyzer and to confirm
that the major functions of the spectrum analyzer are operating correctly.
1. Press [UTIL] [1] [1] to recall FACTORY DEFAULT POWER-UP settings.
The factory defaults set the RF attenuation to 50 dB. This affords the most
protection to the spectrum analyzer, because any signal at the input
undergoes maximum attenuation before reaching the power-sensitive mixer
circuit. We recommend that you use this setting when connecting unknown
signals to the spectrum analyzer.
2. Press [CATV/APPL] [8] [0] to disable the CATV mode.
3. Press [MAX] then [AUTO] (in the RES BW block) to enable maximum
span and AUTO RES BW.
The span goes to 180 MHz per division, and the resolution bandwidth goes
to 5 MHz. This is maximum span and is indicated by the word MAX in the
span readout. This is the safe setting for introducing new signals. It enables
you to view the entire measurement range (1.8 GHz) of the spectrum
analyzer. If a smaller span is used, large signals can be present off-screen.
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Getting Started
CAUTION. The total signal power (that is, all signals on-screen or off added
together), not just the signal of interest, must remain below +70 dBmV. With a
small span, it is also possible to reduce the attenuation to view a low level,
on-screen signal while inadvertently allowing an off-screen, high-level signal to
saturate the mixer, causing spurious responses and possibly even damaging the
mixer.
4. Press [INPUT] [9] to turn on the built-in calibrator.
NOTE. The amplitude of the internal calibrator is 18.8 dBmV. This places the
peak level at the top graticule line with the reference level set at 18.8 dBmV and
0 dB internal attenuation.
To measure the calibration signal, you are going to use the three primary controls
on the spectrum analyzer. These are located in the central dark gray function
block and are shown in Figure 2–4. The three primary controls and the FREQ/
MKRS knob to the left are the controls you will use most often. In general, you
can make most measurements with only these controls, although you will find
that other controls and menu features enable you to make many measurements
more quickly and conveniently.
Selects
frequency for
immediate
keypad entry
Selects span/div for
immediate keypad entry
Selects reference
level for immediate
keypad entry
Change frequency in
designated step size
Decrease Increase
Decrease
Increase
Increase
Decrease
Change span/div in
1–2–5 sequence
Change reference
level in 1 dB or
10 dB steps
Figure 2–4: The Primary Controls
First, raise the displayed signal height by reducing the reference level. The
reference level represents the signal power needed to deflect the displayed
spectrum to the top graticule line. The 2715 provides several methods of directly
changing the reference level. The most convenient method is to press the
arrow keys.
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2715 User Manual
Getting Started
5. Press [ b ] to the right of [REF LEVEL] three times to reduce the reference
level 30 dB.
For numeric entry, the W key terminates any channel number; whereas, the X, Y,
or Z keys terminate channel/frequency entry. On channel/frequency, the 2715
selects the channel closest to the new channel/frequency.
Figure 2–5 shows what the resulting display should look like, although some of
the signal peaks on your spectrum analyzer may have slightly different amplitudes than those shown. Notice that both the reference level and RF attenuation
readouts have decreased 30 dB (the reference level is 38.8 dBmV and the RF
attenuation is 20 dB).
Normally the arrow keys change the reference level 10 dB per press, but in FINE
mode the value changes 1 dB per press. Another method is to set the reference
level to 20.8 dBmV, less than half a division above the expected signal amplitude. We choose this value for the following reasons:
H Signal amplitudes are read out and displayed most accurately when they are
near the reference level.
H 2 dB provides a small amount of “headroom” in case the signal should be
slightly larger than anticipated.
Fundamental
2nd 4th 10th
900.0MHZ
38.8DBMV
180MHZ/MAX
5MHZ RBW
FREQ
Harmonics
3rd
ATTN 20DB
VF WIDE
10 DB/
18.8 dBmV
CALIBRATOR
2715 User Manual
Figure 2–5: Calibrator Signal and Harmonics
2–15
Getting Started
To specify a predetermined value, press [REF LEVEL] to place the reference
level in the immediate entry mode. The abbreviation REFL will appear at left
center of the screen.
The REFL indicator tells you that you can enter the reference level directly from
the keypad by typing a value followed by an appropriate terminator key.
NOTE. In the spectral display mode, the abbreviation for the control last placed
in the immediate entry mode remains on screen until another control is chosen.
When a control is in the immediate entry mode, repeated settings for that control
can be entered without having to press [CHAN/FREQ], [SPAN/DIV], or [REF
LEVEL] again. Only primary controls can be placed in immediate entry mode.
6. Press [2] [0] [] [8] to set the reference level to 20.8 dBmV.
The numbers you type appear on screen to the right of REFL. If you make a
mistake, you can correct it by repeatedly pressing [BKSP] (the backspace
key) until the incorrect number disappears and then entering the correct
value.
7. Press [Y] after the correct number has been entered.
The Y key can represent units of kHz or +dB. Because you selected an entry
mode (immediate reference level entry) that requires decibels, and because the
factory-default unit is dBmV, the spectrum analyzer correctly interprets the
currently displayed entry as 20.8 dBmV. If the currently selected reference level
units had been dBm or dBW, the 2715 would have interpreted your entry
correctly when you pressed the terminator key.
The RF attenuation is reduced to 2 dB and the reference level readout indicates
the desired 20.8 dBmV. For the parameters established for this example, this
entry method enabled you to specify a reference level that could not be achieved
with the arrow keys unless you switched to the FINE mode. You can also enter
fractional reference levels to the nearest 0.1 dB with this method.
The spectrum analyzer is still in the MAX SPAN mode, which means that the
harmonics of the calibrator signal are barely more than one half division apart.
Spread them out by reducing the span/div. As in the case of the reference level,
the spectrum analyzer provides two direct entry methods.
8. Press [ b ] to the right of [SPAN/DIV] twice to reduce the span to 50 MHz/
division.
Notice that the readout now indicates 50 MHz/, and the harmonics are two
divisions apart.
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Getting Started
Suppose that you want to view just a single harmonic and the 30 MHz band to
either side of it. You can do this by setting the span to 6 MHz/division. This is
not a value obtainable with the arrow keys, but you can to get it in the immediate
entry mode.
9. To set the span/division to a predetermined value, first press [SPAN/DIV] to
place span in the immediate entry mode.
Notice that the abbreviation SPAN appears at the left center of the screen.
The SPAN indicator tells you that you can enter the span/div directly from the
keypad. This is done by keying in a permissible value followed by an appropriate
terminator key.
10. Press [6] to set the span/div to 6 MHz.
Any number you type appears on screen to the right of SPAN. If you make a
mistake, you can correct it by repeatedly pressing [BKSP] (the backspace
key) until the incorrect number disappears and then entering the correct
value.
11. Press [X] after the correct number has been entered.
This key can represent units of MHz, ms, or mV. Because you selected an
entry mode that requires a frequency, the 2715 correctly interprets the
currently displayed entry as 6 MHz. If a time or voltage unit had been
required, the 2715 would have interpreted your entry as 6 ms or 6 mV,
respectively.
The span now is set to 6 MHz, and the ninth harmonic of the calibrator signal is
centered on screen at 900 MHz. You may have noticed that the resolution
bandwidth changed to 1 MHz. This demonstrates the AUTO resolution
bandwidth selection mode of the 2715. The spectrum analyzer reduces its
resolution bandwidth as you reduce the span/div, so the resolving power of the
instrument automatically increases as you look at the spectrum more closely.
To look at the calibrator signal fundamental, you must change the center
frequency. The spectrum analyzer provides three direct methods of doing so,
each appropriate under different circumstances.
12. Press [ b ] to the right of [CHAN/FREQ] twice.
Notice that the center frequency readout now indicates approximately
894.0 MHz. The frequency arrow keys change the center or start frequency
by the same as the span/div, but you can change the tuning rate. See
Selecting the Tuning Increment on page 6–21. You could continue pressing
[ b ] until the correct frequency is reached, but this would require a large
number of presses.
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Getting Started
This method of changing frequency is very useful for scanning relatively small
bands. To change by larger amounts, use the immediate entry mode to set the
center or start frequency to a predetermined value.
13. Press [CHAN/FREQ] to place the center or start frequency in the immediate
entry mode.
Notice that the abbreviation FREQ appears at left center of the screen.
The FREQ indicator tells you that you can enter the center frequency directly
from the keypad by keying in a permissible value followed by an appropriate
terminator key.
14. Press [1] [0] [1] to set the center frequency to 101 MHz.
The numbers you press appear on screen to the right of FREQ. If you make a
mistake, you can correct it by repeatedly pressing the backspace key until the
incorrect number disappears and then entering the correct value.
15. Press [X] after the correct number has been entered.
This key can represent units of MHz, ms, or mV. Had you wanted to set the
frequency to 101 kHz, you would have pressed [Y].
This method of changing center or start frequency is most useful when large
changes are required or if you know ahead of time exactly what frequency is
required.
The span is now set to 6 MHz and the fundamental of the calibrator signal is not
quite centered on screen. Center the calibrator signal with the FREQ/MKRS
knob.
16. Turn the FREQ/MKRS knob several clicks counterclockwise to reduce the
center or start frequency.
Each click reduces the frequency by the currently selected tuning increment
(0.02 times the span/div, or 0.12 MHz in this case). The control functions as
the “fine” frequency adjustment. Rotating the knob clockwise increases the
frequency at the same rate.
17. Continue turning the knob in either direction until the signal is centered.
Your screen should now resemble Figure 2–6.
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2715 User Manual
Signal Frequency = Center Frequency
(100 MHz)
Getting Started
Signal Amplitude
18.8 dBmV
Figure 2–6: Calibrator Signal Fundamental
The signal frequency is 100 MHz and the signal peak is 0.2 division below the
reference level so its amplitude is 18.8 dBmV as shown in the following
equation:
20.8 dBmV ref level – 0.2 div × 10 dB/div = 18.8 dBmV
Using only the frequency, span, and reference level controls you have verified
the basic operation of the 2715, and determined the frequency and amplitude of
its calibrator signal.
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Getting Started
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Operating Basics
Operating Basics
Display Screen
This section provides an overview of the spectrum analyzer display, menus,
controls, and connectors. The experienced spectrum analyzer user will find it a
handy guide.
The spectrum analyzer display consists of an 8 division high by 10 division wide
graphical sweep screen with a 16 row by 32 character text screen overlay. In the
spectral display mode, both the graphic and text data are normally present,
although the text screen can be toggled on and off by pressing [READOUT]. In
the menu display mode, only the text screen is normally present, but the sweep
display can be turned on (see The Spectral Display in Menus on page 6–74).
The entire screen area is available for the sweep display, but contents of the text
screen are placed in predetermined locations. Figure 3–1 shows the text screen
layout used in the spectral display mode. When the optional Display Title line is
not used, rows 2 through 11 and rows 13, 14, and 15 move up one.
LINE # SCREEN CONTENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Display Title (optional)
Center Freq/Start Freq RF Atten/Mkr Freq/Counter Freq
Reference Level Vid Fltr BW/Marker amplitude*
Horizontal Scale ”TRKG” Indicator Vert Scale*
Resolution BW Blank/TV Channel/V ideo Line
”UNCAL” Indicator Single Sweep Messages
Error Message
User Defined Program Title
Displayed Message
UDP Status
Keypad entry/WFM to Save
Real-time Clock Display
”CALIBRAT OR” Indicator
”WARMUP TIME 15 MIN” Message/GPIB & RS-232 Status
* May also contain C/N, NOISE NORM’D, BW, & OBW results.
Figure 3–1: Layout of the Text Screen in the Spectral Display Mode
2715 User Manual
3–1
Operating Basics
Figure 3–2 shows the text screen for the menu display mode. The menu footer
area contains prompts, general information, and additional data entries shown
below:
H Which key to press to return to the spectral display
H Which key to press to back up one menu level
H Which menu key was pressed to enter this menu
H What data to enter
H Data that has already been entered
H Which terminator key to press
LINE # SCREEN CONTENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Menu Title
Up To 10
Items (0–9) Displayed
Here
:
:
:
:
:
:
:
Error Message
Data Entry
Footer area containing prompts
general information, and data entries.
Figure 3–2: Layout of the Text Screen in the Menu Display Mode
Connectors, Controls, and Menus
Most of the spectrum analyzer front-panel controls are located in function blocks
that are denoted by their borders or background colors. Each block contains
related controls. The central gray-colored block contains the fundamental
channel, center (or start) frequency, span, and reference level controls. For
convenience, one function block is dedicated exclusively to menu display. The
control panel and its major functional areas are shown in Figures 3–3 through
3–8. The Dedicated Controls section contains detailed discussions of
the controls.
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2715 User Manual
Operating Basics
Trace alignment controls and various input/output connectors are located at the
rear panel. Figure 3–9 on page 3–10 shows the spectrum analyzer back panel and
its connectors. The alignment controls are discussed in Miscellaneous Controls
on page 4–33, and the connector terminations are described in Appendix E:
External Input and Output.
The menu structures are shown starting on page 3–11. Some menu items are not
present because they either are not available at the current menu level, are
intended primarily for factory calibration and troubleshooting, or they apply to
instrument options not currently installed.
A brief description of the function of each of the listed menu selections is given.
The functions of the menu selections are discussed in greater detail in the CATV
Measurements and Spectrum Analyzer Menus sections.
FREQ/MKRS
CTR-MEAS/TRKG
Figure 3–3: The Frequency/Marker Function Block
In the normal spectral display mode, the knob changes the center, or start,
frequency by 0.02 of the span/div per click. In programmed or tabular tuning
modes frequency is changed by the designated tuning increment per click. In
ZERO SPAN frequency is changed by a percent of the resolution BW per click
(see Selecting the Tuning Increment on page 6–21). In other modes, the knob
may control marker horizontal position or video line number.
One press initiates a center measure. The frequency of the signal nearest center
screen (or nearest the marker, if active) is measured and made the new center
frequency. Signal frequency and amplitude are displayed at the upper right of the
screen. Two quick presses enter the signal track mode (continuously repeated
center measures, enabling a drifting signal to be tracked); signal frequency
readout is optional in this mode and is enabled by pressing [MKR/FREQ] [9] [1].
A third press returns to normal operation.
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Operating Basics
PEAK FIND
MKR/D/OFF
MKR [ĂaāĂ] [Ă'āĂ] Keys
The marker is moved to the highest on-screen signal peak (turns the marker on if
it is not active) independent of the detection threshold.
The first press turns on a single marker at center screen; its position is controllable with the FREQ/MKRS knob. A second press fixes the position of the first
marker and turns on a second marker (delta marker mode); its position is
controllable with the FREQ/MKRS knob. A third press turns off both markers.
Each key, respectively, jumps the moveable marker from its current position to
the next on-screen signal peak to the left or right. Signals must be above the
detection threshold (see Setting the Signal Threshold on page 6–22).
CHAN/FREQ
SPAN/DIV
Figure 3–4: Fundamental Analyzer Controls
Selects the channel number immediate entry mode when CATV mode is active.
CHAN appears on the screen at left center. Enter the desired channel from the
keypad; terminate with [W]. In nonCATV mode, it selects the center, or start,
frequency for immediate entry mode. FREQ appears on the screen at left center.
Enter the desired frequency from the keypad; terminate with [Hz], [kHz], [MHz],
or [GHz] key.
Range: 0 Hz to 1.8 GHz
Selects the span per division for the immediate entry mode. SPAN appears on the
screen at left center. Enter the desired span/div from the keypad; terminate with
[Hz], [kHz], [MHz], or [GHz] key.
Range: 1 kHz to 180 MHz
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Operating Basics
REF LEVEL
REF LEVEL [yĂ] [bāĂ]
Keys
ZERO and MAX Keys
Selects the reference level for the immediate entry mode. REFL appears on the
screen at left center. Enter the desired reference level from the keypad; terminate
with [+dBx] or [–dBx] key.
Range: +68.8 to –21.2 dBmV (or equivalent in other units)
The arrow buttons increase y or decrease b the FREQUENCY, SPAN/DIV, and
REF LEVEL by a specified amount. They are always active in the spectral
display mode, even if the parameter is not selected for immediate entry.
CHAN Change (CATV mode): changes by one channel in the channel table,
skipping the SKIPPED channels
FREQUENCY change: equivalent of 50 knob clicks or 1 major division
in the AUTO tuning increment mode, and by the
designated tuning increment in other modes
SPAN/DIV change: in a 1–2–5 sequence from 1 kHz to 180ĂMHz
REF LEVEL change: 1 dB or 10 dB per step depending on REF LVL
STEP setting
Shortcuts, respectively, to the zero span and maximum span settings. The keys
are toggles; one press activates the setting, the second returns to the span used
prior to the first press.
REF LVL STEP
ZERO SPAN: no frequency sweep, horizontal axis calibrated
in time/div, and the display is a time domain
representation of the signal at the indicated
center, or start, frequency
MAX SPAN: 180 MHz/div (often used to view full input
range of 0–1.8 GHz)
Toggles the amount by which the REF LEVEL arrow keys change the reference
level between 1 dB and 10 dB per press. The adjacent FINE indicator is
illuminated when 1 dB is selected.
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Operating Basics
Figure 3–5: The Keypad
Numeric Keys (0–9)
Terminator Keys
(W, X, Y, Z)
Dot Key (Ă
DĂ)
BKSP Key
Numeric keys are used to enter numerical values in the immediate entry mode or
in response to menu prompts. They are also used to select the numbered items
from menus.
The terminator keys signify the end of an entry, and supply the appropriate units
for the entry. They are context sensitive; if you press [X], the spectrum analyzer
automatically interprets it as MHz, ms, or mV depending on the parameter being
entered.
The dot key supplies the decimal point in numeric entries, and can be used as a
period in label and title entries.
The backspace key erases the last character pressed in data entry modes and
backs up one menu level when menus are active.
Register Select and Save
Keys (A, B, C, D)
3–6
Figure 3–6: Display Register Control
Pressing [A], [B], [C], or [D] when SAVE ENABLE is not armed turns its
respective register on and off for display. When the register is displaying data
(saved or current), the red LED to the lower right of the key is lighted.
When SAVE ENABLE is armed, press [A], [B], or [C] to store the current sweep
if the register is cleared, or clear the register if it contains saved data.
2715 User Manual
Operating Basics
The saving or clearing action occurs whether the register is displaying data or
not. The green LED to the lower left of the key lights when the register contains
saved data.
Pressing [D] when SAVE ENABLE is armed toggles the spectrum analyzer in
and out of waterfall display mode. All registers must first be cleared. Individual
sweeps cannot be saved in D.
SAVE ENABLE
MAX HOLD A&B
Arms the save (clear) function. Press [SAVE ENABLE] and then press the key
corresponding to the register to be saved (cleared). The LED below the key lights
when SAVE ENABLE is armed.
Enables max hold mode. When MAX HOLD is enabled, the A and B registers
retain the largest signal observed (unless they contain saved waveforms). The
LED below the key lights when MAX HOLD is active.
VERT SCALE
2715 User Manual
PLOT
Figure 3–7: Vertical Scale and Other Controls
This area of the front panel contains the following controls:
10/5/1. Press repeatedly to cycle the vertical scale in a 10–5–1–10... sequence in
LOG (logarithmic) display mode.
LIN. Toggles the vertical display mode from LOG (logarithmic) to LIN (linear)
and back again. Scale factor is controlled by the reference level controls in the
LIN mode and by [10/5/1] in the LOG mode.
Initiates a screen plot on an optional printer or plotter. Plotter and interface must
be correctly configured (see System Configuration on page 6–67).
3–7
Operating Basics
READOUT
POWER
INTENSITY
LEVEL
AM VOL and FM VOL
VID FLTR
Toggles the on-screen readouts on and off. Use when readouts overlay data, or to
eliminate blanking intervals in analog display.
Toggles spectrum analyzer power on and off. Green LED next to key is
illuminated when power is on.
Turning the knob clockwise increases CRT brightness.
The inner knob sets trigger level in INT, EXT, and (AC) LINE trigger modes (as
on a conventional oscilloscope), horizontal position in manual scan mode, and
picture framing in video monitor mode.
Outer knob controls volume of the AM and FM demodulators.
Lights when the AM or FM demodulators are active to indicate that the outer
knob of the LEVEL control sets the audio volume. See DEMOD on page 6–56.
Normally the spectrum analyzer smooths the detected signal with a video filter
having a bandwidth equal to the resolution bandwidth. The filter bandwidth is
indicated in the right-hand readout column. However, pressing [VID FLTR] (see
Figure 3–8) toggles an alternate, automatically selected or user-designated video
filter on and off. Its bandwidth replaces the normal video filter readout.
3–8
Figure 3–8: Resolution BW and Sweep Control
2715 User Manual
Operating Basics
You can designate the video filter bandwidth using the UTIL Menu (see
Menu-Entered Control Settings on page 6–60).
Automatic Selection: 1/100 of the resolution BW
Fixed Range: 3 Hz to 300 kHz and WIDE in a 1–3 sequence
SINGLE
AUTO
[ b ] [ y ]
Press [SINGLE] to place the 2715 in a single sweep mode similar to a conventional oscilloscope. SGLSWP MODE appears on the screen. With the 2715’s
sweep in free run mode (default), press the key again to start a sweep. In other
trigger modes, the sweep begins with the first trigger signal following entry into
single sweep. SGLSWP ARM appears briefly at the start of each sweep. Pressing
[AUTO] in the SWEEP function block exits the single sweep mode, but
preserves the current auto or manual sweep rate selection mode.
The AUTO keys in the RES BW and SWEEP function blocks toggle the
spectrum analyzer into and out of automatic resolution bandwidth and sweep rate
selection modes, respectively. Pressing SWEEP [AUTO] also exits single sweep
mode (but preserves the sweep rate selection mode). The LEDs below the keys
are lit when the automatic mode is selected. When toggling out of the automatic
mode, the resolution BW and sweep rate remain as they were until manually
changed. When toggling into the automatic mode, the spectrum analyzer selects
the resolution bandwidth and sweep rate appropriate to the currently selected
span.
The RES BW and SWEEP arrow keys increase [ y ] and decrease [ b ] the
resolution bandwidth and sweep rate (time/div) in a specified sequence. They are
always active in the spectral display mode, but using either disables automatic
resolution BW or sweep rate selection, respectively.
2715 User Manual
RES BW: sequences through the installed filters 300ĂHz,
1 kHz, 3 kHz, 10 kHz, 30 kHz, 100 kHz,
300 kHz, 1 MHz, 5 MHz
SWEEP: follows 1–2–5 sequence from 2 s/div to
1 ms/div. Rates <100 ms/div are useable only in
the analog display mode
CAUTION. The spectrum analyzer RF signal input is an F-type 75 W connector.
Observe Maximum Input Ratings.
Input signal:
Maximum Amplitude: <+70 dBmV
Maximum DC: 100 Volts
Frequency Range: 9 kHz to 1.8 GHz
3–9
Operating Basics
Ventilation Openings
DO NOT BLOCK
Option 15
First LO Output
SMA Female 50W (For
Model 1405 TV
Sideband Analyzer or
2707 External Tracking
Generator)
External Trigger Input BNC Female
Trigger Level u0.1 Vt 50V Peak
Duration u 0.1ms
v
Accessory Connector
v
TRACE
ROT
DB-9 Female
VERT
POS
HORIZ
POS
Communications
Connector (Depends
on Interface Selected –
See Programmer
Manual)
Figure 3–9: The 2715 Back Panel
3–10
2715 User Manual
Operating Basics
The remainder of this section shows structure of the menus and submenus
displayed by pressing the following keys in the MENUS block:
H SWP/TRIG
H UTIL
H MKR/FREQ
H CATV/APPL
H DEMOD
H DISPL
H USER DEF
H INPUT
Some of the submenus are used for servicing; information about these submenus
is in the optional 2715 Spectrum Analyzer Service Manual. Refer to
Table F–2: Optional Accessories on page F–1 for the part number of the service
manual.
0 FREE RUN
1 INTERNAL
2 EXTERNAL
3 LINE
4 TV LINE
5 TV FIELD
SWEEP MENU
6 SWEEP RATE
7 MANUAL SCAN
8 SYNC POLARITY
9 SETUP TABLE
SWP/TRG Menu Structure
HORIZONTAL LINE TRIGGERING
0 CONTINUOUS
1 KNOB SELECTABLE
2 KEYPAD ENTERED LINE
3 KEYPAD ENTRY
4 TV LINE STANDARD
2715 User Manual
3–11
Operating Basics
UTIL Menu Structure (1 of 2)
1 STORED SETTINGS / DISPLAYS
2 KEYPAD ENTERED SETTINGS
3 NORMALIZATIONS
4 SYSTEM CONFIGURATION
5 INSTR DIAGNOSTICS/ADJUSTMENTS
6 SERVICE REQUEST
9 MORE
0 LAST POWER–DOWN
1 FACTORY DEFAULT POWER–UP
2 USER DEFINED POWER–UP
3 User Defined
4 User Defined
5 User Defined
6 User Defined
7 User Defined
8 User Defined
9 MORE*
0 FREQUENCY
1 REFERENCE LEVEL
2 SPAN/DIV
3 RF ATTENUATION
4 RESOLUTION BW
5 VIDEO FILTER
6 VERTICAL SCALE
7 SWEEP RATE
0 ALL PARAMETERS
1 FREQUENCY ONLY
2 AMPLITUDE ONLY
0 COMMUNICATION PORT CONFIG
1 SCREEN PLOT CONFIGURATION
2 PRINTER CONFIGURATION
3 INSTRUMENT CONFIGURATION
4 REAL–TIME CLOCK SETUP
5 STORED SETTINGS PROTECT
6 FILE SYSTEM DIRECTORY
7 PROTECT FILE
9 INSTALLED OPTIONS DISPLAY
*
Expands to registers 10–18, 20–28
and 30–39.
0 AUTO
1 FIXED
0 AUTO
1 FIXED
0 LOG 1 DB/DIV
1 LOG 5 DB/DIV
2 LOG 10 DB/DIV
3 LINEAR
0 GPIB
2 RS–232
0 COMM PORT
1 PLOTTER LANGUAGE
2 PLOT SPEED*
3 PLOTS PER PAGE**
5 GRATICULE LINES ON PLOT
0 AUDIO ALERT
1 MINIMUM SIGNAL SIZE
2 WA VEFORM TO PRINTER
3 WA VEFORM OUTPUT FORMAT
4 PHASELOCK
5 FREQUENCY CORRECTIONS
6 SPECTRAL DISPLAY IN MENUS
7 SWEEP HOLDOFF
0 STATUS
1 GPIB ADDRESS
2 POWER ON SRQ
3 EOI/LF MODE
4 TALK ONLY MODE
0 STATUS
1 BAUD RATE
2 DATA BITS
3 PARITY
4 EOL
5 FLOW CONTROL
6 ECHO
7 VERBOSE
3–12
0 SET DAY
1 SET MONTH
2 SET YEAR
3 SET HOUR
4 SET MINUTE
5 SET SECONDS TO :00
6 DISPLAY DATE/TIME
**
Displayed when selected plotter
language is HPGL.
2715 User Manual
UTIL Menu Structure (2 of 2)
1 STORED SETTINGS / DISPLAYS
2 KEYPAD ENTERED SETTINGS
3 NORMALIZATIONS
4 SYSTEM CONFIGURATION
5 INSTR DIAGNOSTICS/ADJUSTMENTS
6 SERVICE REQUEST
9 MORE
0 PRINT READOUTS
8 EDIT CHANNEL TABLE
(shortcut)
9 MORE
1
Option 50 and Option 75 only
Operating Basics
0 DIAGNOSTICS
1 EXTENDED DIAGNOSTICS
2 MANUAL ADJUSTMENTS
3 DEBUG MENU
4 INTERNAL PARAMETERS
5 SERVICE NORMALIZATIONS
6 DIGITAL OPTIONS DIAGNOSTICS
1
8 CALIBRATION MODE
*
Factory troubleshooting aids: not
discussed in this manual.
*
*
*
1 DEFLECTION AMP CAL
2 DISPLAY STORAGE CAL
3 SWEEP CAL
*
4 CFCV1 ADJUSTMENTS*
5 TOGGLE VD DAC LO/HI*
6 VD DAC TO VIS CARR*
7 AFC TOGGLE*
8 GATE TOGGLE*
9 QUERY LOCK STATUS*
0 SETTINGS VERIFY
1 FILE SYSTEM MENU
2 YIG SETTLE DELAY
0 FREQUENCY NORMALIZATIONS
1 REFERENCE NORMALIZATIONS
2 AMPLITUDE NORMALIZATIONS
*
*
0 THRESHOLD
1 PROGRAMD TUNING INC
2 KNOB FUNCTION
3 MARKER TO REFERENCE LEVEL
4 MOVE MARKER TO NEXT PEAK
5 TRANSPOSE MARKERS
6 MARKER START/ST OP
7 FREQUENCY START/ST OP
8 TUNING INCREMENT
9 SETUP TABLE
MRK/FREQ Menu Structure
0 CENTER FREQ
1 MARKER FREQ
2 KEYPAD ENTRD INC
3 KEYPAD ENTRY
4 RETURN TO AUTO
0 FREQUENCY
1 MARKER
2 VIDEO LINE*
0 FREQ START ENTRY
1 FREQ STOP ENTRY
0 CENTER/START FREQ
1 COUNTER RESOLUTION
3 FREQ OFFSET
4 FREQ OFFSET MODE
*
Displayed only if KNOB SELECTABLE is se-
lected in the SWEEP MENU SETUP TABLE.
4 NORMALIZATION VALUES
5 PRINT ALL NORM VALUES
6 NORM DEBUG TO PRINTER
*
Factory troubleshooting aids: not
discussed in this manual.
0 COUNTER OFF WHEN TRKG (1 HZ)
1 1HZ
2 1KHZ
2715 User Manual
3–13
Operating Basics
CATV/APPL CATV Measurements Page 1 Menu Structure (1 of 3)
0 RECENTER CHANNEL xx
1 CARRIER LEVEL -– AVG POWER
2 CARRIER SURVEY
3 MODULATION DEPTH
4 AURAL (FM) DEVIATION
5 CARRIER/NOISE -- DESIRED/UNDESIRED
6 HUM/LFD
7 FREQUENCY RESPONSE
8 CATV MEASUREMENTS SETUP
9 MORE
0 RUN LEVELS - POWER
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 SET UP CARRIER LEVELS
6 EXTERNAL ATTEN/AMPL
9 LEAVE CARRIER LEVEL -– AVG PWR
0 RUN CARRIER SURVEY
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 SET UP CARRIER SURVEY
6 EXTERNAL ATTEN/AMPL
9 LEAVE CARRIER SURVEY
TEST MODES
0 ACCURATE FREQUENCY AND AMPL
1 ACCURATE AMPLITUDE ONLY
2 FAST AMPLITUDE ONLY
0 ON/OFF
1 ATTEN/AMPL ENTRY
TEST MODES
0 ACCURATE FREQUENCY AND AMPL
1 ACCURATE AMPLITUDE ONLY
2 FAST AMPLITUDE ONLY
0 RUN MODULATION DEPTH
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 SET UP ADJUSTMENT MODE
6 ENTER ADJUSTMENT MODE
9 LEAVE MODULATION DEPTH
0 RUN FM DEVIATION
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 SET UP AURAL (FM) DEVIATION
6 ENTER ADJUSTMENT MODE
9 LEAVE AURAL (FM) DEVIATION
*
RS-232 only.
0 ON/OFF
1 ATTEN/AMPL ENTRY
0 VIEW MODULATION MODE
1 TARGET LINE
2 CYCLE DELAY
3 TARGET LINE DURATION
TEST MODES
0 INTERACTIVE
1 AUTO
5 MEASUREMENT TIME
3–14
2715 User Manual
CATV/APPL CATV Measurements Page 1 Menu Structure (2 of 3)
0 RECENTER CHANNEL xx
1 CARRIER LEVEL -- AVG POWER
2 CARRIER SURVEY
3 MODULATION DEPTH
4 AURAL (FM) DEVIATION
5 CARRIER/NOISE -- DESIRED/UNDESIRED
6 HUM/LFD
7 FREQUENCY RESPONSE
8 CATV MEASUREMENTS SETUP
9 MORE
Operating Basics
0 RUN C/N -- D/U
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS
4 PRINT STORED RESUL TS
5 SET UP CARRIER/NOISE
7 IN–SERVICE
9 LEAVE C/N -– D/U
0 RUN HUM/LFD
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 POWER LINE FREQ
9 LEAVE HUM/LFD
0 RUN FREQ RESP
CURRENT REFERENCE
5 SET UP FREQ RESP
9 LEAVE FREQUENCY RESPONSE
*
RS-232 only.
TEST MODES
0 INTERACTIVE
1 AUTO
2 AUTO (PAUSE FOR CARRIER OFF)
5 NOISE NORM’D BW
TEST MODES
0 ✱NO REF
1 WITH REF
SWEEP RANGE
2 START FREQUENCY
3 STOP FREQUENCY
4 USE DEFAULT START/STOP
TEST MODES
0 NO REF
1 ✱WITH REF
REFERENCE ACQUISITION
2 START FREQUENCY
3 STOP FREQUENCY
4 USE DEFAULT START/STOP
5 ACQUIRE NEW REFERENCE
6 STORED REFERENCE MENU
7 EDIT CURRENT REFERENCE NAME**
2715 User Manual
**Displayed only if a reference has been acquired.
3–15
Operating Basics
CATV/APPL CATV Measurements Page 1 Menu Structure (3 of 3)
0 RECENTER CHANNEL xx
1 CARRIER LEVEL -- AVG POWER
2 CARRIER SURVEY
3 MODULATION DEPTH
4 AURAL (FM) DEVIATION
5 CARRIER/NOISE -- DESIRED/UNDESIRED
6 HUM/LFD
7 FREQUENCY RESPONSE
8 CATV MEASUREMENTS SETUP
9 MORE
To CATV/APPL
CATV Measurements Page 2
0 EXIT CATV MEASUREMENT MODE
1 CHANNEL TABLE
2 SKIP CHANNEL
3 ALL CHANNELS
4 SITE
5 OPERATOR
6 REF LEVEL UNIT
7 EDIT CHANNEL TABLES
8 REMOVE ALL STORED RESUL TS
9 LEAVE CATV MEASUREMENTS SETUP
2
0 STD
1 HRC
2 IRC
3 User Defined
4 User Defined
5 User Defined
6 User Defined
7 User Defined
8 User Defined
9 User Defined
2
Option 50 and Option 75 only
3–16
2715 User Manual
Operating Basics
ATV/APPL CATV Measureme
age 2 Menu
ructure
0 ADJACENT CHANNEL LEAKAGE
1 VIEW MODULATION (FIELD)
2 VIEW MODULATION (LINE)
3 VIEW PICTURE
4 LISTEN
5 CTB
6 CSO
7 CROSS MODULATION
8 IN-CHANNEL RESPONSE
9 MORE
C
(1 of 2)
0 RUN CTB
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT LEVELS*
4 PRINT STORED RESUL TS*
5 SET UP CTB
6 DIGITAL/ANALOG
9 LEAVE CTB
0 RUN CSO
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT LEVELS*
4 PRINT STORED RESUL TS*
nts P
0 RUN ADJACENT CHANNEL LEAKAGE
TEST MODES
0 INTERACTIVE
1 AUTO
2 AUTO (PAUSE FOR CARRIER OFF)
3 SINGLE-SWEEP
5 SET UP TEST FREQUENCIES**
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 MEASURE SIDE
9 LEAVE ACL
St
TEST FREQUENCIES
0 User Defined
1 User Defined
2 User Defined (+0.00000HZ Default)
3 User Defined
4 User Defined
5 USE DEFAULT TEST FREQUENCIES
5 SET UP CSO
6 DIGITAL/ANALOG
7 IN-SERVICE
9 LEAVE CSO
*
RS-232 only.
TEST MODES
0 INTERACTIVE
1 AUTO
2 AUTO (PAUSE FOR CARRIER OFF)
3 SINGLE-SWEEP
4 CONTINUOUS
5 SET UP TEST FREQUENCIES AND
CONTINUOUS MODE PRMTRS**
TEST MODES IN-SERVICE
0 INTERACTIVE
1 AUTO
5 SET UP TEST FREQUENCIES**
**
Not displayed in INTERACTIVE mode.
TEST FREQUENCIES
0 User Defined (+1.25000MHZ Default)
1 User Defined (+750.000KHZ Default)
2 User Defined
3 User Defined (-750.000KHZ Default)
4 User Defined (-1.25000MHZ Default)
5 USE DEFAULT TEST FREQUENCIES
CONTINUOUS MODE PARAMETERS***
6 CARRIER FREQ***
7 TEST INTERVAL***
8 NORMALIZATION INTER VAL***
***
Displayed only if CONTINUOUS mode
is selected.
2715 User Manual
3–17
Operating Basics
0 ADJACENT CHANNEL LEAKAGE
1 VIEW MODULATION (FIELD)
2 VIEW MODULATION (LINE)
3 VIEW PICTURE
4 LISTEN
5 CTB
6 CSO
7 CROSS MODULATION
8 IN-CHANNEL RESPONSE
9 MORE
CATV/APPL CATV Measurements Page 2 Menu Structure (2 of 2)
0 RUN CROSS MODULATION
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 METHOD (FREQUENCY DOMAIN or TIME DOMAIN (NCTA))
To CATV/APPL
CATV Measurements Page 1
9 LEAVE CROSS MODULATION
0 RUN IN-CHAN RESP
1 STORE CURRENT RESULTS
2 DISPLAY RESULTS
3 PRINT CURRENT RESULTS*
4 PRINT STORED RESUL TS*
5 SET UP IN-CHAN RESP
6 TEST SIGNAL LINE NUMBER**
7 IN-SERVICE
9 LEAVE IN-CHAN RESP
*
RS-232 only.
**
Displayed only when IN-SERVICE is On.
TEST MODES
0 INTERACTIVE
1 AUTO (PAUSE FOR SIGNAL ON)
TEST FREQUENCIES
2 User Defined (-500.000KHZ Default)
3 User Defined (+500.000KHZ Default)
4 User Defined (+1.25000MHZ Default)
5 User Defined (+2.00000MHZ Default)
6 User Defined (+3.00000MHZ Default)
7 User Defined (+3.75000MHZ Default)
8 USE DEFAULT TEST FREQUENCIES
TEST MODES IN-SERVICE
0 INTERACTIVE
1 AUTO
TEST FREQUENCIES
2 User Defined (-500.000KHZ Default)
3 User Defined (+500.000KHZ Default)
4 User Defined (+1.25000MHZ Default)
5 User Defined (+2.00000MHZ Default)
6 User Defined (+3.00000MHZ Default)
7 User Defined (+3.75000MHZ Default)
8 USE DEFAULT TEST FREQUENCIES
3–18
2715 User Manual
0 BANDWIDTH MODE
1 CARRIER TO NOISE
2 NOISE NORM’D
3 SIGNAL SEARCH MENU
4 OCCUPIED BW
7 FM DEVIATION MODE
8 CATV MEASUREMENT MODE
9 SETUP TABLE
Operating Basics
CATV/APPL Applications Menu Structure
0 BEGIN FREQ
1 END FREQ
2 START TEST
3 DISPLAY RESULTS
0 DB DOWN FOR BW MODE
1 NORM BW FOR C/N
2 NOISE NORM’D BW
3 PERCENT OCCUPIED BW
DEMOD Menu Structure
0 OFF
1 AM DEMODULATOR
2 FM DEMODULATOR
3 BROADCAST (AM) VIDEO
9 VIDEO MONITOR SETUP
0 VIDEO DETECT MODE
1 SYNC POLARITY
2 VIDEO POLARITY
2715 User Manual
3–19
Operating Basics
0 DIGITAL/ANALOG
1 ENSEMBLE AVERAGING
2 B, C MINUS A
3 B, C MINUS A OFFSET TO
4 ACQUISITION MODE
5 TITLE MODE
6 GRATICULE ILLUMINATION
7 DISPLAY SOURCE (AM)
8 DISPLAY LINE
9 MIN HOLD
DSPL Menu Structure
1 INITIATE AVERAGING
2 TERMINATE AVERAGING
3 MAX
4 MEAN
5 MIN
6 MAX/MIN
7 NUMBER OF AVERAGES
8 SAVE RESULTS IN DISPLAY
1 TITLE MODE
2 TITLE MODE EDIT
3 PLOT LABELING
4 PLOT LABELING EDIT
0 User Defined
1 User Defined
2 User Defined
3 User Defined
4 User Defined
5 User Defined
6 User Defined
7 User Defined
8 User Defined
9 USER DEF PROGRAM UTILITIES
1 ON/OFF
2 VALUE ENTRY
3 DISPLAY LINE TO MARKER
4 LIMIT DETECTOR
USER DEF Menu Structure
0 ACQUIRE KEY STROKES
1 TITLE EDIT
2 WAIT FOR END OF SWEEP
3 DISPLAY MESSAGE
4 PAUSE FOR “USER DEF” KEY
5 CONTINUOUS EXECUTION
6 STORE
7 DELETE
8 PROTECT
9 TIME DELAY SETUP
0 SET DAY
1 SET HOUR
2 SET MINUTE
3 REPEAT INTERVAL
4 RUN N TIMES
5 CLEAR TIME
3–20
2715 User Manual
1 PREAMP
Operating Basics
INPUT Menu Structure
3 REF LEVEL UNIT
4 1ST MXR INPUT LVL
5 RF ATTENUATION
6 EXTERNAL ATTEN/AMPL
9 CAL SIG @ 100MHZ 18.8DBMV
0 DBM*
1 DBMV
2 DBV*
3 DBUV
4 DBUW*
5 DBUV/M IN WFM x*
9 DBUV/M SETUP
0 ON/OFF
1 ATTEN/AMPL ENTRY
*Not available in CATV Measurements Mode.
0 EDIT ANTENNA TABLE
1 User Defined
2 User Defined
3 User Defined
4 User Defined
5 User Defined
6 MEASUREMENT DIST
7 SAVE RESULTS IN WFM
9 MARKER DISPLAY
0 BEGIN EDIT
1 TITLE EDIT
2 STORE
3 LOAD
4 DELETE
5 PRINT
6 ANTENNA SETUP
1 START FREQUENCY
2 STOP FREQUENCY
3 INC FREQUENCY
4 REFERENCE DISTANCE
2715 User Manual
3–21
Operating Basics
3–22
2715 User Manual
Dedicated Controls
Dedicated Controls
This section describes in detail the dedicated controls of the 2715. All of the
dedicated controls are on the 2715 front panel except the trace alignment
controls, which are on the back. These dedicated controls are used to carry out
the most common and general spectrum analyzer operations without the need to
call up the menus. The first part of the section covers the controls that initiate
frequently performed actions. Included in this category are all the operating
increment and decrement functions of span, channel entry, frequency, and
reference level. The second part of the section covers the enhanced versatility
controls that increase your ability to make accurate spectral measurements easily
and conveniently.
Fundamental Operations
Getting Started described the amplitude and frequency measurement of a
continuous narrow-band signal (the calibration signal) using only three controls.
This section will repeat the initial measurement, but this time with the [CHAN/
FREQ], [SPAN/DIV], [REF LEVEL], and associated controls contained in the
gray-colored central function block. These controls are fundamental to most
spectrum analyzer operations. You can perform a majority of spectral measurements with only these controls.
First set the 2715 controls to the values shown in the following settings box:
Frequency (AUTO SWEEP) ATT 50DB
38.8DBMV VF 300KHZ
600.0KHz/ MAX 10 DB/
300KHz RBW Channel Table Name
CH nn CALIBRATOR
Frequency = Center of default power-up channel, center of
currently selected channel, or selected frequency
nn = Channel number
This is most easily done by pressing [UTIL] [1] [1] to recall the factory default
settings.
2715 User Manual
4–1
Dedicated Controls
SP AN/DIV
The span controls change the total display frequency span range symmetrically
about the center frequency, select channel table entries, and set the 2715 in the
maximum span or zero span modes.
1. Press [INPUT] [9] to turn on the calibration signal.
2. Press [MKR//OFF] twice to turn off the markers.
3. Press [CHAN/FREQ] [4] [0] [0] [X] to set the 2715 center frequency to
400 MHz.
4. Press [MAX] and [AUTO] RES BW. Remember that in MAX SPAN the
marker changes position and not the frequency at screen center.
5. Press [REF LEVEL] [3] [8] [] [8] [Y] to set the reference level to
38.8 dBmV.
Arrow Keys. The arrow keys to the right of [SPAN/DIV] change the frequency
span represented by one horizontal division on the screen. The arrows directly
increase or decrease the span per division.
6. Beginning with maximum span, press [ b ] to the right of [SPAN/DIV]
1
several times to decrease the span/div to 20 MHz
.
This causes the 2715 to zoom in on the spectral display.
7. Now press [ y ] until the span/div increases to 180 MHz.
Watch the spectral display zoom out just as though it was moving away from
you.
The up arrow increases the span/div, compressing or squeezing the spectrum
together. The down arrow decreases the span/div and expands or stretches the
spectrum. The arrow keys are active whenever the 2715 is in the spectral display
mode. Experiment by pressing each arrow key until the span/div no longer
changes. You will notice two characteristics of the 2715:
H Span/div changes in a 1–2–5 sequence between 1 kHz and 100 MHz, plus
180 MHz/div in maximum span
H Resolution BW changes automatically as the span changes (later, we show
how this can be changed)
1
If you request a narrow span before the 2715 is completely warmed up, you may get
a NORMALIZA TION SUGGESTED message. This message should not appear after
the 2715 warms up.
4–2
2715 User Manual
Dedicated Controls
Keypad Entry. The preset span/div values are sufficient for most measurement
needs. However, other span/div settings can be specified to the nearest tenth of a
unit. To set the span/div to an arbitrary value do the following steps:
8. Press [SPAN/DIV] to place span in the immediate entry mode.
Notice that the word SPAN appears at left center of the 2715 screen. The
word SPAN indicates that you can enter the span/div directly from the
keypad (immediate entry mode) by keying in a permissible value followed
by an appropriate terminator key. Any value from 1 kHz/div to 180 MHz/div
is acceptable. You can enter up to 25 characters, but the 2715 rounds the
value to three decimal points and stores it. In the spectral display, the value
is shown rounded to one decimal point (to see the stored value, press
[UTIL] [2]).
9. Press [3] [3] [] [3] [X] to set the span/division to 33.3 MHz.
The numbers you type appear on screen to the right of SPAN. If you make a
mistake, you can correct it any time prior to pressing [X] by repeatedly
pressing [BKSP] (the backspace key) until the incorrect entry disappears and
then entering the correct value.
Pressing a terminator button ([W], [X], [Y], or [Z]) determines the units and
enters the data. [X] can represent units of MHz, ms, or mV. Because the
immediate span/div entry mode requires a frequency, the 2715 correctly
interprets the currently displayed value as 33.3 MHz when you press [X]. If a
time or voltage unit had been required, the 2715 would have interpreted your
entry as 33.3 ms or 33.3 mV, respectively, when you pressed [X]. On the other
hand, had you wanted the entry to represent a span/div of 33.3 kHz, you would
have pressed [Y] instead of [X].
10. Press [ b ].
The span/div changes to 20 MHz; the nearest span/div value in the downward direction in the normal 1–2–5 sequence. Had you pressed [ y ], the
span/div would have changed to 50 MHz; the nearest value in the upward
direction.
The span readout now indicates 20MHZ/ and the 4
th
harmonic of the
calibration signal is at the center frequency of 400 MHz.
MAX. There is often a need to view the entire input frequency range of the 2715,
such as when connecting new signals to the 2715 input. In this mode, the 2715 is
in MAX SPAN. The dedicated front-panel key is provided to conveniently enter
and exit this mode.
2715 User Manual
11. Press [MAX] to obtain the largest span available on the 2715.
The span/div readout now indicates 180MHz/MAX.
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Dedicated Controls
12. Press [MAX] a second time to return to 20KHZ/.
Many of the keys on the 2715 are toggle action. The ability to undo an action by
pushing the same button that carried out the action is typical. MAX is a
toggle-action key taking you from the current span/div to 180 MHz/div and
back.
ZERO. The following example demonstrates the effects of using zero span.
13. Set the center frequency to 100 MHz.
Notice that the calibration signal is centered in the display.
14. Press [ZERO].
The signal is a straight, horizontal line.
In the zero span mode, the 2715 remains at a fixed frequency. What you see is
the variation in time of the signal power coming through the RBW filter at that
frequency. Since the calibration signal has constant amplitude, the display is
constant.
Channel Entry
15. Turn the FREQ/MKRS knob to slowly increase the center frequency.
The signal amplitude decreases and the noise increases as you tune away
from the calibration signal. The noise generated internally by the 2715 has a
time-varying random amplitude.
In the zero span mode, the 2715 does not sweep the frequency spectrum. Rather,
the local oscillator remains at a fixed frequency so that the resolution bandwidth
filter brackets the designated center frequency. Because the display screen is still
swept, the span readout indicates sweep speed (time per division rather than
frequency per division). The word ZSPAN follows the sweep speed to denote
zero span operation. In a sense, you have turned your spectrum analyzer into an
oscilloscope.
16. Press [ZERO] to return to 20 MHz/div span.
The following procedures demonstrate two methods of entering a channel
selection.
Arrow Keys. This procedure uses the arrow keys to select a channel from a
selected channel table:
1. Press [UTIL] [1] [1] to restore the factory defaults.
4–4
2. Press [ y ] adjacent to [CHAN/FREQ].
The channel selection steps to the next channel in the selected channel table.
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Dedicated Controls
3. Press [ b ] adjacent to [CHAN/FREQ].
The channel selection steps to the previous channel.
The up arrow selects the next higher channel in the channel table, whereas the
down arrow selects the previous channel. If you step past the end of the channel
table, the display wraps to the start of the table (and vice versa). The keys remain
active whenever the 2715 is in the spectral display mode.
Keypad Entry. CHAN/FREQ defaults to CHAN whenever the CATV mode is
active. The abbreviation CHAN appears at left center of the 2715 screen. CHAN
indicates that you can enter the channel number directly from the keypad. This is
done by keying in a permissible channel number (according to the selected
channel table) followed by [W]. Enter the desired channel number with the
front-panel keypad to select a channel.
NOTE. In the CATV mode, frequency can be entered by terminating the entry with
the [X], [Y], or [Z].
Frequency Entry
(Normal Mode)
In the nonCATV mode, [CHAN/FREQ], the associated [ y ] and [ b ], and all
the terminator keys exclusively control frequency. The nonCATV mode is enabled
by pressing [CATV/APPL] [8] [0].
For instance, to select channel 8 in the specified table, do the following steps:
4. Press [8] [W].
The numbers appear on the screen to the right of CHAN. If you make a
mistake, correct it any time prior to pressing [W] by repeatedly pressing
[BKSP] (the backspace key) until the incorrect number disappears and then
type the correct number. Pressing [W] ends the entry, and the 2715 interprets
the currently displayed value as Channel 8.
The other terminators are used for channel frequency entry. For example, if you
enter a certain frequency, the displayed channel number defaults to the channel
within whose limits the entry falls.
The frequency controls set the 2715 normal center or start frequency in the
normal or CATV mode.
FREQ/MKRS. This procedure shows how to adjust the center frequency using the
FREQ/MKRS knob.
2715 User Manual
1. Press [INPUT] [9] to turn on the calibration signal.
2. Press [1] [0] [0] [X] to set the center frequency to 100 MHz.
4–5
Dedicated Controls
3. Press [SPAN/DIV] [1] [0] [0] [X] to set the span to 100 MHz/div.
4. Press [REF LEVEL] [3] [8] [] [8] [Y] to set the reference level to
38.8 dBmV.
5. Press RES BW [AUTO].
6. Turn the FREQ/MKRS knob a few clicks clockwise.
Each click of the knob increases the center frequency by 2.0 MHz.
7. Turn the FREQ/MKRS knob counterclockwise, and the center frequency
decreases by the same amount.
8. Reduce the span to 20 MHz/div.
9. Turn the FREQ/MKRS knob a few clicks clockwise.
The spectral display appears to move sideways at about the same rate as it
originally did. However, it is now moving only 0.4 MHz per click. We call
this visual behavior constant rate tuning. It occurs because the knob normally
2
changes the center frequency at 0.02 of the span/div per click.
Obviously, it
would take 250 clicks to change the frequency by 100 MHz at 20 MHz/div.
The knob remains active whenever the 2715 is in the spectral display mode.
Arrow Keys. The arrow keys can also be used to change the normal center or start
frequency as discussed in the following example:
10. Press [ y ] adjacent to [CHAN/FREQ].
The frequency changes by channel allocation width of the currently selected
channel table (6 MHz for the STD, HRC, and IRC channel tables).
If you had previously selected a channel by entering a frequency value that is not
centered about the channel allocation width, the first increment will move the
center frequency to the center of the next channel. Subsequent increments then
default to the channel allocation width.
The up arrow selects the next channel, and the down arrow selects the previous
channel. This means that even though the 2715 is in the CATV mode, you can
increase and lower the center frequency by the channel allocation width using the
up and down arrows. You can then fine-tune the center frequency using the
FREQ/MKRS knob.
The keys remain active whenever the 2715 is in the spectral display mode.
4–6
2
In MAX SPAN the indicated frequency changes alternately by 3 or 4 MHz and as a
percent of the Resolution BW in ZERO SPAN. See Selecting the T uning Increment on
page 6–21 for a description of how you can change the tuning rate.
2715 User Manual
Dedicated Controls
Keypad Entry. For very large frequency changes, or to preset a known center or
start frequency, the direct entry mode is faster. To set the center or start frequency
to a predetermined value, do the following steps:
11. Press [CHAN/FREQ] to place the center or start frequency in the immediate
entry mode.
Even though the word CHAN appears at left center of the 2715 screen, you can
enter the center frequency directly from the keypad (immediate entry mode) by
keying in a permissible value followed by an appropriate terminator key ([X],
[Y], or [Z]). You can enter any value from 0 Hz to 1800 MHz, even though the
2715 low-frequency specification is 9 kHz. Your entry can contain up to 25
characters, but regardless of how many you enter, the 2715 attempts to control
frequency to the nearest hertz. The frequency is displayed at the top of the
left-hand data column to 1% of the span/div.
12. Press [1] [] [2] [5] [X] to set the center frequency to 1.25 MHz.
The numbers you type appear on-screen to the right of CHAN. If you make a
mistake, correct it any time prior to pressing the MHz terminator by
repeatedly pressing [BKSP] until the incorrect number disappears, and then
enter the correct value.
Frequency Entry
(NonCATV Mode)
Pressing a terminator key ([X], [Y], [Z]) determines the units and enters the data.
[X] can represent units of MHz, ms, or mV. Because the frequency immediate
entry mode requires a frequency, the 2715 interprets the currently displayed
value as 1.25 MHz when you press [X]. If a time or voltage unit had been
required, the 2715 would have interpreted your entry as 1.25 ms or 1.25 mV,
respectively, when you pressed [X]
3
. On the other hand, had you wanted the
entry to represent a frequency of 1.25 GHz, you would have pressed [1] [2] [5]
[0] [X]. (Use the correct multiple and [X] to select GHz while the 2715 is in the
CATV mode.)
Now use the direct entry method to set the center frequency to 100 MHz:
13. Press [CHAN/FREQ] [1] [0] [0] [X].
The following procedures demonstrate how to change the frequency when
operating in the nonCATV mode.
Arrow Keys. You can adjust the frequency using the arrow keys as shown in the
following procedure:
1. Press [CATV/APPL] [8] [0]) to exit CATV mode.
2. Press [1] [0].
2715 User Manual
3
However, neither is a permissible value at this menu level, and your entry would
have been rounded to the nearest allowable value.
4–7
Dedicated Controls
3. Press [ y ] adjacent to [CHAN/FREQ].
The frequency changes by 10 MHz. (It would take ten presses of the arrow
key to change the frequency by 100 MHz.)
The frequency arrow keys change the frequency by one division.
4. Change the span/div to 100 MHz.
5. Press [ b ] adjacent to [CHAN/FREQ].
The frequency changes by one division (100 MHz). At large span/div
settings, the arrow keys can change the frequency very rapidly.
Keypad Entry. For very large frequency changes, or to preset a known center or
start frequency, the direct entry mode using the keypad is faster. To set the center
or start frequency to a predetermined value, press [CHAN/FREQ] to place the
center or start frequency in immediate entry mode. The abbreviation FREQ
appears at left center of the 2715 screen.
The abbreviation FREQ indicates that you can enter the center frequency directly
from the keypad. This is done by keying in a permissible value followed by an
appropriate terminator key. You can enter any value from 0 Hz to 1.8 GHz, even
though the 2715 low-frequency specification is 9 kHz. Your entry can contain up
to 25 characters, but regardless of how many you enter, the 2715 attempts to
control frequency to the nearest hertz, and the frequency is displayed at the top
of the left-hand data column to 1% of the span/div.
6. Press [CHAN/FREQ] to enter the immediate entry mode.
7. Press [1] [] [2] [5] [X] to set the center frequency to 1.25 MHz.
The numbers you type appear on screen to the right of FREQ. If you make a
mistake, correct it any time prior to pressing MHz by repeatedly pressing
[BKSP] until the incorrect number disappears, and then enter the correct
value.
Pressing a terminator key ([W], [X], [Y], [Z]) determines the units and enters the
data. [X] can represent units of MHz, ms, or mV. Because the frequency
immediate entry mode requires a frequency, the 2715 interprets the currently
displayed value as 1.25 MHz when you press [X]. If a time or voltage unit had
been required, the 2715 would have interpreted your entry as 1.25 ms or
1.25 mV, respectively, when you pressed [X]. On the other hand, had you wanted
the entry to represent a frequency of 1.25 GHz, you would have pressed [W]
instead of [X].
4–8
8. Press [CATV/APPL] [8] to return the 2715 to CATV mode.
9. Press [INPUT] [9] to turn on the calibrator.
2715 User Manual
Dedicated Controls
10. Press [REF LEVEL] [3] [8] [] [8] [Y] to set the reference level to
38.8 dBmV.
11. Press [MKR//OFF] twice to turn off markers.
12. Press [CHAN/FREQ] [1] [0] [0] [X] to use the direct entry method to set the
center frequency to 100 MHz.
REF LEVEL
The Ref Level controls adjust the reference level of the display and increment
and decrement the reference level step size. Following is a review of the
reference level adjustment.
Arrow Keys. You can adjust the reference level using the arrow keys as shown in
the following procedure:
1. Notice the height of the signal peak and then press [ b ] adjacent to [REF
LEVEL].
The signal peak appears to increase 10 dB when you press the key. Actually,
the calibration signal amplitude does not change when you change the
reference level. Instead, the reference level decreases (changes in the
direction indicated by the arrow key) to 28.8 dBmV and the attenuation to
10 dB. The signal only appears larger because the reference level has been
lowered 10 dB and now represents a signal level of 28.8 dBmV, 10 dB or
one division greater than the calibration signal.
2. Press [ y ] adjacent to [REF LEVEL] to reduce the on-screen signal height
one division.
The reference level readout increases 10 dB to 38.8 dBmV (changes in the
direction indicated by the arrow) and RF attenuation changes to 20 dB. The
signal peak drops one division, but its amplitude is still 18.8 dBmV.
2715 User Manual
The up arrow increases the reference level, and the down arrow lowers it. The
keys remain active whenever the 2715 is in the spectral display mode.
NOTE. The direction of the arrows always represents the direction of change of
the 2715 setting. ([ y ] adjacent to [REF LEVEL] increases the reference level
and lowers the displayed signal height.)
4–9
Dedicated Controls
Keypad Entry. As with frequency and span/div, you can directly enter the
reference level from the keypad. This feature is especially handy when you have
a good estimate ahead of time of what the signal amplitude is, or when you are
simply interested in how much below a given amplitude a particular signal is.
For instance, you might want to preset the reference level to +15 dBmV to
examine cable TV signals at a customer drop.
The following procedure shows you how to set the reference level to a predetermined value:
3. Press [REF LEVEL] to place the reference level in the immediate entry
mode.
Notice that the abbreviation REFL has appeared at left center of the 2715
screen.
The REFL notation indicates that you can enter the reference level directly from
the keypad. This is done by keying in a permissible value followed by an
appropriate terminator key. You can enter any value from –21.2 to +68.8 dBmV
(or the equivalent in other units). You can enter up to 25 characters, but
regardless of how many you enter, the 2715 rounds and displays the reference
level to a tenth of a dB.
4. Press [2] [1] [] [3] [Y] to set the reference level to 21.3 dBmV.
The numbers you type appear on screen to the right of REFL. If you make a
mistake, you can correct it any time prior to pressing [Y] by repeatedly
pressing [BKSP] until the incorrect number disappears, and then typing the
correct value.
Pressing a terminator key (only [Y] or [Z] in this case) determines the units. The
[Y] key can represent units of kHz, mSEC, mV, or +dBx. Because the reference
level immediate entry mode requires decibels, and because the reference level
unit is dBmV, the 2715 correctly interprets the currently displayed value as
21.3 dBmV when you press [Y]. If a frequency unit had been required, the 2715
would have interpreted your entry as 21.3 kHz when you pressed [Y]. On the
other hand, had you wanted to enter a negative reference level, you would have
pressed [Z] for –dBx. The 2715 ignores the [W] or [X] terminator keys because
they do not represent acceptable reference level units.
REF L VL STEP. The calibration signal peak is now less than one division below
the reference level.
5. Press [REF LVL STEP].
Nothing happened on screen, but the red LED next to the key is illuminated.
This indicates that the rate at which the reference level arrow keys change
the on-screen signal height and reference level is now 1 dB per press rather
than 10 dB.
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2715 User Manual
Dedicated Controls
6. Press [ b ] three times.
The signal peak rises until it is just above the reference level, and the readout
indicates 18.3 dBmV. You cannot get the signal peak closer to the reference
level without entering a new reference level in the immediate entry mode.
7. Press [ y ] ten times.
The signal peak should drop to almost one division below the reference
level. The reference level readout should indicate 28.3 dBmV.
8. Press [REF LVL STEP] again.
REF LVL STEP is another toggle-action key. The LED goes out indicating
that the reference level is back in 10 dB per press mode.
9. Press [ b ].
Confirm that the reference level returns to 18.3 dBmV.
10. Reset the reference level to 38.8 dBmV.
Enhanced Versatility
Res BW
The first part of this section covered the fundamental controls of the 2715. This
second part covers the remaining controls and how they enhance your ability to
make accurate spectral measurements easily and conveniently. We cover how to
control the resolution bandwidth, vertical scale factor, and sweep speed. We
show how to use display storage and marker controls to quickly measure signal
amplitude and frequency with maximum accuracy; and we show how to make
direct spectral comparisons and to save important results for future reference in
nonvolatile RAM (NVRAM).
100.0MHz (AUTO SWEEP) ATTN 20DB
38.8DBMV VF WIDE
20.0MHz/ 10 DB/
5MHz RBW (AUTO) Channel Table Name
CH nn CALIBRATOR
The Res BW controls select the 2715 resolution bandwidths of 300 Hz to 5 MHz
and allow time to be automatically selected to match the selected bandwidth.
2715 User Manual
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Dedicated Controls
Set the 2715 parameters as follows to match the preceding settings box:
1. Press [UTIL] [1] [1] to recall factory default settings.
2. Press [CHAN/FREQ] [1] [0] [0] [X] to set the center frequency to
100 MHz.
3. Press [SPAN/DIV] [2] [0] [X] to set the span/div to 20 MHz.
4. Press [REF LEVEL] [3] [8] [.] [8] [Y] to set the reference level to
38.8 dBmV.
5. Press [INPUT] [9] to enable the calibrator.
6. Press [AUTO] to set the resolution bandwidth to 5 MHz.
7. Press [MKR//OFF] twice to disable the markers.
Arrow Keys. Until now, resolution bandwidth has been left in the AUTO mode,
which enables you to make measurements without worrying about where the
resolution bandwidth is set. The 2715’s default is a fixed resolution bandwidth of
300 kHz. AUTO mode is available, but it is not the normal operating mode.
There are circumstances in which you will want to control the resolution
bandwidth yourself. For instance, if you look at the time domain representation
of a TV video signal using zero span, you will want to use the 5 MHz (maximum
bandwidth) filter to ensure enough bandwidth for the video signal. In other cases,
you may want to select a very narrow resolution bandwidth in order to resolve
signal sidebands or intermodulation distortion products. The RES BW arrow
keys enable you to select resolution bandwidths of 300 Hz, 1 kHz, 3 kHz,
10 kHz, 30 kHz, 100 kHz, 300 kHz, 1 MHz, and 5 MHz in the 2715.
4–12
It is important to know how far signals must be separated before we can see them
as separate. The answer depends on the particular filters, bandwidths, signal
levels and other factors, but the following rules apply:
H If the signal amplitudes are less than 3 dB different, they are resolved when
their frequency separation equals the resolution bandwidth.
H For signals more widely separated in amplitude and frequency, let A be the
amplitude difference. Then:
A
F + (1 )
where F is the required frequency separation. This rule is based on the fact
that the 2715’s 60 dB filter bandwidths tend to be approximately 7 times the
6 dB bandwidth and assumes the filter roll-off is approximately linear in dB.
Using this condition, if the signals are 30 dB different in amplitude (A), then
they have to be separated by approximately 2.4 × resolution BW.
) resolution BW
22
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Dedicated Controls
8. Set the span to 2.0 MHz/div.
The resolution bandwidth readout indicates 300 kHz.
9. Press [ y ] in the RES BW function block to change the resolution
bandwidth.
Notice that the noise floor increases approximately 12 dB as you switch from
300 kHz resolution bandwidth to 5 MHz. The reason for this rise in the noise
floor is that the noise coming through a filter is proportional to the filter
bandwidth. A wide filter passes more white noise components (frequencies)
than a narrow filter. Consequently, more noise comes through a 5 MHz filter
than through a 300 kHz filter.
The LED below the RES BW AUTO key went out indicating that the
resolution bandwidth is no longer being automatically selected, and the
resolution bandwidth readout indicates 5 MHz. The calibration signal now
appears to be 5 MHz wide. Theoretically, the calibration signal should be
infinitely narrow — a spike at 100 MHz.
To understand what has happened, you must recall the process going on within
the 2715. It is sweeping a narrow-band signal (the calibration signal) past a
broadband filter (the 5 MHz resolution filter). As the signal is moved past the
filter, it maps the shape of the resolution filter. What you see is the spectral shape
of the filter rather than that of the calibration signal. This means that on
unmodulated signals a resolution bandwidth filter that is too wide can artificially
broaden the displayed spectrum (although the signal peak remains accurate).
10. Repeatedly press [ b ] in the RES BW function block to narrow the
resolution bandwidth until the on-screen readout indicates 3 kHz.
There is a high-level beep and the message UNCAL (if there is no beep,
check that the audio alert is set to ERROR ONLY or BOTH — see The
Audio Alert on page 6–71).
The 2715 is now sweeping the calibration signal past the resolution filter too
quickly for the filter output to rise to its steady-state value before the signal is no
longer present at the filter input. This can result in low amplitude and skewed
frequency readings. This means that a resolution bandwidth that is too narrow
can result in incorrect amplitude and skewed frequency measurements. Measurement accuracy is compromised when the UNCAL message is present.
AUTO. Pressing [AUTO] in the RES BW function block toggles between manual
and automatic selection of the resolution bandwidth. When the resolution
bandwidth is selected automatically by the 2715, the LED below the key is
illuminated.
2715 User Manual
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Dedicated Controls
11. Press [AUTO] to place the resolution bandwidth in the automatic mode.
The red LED lights. You can take the 2715 out of AUTO mode by pressing a
RES BW arrow key or by pressing [AUTO].
12. Set the span/div to 50 MHz.
13. Note the indicated resolution bandwidth.
14. Press [ b ] in the RES BW function block.
The LED turns off, and the resolution bandwidth goes to 300 kHz.
15. Press [AUTO].
The LED lights, and the resolution bandwidth is switched back to 5 MHz.
16. Press [AUTO] again.
The LED turns off, but the resolution bandwidth is still 5 MHz. Toggling out
of the AUTO mode with [AUTO] maintains the automatically selected
resolution bandwidth until you change it with a RES BW arrow key.
Video Filter
700.0MHz (AUTO SWEEP) ATTN 20DB
28.8DBMV VF WIDE
50.0MHz/ 10 DB/
5MHz RBW (AUTO) Channel Name CH nn
CALIBRA T OR
A video filter is a postdetection filter (sometimes referred to as a noise-averaging
filter) used to reduce noise in the displayed spectrum to its average value,
making low-level signals more easily detectable. Normally, the 2715 uses a
video filter about as wide as the resolution bandwidth. This limits postdetection
noise, but does not significantly alter the displayed amplitude of narrow-band
signals. However, if you must measure very wideband or pulse-like signals, you
may wish to use a filter somewhat wider than that automatically selected by the
2715. See Menu-Entered Control Settings on page 6–60.
The video filter width is indicated in the on-screen readouts by VF bandwidth,
where bandwidth is equal to the bandwidth of the video filter being used. This is
true except in the case of the 5 MHz or the 1 MHz filter where the WIDE video
filter is automatically selected. You can select WIDE video filter for any
resolution bandwidth.
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Dedicated Controls
When you press [VID FLTR], the 2715 automatically selects a narrower video
filter bandwidth approximately 1/100 of the resolution BW (specifying particular
filter bandwidth using the UTIL menu is described later in this section). The
narrow video filter dramatically reduces the noise and enhances the visibility of
narrow-band signals. Care must be taken, though, because it will also reduce the
indicated amplitudes of wideband signals such as video modulation and short
duration pulses.
The following steps demonstrate the effects of the video filter:
1. Ensure that the 2715 is set as in the settings box on page 4–14, and note if
the signal peaks at 700 MHz, 800 MHz, and 900 MHz are visible.
2. Press [VID FLTR].
The red LED below the key lights, indicating that a narrow video filter is
being used, and the bandwidth of the filter is indicated on screen.
Notice how much less noisy the lower portion of the spectral display appears. By
filtering the noise, it is sometimes possible to reveal low-level signals that are in
the noise. This is the primary reason for using a video filter. The signal peaks at
700 MHz, 800 MHz, and 900 MHz (the seventh, eighth, and ninth harmonics of
the calibration signal) should now be visible. There are small differences from
instrument to instrument, but you should be able to spot the peaks above the
noise.
Video filtering works well for continuous wave and other narrow-band signals,
but when examining pulsed or wideband signals such as television video
(especially the sync pulses), a video filter may prevent you from accurately
seeing signal characteristics in much the same way that using a resolution
bandwidth that is too narrow does.
Although it may not have been apparent, the sweep speed also decreased in order
to accommodate the longer time constant of the video filter. Just as with the
resolution bandwidth filter, a signal needs more time to reach its peak amplitude
when propagating through a narrow video filter.
3. Press [VID FLTR] again to toggle the video filter off.
2715 User Manual
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Dedicated Controls
Vert Scale
The Vert Scale controls select from the available logarithmic vertical scale
factors or convert to the linear mode.
100.0MHz (AUTO SWEEP) ATTN 6DB
23.8DBMV VF WIDE
20.0MHz/ 10 DB/
5MHz RBW (AUTO) Channel Name CH nn
CALIBRA T OR
10/5/1. The VERT SCALE function block contains a three-way toggle key
labeled 10/5/1. This label expresses the three logarithmic vertical scale factors
available on the 2715: 10, 5 and 1 decibels per major vertical division. Press the
key to cycle the vertical scale factor through the three values in a 10 dB –5 dB
–1 dB –10 dB... sequence.
1. Press [10/5/1].
The signal peak is now one division down from the reference level. Also, the
vertical scale factor readout now indicates 5dB/. The noise also seems to
have disappeared; the signal-to-noise difference is the same, but the scale
factor change has moved the noise below the bottom of the screen.
2. Press [10/5/1] again.
The signal peak is now five divisions down and the readout says 1 dB/. The
primary use for this feature is to more accurately read displayed signal peaks.
3. Press [10/5/1] once again to restore the 10dB/ setting.
LIN. The second key in the VERT SCALE function block is also toggle-action. It
converts the vertical scale from logarithmic to linear and back again.
4. Ensure that the calibration signal is centered and the reference level is set to
23.8 dBmV.
5. Press [LIN].
The vertical scale readout now indicates 1.94MV/. When the LIN mode is
initially selected, the 2715 converts the vertical scale so the bottom graticule
line is 0 V and the scale factor is converted from dB to volts. The display is
similar to what you see on an oscilloscope. Thereafter, the REF LEVEL
arrow keys change the scale factor in a 1-2-5 sequence. Consequently, the
reference level changes by 6 or 8 dB when changing scale factors. If the
FINE reference level step size is selected while in the LIN mode, the arrow
keys change the scale factor at a rate of approximately 0.02 division per step
and the corresponding reference level changes approximately 0.2 dB.
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Sweep
Dedicated Controls
6. Press [LIN] to toggle back to logarithmic mode.
When switching back to logarithmic from linear, the last selected log scale is
implemented.
100.0MHz (AUTO SWEEP) ATTN 0DB
–21.2DBMV VF 3KHz
50.0KHz/ 10 DB/
10KHz RBW (AUTO)
The Sweep function block controls the 2715 normal sweep rate, auto sweep, and
single sweep feature (other trigger modes are discussed in SWP/TRIG on page
6–83). The rate at which the CRT beam sweeps across the screen is known as the
sweep rate. It is also the rate at which the displayed spectrum is swept.
Arrow Keys. Normally, sweep rate is automatically selected by the 2715.
However, in some cases, such as when looking at the time domain representation
of a signal in zero span, you may want to vary the sweep rate for a better view of
the signal:
1. Ensure that the calibrator is turned off, and enter the zero span mode.
The currently selected sweep rate is displayed on screen as the horizontal
scale factor in zero span mode and has units of time/division (in the spectral
mode, view the sweep rate by pressing [SWP/TRIG]). The sweep rate
readout indicates 50MS/ZSPAN (50 ms/div in zero span) and the internal
noise is displayed.
2. Press [ b ].
The LED below AUTO in the SWEEP function block turns off, indicating
the sweep rate is no longer being automatically selected.
3. Press [ b ] continuously until the sweep rate readout changes to
1MS/ZSPAN.
The SWEEP down arrow key decreases the sweep rate in a 1-2-5 sequence.
The noise on the trace is no longer visible. Variations in the noise waveform can
be seen occurring in a millisecond or less. Even faster sweep rates are possible
(1 ms/div) with display storage disabled.
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Dedicated Controls
4. Press [ y ] several times.
The noise is compressed to a grass-like appearance and the indicated sweep
rate increases. The SWEEP [ y ] key increases the sweep rate in a 1-2-5
sequence.
The [ b ] and [ y ] keys perform reciprocal actions; they decrease or increase
the time required to sweep one division. Pressing either key removes the 2715
from the automatic sweep rate selection mode, and [ y ] or [ b ] thereafter
function like the sweep rate selector on a conventional oscilloscope.
NOTE. Because sweep rate is the inverse of sweep speed, decreasing sweep rate
increases sweep speed.
5. Reset the sweep rate to 50 ms/div and the span/div to 50 kHz.
6. Set the reference level to 38.8 dBmV, and turn on the calibrator.
7. Press [ b ] repeatedly to reduce the time/div.
A beep sounds and the word UNCAL appears.
8. Continue to press [ b ] to increase the sweep speed, and notice the signal
peak decrease and shift to the right.
This condition occurs when sweeping too fast for a given resolution BW and
demonstrates how measurement errors can occur. The resolution filter is
sweeping so fast that its output does not have time to reach steady-state.
9. Reselect ZERO SPAN.
The UNCAL message disappears, because in the zero span mode the filter is
not being swept at all.
10. Reset the displayed sweep speed to 1 ms/div.
AUTO. The AUTO key in the SWEEP function block serves two purposes. First,
it is used in much the same way as the AUTO key in the RES BW function
block — as a toggle-action key that switches the 2715 between automatic and
manual selection of sweep rate. When AUTO sweep rate selection is active, the
sweep rate selected by the 2715 depends on the span/div, resolution bandwidth,
and video filter in use. Second, pressing the SWEEP AUTO key when the 2715
is in the single sweep mode exits from that mode.
4–18
11. Press [ZERO] to exit the zero span mode.
Notice how distorted the calibration signal is.
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Dedicated Controls
12. Press [AUTO] in the SWEEP function block.
The LED below the key lights, indicating that the sweep rate is being
automatically selected by the 2715. The sweep rate is now 50 ms/div, the
UNCAL message has disappeared, and the calibration signal is correctly
indicated as 18.8 dBmV at 100 MHz.
13. Press [AUTO] again in the SWEEP function block.
The LED turns off but the display does not change. Toggling out of
the AUTO mode maintains the automatically selected rate until you change it
with [ y ] or [ b ].
14. Reactivate the AUTO sweep mode.
SINGLE SWEEP
100.0MHz (AUTO SWEEP) ATTN 20DB
38.8DBM VF 300KHz
1.0MHz/ 10 DB/
300KHz RBW (AUTO)
The 2715 is equipped with a single-sweep feature. When activated by pressing
[SINGLE], the 2715 makes only one sweep. Other controls (except AUTO in
the SWEEP function block) operate normally, and signals at the input to the
2715 are treated just as they would be otherwise. Pressing [AUTO] in the
SWEEP function block exits from the single sweep mode.
When a sweep begins will depend on how the 2715 is triggered. The factory
default mode is free run; this is the mode the 2715 currently should be in.
15. Set the resolution BW to 3 kHz.
The sweep now takes two seconds.
16. At midsweep, press [SINGLE].
The current sweep is aborted and the message SGLSWP MODE appears on
screen under the right readout column. The message means the sweep circuit
is in the single sweep mode and halted.
2715 User Manual
17. Press [SINGLE] again.
This prepares the sweep to begin as soon as it receives the next trigger signal
(which occurs automatically in the free-run mode). A message reading
SGLSWP ARM momentarily appears and a single sweep is carried out. The
sweep will progress across the screen as a new spectral display is created.
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Dedicated Controls
When the sweep is completed, the SGLSWP MODE message reappears
indicating the 2715 has completed the sweep and is ready to be rearmed.
If the 2715 is not in the free-run trigger mode (see SWP/TRIG on page 6–83 to
change modes), behavior is much the same.
Pressing [SINGLE] causes the current sweep to abort and the SGLSWP MODE
message to appear. If you press the key again, the SGLSWP ARM message
appears. This time, however, the 2715 waits for the first designated trigger
signal; when detected, a single sweep begins. After the sweep is complete, the
SGLSWP MODE message reappears.
You can start a new single sweep in any trigger mode as often as you wish by
pressing [SINGLE] after the SGLSWP MODE message appears.
18. Press [AUTO] in the SWEEP function block to exit from the single-sweep
mode.
The single-sweep mode is useful when you want to prevent a succeeding sweep
from overwriting a trace you just acquired or to capture the characteristics of
intermittent signals.
Level
Display Storage
There is a dual, concentric-shaft LEVEL control below the FREQ/MKRS knob.
The inner knob controls the triggering level when the 2715 is in internal,
external, or line trigger modes, just as the equivalent control does on a conventional oscilloscope. It also controls the horizontal sweep position in the manual
scan mode. It has no effect in the other trigger modes.
The outer knob controls the volume of the AM and FM demodulators and picture
framing in video monitor mode.
Alternate uses of the LEVEL control are discussed under DEMOD on page 6–56
and Manually Scanning on page 6–89.
The 2715 can display an analog spectrum of up to four sampled and stored
digital spectra. A major advantage of display storage is that it results in a
flicker-free sweep.
100.0MHz (AUTO SWEEP) ATTN 20DB
38.8DBM VF 300KHz
5.0MHz/ 10 DB/
300KHz RBW (AUTO) CALIBRA T OR
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Dedicated Controls
Display Registers. The digital display storage registers are named A, B, C, and D.
Their status is controlled by the [A], [B], [C], and [D] keys; the red and green
LEDs below each key indicate the status of the corresponding register. When a
red LED is illuminated, the contents of the corresponding register are displayed.
The contents of a register can be either the measurement currently being carried
out or previously saved data.
When only a red LED is illuminated, the register contents are the result of the
2715’s current activity. Current results are updated from the signal at the 2715
input during each sweep. The present control settings are used for the update.
When an A, B, or C green LED is illuminated, the corresponding register
contains a saved sweep (the on-screen readouts are saved along with the sweep).
A saved sweep cannot be erased, modified, or updated without operator
interaction.
When the D green LED is lighted, the 2715 is in the “waterfall” mode.
[A], [B], [C], and [D] are toggle-action keys that activate and deactivate the
display registers. A register’s contents are displayed only when it is active (red
LED lighted), although it still contains saved data as long as its green LED is
lighted.
1. Press [C] to turn on the C register.
The only change that might be apparent is an increase in intensity, since the
2715 is now displaying the C trace on top of the D trace.
2. Press [A] and [B] to turn on the A and B registers.
There may be an increase in intensity, but the shape of the spectral display
should not change because each register contains exactly the same information.
3. Press [B], [C], and [D] to deactivate the B, C, and D registers.
This display is no different than the D register waveform. Verify this by
turning on the D register and turning off A (press [D] and then [A]). Verify
that this is true of the other registers by alternately switching a new one on
and the previous one off.
Deactivate all registers to display the analog output of the 2715.
Note its similarity to the MAX/MIN display.
Any time all four red LEDs are extinguished, the analog output of the 2715’s
detector is displayed. The digitizer is still working; you have just disabled all the
display registers. The analog display can be very useful for viewing time-varying
modulation such as television video signals.
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Dedicated Controls
It is also useful if you are used to a spectrum analyzer that may not have digital
display capabilities; since it provides a display you are familiar with and allows
you to see the similarity between the MAX/MIN display and the analog signal.
You can usually obtain a sharper analog display, especially at higher sweep
speeds, by varying the intensity (see INTENSITY on page 4–35) and/or turning
off the on-screen readouts.
4. Activate the D register.
SA VE ENABLE, A, B, C Registers. The SAVE ENABLE key modifies the function
of the [A], [B], [C], and [D] keys. When used with [A], [B] or [C] key, it enables
you to save the current digitizer output in the corresponding register.
NOTE. The CATV mode assumes full control of the waveform storage registers.
Therefore, waveforms stored manually will be erased when CATV mode is
activated at power-up, during a reboot cycle ([UTIL] [5] [0] [9]), or when it is
reactivated after having been disabled.
5. Press [SAVE ENABLE] to manually save a waveform.
The red LED below SAVE ENABLE lights. This indicates that the SAVE
function is armed.
6. Press [A] to save into the A register what is presently being displayed.
The green LED below [A] lights, but observe that the A register was turned
off and remains turned off.
7. Press [D] to turn off the D register.
8. Press [A] to turn on the A register.
Notice that the display does not change with time. The contents of the
A register are not being updated. You are viewing a saved sweep.
9. Now save a waveform into the B register.
10. Activate the B register and ensure the A register is turned off.
11. Set the resolution bandwidth to 30 kHz.
12. Press [SAVE ENABLE] [B].
The current sweep is saved and the B green LED lights. The register remains
active, but because it is now saved, it is no longer updated.
4–22
NOTE. Status of the red LED is not changed by the save operation.
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Dedicated Controls
13. Deactivate all registers (all red LEDs extinguished).
14. Set the resolution bandwidth to 5 MHz.
15. Press [SAVE ENABLE] [C].
The green C LED lights.
16. Activate the C register.
The digitized and saved version of the analog sweep is displayed. The
digitizer is continuously updated, whether it is being displayed or not.
Further, it is always the current digitizer output that is saved. You cannot, for
instance, save one register into another. However, nonvolatile RAM does
make it possible to permanently save the contents of the display registers by
transferring them to stored settings registers (see Other User-Defined
Settings on page 6–63).
17. Press [SAVE ENABLE] [A] to deactivate the C register and activate A.
The A green LED turns off, indicating there is nothing stored in the
A register. The register remains active, but the displayed spectrum is now
updated during each sweep.
The on-screen readouts are stored along with the sweep. Since the 2715 displays
only one group of readouts at a time, the readouts for the highest priority register
are displayed when multiple registers are active. Register priority is shown in the
following chart.
Priority
Highest D-register, current waveform
: C-register, current waveform
: B-register, current waveform
: A-register, current waveform
: D-register, saved waveform
: C-register, saved waveform
: B-register, saved waveform
Lowest A-register , saved waveform
Register
To see how register priority works, view some spectra:
18. Turn off A, turn on B, and note the on-screen readouts.
The indicated resolution bandwidth should read 30 kHz.
2715 User Manual
19. Turn on C.
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Dedicated Controls
The resolution bandwidth should read 5 MHz (C has a higher priority than
B, so its readouts are displayed).
20. Turn on the A register and set the resolution bandwidth to AUTO.
Notice the RBW readout change. Any register containing a current sweep
has a higher priority than a register containing a saved sweep, so the
A-register readouts are now displayed.
21. Clear and deactivate the B and C registers. Leave only the D register active.
The SAVE ENABLE key changes the function of the D key. [SAVE ENABLE]
[D] places the 2715 in the waterfall mode (symbolized by the
icon below the
D key). This waterfall display is more effective in peak acquisition mode
(discussed under DSPL on page 6–27).
100.0MHz (AUTO SWEEP) ATTN 40DB
58.8DBM VF 300KHz
5.0MHz/ 10 DB/
300KHz RBW (AUTO) CALIBRA T OR
22. Press [DSPL] [4] to enter the peak acquisition mode.
23. Press [SAVE ENABLE] [D] to enter the waterfall mode.
All eight of the register status LEDs light and four traces appear. Registers
A, B, and C must be cleared before the 2715 allows you to enter the
waterfall mode, because the waterfall mode uses all four registers. This is a
safeguard to prevent accidental overwriting of previously saved data. If you
attempt to enter this mode without first clearing the registers, you receive an
error message.
Look at Figure 4–1. D is the bottom waveform and A the top. Each waveform is
displaced upwards one division from the preceding waveform and shifted 1/2
division to the right. The current sweep is in the D register, the previous sweep
in C, the next previous in B, and so on. At the end of each sweep, the waveforms
are all shifted up one register. This display can be used to watch slowly varying
spectra evolve or to obtain a feel for the variability of signals. Waterfall can also
be useful for catching an event that occurs quickly. In the present case of the
calibration signal, you will observe that there is virtually no variation.
4–24
24. Create a small signal shift by slightly changing the center frequency.
Notice how the waterfall mode records the shift.
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1/2 Division Displacement
Dedicated Controls
Registers
A
B
C
D
Oldest
Sweep
Newest
Sweep
Figure 4–1: Example of a Waterfall Display
25. Press [SINGLE] in the SWEEP function block to halt the waterfall action.
Thereafter, each time you press [SINGLE] the waterfall will advance one
trace.
26. Press [AUTO] in the Sweep function block to exit from the single sweep
mode and continue the waterfall display.
You do not have to view all the traces.
27. Turn off the A and C registers.
28. Turn off B and D registers.
29. Turn A and C registers back on.
You can view any, all, or none of the registers. Turn them all off and the
analog display reappears. However, the 2715 is still in waterfall mode. You
cannot selectively erase a register or store new data in it without first exiting
from the waterfall mode.
30. Turn on all registers.
31. Press [SAVE ENABLE] [D] to exit from the waterfall display mode.
All LEDs except the red D turn off, and the waterfall display collapses to a
single D register trace.
32. Reset the center frequency to 100 MHz.
33. Press [DSPL] [4] to return to the MAX/MIN acquisition mode.
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Dedicated Controls
MAX HOLD A & B. The A and B registers can be used in the MAX HOLD mode to
save the peak values of measured spectra. The register must be cleared before
you can use it in the MAX HOLD mode.
The MAX HOLD feature compares the amplitude of the current sweep, point for
point, with the stored maximum value of previous sweeps. If the current
amplitude is greater, the current value becomes the new stored maximum; if not,
the previous value is retained.
34. Deactivate the D register.
35. Make sure the A register is cleared and activated, then press
[MAX HOLD A & B].
The red LED below the MAX HOLD A & B key lights signifying that you
have entered the MAX HOLD mode. The spectral display, especially the
noise, is much smoother. After several minutes, the noise floor appears to
drift upwards a couple of dB. Because the calibration signal is constant, there
is no noticeable change in it. The upward drift of the noise floor slows and
stops as the most likely maximum values are observed and stored. Now only
an occasional noise peak exceeds the previously stored values.
Freq/Mkrs
36. Activate the D register.
Note that the waveform in the D register (waveform without MAX HOLD)
is always less than the A register waveform. Recording the peak signal
excursions observed during a large number of sweeps using the MAX HOLD
feature yields an estimate of the maximum signal values. It can also be very
useful for determining maximum signal amplitude during transient conditions or for making low-level fluctuating signals more apparent by saving
their peak value. You can observe as many sweeps as you wish. You could
equally as well have used the B register for MAX HOLD.
37. Press [MAX HOLD A & B] when you are ready to exit the MAX HOLD
mode.
The red LED goes out, and only the D register sweep remains.
A feature called MIN HOLD, similar to MAX HOLD and activated by pressing
[DSPL] [9], saves the minimum signal values. Using both MIN HOLD and
MAX HOLD, you can measure a signal’s total excursion.
The Freq Mkrs controls select single and delta markers, select center measure
tracking, and control the marker peak find features.
4–26
MKR/
/OFF. The MKR/D/OFF key is a three-way toggle that enables you to
control one, or a pair, of markers. A marker is a bright spot that appears on the
digitized waveform. Markers can be used only with the digital display. When the
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Dedicated Controls
marker mode is turned off, the spot on the display indicates either the center or
starting frequency of the display. When a single marker is turned on, it can be
moved to any point along the displayed waveform using the FREQ/MKRS knob.
The corresponding signal amplitude and frequency are displayed on screen. The
marker amplitude readout represents the most accurate method for determining
signal amplitude with the 2715 (unless a separate, extremely precise signal is
used for direct comparison). In general, amplitude accuracy is further enhanced if
the signal being measured is first moved to within one division of the top
graticule line using the REF LEVEL controls.
In delta (D) marker mode, two markers designate the points on the waveform
between which the differences in signal amplitudes and frequencies are measured
and displayed. It is not possible to display one marker on a particular trace while
displaying the second marker on another trace. More than one register can be
displayed, but the markers appear only on the highest priority waveform.
1. Press [MKR//OFF] to activate the marker.
The sweep does not change, but the RF attenuation and video filter readouts
have been replaced by approximate marker frequency and amplitude readouts
such as the following:
M 100.0MHZ
M 18.8DBMV
The M preceding the readouts represent the amplitude and frequency of the
signal at the marker position.
2. Turn the FREQ/MKRS knob several clicks clockwise.
The marker moves to the right and the readout tracks it. The knob now
controls the marker position rather than the center frequency.
3. Turn the FREQ/MKRS knob to move the marker into the noise.
Notice that the marker actually moves up and down between the max and
min noise values on alternate clicks of the knob. This is because each click
of the knob moves the marker to the next bit in the digital waveform
memory, thus tracking the stored max and min values.
4. Turn the FREQ/MKRS knob counterclockwise and the marker moves left.
Again, the readout tracks the signal amplitude and frequency at the marker
position.
Be aware that the marker frequency accuracy is not as good as the center
frequency accuracy because it includes a span nonlinearity component (see
CTR-MEAS/TRKG on page 4–29 for a discussion of frequency measurement
accuracies).
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Dedicated Controls
If you attempt to move the marker past either edge of the display, the spectrum
will move towards the opposite edge while the marker remains stationary. If you
move the marker past the right edge, the signal peak moves to the left.
5. Turn the FREQ/MKRS knob a few clicks counterclockwise.
The marker moves to the left but the spectrum will not move back towards
its original position until you attempt to move the marker past the other edge
of the display.
6. Recenter the calibration signal peak by trying to move the marker past the
left edge of the display.
7. Ensure the marker and the calibration signal peak are centered, and press
[MKR//OFF] again.
The spectral display did not change, but the marker frequency and amplitude
readouts now read something like the following:
D 0KHZ
D 0.0DB
The delta-marker mode is turned on.
8. Turn the tuning knob clockwise.
Now you can see both markers. One remains at the original marker position
while the position of the second is controlled by the knob. The right column
indicates the difference (denoted by the letter D preceding the readouts) in
frequency and amplitude between the two marker positions.
9. Increase the span to 50 MHz/div.
10. Use the tuning knob to place the movable marker at the top of the first signal
peak to the right of center (the calibration signal second harmonic).
The right column now reads as follows:
D 100MHz
D –13.0 DB
NOTE. The values displayed by your instrument may not exactly match those
illustrated.
You are measuring the difference in frequency and amplitude between the
fundamental and second harmonic of the calibration signal. Your instrument may
not read these values exactly, but it should be close.
4–28
If you attempt to move the movable marker past the edge of the display, you will
see that the spectral display behaves almost the same as it did for the single
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