Agilent 53181A Operations Guide

HP 53181A 225 MHz Frequency Counter

Operating Guide

This guide describes how to use the HP 53181A 225 MHz Frequency Counter. The information in this guide applies to instruments having the

number prefix listed below, unless accompanied by a “Manual Updating Changes” package indicating otherwise.

SERIAL PREFIX NUMBER: 3409 AND ABOVE

HP 53181A 225 MHz Frequency Counter



Printed: January 1999 Printed in USA

Manual part number 53181-90001

Certification and Warranty

Certification

Hewlett-Packard Company certifies that this product met its published specification at the time of shipment from the factory. Hewlett-Packard further certifies that its calibration measurements are traceable to the United States National Institute of Standards and Technol ogy (formerly National Bureau of Standards), to the extent allowed by the

Institute’s calibration facility, and to the calibration facilities of other International Standards Organization members.

Warranty

HP warrants HP hardware, accessories and supplies against defects in materials and workmanship for a period of three years from date of shipment. If HP receives notice of such defects during the warranty period, HP will, at its option, either repair or replace products which prove to be defective. Replacement products may be either new or like-new.

HP warrants that HP software will not fail to execute its programming instructions, for the period specified above, due to defects in material and workmanship when properly installed and used. If HP receives notice of such defects during the warranty period, HP will replace software media which does not execute its programming instructions due to such defects.

For detailed warra nty information, see back matter.

Safety Considerations General

This product and related documentation must be reviewed for familiarizat ion with this safety marki ngs and instructions before operation.

Before Cleaning

Disconnect the product from operating power before cleaning.

Warning Symbols That May Be Used In This Book

Instruction manual symbol; the product will be marked with this symbol when it is necessary for the user to refer to the instruction manual.

Indicates hazardous voltages.

Indicates earth (ground) terminal.

Indicates terminal is con n ected to chassis when such connection is not apparent.

Indicates Alternating current.

Indicates Direct current.

Safety Considerations (contd)

WARNING

BODILY INJUR Y OR DEATH MAY RESULT FROM FAILURE TO HEED A WARNING. DO NOT PROCEED BEYOND A WARNING UNTIL THE INDICATED CONDITIONS ARE FULLY UNDERSTOOD AND MET .

CAUTION

Damage to equipment, or incorrect measurement data, may result from failure to heed a caution. Do not proceed beyond a CAUTION until the indicated conditions are fully understood and met.

Safety Earth Ground

An uninterruptible safety earth ground must be maintained from the mains power source to the product’s ground circuitry.

WARNING

WHEN MEASURING POWER LINE SIGNALS, BE EXTREMELY CAREFUL AND ALWAYS USE A STEP-DOWN ISOLATION TRANSFORMER WHICH OUTPUT IS COMPATIBLE WITH THE INPUT MEASUREMENT CAPABILITIES OF THIS

PRODUCT. THIS PRODUCT’S FRONT AND REAR PANELS ARE TYPCIALLY AT EARTH GROUND.

TO MEASURE AC POWER LINE SIGNALS WITHOUT AN ISOLATION TRANSFORMER.

For additional safety and acoustic noise information, see back matter.

THUS, NEVER TRY

Hewlett-Packard Company 7.NC.NL.A.11.03.97.R1.P.CW6FC Santa Clara Division 5301 Stevens Creek Boulevard Santa Clara, California 95052-8059

Contents

In This Guide

Contents and Organization xii Related Documents xiii Types of Service Available if Your Instrument Fails xiv

Standard Repair Services (Worldwide) xiv Express Repair/Performance Calibration Service

(USA Only) xiv Repair Instrument Yourself xiv

Repackaging for Shipment xv Description of the 225 MHz Frequency Counter xvi Options xvii

Hardware xvii Support xvii

Accessories Supplied and Available xviii

Accessories Supplied xviii Accessories Available xviii

HP 53181A Quick Reference Guide xix

1 Getting Started

The Front Panel at a Glance 1-2 The Front Panel Indicators at a Glance 1-3 The Front Panel Indicators at a Glance (Cont.) 1-4 The Front Panel Menus at a Glance 1-5 The Front Panel Menus at a Glance (Cont.) 1-6 The Front Panel Menus at a Glance (Cont.) 1-7 The Display Annunciators at a Glance 1-8 The Display Special Characters at a Glance 1-9

The Underscore Placeholder 1-9 The Asterisk Placeholder 1-9

Operating Guide iii

Contents

The Limit Test Graph Characters at a Glance 1-10 The Rear Panel at a Glance 1-11 Making Measurements 1-12

To Measure Frequency 1-14 To Select Input Coupling and Impedance 1-15

Selecting Input Coupling 1-15 Selecting Input Impedance 1-15

To Set Input Channel Trigger Level/Sensitivity 1-16

Changing Trigger Mode 1-16 Modifying Input Trigger Level 1-17 Selecting Input Trigger Slope 1-18 Selecting Input Sensitivity 1-18 Starting the Measurement 1-19

To Select Scale and Offset 1-19

Entering the Scale Value 1-19 Entering the Offset Value 1-20 Displaying the Math Results 1-21 Disabling Math 1-22

To Set Limits of Measurements 1-23

Setting the Upper Limit 1-24 Setting the Lower Limit 1-25 Setting the Counter to Flag and Stop Measuring On

Out-of-Limit Measurements 1-27 Setting the Counter to Flag On Limits But Continue

Measuring 1-28 Disabling Limit Testing 1-28 Disabling Math 1-29

To Perform Statistics on Measurements 1-29

Selecting the Type of Statistics (Stats) 1-29 Computing Stats on Filtered Data Only 1-31 Displaying Stats After Filtering Data of Input

Signal 1-33 Disabling Stats and Math 1-34

To Control Measurement 1-35

iv Operating Guide

Contents

2 Operating Your Frequency Counter

Introduction 2-2

Chapter Summary 2-2 Where to Find Some Key Working Examples 2-3

How this Counter Wor k s for You 2-4 Summary of the Measurement Sequence 2-5 Using the Measurement Control Keys (Run and Stop/

Single) 2-6

Overview of the Measurement Control Keys 2-6 To Use the Measurement Control Keys 2-7

Using Entry/Select (Arrow) Keys 2-9

To Use During Numeric Entry 2-9 To Use When Sequencing Through the Other Meas and

Recall Menus 2-9 To Use During State Changing (ON/OFF, LO/MED/

HI, etc.) 2-10 To Use on Prompted Help Messages (MATH HELP: NO/

YES, PRT HELP: NO/YES) 2-10

Using the MEASURE Menu Keys 2-11

Overview of the MEASURE Menus 2-11 To Measure Frequency 2-12 To Measure Frequency Ratio (Optional) 2-13 To Measure Period 2-13 To Measure Positive/Negative Volt Peaks 2-14

Using the Gate & External Arm Menu Key 2-15

Overview of Gate/External Arming Functions 2-15

TIME Arming 2-15 AUTO Arming 2-15 EXTERNAL Arming 2-15 DIGITS Arming 2-16

To Use the Gate and External Arm 2-17

Example Procedure for Gate and External Arm 2-17

Operating Guide v

Contents

Example Procedure for Changing the Number of Digits of Resolution Displayed for More Precise Measurements 2-19

Using the MATH Menu Keys 2-21

Overview of Scale/Offset Math Menu 2-21 To Use the Scale/Offset Math Menu 2-22

Example Procedure for Scale Function 2-22 Example Procedure for Offset Function 2-23 Example Procedure for Turning Off Math Mode 2-25

Example Procedure for Set Reference Function—Offset From the Last Measurement Value (Seeing Digits Not

Visible on the 12-Digit Display) 2-25 Overview of Statistics (Stats) Menu 2-26 To Use the Stats Menu for Automatic and Continuous

Statistical Analysis 2-27

Example Procedure for Computing Stats 2-27

Example Procedure for Easy Viewing of Stats 2-28

Example Procedure for Filtering Data (Using Limits)

During Stats 2-29

Example Procedure for Configuring SINGLE to Initiate

N Measurements 2-30

Example Procedure for Turning Off Stats Mode 2-30

Using the LIMITS Menu Keys 2-31

Overview of Limits Menus 2-31 To Set and Use Automatic Limit Testing 2-32

Limits Testing Example 1—Flag and Stop Measuring

On L imits 2-32

Limits Testing Example 2—Flag On Limits but

Continue Measuring 2-34

Limits Testing Example 3—Use Analog Graph Display

While Adjusting/Aligning Input Signal 2-34

Limits Testing Example 4—Selecting Filtering

Conditions of Stats Computation 2-36

vi Operating Guide

Contents

Limits Testing Example 5—Sending the Limit-Detect Output to the RS-232 Serial Port 2-38

Using the DISPLAY Digits Keys 2-39

Overview of the DISPLAY Digits Keys 2-39 To Use the DISPLAY Digits Keys 2-40

Using CHANNEL 1 Input Conditioning Keys 2-41

Overview of Trigger/Sensitivity Menu 2-41 To Use the Trigger/Sensitivity Key to Adjust Counter’s

Trigger Voltage and Sensitivity Levels 2-44 Overview of Input Conditioning Toggle Keys 2-47

Using the Save and Recall Menus 2-48

Overview of Save and Recall Functions 2-48 To Use the Save Function 2-49 To Use the Recall Function 2-50 To Unsave a Measurement Setup 2-51

Using the Print Menu 2-52

Overview of the Print Menu 2-52 To Use the Print Menu 2-52

Using the Utility Menu 2-53

Overview of the Utility Menu 2-53 To Set the HP-IB Address 2-54

Selecting Operating Mode (Talk/Listen, TalkOnly) 2-54

Setting the HP-IB Address 2-54 To Choose the Timebase Source 2-55 To Run the Self-Test Routines 2-56

Overview of the Self-Test Routines 2-56

Example Procedure for Running the Self Test 2-57 To Configure the RS-232 Serial Port for Printing 2-58

Setting the Hardware Pacing 2-58

Setting the Baud Rate 2-59

Setting the Parity 2-59

Setting the Software Pace 2-59

Operating Guide vii

Contents

To Configure the RS-232 Serial Port for Sending Limit-Detect Output 2-60

To Select the Numerical Convention for the Display 2-61 To Connect the Counter to a Serial Printer via the RS-232

Port 2-61 To Connect the Counter to a Printer via HP-IB 2-62 To Select the HP-IB Talk-Only Mode for Printing 2-62

Front Panel Display Messages 2-63

Measurement Result Displays 2-63 Power-Up/Self Test Messages 2-64 Menu Messages 2-65 HP-IB Messages 2-67

Preset Values After Power-up and *RST 2-68

Preset Values for Functions Accessible Via Front Panel or HP-IB 2-68

Preset Values for Functions Accessible Via HP-IB Only 2-72

Common Questions 2-74

Why is Stats result not available yet? 2-74

Why won’t printer work? 2-74 Why did Counter stop measuring? 2-74 Why did Counter go to its default state after I set up my RS-

232 port? 2-74 Counter’s numeric display does not follow the numerical

convention for my country. 2-74

3 Specifications

Introduction 3-2

Instrument Inputs 3-2 Instrument Inputs (Continued) 3-3 Time Base 3-4 Measurement Specifications 3-5 Measurement Specifications (Continued) 3-6

viii Operating Guide

Index

Contents

Measurement Specifications (Continued) 3-12 Measurement Definitions 3-15 Measurement Arming and Processing 3-16 General Information 3-17

Operating Guide ix

Contents

x Operating Guide

In This Guide

This book is the operating guide for the HP 53181A 225 MHz Frequency Counter. It consists of a table of contents, this preface, a quick reference guide, three chapters, and an index.

This preface contains the following information:

• Contents and Organization

• Related Documents

• Types of Service Available if Your Instrument Fails

• Repackaging for Shipment

• Description of the 225 MHz Frequency Counter

•Options

• Accessories Supplied and Available

page xii page xiii page xiv page xv page xvi page xvii page xviii

Operating Guide xi

In This Guide

Contents and Organization

The Table of Contents lists the beginning of each chapter in the guide, helping you locate information.

The Preface introduces you to the operating guide, the Frequency Counter, and provides general information about the Counter.

The Quick Reference Guide consists of a Menu Tree (tear-out sheet) that serves as a tool to trigger your memory or get you quickly reacquainted with the instrument, and Menu Roadmaps that illustrate how to navigate through the menus. It is located after this preface.

Chapter 1, “Getting Started,” is a quick start guide that gives you a brief

overview of the Counter’s keys, indicators, menus, display, and connectors. Last, a graphical procedure for performing a complete measurement is provided.

Chapter 2, “Operating Your Frequency Counter,” is an operator’s reference. You are given an overview of each group of front-panel keys, operating functions, and menus followed by a series of exercises that guide you through the operation of the Counter.

Chapter 3, “Specifications,” lists the specifications and characteristics of the Counter.

The Index helps you find items easily by arranging information in a sequence different from that found in the Table of Contents, disclosing relationships among items.

xii Operating Guide

In This Guide

Types of Service Available if Your Instrument Fails

If your Counter fails within three years of original purchase, HP will repair it free of charge. If your instrument fails after your 3-year warranty expires HP will repair it, or you can repair it yourself by ordering the service guide.

There are three types of repair services:

• Standard repair service—if downtime is not critical.

• Express Repair/Performance Calibration Service—if downtime is critical.

• Use the Assembly-Level Service Guide and repair the unit yourself.

Standard Repair Services (Worldwide)

Contact your nearest HP Service Center. They will arrange to have your Counter repaired.

Express Repair/Performance Calibration Service (USA Only)

If downtime is critical, you can receive your repaired Counter via overnight shipment. Just call 1-800-403-0801 and ask for Express Repair/Performance Calibration Service. When your Counter is repaired, it will be returned via overnight shipment.

Repair Instrument Yourself

If your Counter 3-year warranty has expired and you choose to repair the instrument yourself or would like more details on self test and calibration, use the procedures in the Assembly-Level Service Guide.

xiv Operating Guide

In This Guide

Repackaging for Shipment

For the Express Repair/Performance Calibration Service described above, return your failed Counter to the designated HP Service Center, using the shipping carton of the instrument. HP will notify you when your failed instrument has been received.

If the instrument is to be shipped to HP for service or repair, be sure you do the following:

• Attach a tag to the instrument identifying the owner and indicating the required service or repair. Include the instrument model number and full serial number.

• Place the instrument in its original container (if available) with appropriate packaging material.

• Secure the container with strong tape or metal bands.

If the original shipping container is not available, place your unit in a container which will ensure at least 4 inches of compressible packaging material around all sides of the unit. Use static free packaging materials to avoid additional damage to your unit.

HP suggests that you always insure shipments.

Operating Guide xv

In This Guide

Description of the 225 MHz Frequency Counter

The HP 53181A is a frequency counter capable of measuring frequencies to 225 MHz on Channel 1. Depending on which optional Channel 2 the counter contains, this capability is extended to 1.5 GHz (Option 015),

3.0 GHz (Option 030), 5.0 GHz (Option 050) or 12.5 GHz (Option 124). The HP 53181A has a frequency resolution of 10 digits in one second.

The HP 53181A provides users with a HP-IB measuring speed of up to 200 measurements per second, and is suitable for bench-top and ATE operation.

The HP 53181A basic measurement functions include Frequency, Period, Peak Voltage, and Frequency Ratio (if Channel 2 is installed).

The HP 53181A includes additional measurement functions and features that are designed specifically for manufacturing and service applications:

• 1, 5, 10 MHz external reference capability—to match customer’s house standard,

• optional ultra high, high, or medium stability oven oscillators for high accuracy needs and lengthened calibration cycles,

• external gating,

• full math and statistics,

• automatic limit testing,

• analog display mode limit testing, and

• SCPI programming capability.

Programmable control is performed via an HP-IB. The HP-IB and a talk-only RS-232C serial port are standard for the HP 53181A. The serial port is for printing measured and analyzed data on serial printers, or for outputting an out-of-limit signal.

xvi Operating Guide

In This Guide

Options

The options available for the HP 53181A 225 MHz Frequency Counter are listed following this paragraph. Specifications for the options are listed in

Chapter 3, “Specifications.” If you’ve purchased an option with the initial order, it will be installed at the factory and ready for operation at delivery. Refer to the “Retrofitting Options” chapter in the Assembly-Level Service Guide for instructions on field installation of the options.

NOTE

The “0s” and “1s” in the following option numbers are numeric characters (that is, they are not letters).

Hardware

• Medium Stability Oven Timebase, Option 001

• DC Power Input, Option 002

• High Stability Oven Timebase, Option 010

• Ultra High Stability Oven Timebase, Option 012

• 1.5 GHz RF Input Channel (Channel 2), Option 015

• 3.0 GHz RF Input Channel (Channel 2), Option 030

• 5.0 GHz RF Input Channel (Channel 2), Option 050

• 12.4 GHz RF Input Channel (Channel 2), Option 124

• Rear Terminals

, Option 060

• Rack Mount Kit, Option 1CM

Support

• 5-year Return to HP for Repair, Option W50

• 5-year Return to HP for Calibration, Option W52

Channel 1 will have both front and rear terminals. Option 015 and Option 124 Channel 2 will have a front

terminal only.

Operating Guide xvii

In This Guide

Accessories Supplied and Available

Accessories Supplied

• Power cord, 2.3 meters

Accessories Available

• HP 34161A Accessory Pouch

• HP 34131A Transit Case

• Printer RS-232 Interface cables, HP 24542G or HP 24542H

• HP-IB cables, HP 10833A/B/C/D

xviii Operating Guide

HP 53181A Quick Reference Guide

The Quick Reference Guide is designed for experienced users of the HP 53181A Frequency Counter. It is intended to be used as a tool to trigger your memory. If you are using the HP 53181A for the first time, HP recommends that you at least read Chapter 1, “Getting Started,”

in the Operating Guide first. The Quick Reference Guide follows this page, and consists of the following

items:

• A Menu Tree which may be torn out of the guide for external use (pages 1 an d 2).

• Menu Roadmaps which illustrate via key-press sequences how to navigate through the menus under the menu keys (pages 3 through 10). Key-press sequences are provided for the following menu keys:

–Freq Ch1 –Freq Ch2 –Other Meas – Gate & ExtArm – Uppr & Lower – Limit Modes – Scale & Offset –Stats – Trigger/Sensitivity

Operating Guide xix

Preface

xx Operating Guide

HP 53181A

Frequency Counter

Freq Ch 1

FREQUENCY 1

Freq Ch 2

FREQUENCY 2

Uppr & Lower

UPPR: 0.000000 LOWR: 0.000000

Other Meas

PERIOD 1 RATIO 1 TO 2 RATIO 2 TO 1 VOLT PEAKS 1

Limit Modes

LIM TEST: OFF

LIM TEST: ON

ON FAIL:GO ON

ON FAIL: STOP

SHOW: NUMBER

SHOW: GRAPH

GATE: TIME

TIME: .100 s

SCALE:1.000000 OFFS: 0.000000 SET REF: NO

SET REF: YES SET REF: HELP

MATH: OFF

MATH: ON

MATH HELP : NO

MATH HELP: YES

GATE: AUTO

Scale & Offset

Gate & ExtArm

START: POS

START: NEG

STOP: AUTO

STOP: NEG STOP: POS STOP: TIME

TIME: .100 s

Stats

SHOW: MEAS

SHOW: STD DEV SHOW: MEAN SHOW: MAX SHOW: MIN

N: 100 STATS: OFF

STATS: ON

USE: ALL MEAS

USE: IN LIMIT

ON SINGLE: 1

ON SINGLE: N

GATE: DIGITSGATE: EXTERNL

DIGITS: 4

HP 53181A

Frequency Counter

Recall

NO REGISTERS RECALL 0 RECALL 1 RECALL 2 RECALL 3 RECALL 4 RECALL 5

RECALL 20

50Ω 1MΩ

CH 1: 50 OHM

CH 1: 1M OHM

Save & Print

SAVE: UNSAVE: PRINT: OFF

PRINT: ON

PRT HELP: NO

PRT HELP: YES

DC AC

CH 1: DC

CH 1: AC

AUTO TRG: ON LEVEL: 50 PCT

SLOPE: POS

SLOPE: NEG

SENSTVTY: HI

SENSTVTY: LO SENSTVTY:MED

X10 Attenuate

CH 1: X10 ATT

CH 1: X1 ATT

Trigger Sensitivity

AUTO TRG: OFF

LEVEL: 0.000V

100kHz Filter

CH 1: LP FILT

CH 1: NO FILT

HP 53181A Frequency Counter

Freq Ch 1

MEASURE

Freq Ch 2

Other Meas

Freq Ch 1

FREQUENCY 1

Freq Ch 2

FREQUENCY 2

Other Meas

PERIOD 1

RATIO 1 TO 2

RATIO 2 TO 1

VOLT PEAKS 1

HP 53181A Frequency Counter

Freq Ch 1

FREQUENCY 1

MEASURE

– – – – – – – – – – – –

Gate & ExtArm

GATE: TIME

GATE: AUTO

GATE: EXTERNL

Gate & ExtArm

GATE: DIGITS

STOP:

TIME: .100

Gate &

TIME: .100

ExtArm

TIME: .200

Gate &

START:

ExtArm

START: POS START: NEG

STOP: AUTO STOP: NEG STOP: POS STOP: TIME

TIME: .200

Gate &

DIGITS: 4

ExtArm

Enter

Gate & ExtArm

RUN

DIGITS: 5

Enter

RUN

HP 53181A Frequency Counter

Uppr & Lower

LIMITS

Uppr & Lower

Limit Modes

Uppr & Lower

Limit Modes

UPPR: 0.000000

Uppr &

LOWR: 0.000000

Lower

LIM TEST:

Limit

ON FAIL:GO ON

Modes

Limit

SHOW: NUMBER

Modes

UPPR: 5.100000

LOWR: 4.900000

LIM TEST: OFF LIM TEST: ON

ON FAIL:GO ON ON FAIL: STOP

SHOW: NUMBER SHOW: GRAPH

Enter

RUN

HP 53181A Frequency Counter

Scale & Offset

MATH

Scale & Offset

SCAL: 1.000000

OFFS: 0.000000

SET REF:

SET REF: NO SET REF: YES SET REF: HELP

MATH:

MATH HELP: YES

MATH HELP: NO

SCAL: 2.000000

OFFS: 0.500000

Enter

OFFS:-nnnnnnn

MATH: OFF MATH: ON

Enter

(MEAS X SCALE) + OFFS = RESULT

RUN

HP 53181A Frequency Counter

Stats

MATH

Stats

SHOW:

SHOW: MEAS SHOW: STD DEV SHOW: MEAN

SHOW: MAX

SHOW: MIN

Stats

N: 100

N: 200

STATS:

STATS: OFF STATS: ON

USE:

USE: ALL MEAS USE: IN LIMIT

ON SINGLE:

ON SINGLE: 1 ON SINGLE: N

Enter

RUN

Run

HP 53181A Frequency Counter

Trigger Sensitivity

CHANNEL 1

Trigger Sensitivity

AUTO TRG:

Enter

Trigger Sensitivity

AUTO TRG: ON

AUTO TRG: OFF

LEVEL: 0.000V

LEVEL: 2.000V

LEVEL: 50 PCT

LEVEL: 80 PCT

SLOPE:

SLOPE: POS SLOPE: NEG

SENSTVTY:

SENSTVTY: HI SENSTVTY: LO SENSTVTY: MED

RUN

Getting Started

Chapter 1 Getting Started

The Front Panel at a Glance

53181A

FREQUENCY COUNTER

Period Freq Ch 1 Ch 2 ExtRef

Remote Error (Flashing)

SRQ

POWER

Utility Menu:

STBY

Hold at power up

1 Measurement function menu keys 2 Limits menu keys 3 Math menu keys 4 Sign (+ or −) selection toggle ke y 5 Data Entry/Select (or arrow) keys 6 Enter numeric data (terminate) key.

MEASURE LIMITS MATH DISPLAY CHANNEL 1

Freq Ch 1

Other Meas

Recall

Freq Ch 2

Gate & ExtArm

LocalUtility

Save & Print

Also tranverses a menu and ex i ts at the end of a menu.

3 GHz

Uppr & Lower

Limit Modes

Run

Scale & Offset

Stats

Stop/ Single

MHz µs

Limit

Gate

More Digits

Fewer Digits

8 Utility menu key (Hold during power-up to

access Utility functions.)

9 Recall, Save and Print menu keys 10 Gate and External Arm menu key 11 Measurement control keys 12 Display Digits keys 13 Channel 1 Trigger/Sensitivity menu key and

input conditioning keys

+/–

Enter

Trigger Sensitivity

50Ω 1MΩ

DC AC

X10 Attenuate

CHANNEL 2

100 MHz to MAX

Damage Lvl: 5V rms MAX.50Ω

0.1 Hz − 225 MHz

Damage Lvl: 5V rms MAX.50Ω

100kHz Filter

7 Channel 2 optional RF input

NOTE

It is normal operation for the fan in the Counter to continue to run after the Counter is placed in Standby mode. Power to the timebase is continuous to maintain long term measurement reliability, and the fan helps maintain timebase temperature stability.

1-2 Operating Guide

Chapter 1 Getting Started

The Front Panel Indicators at a Glance

There are eight different gro ups of indicato rs or LEDs. They are listed and described in the following table.

Indicators Description of the Indicators

When the indicator for the Freq Ch 1 or Freq Ch 2

Freq Ch 1

Other Meas

Scale & Offset

Stats

+/–

Freq Ch 2

Limit Modes

Local Save & Print

Trigger Sensitivity

Enter

keys is lit, it indicates that the Frequency function is enabled for the corresponding input channel.

When the indicator for the Other Meas key is li t , i t

simultaneously indicates that the key’s menu and its menu item (for example, PERIOD 1) is enabled.

When these indicators are lit, the key’s “enable” menu item (that is, Limit Modes/LIM TEST, Scale & Offset/MATH, Stats/STATS, and Save & Print/PRINT) is enabled.

When this indicator is lit, it indicates that auto-triggering is enabled.

When this indicator flashes, it indicates that the arrow keys can be used to modify or enter data.

The Enter key is used to enter numeric values or parameters. It can also be used to traverse through a menu. Pressing the Enter key at the end or bottom of a menu will cause the Counter to exit the menu and return to the measurement mode.

When one of these indicators is lit, it indicates that

Run

Stop/ Single

the Run or Single function is enabled.

Operating Guide 1-3

Chapter 1 Getting Started

The Front Panel Indicators at a Glance (Cont.)

Indicators Description of the Indicators

When this indicator flashes, it indicates that the Counter is triggering on the input signal. If the input signal is too high, this indicator remains ON. If the input signal is too low, this indicator is OFF.

When one of these indicators is lit, it indicates that

50Ω 1MΩ

X10 Attenuate

Remote Error (Flashing)

SRQ

DC AC

100kHz Filter

the adjacent choice (that is, 50Ω, DC, X10, or 100kHz Filter) is enabled or active. Note that when these indicators are not lit, then the other choice (that is, 1MΩ, AC, X1, or no filter) is active.

A lit Remote indicator indicates that the Counter is in remote mode (Note: In the remote mode, the Save & Print key becomes the Local key.)

If (while in remote) an error occurs, the Remote indicator will flash. The indi cator will continue flashing until the controller has read or cleared the error queue, or until the front panel returns to local mode.

An unlit Remote indicator indicates that the Counter is in local mode.

The SRQ indicator indicates that the Counter has requested service from th e controller. The SRQ indicator will remain lit until the controller has recognized the service request and serial poll ed the Counter, or taken specific action to cancel the request (for example, *CLS command).

1-4 Operating Guide

Chapter 1 Getting Started

The Front Panel Menus at a Glance

Freq Ch 1

Other Meas

Gate & ExtArm

FREQUENCY 1

Freq Ch 2

FREQUENCY 2

Uppr & Lower

UPPR: 0.000000 LOWR: 0.000000

PERIOD 1

RATIO 1 TO 2

RATIO 2 TO 1 VOLT PEAKS 1

Limit Modes

LIM TEST: OFF

LIM TEST: ON

ON FAIL:GO ON

ON FAIL: STOP

SHOW: NUMBER

SHOW: GRAPH

GATE: TIME

TIME: .100 s

Scale & Offset

GATE: AUTO

SCALE:1.000000 OFFS: 0.000000 SET REF: NO

SET REF: YES SET REF: HELP

MATH: OFF

MATH: ON

MATH HELP: NO

MATH HELP: YES

GATE: EXTERNL

START: POS

START: NEG

STOP: AUTO

STOP: NEG STOP: POS STOP: TIME

TIME: .100 s

Stats

SHOW: MEAS

SHOW: STD DEV SHOW: MEAN SHOW: MAX SHOW: MIN

N: 100 STATS: OFF

STATS: ON

USE: ALL MEAS

USE: IN LIMIT

ON SINGLE: 1

ON SINGLE: N

GATE: DIGITS

DIGITS: 4

These menu items appear only if your Counter contains the optional 1.5 GHz, 3.0 GHz, or 5.0 GHz RF Input (Channel 2).

Refer to Chapter 2 in this guide for details on the Gate & ExtArm menu.

Operating Guide 1-5

Chapter 1 Getting Started

The Front Panel Menus at a Glance (Cont.)

Recall

NO REGISTERS

RECALL 0 RECALL 1 RECALL 2 RECALL 3 RECALL 4 RECALL 5

RECALL 20

50Ω 1MΩ

CH 1: 50 OHM

CH 1: 1M OHM

This appears when nothing can be recalled.

Only registers which can be recalled will appear in this menu.

This menu item only appears if an instrument setup has been saved.

Save & Print

SAVE:

UNSAVE: PRINT: OFF

PRINT: ON

PRT HELP: NO

PRT HELP: YES

DC AC

CH 1: DC

CH 1: AC

Trigger Sensitivity

AUTO TRG: ON LEVEL: 50 PCT

SLOPE: POS

SLOPE: NEG

SENSTVTY: HI

SENSTVTY: LO SENSTVTY:MED

X10 Attenuate

CH 1: X10 ATT

CH 1: X1 ATT

AUTO TRG: OFF LEVEL: 0.000V

100kHz Filter

CH 1: LP FILT

CH 1: NO FILT

1-6 Operating Guide

Chapter 1 Getting Started

The Front Panel Menus at a Glance (Cont.)

NOTE

Turn power off, press and hold Recall (Utility) key, then press POWER key to access this menu.

POWER

On / Stby

REV: X X X X HP-IB: 3 TIMEBAS: AUTO

TIMEBAS: INT TIMEBAS: EXT

CAL HELP: NO

CAL HELP: YES

TEST LOOP: OFF

TEST LOOP: ON

TST PRINT:OFF

TST PRINT: ON

Utility

Recall

TEST: NO

TEST: DISP TEST: CPU TEST: ROM TEST: RAM TEST: EEPROM TEST: HP-IB TEST: QSPI TEST: FPGA TEST: FR END TEST: MEAS TEST: INTERP TEST: KEYPAD TEST: PRINT

BAUD: 9600

BAUD: 19200 BAUD: 300 BAUD: 1200 BAUD: 2400

PARITY: OFF

PARITY: EVEN PARITY: ODD

SW PACE: XON

SW PACE: NONE

DTR: HIGH

DTR: LIMIT DTR: HW PACE

SHOW 9 AS: 9.0

SHOW 9 AS: 9,0

These menu items appear only if TEST LOOP is OFF.

Operating Guide 1-7

Chapter 1 Getting Started

The Display Annunciators at a Glance

MHz

µs

Gate

Period Freq Ch 1 Ch 2 Limit ExtRef

Annunciator Indication

Period Counter is set to measure Period. Freq Counter is set to measure Frequency. Ch 1 Counter’s channel 1 is selected to measure an input signal. Ch 2 Counter’s channel 2 is selected to measure an input signal. Limit Counter is limit testing and the current measurement

exceeds the user-entered limits.

ExtRef Counter is set to use the signal connected at rear panel

Ref In connector as the timebase (TIMEBAS: EXT); or Counter is set to automatically (TIMEBAS: AUTO) select the timebase and ha s chosen the signal con nected at th e rear panel Ref In connector.

Hz The displayed data is in units of Hertz. M The prefix for the units of the displayed data is mega (10

µ The prefix for the units of the displayed data is micro (10

s The displayed data is in units of seconds. Gate The gate is open. Before a measurement cycle starts, this

annunciator is OFF, indicating the gate is closed. During a measurement cycle, the annunciator is ON, indicating the gate is open.

−

1-8 Operating Guide

Chapter 1 Getting Started

The Display Special Characters at a Glance

The Underscore Placeholder

Freq Ch 2

Special Character Description

A placeholder that indicates the digit has been blanked using the Display Digits keys.

The Asterisk Placeholder

Freq Ch 1

MHz

Special Character Description

A placeholder that indicates this digit is not significant because of the measurement resolution. (The appearance of this asterisk is determined by the Counter; thus, these cannot be removed by the Display Digits keys.)

Operating Guide 1-9

Chapter 1 Getting Started

The Limit Te st Graph Characters at a Glance

The Limit Test Graph Characters at a Glance

Freq Ch 1

Special Character Description

The colons represent the lower and upper limits.

The asterisk represents the last measurement.

1-10 Operating Guide

Chapter 1 Getting Started

The Rear Panel at a Glance

1 2

WARNING:

I N P U T S

WARNING:

NO OPERATOR SERVICEABLE PARTS INSIDE, REFER SERVICING TO SERVICE TRAINED PERSONNEL.

60 VA

10 MHz Out

AC LINE:

50/60 Hz

50/60/400 Hz

100 - 120 VAC

200 - 240 VAC

Ext Arm

Ref In

FOR CONTINUED FIRE PROTECTION, USE SPECIFIED ~ LINE FUSE.

5 6 8 9

1 Rear-panel input connectors

(optional)

2 Power module (Senses incomin g

voltage and automa tically selects proper setup.)

3 Fan 4 External Arm input connector 5 External Reference Input connector

ISM 1-A

FOR LABORATORY USE BY QUALIFIED PERSONNEL FOUR USAGE EN LABORATOIRE PAR PERSONNEL QUALIFIE

OPTIONS

001 MS Oven 010 HS Oven 012 US Oven

To Configure: Hold Recall during turn-on.

Osc Adjust

SERIAL PLATE

RS - 232

6 10 MHz Output connector 7 HP-IB (IEEE-488.1) interface

connector

8 Oscillator Adjust potentiometer 9 RS-232 Interface or Limit Output

connector

NOTE

Operating Guide 1-11

Chapter 1 Getting Started

Making Measurements

One of the first things you will want to do with your Counter is to become acquainted with its front panel. Therefore, we have written the procedures in this section to familiarize you with some of its controls. The following procedures are provided:

• First you are shown how to turn on the Counter and measure the frequency of a signal applied to the Counter’s input channels.

• Second, you are shown how to use the input coupling, impedance, and trigger/sensitivity keys to set the input conditions of Channel 1 to match the signal being measured.

• Third, you are shown how to scale and offset the measurement result.

• Fourth, you are shown how to set upper and lower limits for measurements.

• Fifth, you are shown how to enable the Counter to compute statistics (such as standard deviation) and display statistics of measurements.

• Last, you are shown how to use the Run and Stop/Single keys to control measurements.

The order of the procedures in this chapter is the recommended order for making measurements with this Counter.

1-12 Operating Guide

Chapter 1 Getting Started

Making Measurements

Study and refer to the following legend, as needed, to understand the meaning of the icons which are used throughout this chapter.

1 Press key one time

and release

2 Press key two times

and release

3 Repeated key presses 4 Press and hold

5 Result 6 Auto operation 7 Connect signal 8 Disconnect signal

Legend

91110

9 Indicator off

10 Indicator on

11 Indicator flashing

Operating Guide 1-13

Chapter 1 Getting Started

Making Measurements

To Measure Frequency

POWER

On / Stby

Period Freq Ch 1 Ch 2 Limit ExtRef

Freq Ch 1

MHz

µs

Gate

Connect (for demonstration purposes) the Counter’s rear-panel 10 MHz Out signal to CHANNEL 1 input as shown in the illustrated procedure, below.

CHANNEL 1

MHz

Gate

Damage Lvl: 5V rms MAX.50Ω

Freq Ch 1

The Counter will automatically display the measured frequency of the input signal.

1-14 Operating Guide

Chapter 1 Getting Started

CHANNEL 1

Trigger Sensitivity

DC AC

50Ω 1MΩ

X10 Attenuate

100kHz Filter

Damage Lvl: 5V rms MAX. 50Ω

Making Measurements

If you need or want to change CHANNEL 1’s coupling, impedance, and triggering conditions to match the input signal you are trying to measure, the next procedures “To Select Input Coupling and Impedance” and “To Set Input Channel Trigger Level/Sensitivity” demonstrate this. Perform these procedures whether or not you want to customize the Counter’s input conditions to measure your signal; doing this will help you become familiar with the DC/AC, 50Ω/1MΩ, and Trigger/Sensitivity keys.

To Select Input Coupling and Impedance

Selecting Input Coupling

DC AC

Channel 1’s input coupling is now set to dc.

NOTE

If you want to change the coupling back to the default ac coupling, perform the following step.

DC AC

Selecting Input Impedance

50Ω 1MΩ

Channel 1’s input impedance is now set to 50Ω.

The “arrow” keys can also be used to toggle the state of toggle keys (DC/AC, 50Ω/1MΩ, etc.) as indicated by the flashing indicator within the arrow keys. However, for simplicity in this procedure, use the corresponding toggle key to change states.

Operating Guide 1-15

Chapter 1 Getting Started

Enter

+/–

Making Measurements

If you want to change the input impedance back to the default 1MΩimpedance, perform the following step.

50Ω 1MΩ

Freq Ch 1

MHz

Gate

To Set Input Channel Trigger Level/Sensitivity

Changing Trigger Mode

Trigger Sensitivity

Press any one of these arrow keys to toggle to the next state of Auto Trigger.

1-16 Operating Guide

Chapter 1 Getting Started

Making Measurements

Modifying Input Trigger Level

Trigger Sensitivity

The leftmost “0” digit in the LEVEL display is highlighted, indicating that if you press the d key once the displayed value will increase to 1.000 volt as shown in the following step.

Enter

Channel 1’s trigger level is now set to +1V. To set the trigger level to −2V, perform the following steps.

+/–

Enter

Channel 1’s trigger level is now set to −2V.

Operating Guide 1-17

Chapter 1 Getting Started

Making Measurements

Selecting Input Trigger Slope

Trigger Sensitivity

Display 1, 7/13/92

Refer to the sub-section titled “To Use the Trigger/Sensitivity Key to Adjust Counter’s Trigger Voltage and Sensitivity Levels” in Chapter 2 for more information about trigger slope, if needed.

Selecting Input Sensitivity

Trigger Sensitivity

Display 1, 7/13/92

Refer to the sub-section titled “To Use the Trigger/Sensitivity Key to Adjust Counter’s Trigger Voltage and Sensitivity Levels” in Chapter 2 for more information about sensitivity, if needed.

1-18 Operating Guide

Chapter 1 Getting Started

Stats

Scale & Offset

MATH

Making Measurements

Starting the Measurement

Run

Freq Ch 1

MHz

Gate

The Run key initiates repetitive measurements, and is described in the

section titled “To Control Measurement” at the end of this chapter.

To Select Scale and Offset

The Scale & Offset key allows for multiplication and addition, respectively, of the measurement by user-specified cons tants. Modification of the displayed mea su rement by th ese Ma th op erat io ns is re pres ent ed by the following equation:

(Measurement × Scale) + Offset = Displayed Results

The Scale and Offset Math operations can be used, for example, to subtract systematic errors or display the percentage difference between signals.

Entering the Scale Value

Scale & Offset

To demonstrate the Scale Math operation, set Scale to 10 as shown in the following steps.

Operating Guide 1-19

Chapter 1 Getting Started

Making Measurements

Press and hold the d key until the value of Scale is 10 as shown in the following step.

Enter

NOTE

BE SURE to press the Enter key to enter the value of 10.

The Scale is now set to 10, and MATH has been enabled. The Scale & Offset indicator is now lit to show that MATH is enabled. Since MATH is enabled, the results are being scaled and offset.

Entering the Offset Value

To demonstrate the Offset Math operation, set the Offset to 1 MHz as shown in the following steps.

Scale & Offset

At this point, pressing the s key will cause the Counter to display the full display of the Offset value as shown in the following step.

1-20 Operating Guide

Chapter 1 Getting Started

Making Measurements

Press the s key six more times to cause the Counter to display your entry in Mega units as shown in the following step.

NOTE

The leftmost “0” digit in the OFFSet display is highlighted, indicating that if you press d key once the displayed value will increase to 1 Mega (that is, 1E6) as shown in the followi ng step.

Enter

BE SURE to press the Enter key to enter the 1 Mega value.

The Offset is now set to 1 Mega.

Displaying the Math Results

Run

Freq Ch 1

The Counter displays th e modi fi ed measu rement res ults , whi ch are bas ed on the scale and offset values that you selected in the previous steps. (For more details and real applications of the Ma th Scale and Offset operations, refer to the appropriate section in Chapter2, “Operating Your Frequency Counter.”)

Operating Guide 1-21

Chapter 1 Getting Started

Making Measurements

Disabling Math

Scale & Offset

Display 1, 7/13/92

Note that the Scale & Offset key indicator is now off.

MHz

Gate

NOTE

Run

Freq Ch 1

DO NOT cycle POWER because you will need to use these Scale and

Offset values in the follow ing procedure “To Set Limits of Measu rements.” Continue to the following procedure.

1-22 Operating Guide

Chapter 1 Getting Started

Making Measurements

To Set Limits of Measurements

To demonstrate how Math and Limits work together, use the Scale (10)

and Offset (1 Mega) values selected in the previous procedure “To Select Scale and Offset.” Enable Math by performing the following steps.

Scale & Offset

Display 1, 7/13/92

Run

Freq Ch 1

The result of this Math operation is a measurement of 101 MHz.

(Measurement × Scale) + Offset = Result (10 MHz × 10) + 1 Mega = 101 Mega

Now, set the upper limit to 102 Mega and the lower limit to100 Mega by performing the following procedures. (Figure 1-1 and Figure 1-2 illustrate the limits settings.)

Operating Guide 1-23

Chapter 1 Getting Started

Limit Modes

Uppr & Lower

LIMITS

Making Measurements

Setting the Upper Limit

Uppr & Lower

Press the s key nine times to cause the Counter to display your entry in hundreds of Mega units as shown in the following step.

The leftmost “0” digit in the UPPR display is highlighted as shown above, indicating that each press of the d key will increase the displayed value.

NOTE

Enter

BE SURE to press the Enter key to enter the 102 Mega value.

1-24 Operating Guide

Chapter 1 Getting Started

Making Measurements

1 102 Mega Upper Limit 2 101 Mega Scale/Of fset Measurement

Figure 1-1. 102 Mega Upper Limit Setting

Setting the Lower Limit

Uppr & Lower

NOTE

Press the arrow keys as shown in th e foll owing steps to set th e lower limi t value.

Press the s key nine times to cause the Counter to display your entry in hundreds of Mega units as shown in the following step.

Enter

BE SURE to press the Enter key to enter the 100 Mega value.

Operating Guide 1-25

Chapter 1 Getting Started

Making Measurements

Limits should now be set as shown in Figure 1-2.

1 102 Mega Upper Limit 2 101 Mega Scale/Of fset Measuremen t 3 100 Mega Lower Limit

1 2

Figure 1-2. 100 Mega Lower and 102 Mega Upper Limits Settings

Figure 1-3 represents what transpired during this Math and Limits procedure.

234

1 Raw Measurements 2 Math

3 Limits 4 Measurements (Scale/Offset Results)

within Limits

Figure 1-3. Math and Limits Results

1-26 Operating Guide

Chapter 1 Getting Started

Making Measurements

Setting the Counter to Flag and Stop Measuring On Out-of-Limit Measurements

If you want the Counter to stop measuring when the signal exceeds the limits (102 to 100 Mega) that you entered in the previous procedure, perform the following steps to select the STOP choice in the ON FAIL display. (Note that ON FAIL: GO ON is the default state after power-up.)

Limit Modes

Run

Freq Ch 1

M Gate

The current modified measurement of the input signal applied to CHANNEL 1 is displayed.

Since the Counter is now in the stop-on-fail mode, the Limit annunciator in the display will light and the Counter will stop making measurements when a measurement exceeds the limits you se t. The mea sur ement result that exceeded the entered limits will be held on the display for observation.

Operating Guide 1-27

Chapter 1 Getting Started

Making Measurements

Setting the Counter to Flag On Limits But Continue Measuring

Perform the following steps to select the GO ON choice in the ON FAIL

display if you want the Counter to continue measuring even though an measurement result exceeds the limits previously entered.

Limit Modes

Run

Freq Ch 1

Gate

The current modified measurement of the input signal applied to CHANNEL 1 is displayed.

Since the Counter is now in the go-on-fail mode, the Limit annunciator in the display will light each time a measurement exceeds the limits you set. However, the Counter will continue to make measurements.

Disabling Limit Testing

Limit Modes

The Counter is now making measurements without limit testing.

1-28 Operating Guide

Chapter 1 Getting Started

Stats

Scale & Offset

MATH

Making Measurements

Disabling Math

Scale & Offset

Display 1, 7/13/92

Run

Freq Ch 1

MHz

Gate

The Counter is now making measurements without the scale/offset values calculated into the measurements.

To Perform Statistics on Measurements

Selecting the Type of Statistics (Stats)

Suppose you want the Counter to compute and display the standard deviation of the current input data (which is the 10 MHz signal applied

to CHANNEL 1). Also, you want the Counter to make 20 measurements before it computes the standard deviation. Perform the following steps.

Stats

Operating Guide 1-29

Chapter 1 Getting Started

Making Measurements

Updating the SHOW configuration caused Stats to be enabled. The Stats

indicator is now lit.

NOTE

BE SURE to press the Enter key to enter the value of 20.

Stats

Enter

1-30 Operating Guide

Chapter 1 Getting Started

Making Measurements

The Counter is now set to make statistics based on 20 measurements.

Run

Freq Ch 1

Gate

In this case, the displayed standard deviation value is computed on all measurements of the 10 MHz signal since no limits were set.

Computing Stats on Filtered Data Only

A special feature of the Counter allows you to use the upper and lower limits to filter data before statistical processing or computation as shown in Figure 1-4.

1 Raw Measurements 2 Limits

3 Filtered data (USE: IN LIMIT) 4 Statistics

Figure 1-4. Filtering Data Before Statistical Computation

Operating Guide 1-31

Chapter 1 Getting Started

Making Measurements

Perform the following steps to select the IN LIMIT choice in the USE

display if you want the Counter to compute statistics on only frequency

measurements within the limits you set.

Stats

Display 1, 7/13/92

Since the Limits were set to 100 Mega and 102 Mega values that are

based on a scale of 10 and offset of 1 Mega, you must re-enable Math now

to get the measurements to be within the limits. Perform the following

steps.

Scale & Offset

Display 1, 7/13/92

1-32 Operating Guide

Chapter 1 Getting Started

Making Measurements

Displaying Stats After Filtering Data of Input Signal

Let’s assume you have set the upper and lower limits for the input signal, and selected the IN LIMIT (filtering) choice. Now, perform the following steps to display the standard deviation of the filtered measurements. (Note that the first step in the following procedure is optional since you

should have already set Stats to show standard deviation at the beginning of this Stats procedure. But, you may want to perform the step anyway to verify that the Counter is displaying the standard deviation of the measurement.)

Stats

Display 1, 7/13/92

Run

Freq Ch 1

Gate

The standard deviation value shown in the previous illustration is for demonstration purposes . The statistic is computed using only those measurements which fell within the limits you set.

(For more details on the Stats and Limits functions, refer to the appropriate sections in Chapter 2, “Operating Your Frequency Counter.”)

Now, disable Math and Stats as shown in the following procedure.

Operating Guide 1-33

Chapter 1 Getting Started

Making Measurements

Disabling Stats and Math

Stats

Scale & Offset

Display 1, 7/13/92

Run

Freq Ch 1

MHz

Gate

The Counter is now making and displaying normal measurements

(that is, the Counter is not showing statistics or scale/offset results).

1-34 Operating Guide

Chapter 1 Getting Started

Run Single/

Stop

Making Measurements

To Control Measurement

Use these two keys to control the measurement of the Counter. The Run key provides repetitive measurements, whereas the Stop/Single key allows you to make one measurement.

With the 10 MHz signal still connected to CHANNEL 1, perform the following steps so you can better understand the Run and Stop/Single operations.

Run

Freq Ch 1

MHz

Gate

The Counter is now making repetitive measurements (continuously

making “live” measurements).

Stop/ Single

Freq Ch 1

MHz

The Counter stopped making measurement s. The Gate annunciator is not lit. Hence, pressing the Stop/Single key while the Counter is making measurements (in Run) causes the Counter to stop after the measurement in progress is completed. If you pres s the Stop/Single key again while the Counter is stopped, the Counter will make a single measurement and then stop—the Gate annunciator will light one time, momentarily.

If you press the Stop/Single key while the Counter is stopped and when the Stats menu item ON SINGLE is set to N, the Counter will make N measurements and then stop. This enables a set of statistics to be computed.

While the Counter is still stopped, perform the following step.

Run

Freq Ch 1

MHz

Gate

The Counter is making repetitive measurements again.

Operating Guide 1-35

Chapter 1 Getting Started

Making Measurements

1-36 Operating Guide

Operating Your Frequency Counter

Operator’s Reference

Chapter 2 Operating Your Frequency Counter

Introduction

This is the operator’s reference chapter which contains information and

procedures for the front-panel keys, operating functions, and menus of the

HP 53181A 225 MHz Frequency Counter.

Chapter Summary

• How this Counter Works for You page 2-4

• Summary of the Measurement Sequence page 2-5

• Using the Measurement Control Keys (Run and Stop/Single)

• Using Entry/Select (Arrow) Keys page 2-9

• Using the MEASURE Menu Keys page 2-11

• Using the Gate & External Arm Menu Key page 2-15

• Using the MATH Menu Keys page 2-21

• Using the LIMITS Menu Keys page 2-31

• Using the DISPLAY Digits Keys page 2-39

• Using CHANNEL 1 Input Conditioning Keys page 2-41

• Using the Save and Recall Menus page 2-48

• Using the Print Menu page 2-52

• Using the Utility Menu page 2-53

• Front Panel Display Messages page 2-63

• Preset Values After Power-up and *RST page 2-68

• Common Questions page 2-74

page 2-6

2-2 Operating Guide

Chapter 2 Operating Your Frequency Counter

Introduction

Where to Find Some Key Working Examples

• Example Procedure for Gate and External Arm page 2-17

• Example Procedure for Changing the Number of Digits of Resolution Displayed for More Precise Measurements

• Example Procedure for Scale Function page 2-22

• Example Procedure for Offset Function page 2-23

• Example Procedure for Set Reference Function—Offset From the Last Measurement Value (Seeing Digits Not Visible on the 12-Digit Display)

• Example Procedure for Computing Stats page 2-27

• Limits Testing Example 1—Flag and Stop Measuring On Limits

• Limits Testing Example 2—Flag On Limits but Continue Measuring

• Limits Testing Example 3—Use Analog Graph Display While Adjusting/Aligning Input Signal

• Limits Testing Example 4—Selecting Filtering Conditions of StatsComputation

• Limits Testing Example 5—Sending the Limit-Detect Output to the RS-232 Serial Port

page 2-19

page 2-25

page 2-32

page 2-34

page 2-36

spage 2-38

Operating Guide 2-3

Chapter 2 Operating Your Frequency Counter

How this Counter Works for You

The followin g text lists some of the key things the Counter does for you.

• The Counter presets the menus to default states and values at power-up (refer to Table 2-6 for a detailed list of the preset values). Cycling the POWER key presets the Counter.

• The Counter’s Utility menu allows you to select such things as timebase source, HP-IB configuration, and RS-232 serial port

configuration. After your selections, the Counter automatically stores all these selections in non-volatile memory (except the timebase source); thus, these settings (except timebase source) will not change when power has been off or after a remote interface reset.

• The Counter automatically displays measurement(s) in a couple of seconds after you select a measurement function (e.g., Period).

• The Counter accepts your numeric entry for a menu item after you press the Enter key. You MUST press the Enter key to complete

numeric entry.

• The Counter automatically enables Limits when you enter a numeric value for upper and/or lower limits, or update any menu item in the Limit Modes menu.

• The Counter automatically enables Math after you enter a numeric value for scale and offset.

• The Counter performs Statistical analyses for you, and will enable Stats when you update any item in the Stats menu.

• The Counter automatically disables Limits, Math, and Stats when you select another measurement function.

• The Counter saves measurement setup(s).

• The Counter instantly recalls the measurement setup you want to use.

• The Counter prints out your measurement and analysis data.

2-4 Operating Guide

Chapter 2 Operating Your Frequency Counter

Summary of the Measurement Sequence

Use Utility menu to:

• choose the timebase source.

• configure the HP-IB if you intend to operate the Counter remotely.

• set RS-232 serial port if you intend for the Counter to perform printing and/or limit-detecting.

Use MEASURE menu keys to select the measurement function. Use CHANNEL 1 keys to set up input conditioning. Use Gate & ExtArm key to:

• set the gate time and resolution.

• set arming.

Use Scale & Offset key to set up math operations. Use Uppr & Lower key to set limits. Use Limit Modes key to set up limit testing. Use Stats key to set up statistics and limit filtering. Use Save & Print key to enable or disable printing. Use Run and Stop/Single keys to control measurements.

Operating Guide 2-5

Chapter 2 Operating Your Frequency Counter

Run Stop/

Single

Using the Measurement Control Keys (Run and Stop/Single)

Overview of the Measurement Control Keys

Two measurement control keys are provided on the Counter: Run and Stop/Single. In general, the Run key provides repetitive measurements

while the Stop/Single key allows you to make single-shot measurements. The Run key allows you to:

• put the Counter into a continuous measurement loop.

• exit any measurement after your selection of another measurement function.

• abort the current measurement by starting a new measurement (if already in Run mode or in Single mode with a measurement in progress). This also clears any statistics being processed.

The Stop/Single key allows you to:

• put the Counter into Single mode (if the Counter was in Run mode) where one measurement is taken with each Stop/Single keypress. (Stats menu item ON SINGLE should be set to 1.)

• put the Counter into Single mode (if the Counter was in Run mode) where N measurements are taken with each Stop/Single keypress. (Stats menu item ON SINGLE should be set to N.)

• stop (abort) the current measurement (if the Counter was in Single mode).

2-6 Operating Guide

Chapter 2 Operating Your Frequency Counter

Using the Measurement Control Keys (Run and Stop/Single)

To Use the Measurement Control Keys

The following proced ure demonstrates how these keys function.

1 Connect power source to Counter, and turn on Counter.

All segments of the front-panel display will light up while the Counter performs its power-on self-test, and then dashes are displayed. The Counter is now ready to measure frequency of a signal applied to CHANNEL 1 input. Note that the Freq and Ch1 annunciators light.

2 Connect an input signal to CHANNEL 1.

The Counter automatically displays the measured frequency of the input signal. Note that the Run key indicator is ON.

3Press Stop/Single key.

The Counter is put into Single mode and the current measurement is completed. One measurement is taken with each press of Stop /Single key. Note that the Stop/Single key indicator is ON.

4Press Run key.

The Counter aborts any measurement in progress, and starts making repetitive measurements. That is, the Counter is in a continuous measurement loop.

5Press Stop/Single key.

The Counter is put into Single mode.

Operating Guide 2-7

Chapter 2 Operating Your Frequency Counter

Using the Measurement Control Keys (Run and Stop/Single)

6Press Stats key until

any one of the arrow keys to set

The Counter is set to take N meas urements on each Stop/ Single keypress (note: N = 100 at power-up). The state of

the Stop/Single key operation while statistics are enabled.

Observe that the Stats indicator is ON. This indicates statistical processing is enabled.

7Press Stop/Single key.

One set of N frequency measurements is taken with each press of the Stop/Single key. One set of statistics is computed with each press of the Stop/Single key.

8Press Stats key until

9 Press any one of the arrow keys to select a statistical result to

display, and press Freq Ch 1 key.

The Counter is now displaying one of the statistical results.

10 Press Stop/Single key.

ON SINGLE

SHOW

menu item appears.

menu item appears, then press

ON SINGLE

menu item to N.

menu item affects

One set of N frequency measurements is taken with each press of the Stop/Single key. At the completion of th e Nth meas ur eme nt, the Cou nte r displays the statistical result selected in step 9.

11 Press Stats key until

any one of the arrow keys to set

The Counter is set to take one measurement on each Stop/Sing le keypress.

Disabling the statistics (with the

to cause the Stop/Single key to initiate one measurement at a time.

2-8 Operating Guide

ON SINGLE

STATS: OFF

menu item appears, then press

ON SINGLE

menu item to 1.

menu item) is another way

Chapter 2 Operating Your Frequency Counter

Enter

+/–

Using Entry/Select (Arrow) Keys

There are six entry/select keys of which four are “arrow” keys. The function of the four arrow keys and the Enter key depends on the Counter’s operating mode (that is, numeric entry, state changing, sequencing through choices in a menu, etc.). This section describes how the keys perform in the different operating modes.

To Use During Numeric Entry

•Use the s key to move left to select adjustable digits (it does not wrap around).

•Use the g key to move right to select ad justable digi ts (it doe s not wrap around).

•Use the d key to increment the selected (highlighted) digit of the displayed value.

•Use the f key to decrement the selected (highlighted) digit of the displayed value.

•Use the +/− key to change the sign of the numeric value.

•Use the Enter key to complete a numeric entry. (If a numeric entry is changed and the Enter key is NOT pressed, then the value is not changed.)

To Use When Sequencing Through the Other Meas and Recall Menus

•Use the d or s key to go back to the previous choice in a function or recall menu. Repeatedly pressing this key will cycle through (and loop around) the list of choi ces.

•Use the f or g key to go forward or to the next choice in a function or recall menu. Repeatedly pressing this key will cycle through (and loop around) the list of choi ces.

•Use the Enter key to select the function or execute the recall, or wait for the menu to time out for automatic selection/execution.

Operating Guide 2-9

Chapter 2 Operating Your Frequency Counter

Using Entry/Select (Arrow) Keys

To Use During State Changing (ON/OFF, LO/MED/HI, etc.)

•Press any of the arrow keys to toggle or ch ange to th e next stat e of the parameters found in the following menus:

–Gate & ExtArm –Limit Modes – Scale & Offset –Stats

– Trigger/Sensitivity –50Ω/1M – DC/AC – X10 Attenuate – 100kHz Filter –Save & Print – Utility Menu

•The +/− key is ignored during the st ate changing operating mode.

Ω

To Use on Prompted Help Messages (MATH HELP: NO/YES, PRT HELP: NO/YES)

•When

MATH HELP: YES

“

(MEAS x SCALE) + OFFS = RESULT

PRT HELP: YES

“

CONFIGURE PORT ON UTILITY MENU; REMEMBER TO SAVE

SETUP FIRST

” instruction.

is displayed, press Enter key to display the

” message.

is displayed, press Enter key to display the

2-10 Operating Guide

Chapter 2 Operating Your Frequency Counter

Other Meas

Freq Ch 2

Gate & ExtArm

MEASURE

Freq Ch 1

Using the MEASURE Menu Keys

Overview of the MEASURE Menus

The measurement function menus are divided into three categories:

• Frequency measurements on Channel 1.

• Frequency measurements on Channel 2 (optional).

• Other measurements (period, ratio (optional), and peak voltage).

Table 2-1. Menus of the MEASUREment Keys

Freq Ch 1 key Freq Ch 2 key Other Meas key

FREQUENCY 1 FREQUENCY 2

(optional)

PERIOD 1 RATIO 1 TO 2 (optional) RATIO 2 TO 1 (optional) VOLT PEAKS 1

To sequence through the Other Meas menu, you simply need to repeate dly press the Other Meas key to cycle through (and loop around) the items (or measurement functions) under the key. Each press of a Other Meas key will advance the Counter to the next measurement function in the menu.

NOTE

The menus under the MEASURE keys will terminate (select function and return to measurement result display) after a short timeout.

WARNING When measuring power line frequencies, be extremely careful and always

use a step-down isolation transformer of which output voltage is compatible with the input measurement capabilities of this product. Since the shell of the BNC input connector is grounded to the chassis of the instrument, the hot side of an ac power line could be connected to the BNC shell and create a direct short to ground. Therefore, NEVER TRY

TO MEASURE AC POWER LINE FREQUENCIES WITHOUT AN ISOLATION TRANSFORMER.

Operating Guide 2-11

Chapter 2 Operating Your Frequency Counter

Using the MEASURE Menu Keys

To Measure Frequency

1 Connect power source to Counter, and turn on Counter.

2 Connect an input signal to CHANNEL 1.

The Counter should automatically display the measured frequency of the

input signal. The trigger levels are set to the 50% points of the signal. However, you may disable auto triggering, and change the trigger levels and slopes.

To set up CHANNEL 1’s coupling, impedance, and triggering conditions to match the input signal you are trying to measure, refer to the procedures “To Select Input Coupling and Impedance” and “To Set Input Channel Trigger Level/Sensitivity” in Chapter 1, “Getting Started,” or the section titled “Using CHANNEL 1 Input Conditioning Keys” in this chapter.

3 To measure the frequency of a signal applied to the optional

CHANNEL 2 input, press Freq Ch2 key.

FREQUENCY 2

annunciators will light. The Counter will be ready to measure the frequency of a signal applied to CHANNEL 2 input.

Note that the Frequency 2 menu item is not available in Counters that do not contain the optional Channel 2.

2-12 Operating Guide

will be momentarily displayed and the Freq and Ch2

Chapter 2 Operating Your Frequency Counter

Using the MEASURE Menu Keys

To Measure Frequency Ratio (Optional)

1 Connect signals to be measured to channels 1 and 2.

2Press Other Meas key until

the frequency ratio between a signal appl ied to CHANNEL 1 input and a signal applied to the optional CHANNEL 2 input.

RA TIO 1 T O 2

annunciators will light. The Counter will be ready to measure the frequency ratio of a signal applied to CHANNEL 1 in relation to a signal applied to CHANNEL 2 (Ch1/Ch2).

RATIO 2 TO 1 is also available (Ch2/Ch1). Note that Ratio 1 to 2 and Ratio 2 to 1 menu items are not available in

Counters that do not con tain the optional Channel 2. Note the result is not scaled by 100; it is not a percentage.

The front-panel “arrow” (or entry/select) keys can also be used when sequencing through the Other Meas menu. Refer to the section titled “Using Entry/Select (Arrow) Keys” for details.

will be momentarily displayed and the Freq, Ch1, and Ch2

RATIO 1 TO 2

is displayed to measure

To Measure Period

Press Other Meas key until

PERIOD 1

light, and the Counter is ready to measure the period of a signal applied to CHANNEL 1.

is momentarily displayed, the Period and Ch1 annunciators

PERIOD 1

is displayed.

Operating Guide 2-13

Chapter 2 Operating Your Frequency Counter

Using the MEASURE Menu Keys

To Measure Positive/Negative Volt Peaks

Press Other Meas key until

VOLT PEAKS 1

and the Counter is ready to measure minimum and maximum voltage peaks of signals applied to CHANNEL 1.

NOTE

In Volt Peaks function, the Counter measures the input signal after the signal has been conditioned by the input settings (impedance, coupling,

attenuation, and filter). One reminder of this is the ( message, which is displayed when Voltage Peaks is selected and the measurement channel is ac coupled.

The result is corrected for X10 attenuation.

Arming is not used for Voltage Peaks measurements. Also, Limits, Math,

and Display Digits are not available for Voltage Peaks measurements.

is momentarily displayed, the Ch1 annunciator lights,

VOLT PEAKS 1

is displayed.

AC COUPLED

)

2-14 Operating Guide

Chapter 2 Operating Your Frequency Counter

Other Meas

Freq Ch 2

Gate & ExtArm

MEASURE

Freq Ch 1

Using the Gate & External Arm Menu Key

Overview of Gate/External Arming Functions

Table 2-2 lists the menus for all the arming configurations, and shows how the Gate and External Arming menu changes as a function of the arming mode.

The Counter has four arming modes: auto, external, digits and time. The arming modes are defined in the following paragraphs.

TIME Arming

For frequency, period, and frequency rati o, time arming means you can

set the gate time—the length of time for which your signal is measured.

NOTE

Gate time and resolution are linked: the longer the gate time, the greater the resolution. With an increase in resolution, you get a larger number of digits on the display.

Time arming is demonstrated in the sub-section titled “Example Procedure for Gate and External Arm.”

AUTO Arming

For frequency, period, and frequency rati o, auto arming means make individual measurements as fast as possible.

EXTERNAL Arming

For frequency, period, and frequency rati o, external arming means you can start a measurement by using an external signal.

When external arming mode is enabled, a signal must be connected to the Counter’s rear-panel Ext Arm connector.

Operating Guide 2-15

Chapter 2 Operating Your Frequency Counter

Using the Gate & External Arm Menu Key

DIGITS Arming

For frequency, period, and frequency ratio, digits arming means you can

set the number of digits of resolution that you require y our result to provide.

Digits arming is demonstrated in the sub-section titled “Example

Procedure for Changing the Number of Digits Displayed.”

*Table 2-2. The Gate & External Arm Key Menus as a Function of the

Arming Mode

Frequency, Period, Ratio

Time Arming:

GATE: TIME TIME: <time>

Auto Arm i ng:

GATE: AUTO

Digits Arming:

GATE: DIGITS DIGITS: <digits>

External Arming (Refer to page 2-17 or the Menu Roadmap in the Quick Reference Guide, which follows the Preface, for mo r e in fo rm ation.):

GATE: EXTERNL

START: POS

NEG

STOP: AUTO

NEG POS TIME

TIME: <time>

* There is no Gate and External Arm menu available for Voltage Peaks measurements.

2-16 Operating Guide

Chapter 2 Operating Your Frequency Counter

Ext Arm

Using the Gate & External Arm Menu Key

To Use the Gate and External Arm

Example Procedure for Gate and External Arm

For demonstration purposes, you want to set up the Counter so that it uses an external arm to start a measurement. You want to make a Frequency measurement on a signal applied to channel 1. Also, you want to perform the measurement during an interval of 5 milliseconds as shown in the following figure.

NOTE

As shown in the following figure, the Counter is always synchronized to the input signal. Arming occurs on the rising edge of external arm (ExtArm), and the measurement gate is synchronized to the trigger event on CHANNEL 1.

CHANNEL 1

Ext Arm

Gate

5 ms

Perform the following procedure to accomplish this task.

1 Turn on the Counter, and press Stop/Single to put the Counter

into the single measurement mode.

2 Connect the signal to channel 1 input, and press F req Ch 1 key.

3 Connect an external TTL signal to the Counter’s rear-panel

Ext Arm connector.

4Press Gate & ExtArm key.

GATE: TIME

is displayed.

Operating Guide 2-17

Chapter 2 Operating Your Frequency Counter

Using the Gate & External Arm Menu Key

5 Press any one of the arrow keys until

displayed.

6Press Gate & ExtArm or Enter key.

START: POS

press any one of the arrow keys to toggle to the next state—

7Press Gate & ExtArm or Enter key.

STOP: NEG

8 Press any one of the arrow keys until

9 Set the Gate Time to 5 ms by performing the following steps:

a. Press Gate & Ex tArm or Enter key.

TIME: .100

b. Press the appropriate arrow keys until

c. Press Enter key.

NOTE

BE SURE to press the Enter key to complete the numeric entry.

is displayed. (If

is displayed.

seconds (the default time) is displayed.

START: NEG

GATE: EXTERNL

is displayed instead, then

STOP: TIME

TIME: .00500

POS

is displayed.

s is displayed.

The counter will now gate for a duration of 5 ms. The 5 ms interval will

begin after the external edge is detected.

10 Press Stop/Single key to start the measurement.

The measurement is started after the external arm pulse occurs.

2-18 Operating Guide

Chapter 2 Operating Your Frequency Counter

Using the Gate & External Arm Menu Key

Example Procedu re for Chan g i ng th e Nu m be r of Digits of Resolution Displayed for More Precise Measurements

1 Turn POWER key OFF then ON again (cycle POWER key) to preset

the Counter.

2 Connect (for demonstration purposes) the 10 MHz Out signal to

the channel 1 input.

3Press Other Meas key until

After a few seconds, number of digits (or resolution) displays a precise measurement.

4 To demonstrate how to use “digits arming” to change the number

of digits displayed, perform the following steps first. a. Press Gate & ExtArm key

GATE: TIME

b. Press any one of the arrow keys until c. Press Enter or Run key.

0.100,0

In “auto arming” you produce results quickly. The short gate time produces a lower-resolution result.

µs is displayed. Note that fewer digits are displayed.

0.100,000,000,0

is displayed.

PERIOD 1

is displayed.

µs is displayed. Hence, the default

AUTO

is displayed.

Operating Guide 2-19

Chapter 2 Operating Your Frequency Counter

Using the Gate & External Arm Menu Key

5 To change the display to the better measurement resolution using

digits arming, perform the following steps:

a. Press Gate & Ex tArm key

GATE: AUTO

b. Press any one of the arrow keys until

c. Press Gate & ExtArm or Enter key.

DIGITS: 4

d. To set the number of digits displayed to 8, press the appropriate arrow

keys until

e. Press Enter key.

f. Press Run key.

0.100,000,000

Note that 8 digits of resolution are displayed (

For the convenience of the user, the leading “1” does not count as a digit when 8 digits are selected; thus, a result of alternate with a result of no change of settings is required.

is displayed.

DIGITS

is displayed (the default number of digits)

DIGITS: 8

µs is displayed.

is displayed.

1 2 3 4 5 6 7 8

0.100,000,000

0.099,999,999

0.100,000,000

µs with a stable display, and

µs).

µs can

2-20 Operating Guide

Chapter 2 Operating Your Frequency Counter

Stats

Scale & Offset

MATH

Using the MATH Menu Keys

Note that Math and Limits are not available for Voltage Peaks measurements.

Overview of Scale/Offset Math Menu

The Scale and Offset functions within the Math menu allow you to perform simple mathematical operations on the measurement result before it is displayed. The Scale and Offset functions allow for multiplication and addition. Modification of the displayed measurement by these math operations is represented by the following equation:

(Measurement × Scale) + Offset = Displayed Result

The math operations can be used, for example, to subtract systematic errors or display the percentage difference between signals. Also, the overall math operation can be disabled and then re-established without having to re-enter constants.

The menu items of the Scale and Offset Math functions allow you to:

• enter a desired multiplication factor for a measurement (SCAL:).

• enter a desired addition or subtraction value for a measurement (OFFS:).

• get and display the last measurement value, and use it as a negative offset (SET REF: NO or YES).

• disable or enable the Math mode (MATH: OFF or ON)—Note that the Math mode is automatically enabled when you enter the scale and/or offset value(s); thus, the primary function of this menu item is to allow you to turn the Math mode off.

• get Help, which displays the equation “

RESULT

” to tell you how the scale and offset results are computed by

(MEAS X SCALE) + OFFS =

the Counter (MATH HELP: NO or YES).

Operating Guide 2-21

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

To Use the Scale/Offset Math Menu

Example Procedure for Scale Function

For demonstration purposes, you have a motor that has a tachometer attached to its rotating shaft that generates a pulse for every revolution of the shaft.

Your task is to measure the speed or revolutions per minute (rpm) of

the tachometer’s output, and make the Counter directly display the measurement in rpm (which is fundamentally a frequency measurement). The equation for this task is:

1 Connect the output to channel 1 input, and press Freq Ch 1 key.

2Press Scale & Offset key until

3 Set the Scale to 60 (since there are sixty seconds in a minute) by

NOTE

Frequency (Revolution/Sec) × Scale (60 Sec/Min) = Results (Revolution/Min)

Perform the following procedure to accomplish this task.

The frequency of the signal is displayed.

SCAL: 1.000000

performing the following steps: a. Press appropriate arrow keys to set Scale to 60.

b. Press Enter key. BE SURE to press the Enter key to complete the numeric entry.

The scale is now set to 60. When the scale factor is set, both scale and offset are applied to the

measurement result. Verify that the offset value is zero for applications requiring only scale by performing the following step.

is displayed.

2-22 Operating Guide

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

NOTE

4Press Scale & Offset key, if required, until

OFFS: 0.000000

“0.000000”:

a. Press the appropriate arrow keys to set the Offset t o “0.000000.” b. Press Enter key.

BE SURE to press the Enter key to complete the numeric entry.

The offset is now set to 0.

5Press Run key.

The rpm measurement is displa yed. Note that units indicators

should be displayed. If the Offset value is not set to

and s do not appear when MATH is ON.

OFFS:

is displayed.

Example Procedure for Offset Function

The offset function can be use d to add or subtract a fixed value from measurement results. This can be very useful, for example, when tuning or aligning odd frequencies of a local oscillator (LO). The target frequency can be entered as a negative offset, then the Counter can display the differences between the LO’s frequenc y and the target freq ue ncy. You can then adjust the LO until zero is displayed in the Counter’s display.

Your task is to use the offset function to tune or align an LO to the target frequency of 222.127 MHz. Perform the following procedure to accomplish this task.

1Cycle POWER key to preset the Counter.

2 Connect the LO to channel 1, and press Fre q Ch 1 key to measure

the frequency of the LO.

3Press Scale & Offset key until

4 Set Scale to “1” by pressing the appropriate arrow keys to enter

the value 1.000000 if Scale is not already set to “1.”

Operating Guide 2-23

SCAL:

is displayed.

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

5Press Enter key.

NOTE

BE SURE to press the Enter key to complete the numeric entry.

6Press Scale & Offset key, if required, until

OFFS: 0.000000

7 Set the Offset to -222.127 MHz.

Refer to the sub-section titled “Entering the Offset Value” in Chapter 1, “Getting Started,” for details on how to perform numeric entry for Offset.

a. Use the appropriate combination of the arrow keys to display a value

of 222.127 MHz.

b. Press +/− key, which is located below the arrow keys, to change the

plus sign to minus.

OFFS: -222.127 MHz

c. Press Enter key. BE SURE to press the Enter key to complete numeric entry.

8Press Run key.

should be displayed. This is the default value.

is displayed.

OFFS:

is displayed.

The resultant frequency is displayed with -222.127 MHz subtracted from each measurement result.

The Counter displays the error or differences from the targeted

222.127 MHz. For example, the displa y might indicate

9 Adjust the LO as necessary until the Counter displays zero

(

00.000,000,0

Your local oscillator is now properly aligned.

2-24 Operating Guide

+000.023 MHz

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

Example Procedure for Turning Off Math Mode

1Press Scale & Offset key until

2 Press any one of the arrow keys.

MATH: OFF

modify the displayed result.

3Press Run key to return the Counter to its normal operation.

is displayed. Now, Scale and Offset no l onger are used to

MATH: ON

is displayed.

Example Procedure for Set Reference Function—Offset From the Last Measurement Value (See in g Digits Not Visi ble on the 12-Digit Display)

The

SET REF: YES

value, rounded to elev en digits , to set the OFFSET. It also re sets t he scal e value to 1.0. Thus, any diffe rence in the offset (o r now the reference va lue) and the current measurement value is displayed.

Let’s assume you are measuring the frequency of a stable source, but you are only interested in the least significant digi ts of the measurement. Use the value.

Your task is to measure a stable source to obtain the changes in the least significant digits.

SET REF: YES

menu item uses the negative of the last measurement

menu item to configure the appropriate OFFSET

1Cycle POWER key to preset the Counter.

GATE

2 Change gate time to 15.0 seconds on

3 To demonstrate SET REF:, connect a 10 MHz sine wave signal to

channel 1 of the Counter, and press Freq Ch 1 key.

(Note that since the gate time is set to 15 seconds, it will take about 15 seconds to for the Counter to display the measurement.)

10.000,000,000,1 MHz

4Press Scale & Offset key until

Operating Guide 2-25

is displayed.

SET REF:

menu.

is displayed.

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

5 Press the any one of the arrow keys to select

press Enter key.

OFFS: −10.00000 M

Note that this valu e represents the last measurement of the input signal rounded to eleven digi ts. The Counter us es it as the ref erence off set val ue, and reverses the sign from + to − .

6Press Run key.

−

12*

µ (120 µs) is displayed, for example, at the completion of the next

measurement. This value (−0.00012) is the small difference between the signal being

measured and the reference value (

Using the reference allows you to observe small differences in the

13th–15th digits which would not be observable in the 12-digit display.

is displayed, for example.

OFFS: −10.00000 M

SET REF: YES

) obtained in step 5.

, and

Overview of Statistics (Stats) Menu

The Stats menu allows you to:

• select which computed statistics you want displayed (SHOW: STD DEV, MEAN , MAX, or MIN).

• choose between having the actual measurement or statistical result displayed (SHOW: MEAS).

• select the number of measurements you want to make for each computed statistic (N:).

• enable or disable the Stats mode (STATS: ON or OFF).

• enable the Counter to perform statistical computation on only measurements that are within the user-entered limits; that is, filter data (USE: IN LIMIT), or

• enable the Counter to perform statistical computation on all measurements, whether they fall in or out of the user-entered limits (USE: ALL MEAS).

• configure Stop/Single key to initiate a set of N measurements (ON SINGLE: 1 or N).

2-26 Operating Guide

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

To Use the Stats Menu for Automatic and Continuous Statistical Analysis

Example Procedure for Computing Stats

For demonstration purposes, let’s say you need to know the mean (average) and minimum frequency values of a signal. Also, you want the Counter to make 20 measurements before it performs these statistical computations.

Perform the following procedure to accomplish this task.

NOTE

1 Connect the signal to channel 1 input, and press Freq Ch 1 key.

2Press Stats key until

N: 100

3Set N to 20 (since you want t he Counter t o make 20 measurements

before computing the mean and minimum values) by pressing the appropriate arrow keys.

N: 20

4Press Enter key.

BE SURE to press the Enter key to complete numeric entry.

The Counter is now set to make 20 measurements before computing statistics.

5Press Stats key until

6 Press any one of the arrow keys until

is displayed (100 is the default value).

is displayed.

SHOW:

is displayed.

SHOW: MEAN

is displayed.

Operating Guide 2-27

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

7Press Run key.

Immediately after the Run key is pressed, the Counter momentarily displays

DOING STATS

displays the mean frequency value of the input signal.

. When the Coun te r ha s ma de 2 0 v ali d me asu rem en ts , it t he n

NOTE

The Counter will display updated statistics results every 20 measurements.

8Press Stop/Single key after you have a mean value displayed.

9To display the minimum frequency value, perform the following:

a. Press Stats key. b. Press any one of the arrow keys until c. Press Freq Ch 1 key.

CAUTION Pressing the Run key now would clea r the pr esent statistics results and

calculate a new set of results after “N” measurements.

Example Procedure for Easy Viewing of Stats

The d and f arrow keys provide a short cut to viewing each of the stats (that is, standard deviation, mean , maximum, an d minimu m) wh en the Counter is already displaying a statistic measurement. These keys allow you to cycle through the different Stats results and automatically view them.

While the Counter is displaying a statistics measurement, press either the d or f arrow key to cycle through and display each of the four computed statistics, and the current measurement.

SHOW: MIN

is displayed.

NOTE

The Display Digits keys (that is, More Digits and Fewer Digits)

do NOT affect standard deviation display resul ts.

2-28 Operating Guide

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

Example Procedure for Filtering Data (Using Limits) During Stats

1 Using the procedure in the previous sub-section titled “Example

Procedure for Computing Stats,” set up the Counter to display the minimum frequency value of an input signal.

2 Set the upper and lower limits. (Refer to the section in Chapter 1 titled

“To Set Limits of Measurements” if needed.)

3Press Stats key until

4 Press one of the arrow keys to toggle to

USE: IN LIMIT

5Press Run key.

The Counter will now perform the statistical computations (that is, standard deviation, mean, maximum, and minimum) on only those measurements that are within the user-entered limits. The Counter then displays the statistics you picked (minimum, in this case).

6Press Stats key until

7 Press any one of the arrow keys to toggle to

is displayed.

USE: ALL MEAS

8Press Run key.

The Counter will now perform the statistical computations (that is, standard deviation, mean, maximum, and minimum) on all measurements, whether they fall in or out of the user-entered limits. The Counter then displays the statistic you picked (minimum, in this case).

USE:

is displayed.

USE:

is displayed.

IN LIMIT

ALL MEAS

state.

Operating Guide 2-29

Chapter 2 Operating Your Frequency Counter

Using the MATH Menu Keys

Example Procedure for Configuring SINGLE to Initiate N

Measurements

Please refer to the procedure titled “To Use the Measurement Control

Keys” on page 2-7 in this chapter for an example use of ON SINGLE.

Example Procedure for Turning Off Stats Mode

1Press Stats key until

2 Press any one of the arrow keys.

STATS : OFF

3Press Run key to return the Counter to its normal operation.

is displayed.

STATS: ON

is displayed.

2-30 Operating Guide

Chapter 2 Operating Your Frequency Counter

Limit Modes

Uppr & Lower

LIMITS

Using the LIMITS Menu Keys

Note that Math and Limits menus are not available for Voltage Peaks measurements.

Overview of Limits Menus

The menu items under the Limits keys allow you to:

• select the desired upper and lower measurement limits (UPPR:, LOWR:).

• disable or enable Limit Testing (LIM TEST: OFF or ON)—Note that the Limit Testing is automatically enabled when you set the upper and lower limits, or update any menu item in the Limit Modes menu; thus, the primary function of the LIM TEST menu item is to allow you to turn Limit Testing off.

• set the Counter to stop making measurements when a measurement exceeds the user-entered limits (ON FAIL: STOP). (Stop on limits does not have any effect if the Counter is in the single measurement mode.)

• enable the Counter to continue taking measurements after a measurement exceeds the user-entered limits (ON FAIL: GO ON).

• change the Counter display from numeric to analog graph to quickly visualize changes in the signal (or to quickly see when measurements are in or out of limits) (SHOW: NUMBER or GRAPH).

Operating Guide 2-31

Chapter 2 Operating Your Frequency Counter

Using the LIMITS Menu Keys

To Set and Use Automatic Limit Testing

Limits Testing Example 1—Flag and Stop Measuring On Limits

Automatic limit testing can be used to monitor a test signal to assure that it does not drif t outside of a user-entered set of limi ts.

For demonstration purposes, you want to first measure the frequency of a 10 MHz signal applied to channel 1 of the Counter. Next, you want to set limits that would cause the Counter to flag (turn on the Limits annunciator in the front-panel display) and stop making measurements if

this signal drifts more than ±1 kHz.

1 Connect the 10 MHz input signal to channel 1 of the Counter,

and press Freq Ch 1 key. Assume that the frequency measured is 10 MHz. If the drift is not to

be larger than ±1 kHz, then the upper limit should be set to 10.001 MHz and the lower limit to 9.999 MHz. Let’s set these values in the following steps.

NOTE

2Press Uppr/Lower key until

UPPR: 0.000000

3Set UPPR to 10.001 MHz. (Refer to the section in Chapter 1 titled

“To Set Limits of Measurements” if needed.)

After you enter the value 10.001 MHz, BE SURE to press the Enter key to c omplete the en try.

4Press Uppr/Lower key, if required, until

LOWR: 0.000000

2-32 Operating Guide

is displayed (0 is the default value).

UPPR:

is displayed.

LOWR:

is displayed.

Chapter 2 Operating Your Frequency Counter

Using the LIMITS Menu Keys

NOTE

5Set

6Press Limit Modes key until

7Press Limit Modes key.

8 Press any one of the arrow keys to toggle to the next state.

9Press Run key to start making measurements with this

LOWR

After you enter the value 9.999 MHz, BE SURE to press the Enter key to c omplete the en try.

Note that once either the upper or lower limits have been set, the limit testing is automatically enabled as indicated by the display, and the Limit Modes indicator.

ON FAIL: GO ON

ON FAIL: STOP

Counter to stop making measurements when the input signal drifts more

than ±1 kHz.

limits-testing choice selected.

to 9.999 MHz.

is displayed.

is displayed. The

LIM TEST: ON

ON FAIL: STOP

is displayed.

LIM TEST: ON

function tells the

Now, if a measurement drifts out of the user-entered lim its the Limit annunciator in the display will light. The Counter will stop making measurements and hold the out-of-limit measurement in the display.

Operating Guide 2-33

Chapter 2 Operating Your Frequency Counter

Using the LIMITS Menu Keys

Limits Testing Example 2—Flag On Limits but Continue Measuring

If you decide that you want the Counter to flag measurements that are out of limits but to continue taking measurements, then perform the following steps.

1Press Limit Modes key until

2 Press any one of the arrow keys to toggle to the next state.

ON FAIL: GO ON

is displayed.

ON FAIL: STOP

is displayed.

3Press Run key to start making measurements with this

limits-testing choice selected.

Now, each time a measurement drifts out of the user-entered limits the Limit annunciator in the display will light, but the Counter will continue to make measurements.

The Limit annunciator will go on whenever a result is out of limits. As soon as a result is within limits, the Limit annunciator will go off.

Limits Testing Example 3—Use Analog Graph Display While Adjusting/A l ig n i ng In pu t Si g n a l

1 For demonstration purposes, connect a 10 MHz signal to

channel 1, and press Freq Ch 1 key.

2Using the Uppr & Lower key, set the upper limit to 10.2 MHz and

the lower limit to 9.8 MHz. (Refer to the section in Chapter 1 titled

“To Set Limits of Measurements” if needed.)

3Press Limit Modes key until

4 Press any one of the arrow keys to toggle to the next state.

SHOW: GRAPH

2-34 Operating Guide

is displayed.

SHOW: NUMBER

is displayed.

Agilent 53181A Operations Guide

Specifications and Main Features

Frequently Asked Questions

User Manual

In This Guide

Contents and Organization

Related Documents

Types of Service Available if Your Instrument Fails

Standard Repair Services (Worldwide)

Repair Instrument Yourself

Repackaging for Shipment

Description of the 225 MHz Frequency Counter

Options

Hardware

Support

Accessories Supplied and Available

Accessories Supplied

Accessories Available

HP 53181A Quick Reference Guide

The Front Panel at a Glance

The Front Panel Indicators at a Glance

The Front Panel Indicators at a Glance (Cont.)

The Front Panel Menus at a Glance

The Front Panel Menus at a Glance (Cont.)

The Front Panel Menus at a Glance (Cont.)

The Display Annunciators at a Glance

The Display Special Characters at a Glance

The Underscore Placeholder

The Asterisk Placeholder

The Limit Te st Graph Characters at a Glance

The Rear Panel at a Glance

Making Measurements

To Measure Frequency

To Select Input Coupling and Impedance

Selecting Input Coupling

Selecting Input Impedance

To Set Input Channel Trigger Level/Sensitivity

Changing Trigger Mode

Modifying Input Trigger Level

Selecting Input Trigger Slope

Selecting Input Sensitivity

Starting the Measurement

To Select Scale and Offset

Entering the Scale Value

Entering the Offset Value

Displaying the Math Results

Disabling Math

Setting the Upper Limit

Setting the Lower Limit

Setting the Counter to Flag On Limits But Continue Measuring

Disabling Limit Testing

Disabling Math

To Perform Statistics on Measurements

Selecting the Type of Statistics (Stats)

Computing Stats on Filtered Data Only

Displaying Stats After Filtering Data of Input Signal

Disabling Stats and Math

To Control Measurement

Introduction

Chapter Summary

Where to Find Some Key Working Examples

How this Counter Works for You

Summary of the Measurement Sequence

Overview of the Measurement Control Keys

To Use the Measurement Control Keys

Using Entry/Select (Arrow) Keys

To Use During Numeric Entry

To Use When Sequencing Through the Other Meas and Recall Menus

Using the MEASURE Menu Keys

Overview of the MEASURE Menus

To Measure Frequency

To Measure Frequency Ratio (Optional)

To Measure Period

To Measure Positive/Negative Volt Peaks

Using the Gate & External Arm Menu Key

Overview of Gate/External Arming Functions

TIME Arming

AUTO Arming

EXTERNAL Arming

DIGITS Arming