EIP Phasematrix 451 schematic
TM 11-6625-3031-14
.
TECHNICAL MANUAL
OPERATOR’S, ORGANIZATIONAL,
DIRECT SUPPORT,
AND
GENERAL SUPPORT MAINTENANCE MANUAL
COUNTER, PULSE, ELECTRONIC
TD-1338(V)1/USM
(NSN 6625-01-120-7832)
HEADQUARTERS, DEPARTMENT OF THE ARMY
6 MAY 1983
SAFETY STEPS TO FOLLOW IF SOMEONE
IS THE VICTIM OF ELECTRICAL SHOCK
DO NOT TRY TO PULL OR GRAB THE INDI-
VIDUAL
IF POSSIBLE, TURN OFF THE ELECTRICAL
POWER
IF YOU CANNOT TURN OFF THE ELECTRICAL
POWER, PULL, PUSH, OR LIFT THE PERSON
TO SAFETY USING A WOODEN POLE OR A ROPE
OR SOME OTHER INSULATING MATERIAL
SEND FOR HELP AS SOON AS POSSIBLE
AFTER THE INJURED PERSON IS FREE OF CONTACT WITH THE SOURCE OF ELECTRICAL
SHOCK, MOVE THE PERSON A SHORT
DISTANCE AWAY AND IMMEDIATELY START
ARTIFICIAL RESUSCITATION
TM 11-6625-3031-14
TECHNICAL MANUAL
NO. 11-6625-3031-14
REPORTING ERRORS AND RECOMMENDING IMPROVEMENTS
You can help improve this manual.
you know of a way to improve the procedures, please let us know.
Mail your letter,
tions and Blank Forms),
this manual direct to:
Electronics Command and Fort Monmouth, ATTN:
Fort Monmouth, NJ 07703.
DEPARTMENT OF THE ARMY
WASHINGTON, D.C. 6 May 1983
OPERATOR’S,
AND GENERAL SUPPORT MAINTENANCE MANUAL
ORGANIZATIONAL, DIRECT SUPPORT
FOR
COUNTER, PULSE, ELECTRONIC
TD-1338(V)1/USM
(NSN 6625-01-120-7832)
If you find any mistakes or if
DA Form 2028 (Recommended Changes to Publica-
or DA Form 2028-2 located in the back of
Commander, US Army Communications-
DRSEL-ME-MP,
HEADQUARTERS
Chapter
Section I.
In either case,
INTRODUCTION
1.
General Information . . . . . . . . . . . . . . .
Scope. . . . . . . . . . . . . . . . . . . . 1-1
Reports of maintenance forms, records and
reports. . . . . . . . . . . . . . . . . . . . . 1-2
Administrative storage . . . . . . . . . . . . . 1-3
Destruction of Army electronics materiel. . . . . 1-4
Reporting equipment improvement recommendations
(EIR'
S
). . . . . . . . . . . . . . . . . . . . . 1-5
Warranty information . . . . . . . . . . . . . . 1-6
II.
Equipment Description . . . . . . . . . . . . . .
Equipment characteristics, capabilities and
features . . . . . . . . . . . . . . . . . . . . 1-7
Equipment data . . . . . . . . . . . . . . . . . 1-8
III.
Technical Principles of Operation . . . . . . . .
Counter functional operation . . . . . . . . . . 1-9
a reply will be furnished direct to you.
TABLE OF CONTENTS
Para
Page
1-1
1-1
1-1
1-1
1-1
1-1
1-1
1-2
1-2
1-2
1-4
1-4
i
TM 11-6625-3031-14
TABLE OF CONTENTS - Continued
Chapter
Section I.
2.
II.
III.
Para
Basic counter A1 . . . . . . . . . . . . . ...1-10
Converter A2 . . . . . . . . . . . . . . . . . . 1-11
OPERATING INSTRUCTIONS
Description and Use of Operator’s Controls and
Indicators . . . . . . . . . . . . . . . . . . .
Front-panel controls, connectors and
indicators . . . . . . . . . . . . . . . . . . .
Rear-panel controls and connectors. . . . . . . .
Preventive Maintenance Checks and Services . . .
General instructions. . . . . . . . . . . . . . .
PMCS procedures. . . . . . . . . . . . . . . . .
Cleaning instructions . . . . . . . . . . . . . .
Operation Under Usual Conditions . . . . . . . .
Assembly and preparation for use . . . . . . . .
Operation as stand-alone instrument . . . . . . .
Externally enabled operation . . . . . . . . . .
Pulse profile measurements. . . . . . . . . . . .
Dynamic characteristics of time varying signals .
Multiple pulse signal measurements . . . . . . .
Timing considerations . . . . . . . . . . . . . .
Accuracy . . . . . . . . . . . . . . . . . . . .
Techniques for improving accuracy . . . . . . . .
Operation using General Purpose Interface Bus . .
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15
Page
1-6
1-8
2-1
2-1
2-1
2-5
2-5
2-5
2-6
2-7
2-7
2-8
2-10
2-10
2-11
2-11
2-11
2-12
2-13
2-13
Chapter
Section I. Lubrication . . . . . . . . . . . . . .
III. Maintenance Procedures . . . . . . . . . . . . . . . . .
Chapter
Section I.
III.
OPERATOR AND ORGANIZATIONAL
3.
II.
Troubleshooting Procedures . . . . . . . . . .
Introduction . . . . . . . . . . . . . . . . . . . . . . .
Inspection. . . . . . . . . . . . . . . . . . . . . . . .
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . .
Replacement . . . . . . . . . . . . . . . . . . . . . . .
Test. . . . . . . . . . . . . . . . . . . . . . . . .
4.
DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE
Repair Parts, Special Tools; Test Measurement,
and Diagnostic Equipment (TMDE); and Support
Equipment. . . . . . . . . . . . . . . . . . . . . . . . .
Common tools and equipment . . . . . . . . . .
Special tools, TMDE,
Repair parts . . . . . . . . . . . . . . . . . . . . . .
II.
Service Upon Receipt . . . . . . . . . . . . .
Troubleshooting . . . . . . . . . . . . . . . . . . . . .
Introduction . . . . . . . . . . . . . . . . . . .
Reference diagrams . . . . . . . . . . . . . .
IV.
Maintenance Procedures . . . . . . . . . . . .
Disassembly, replacement, and reassembly . . .
Adjustments. . . . . . . . . . . . . . . . . .
Performance test . . . . . . . . . . . . . . . . .
and support equipment . .
MAINTENANCE
3-4
3-5
3-6
3-7
3-8
4-1
4-2
4-3
4-5
4-6
4-7
4-8
4-9
3-1
3-1
3-3
3-3
3-3
3-3
3-3
3-3
4-1
4-1
4-1
4-1
4-1
4-1
4-1
4-2
4-17
4-17
4-20
4-28
ii
TABLE OF CONTENTS - Continued
TM 11-6625-3031-14
Section
Preparation for Storage or Shipment . . . . . . .
V.
Preparation of equipment. . . . . . . . . . . . . 4-10
Packing instructions. . . . . . . . . . . . . . . 4-11
Appendix A. REFERENCES. . . . . . . . . . . . . . . . . . . .
Appendix B.
Appendix C.
MAINTENANCE ALLOCATION . . . . . . . . . . . . .
COMPONENTS OF END ITEM AND BASIC ISSUE
ITEMS LISTS. . . . . . . . . . . . . . . . . . .
Appendix D.
Appendix E.
ADDITIONAL AUTHORIZATION LIST . . . . . . . . . .
EXPENDABLE SUPPLIES AND MATERIALS LIST . . . . .
Para
Page
4-33
4-33
4-33
A-1
B-1
C-1
D-1
E-1
iii
TM 11-6625-3031-14
LlST OF ILLUSTRATIONS
Figure
1-1
1-2
1-3
1-4
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
Title
Counter,
Counter,
Basic Counter A1,
Converter A2, Functional Block Diagram . . . . . . . . . . . . . . 1-9
Counter Front Panel. . . . . . . . . . . . . . . . . . . . . . . .2-1
Counter Rear Panel. . . . . . . . . . . . . . . . . . . . . . . .2-4
Pulse Profile Measurement Test Setup . . . . . . . . . . . . . . . 2-10
Pulse Profile Measurement . . . . . . . . . . . . . . . . . . . . 2-10
Time Varying Signal Measurement Test Setup . . . . . . . . . . . . 2-11
Internal Timing Delays . . . . . . . . . . . . . . . . . . . . . . 2-12
GPIB Capabilities and Structure . . . . . . . . . . . . . . . . . 2-15
GPIB IEEE STD 488/1975 ADDRESS SWITCH Positions . . . . . . . . . 2-16
Subassembly and Cable Locations . . . . . . . . . . . . . . . . . 4-3
Counter Interconnect A100, Connector and Switch Locations . . . . 4-17
Counter, Partial Exploded View . . . . . . . . . . . . . . . . . . 4-18
Adjustment Locations. . . . . . . . . . . . . . . . . . . . . . . 4-21
Pulse Generator Output . . . . . . . . . . . . . . . . . . . . . . 4-23
YIG Control A202, Adjustment and Test Point Locations . . . . . . 4-24
Detected Modulation and 20 kHz Reference Pulse Timing . . . . . . 4-24
Converter Sequencer A203, Adjustment and Test Point
Locations. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-26
Return Loss Measurement Setup . . . . . . . . . . . . . . . . . . 4-26
Return Loss Measurement Waveform . . . . . . . . . . . . . . . . . 4-27
Typical Attenuator Control Ramp Offset . . . . . . . . . . . . . . 4-27
Comb Line . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-27
Pulse, Electronic TD-1338(V)1/USM . . . . . . . . . . . . 1-0
Functional Block Diagram. . . . . . . . . . . . . . . . . 1-5
Functional Block Diagram . . . . . . . . . . . . 1-7
Page
FO-1
FO-2
FO-3A
FO-3B
FO-4A
FO-4B
FO-5A
FO-5B
FO-6A
FO-6B
FO-7A
FO-7B
FO-8A
FO-8B
FO-9A
FO-9B
FO-10A
FO-10B
iv
Counter Interconnection Schematic Diagram
Interconnection Diagram,
Component Locator Counter Interconnect (A100)
Schematic Diagram Counter Interconnect (A100)
Component Locator and Descriptive Information Count Chain Control (A102)
Schematic Diagram Count Chain Control (A102)
Component Locator and Descriptive Information Count Chain (A103)
Schematic Diagram Count Chain (A103)
Component Locator and Descriptive Information Control (A104)
Schematic Diagram Control (A104)
Component Locator and Descriptive Information Gate Generator (A105)
Schematic Diagram Gate Generator (A105)
Component Locator and Descriptive Information High Frequency (A106)
Schematic Diagram High Frequency (A106)
Component Locator and Descriptive Information Power Supply (A107)
Schematic Diagram Power Supply (A107)
Component Locator and Descriptive Information Reference Oscillator
Buffer (A108)
Schematic Diagram Reference Oscillator Buffer (A108)
Detailed Technical Schematic
TM 11-6625-3031-14
Figure
FO-11A
FO-11B
FO-12A
FO-12B
FO-13A
FO-13B
FO-14A
FO-14B
FO-15A
FO-15B
FO-16A
FO-16B
LIST OF ILLUSTRATIONS
Title
Component Locator and Descriptive Information Display (A110)
Schematic Diagram Display (A110)
Component Locator Converter Interconnect (A200)
Schematic Diagram Converter Interconnect (A200)
Component Locator and Descriptive Information Source/Amplifier (A201)
Schematic Diagram Source/Amplifier (A201)
Component Locator and Descriptive Information Yig Control (A202)
Schematic Diagram Yig Control (A202)
Component Locator and Descriptive Information Converter Sequencer (A203)
Schematic Diagram Converter Sequencer (A203)
Component Locator and Descriptive Information IF Processor (A204)
Schematic Diagram IF Processor (A204)
(Continued)
Table
1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
3-1
4-1
4-2
4-3
4-4
4-5
4-6
4-7
LIST OF TABLES
Title
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . .
Front-panel Controls, Connectors and Indicators . . . . . . . . .
Rear-panel Controls and Connectors . . . . . . . . . . . . . . . .
Operator Preventive Maintenance Checks and Services . . . . . . .
Counter GPIB Capability Identification Codes . . . . . . . . . . .
GPIB IEEE STD 488/1975 Connector Pin Assignments . . . . . . . . .
On Line and Off Line ADDRESS SWITCH Settings . . . . . . . . . . .
ADDRESS SWITCH Settings vs ASCII Characters . . . . . . . . . . .
Programming Summary. . . . . . . . . . . . . . . . . . . . . . . .
Typical Program Using Hewlett-Packard 9815 Calculator as
Controller. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator and Organizational Troubleshooting . . . . . . . . . . .
Symptom Index . . . . . . . . . . . . . . . . . . . . . . . . . .
Direct Support and General Support Troubleshooting . . . . . . . .
Power Supply Voltages and Adjustments . . . . . . . . . . . . . .
Band B Response Tests . . . . . . . . . . . . . . . . . . . . . .
Preset Frequency Tests . . . . . . . . . . . . . . . . . . . . . .
Control Sequence. . . . . . . . . . . . . . . . . , . . . . . , .
Converter Sequence Functions . . . . . . . . . . . . . . . . . . .
Page
1-1
2-1
2-5
2-6
2-14
2-16
2-17
2-18
2-20
2-26
3-1
4-2
4-4
4-22
4-29
4-31
4-45
4-65
v
TM 11-6625-3031-14
1-0
Figure 1-1.
Counter, Pulse, Electronic TD-1338(V)1/USM
CHAPTER 1
INTRODUCTION
Section I. GENERAL INFORMATION
TM 11-6625-3031-14
1-1.
tion and maintenance of Counter, Pulse,
Electronic TD-1338(V)1/USM. Throughout
this manual it is referred to as the
counter.
measure the frequency of cw, pulsemodulated, or frequency-modulated
microwave signals between 300 MHz and
18 GHz.
as 100 nanoseconds, with a maximum
pulse repetition frequency of 2.5 MHz.
Peak-to-peak deviation of FM signals
may be as great as 40 MHz at 10 MHz
modulation rates.
1-2.
Records and Reports.
Unsatisfactory Equipment.
of the Army forms and procedures used
for equipment maintenance will be
those prescribed by TM 38-750, The
Army Maintenance Management System
(Army) .
AFM 66-1 for maintenance reporting and
TO 00-35D54 for unsatisfactory equipment reporting.
Deficiencies.
SF 364 (Report of Discrepancy (ROD)) as
prescribed in AR 735-11-2/DLAR 4140.55/
NAVMATINST 4355.73/AFR 400-54/MCO
4430.3E.
(DISREP) (SF 361). Fill out and forward
Discrepancy in Shipment Report (DISREP)
(SF 361) as prescribed in AR 55-38/
NAVSUPINST 4610.33B/AFR 75-18/MCO
P4610.19C/DLAR 4500.15.
Scope.
a. This technical manual covers opera-
b. The counter (fig. 1-1) is used to
Pulse widths can be as narrow
Reports of Maintenance Forms,
a. Reports of Maintenance and
Department
Air Force personnel will use
b. Report of Packaging and Handling
Fill out and forward
c. Discrepancy in Shipment Record
1-3.
issued to and used by Army activities
will have preventive maintenance per-
formed in accordance with the PMCS
charts before storing.
the equipment from administrative
storage, the PMCS should be performed
to assure operational readiness.
1-4.
Materiel.
materiel to prevent enemy use shall be
in accordance with TM 750-244-2.
1-5.
Recommendations (EIR’s).
let us know.
user,
what you don’t like about your equipment.
the design or performance.
SF 368 (Quality Deficiency Report).
Mail it to:
Communications-Electronics Command and
Fort Monmouth, ATTN: DRSEL-ME-MP,
Fort Monmouth, New Jersey 07703. We’ll
send you a reply.
1-6.
Microwave, Inc. for 12 months. It
starts on the date, found in block 23,
DA Form 2408-9, in the logbook.
all defects in material or workmanship
to your supervisor, who will take appropriate action through your organizational maintenance shop.
Administrative Storage.
Administrative storage of equipment
When removing
Destruction of Army Electronics
Destruction of Army electronics
Reporting Equipment Improvement
If your counter needs improvement,
Send us an EIR. You, the
are the only one who can tell us
Let us know why you don’t like
Put it on an
Commander, US Army
Warranty Information.
The counter is warranted by EIP
Report
1-1
TM 11-6625-3031-14
Section II. EQUIPMENT DESCRIPTION
1-7.
Equipment Characteristics, Capa-
bilities and Features.
The counter is a portable test
instrument usable as either selfcontained frequency measurement or
monitoring indicator, or as part of a
programmable automatic test equipment
(ATE) system.
readout of frequency from 300
through 18 MHz.
It provides a direct
MHZ
Capabilities and
features include:
a. Measures pulse-modulated microwave
signals.
b. Measures frequency-modulated
microwave signals.
c.
Measures cw microwave signals.
d. Front panel self-test of digital
display.
Table 1-1. Specifications
Frequency Range:
Band A
e. Front panel self-test of internal
circuits.
f. Automatic and selectable resolution
of—readout display.
g. Overload protection built in at
input connector.
h.
Simple change to cover different
power line voltages.
i. Front-panel selection of frequency
scanning limits.
j. Comparable with IEEE STD 488
General Purpose Interface Bus (GPIB).
1-8.
Equipment Data.
Table 1-1 lists the electrical
and physical characteristics of the
counter.
300 MHz to 950 MHz
Band B
Pulse Characteristics:
Pulse width
Pulse repetition frequency
Accuracy:
CW or pulse > 100 µsec
Pulse < 100 µsec
Averaging Error (kHz rms):
100 µsec gate
1 msec gate
Gate error (max)
925 MHz to 18 GHz
100 nsec min, measured at 3-dB points
Minimum 50 Hz or 0 Hz, rear panel
selectable. Maximum 2.5 MHz. Minimum
time between pulses 300 nsec.
Time base accuracy ± 1 count
Time base accuracy ± averaging error
± gate error
Band A Band B
NOTE
PW =
pulse width in µsec
1-2
TM 11-6625-3031-14
Table 1-1.
Time Base:
Crystal frequency
Stability:
Aging rate
Temperature
Line voltage
Sensitivity
Input Impedance
Connector Types
Maximum Input Peak Level:
Operating
Burnout level
Specifications - Continued
Temperature compensated crystal
oscillator
(TCXO)
10 MHz
<|3 X 10
<|2 X 10
<|1 X 10
-7
|
per month
-6
|
, 0 to 50°C
-7
|
for ± 10% change
Band A
300
- 950 MHz:
-10 dBm peak
50 ohms nominal
BNC
+10 dBm
+27 dBm
Band B
925 MHz - 10 GHz:
-10 dBm peak
10 GHz - 18 GHz:
-5 dBm peak
50 ohms nominal
N (precision)
+10 dBm
+30 dBm
Reading Time (sec):
100 µsec gate
1 msec gate
Display
Band B Minimum FM Tolerance:
CW
Pulse
Frequency profile
400
(PW) (PRF)
4000
(PW)(PRF)
100
(PW) (PRF)
1000
(PW) (PRF)
NOTE
PW =
PRF =
pulse width in µsec
pulse repetition frequency
in Hertz
7-digit light emitting diode (LED)
Fixed decimal point
Leading zero suppression
40 MHz p-p deviation for modulation
rates dc to 10 MHz
Without input inhibit:
20 MHz maximum
frequency shift across pulse
With input inhibit:
20 MHz maximum
frequency shift during input inhibit
pulse
1-3
TM 11-6625-3031-14
Table 1-1.
Specifications - Continued
Band B Acquisition Time:
PRF > 100 H
Z
PRF < 100 Hz
Resolution
General Purpose Interface Bus (GPIB)
Power
Operating Temperature
Warm up Time
Weight
Dimensions (inches)
100 msec + 50 msec/GHz
100 msec +
sec/GHz
10 kHz, 100 kHz, 1 MHz
IEEE Standard Digital Interface for
Programmable Instrumentation, IEEE
STD 488-1975
115 or 230 Vac ± 10%, 50/60 Hz;
115 Vac ± 10%, 400 Hz; single phase;
100 watts nominal
0-
50°C
None Required
30 lb
3.5 H x 16.75 W x 19.0 D
Section Ill. TECHNICAL PRINCIPLES OF OPERATION
1-9.
Counter Functional Operation.
(Fig. 1-2.)
a. The counter automatically measures
and displays the frequency of cw or
pulse-modulated signals from 300 MHz
through 18 GHz. With accessory equip-
ment,
the counter can make dynamic
frequency measurements; measurement
windows as narrow as 20 nanoseconds are
possible.
Two primary input connectors
on the front panel, BAND A 300 - 950 MHz
and BAND B 925 MHz - 18 GHz, are used to
connect the counter to the external frequency source.
An auxiliary INPUT
INHIBIT connector on the rear panel can
be used to control the time during
which an actual reading is made.
Control of the counter can be accomplished
by front-panel switches or by a General
Purpose Interface Bus (GPIB) from an
external GPIB controller.
The output
of the counter is displayed on a 7digit, fixed decimal, light emitting
diode (LED) display and can be transmitted through the GPIB for other
purposes.
controlled by Reference Oscillator Buffer A108 with outputs to Basic Counter
Al and Converter A2; a third output is
connected to a rear-panel 10 MHz OUTPUT
connector.
divide-by-four circuit in Prescaler
A109, whose output is directed to Basic
Counter A1 through Dual Delay Line
A116.
counted in the basic counter for either
a 400 microsecond or 4 millisecond
period to obtain 10 kHz resolution readout on Display A110.
in A1 is enabled by the input signal and
is open only when a signal is present.
verter A2, converted to an IF signal by
heterodyning the input signal against a
200 MHz harmonic,
through Delay Line A112.
gate in A1 is enabled by the Input
signal and is open only when a signal
is present.
inversely proportional to the measurement
Accuracy of the counter is
Band A signals are fed into a
b.
The divide-by-four frequency is
The counter gate
Band B signals are fed into Con-
c.
and directed to A1
The counter
In A1, resolution is
1-4
Figure 1-2.
1-5
TM 11-6625-3031-14
TM 11-6625-3031-14
time.
For example:
a 1 microsecond
gate time will give 1 MHz resolution.
To get 10 kHz resolution, the counter
threshold comes from Prescaler A109
while the Band B threshold comes from
I.F. Processor A204 in Converter A2.
automatically averages as many input
pulses as necessary to obtain a total
gate time of 100 microseconds or 1 millisecond.
The required number of
pulses is a function of input pulse
width.
The intermediate frequency from
A2 is processed and counted in A1 and
displayed on A110.
d.
Three rear-panel connectors provide
10–MHz, SIGNAL THRESHOLD, and GATE OUT-
PUTS .
The 10 MHz OUTPUT is a service
convenience for adjusting the temperature compensated crystal oscillator
(TCXO) on Reference Oscillator Buffer
A108.
The other two signal outputs may
be used for dynamic frequency measurements such as pulse profile measurements
or time varying signal measurements.
e.
Power Supply A107 provides +5,
-5.2, +12,
counter circuits.
-12, and +18 volts dc for the
The +18 Vdc output is
unregulated; the other four voltages are
regulated.
processed into the range below 360 MH
and applied to the 400 MHz decade, the
frequency of the signal is determined by
accumulating the number of signal cycles
occurring within a precisely determined
time interval (gate). The gate period
is dependent on the 200 MHz reference
frequency.
gates are 100 microseconds and 1 milli-
second for Band B, or 400 microseconds
and 4 milliseconds for Band A. In order
to measure narrow pulses to a resolution
of 10 kHz, it is necessary to add the
number of cycles counted in each of a
large number of pulses until the
required total time interval is
obtained.
precision interval gate. This function
is considerably more difficult for
pulsed signals than it is for cw signals,
the overall accuracy of the counter
1-10.
Basic Counter A1.
(Fig. 1-3.)
depends.
it supplies a gate to A106 only when an
a. Input signals from either the low
range (300 -
(925 MHz -
950 MHz) or high range
18 GHz) sources, or both,
are applied to the signal processor
circuits on High Frequency Circuit
Card A106.
The signal from Prescaler
input signal is present, and it accumulates the total time of gate application
for periods of either 100 microseconds
or 1 millisecond for Band B, or either
400 microseconds or 4 milliseconds for
Band A.
A109 is the BAND A input frequency,
divided by four (f/4). The signal
from I.F. Processor A204 is the BAND B
input frequency minus the reference
frequency identified as the converter
IF signal.
Selection of which signal
to display is controlled by the front
panel BAND selection switches or by
GPIB selection.
Only one of the signal
inputs can be displayed even though
both may be connected to the counter.
The f/4 and the IF signal inputs are
360 MHz or lower and are directed to the
400 MHz decade circuits on A106.
Two threshold (Band A and/or
b.
Band B) control levels are applied to
Gate Generator A105 to provide a gate
output to the 400 MHz decade through
the gate calibrator.
The Band A
requires that the gate begin after the
signal is present at A106 and to end
before the end of signal. This is done
by generating a gate approximately 30
nanoseconds shorter than the RF signal
start as determined by the associated
Band A or Band B threshold level.
arrival time at A106 of the converter
IF or the prescaler f/4 signal is con-
trolled by delay lines in A116, in
series with the signals, so that the
gate will fall entirely within the signal pulse application.
counting clock pulses when the gate is
open until a total period of 100 micro-
seconds or 1 millisecond for Band B, or
400 microseconds or 4 milliseconds for
When an input signal has been
c.
Z
Total time intervals of the
d. Gate Generator A105 provides a
and it is on this function that
A105 performs two functions;
e. The first function or operation
The
f. The second function is done by
1-6
Figure 1-3.
1-7
TM 11-6625-3031-14
TM 11-6625-3031-14
Band A, is accumulated.
that each gate opening is for an exact
integral number of clock pulses.
MHz clock is used, causing the gate
width to increase in 5 nanosecond steps
until a total of 20,000 steps for
100 microseconds, 80,000 steps for
400 microseconds, 200,000 steps for
1 millisecond, or 800,000 steps for
4 milliseconds is accumulated.
g. The signal passes through the
counter gate and is accumulated in the
counting-chain first decade, the 400
MHz decade on A106.
(f/10) of the 400 MHz decade is fed to
the storage unit through the 6-decade
count chain of A103. The storage unit
on A103 holds all of the digital information from the previous reading.
put from the storage unit is fed to the
display multiplexer which is controlled
by count chain control circuits on the
Count Chain Control A102.
h. Output of the display multiplexer
on A102 is fed to Display A110.
mounted on the front panel along with
LEVEL, LOCK, and GATE status indicators.
The front-panel REMOTE indicator is used
with GPIB controller operations.
all control of the counter is performed
by Control Circuit Card A104. Frontpanel selection switching is routed to
A104 through GPIB Remote/Local Circuit
Card AM121.
REMOTE mode of operation, front-panel
controls and switches are inoperative
except for the SAMPLE RATE control, and
then only under certain programming
instructions from the GPIB controller.
1-11.
input microwave frequencies down to
frequencies between 100 and 360 MHz.
Translation is done by mixing the input
frequencies with a reference frequency
to produce, by heterodyne action, an
amplified intermediate frequency.
IF is then fed to A106 through Delay
Line A112 for counting and processing in
Basic Counter A1.
b. Generation of the heterodyning ref-
erence frequency starts by generating a
Converter A2.
a. Converter A2 translates the Band B
When the counter is in the
This requires
A 200
The signal output
Out-
A110 is
Over-
(Fig. 1-4.)
The
200 MHz reference signal in Source/
Amplifier A201. The 200 MHz reference
in A201 is generated by an L-C oscilla-
tor phase-locked to 10 MHz from Reference Oscillator Buffer A108.
MHz outputs from A201 are directed to
YIG (Yttrium-Iron-Garnet) Comb Generator
A207 and to Gate Generator A105 in
Basic Counter A1.
section on A201 amplifies the 200 MHz
signal before it is applied to A207.
The 200 MHz output to A105 is used to
generate a Band B gate or may be used
for a TEST 200 MHz self-test.
harmonic, frequency is generated in YIG
Comb Generator A207 by taking the 200
MHz signal from A201 and converting it
to a train of narrow pulses containing
all harmonics of 200 MHz up to 18 GHz.
This conversion is done by the YIG comb
generator and a two-stage YIG filter,
which selects the desired 200 MHz
harmonic. The YIG filter is tuned by
varying the current through a pair of
coils, which change magnetic fields in
the assembly.
to Limiter/Attenuator A206.
diode limiter protects Mixer A205 from
power levels in excess of one watt peak
(+30 dBm).
diode attenuator section controls the
RF signal level to the mixer and
switches off the input signal during
portions of converter operation.
wave circuit assembly consisting of a
hybrid coupler, termination, mixer
diode, and dc return. The mixer produces two output signals on a common
line:
ence frequency between the incoming RF
signal from A206 and the reference frequency harmonic from A207, and a video
signal resulting from rectification
(detection) of either the RF or reference inputs. The mixer output is fed to
I.F. Processor A204.
A205 are separated in A204. The IF signal is amplified by the IF amplifier and
sent on as the converter IF signal to
A106, through Delay Line A112, for
The 200
A power amplifier
c.
The local oscillator, or reference
d. Band B input signals are applied
A passive
A multistage matched PIN
e.
Mixer A205 is an integrated micro-
an IF signal equal to the differ-
f. The IF and video signals from Mixer
1-8
Figure 1-4.
1-9
TM 11-6625-3031-14
TM 11-6625-3031-14
counting.
The video signal is amplified
in the video amplifier to produce three
video outputs: (1) a threshold signal
is directed to the rear-panel SIGNAL
THRESHOLD connector through Prescaler
A109;
(2) a threshold signal, identified as attenuator control, is sent to
an attenuator control circuit on Con-
verter Sequencer A203; and
(3) an
analog output is applied to the power
level control portion of A203.
g.
On A203, inputs from the lock
section of I.F. Processor A204 are
sequenced and timed to produce a lock
level signal for Control A104 and a
Band B threshold signal for Gate Gen-
erator A105.
The attenuator control
threshold signal from the video section
of A204 is combined with an input from
the converter sequencer in the attenu-
ator control to give two outputs:
(1) an attenuator control signal, activated at a level approximately 7 dB
above signal threshold, sent to the PIN
attenuator of A206, to reduce signal
level into Mixer A205; and (2) a reduce
signal level sent to the front-panel
REDUCE SIGNAL indicator when the
attenuator control is sending a signal
to the PIN attenuator.
The power level
control circuit receives an analog input
from the video section of A204 and a
digital signal from the converter
sequencer of A203, and provides a signal
to the tuning circuits of A202 to set
the comb line amplitude.
The converter
sequencer function is to control the
sensing, leveling, and control of Converter A2.
YIG Control A202 contains circuits
h.
to step the YIG filter to the proper
comb line, and is controlled by input
lines from Converter Sequencer A204.
On-board circuits include a YIG driver
to supply the required current, a
digital-to-analog converter (DAC) to set
the approximate center frequency, and a
centering circuit to precisely center
the YIG filter passband on a comb line.
The centering process is done by modulating the YIG center frequency by an
auxiliary modulation coil in YIG Comb
Generator A207.
The modulation control
circuit is on A202.
1-10
TM 11-6625-3031-14
CHAPTER 2
OPERATING INSTRUCTIONS
Section I. DESCRIPTION AND USE OF OPERATORS CONTROLS
AND INDICATORS
2-1.
and Indicators.
nectors and indicators are shown in fig-
ure 2-1 and are keyed to table 2-1,
which describes their functions.
Front-Panel Controls, Connectors
Operator’s front-panel controls, con-
2-2.
Connectors.
connectors are shown in figure 2-2 and
are keyed to table 2-2, which describes
their functions.
Rear-panel Controls and
Operator’s rear-panel controls and
Key
1
2
Figure 2-1.
Table 2-1.
Control, connector
or indicator
Display
REMOTE indicator
Front-panel Controls,
Counter Front Panel
Connectors and Indicators
Functional operation
Seven-digit LED display provides
direct numerical readout of input
frequency in GHz and MHz.
When lighted, indicates that all
front-panel controls are disabled
except SAMPLE RATE. This indicator
is controlled by digital programmed
data on the General Purpose Interface Bus (GPIB) and by rear-panel
ADDRESS SWITCH.
2-1
TM 11-6625-3031-14
Table 2-1.
Key
3
4
5
6
7
Front-panel Controls,
Control, connector
or indicator
GATE indicator
LEVEL indicator
LOCK indicator
MANUAL SELECT/AUTO SWEEP
switch
PRESET FREQUENCY/START
FREQUENCY thumbwheel
switch
Connectors and Indicators - Continued
Functional operation
Lights when counter is in measurement portion of cycle.
Lights when input signal level is
high enough to be counted. Light
will blink if signal pulse repeti-
tion frequency is too low.
Lights when input signal has been
acquired.
Selects either manual or automatic
operation of counter for BAND B.
When MANUAL SELECT/AUTO SWEEP switch
(6) is set to MANUAL SELECT, thumb-
wheel switch sets PRESET FREQUENCY;
input signal frequency must be 105
to 325 MHz higher.
SELECT/AUTO SWEEP switch is set to
AUTO SWEEP, thumbwheel switch sets
sweep START FREQUENCY; input signal
frequency must be at least 105 MHz
higher than sweep start.
When MANUAL
8
9
10
11
12
13
14
BAND B 925 MHz - 18 GHz
connector
REDUCE SIGNAL indicator
BAND A 300 - 950 MHz
connector
BAND B pushbutton switch
BAND A pushbutton switch
RESET pushbutton switch
1 ms GATE pushbutton
switch
Type N precision input connector
for Band B operation.
Lights when Band B input power
approaches maximum safe operating
level.
Type BNC input connector for Band A
operation.
Selects Band B operation for frequencies between 925 MHz and 18 GHz.
Selects Band A operation for frequen-
cies between 300 and 950 MHz.
When pushed and released, overrides
SAMPLE RATE control, resets display
to zeros,
reading.
When pushed in, provides 10 kHz
resolution with 1 millisecond gate
time on Band B or 4 millisecond gate
time on Band A for reduced pulse
averaging error.
and initiates a new
2-2
TM 11-6625-3031-14
Table 2-1.
Key
15
16
17
18
Front-panel Controls, Connectors and Indicators - Continued
Control,
or ind
connec
icator
tor
Right RESOLUTION pushbutton
switch
Left RESOLUTION pushbutton
switch
TEST DISPLAY pushbutton
switch
TEST 200 MHz pushbutton
switch
Functional operation
Provides blanking of least signifi-
cant digit for resolution of 100 kHz
with 100 microsecond gate time on
Band B or 400 microsecond gate time
on Band A.
Provides blanking of two least significant digits for resolution of
1 MHz with 100 microsecond gate time
on Band B or 400 microsecond gate
time on Band A.
When pushed and held in, provides
test of all segments of display
LEDS.
Display should read
88 888.88.
When pushed and held in, provides
check of counting circuits.
Display
should indicate 200.00 MHz.
19
20
SAMPLE RATE control
POWER pushbutton switch
Continuously variable control which
varies display time from 0.1 to 10
seconds per reading.
Rotating con-
trol to its switched HOLD position
will cause display to hold last
reading without an update until
RESET switch (13) is pushed in.
When pushed in and released, power
counter is turned on or off.
power is on,
a green indicator is
When
visible in switch.
2-3
TM 11-6625-3031-14
Key
1
2
3
Figure 2-2.
Table 2-2.
Rear-panel Controls and Connectors
Control or connector
10 MHz OUTPUT connector
SIGNAL THRESHOLD OUTPUT
connector
GPIB IEEE STD 488/1975
ADDRESS SWITCH
Counter Rear Panel
Functional operation
Provides output of internal 10 MHz
clock; 1 Vp-p minimum into 50 ohms.
Provides pulse output representing
signal threshold level of input
pulse.
Output pulse typically
delayed 20 nanoseconds from input
pulse.
Used for frequency profile
measurements.
Address switches of counter when
General Purpose Interface Bus (GPIB)
is used.
Setting of various combi-
nations of seven switches permits
the counter to be operated in Talk,
Listen,
or Monitor modes when external GPIB controller is connected
to counter.
2-4
4
GPIB IEEE STD 488/1975
connector
5
Fuse
Provides connection to external
GPIB controller.
Slow-blow line fuse; 1.5 A at
115 Vac or 0.75 A at 230 Vac.
6
Line voltage selector
card
Selects either 115 or 230 Vac line
voltage.
Selected voltage printed
on card is visible when card is
installed.
TM 11-6625-3031-14
Key
7
8
9
10
Table 2-2.
Control or connector
AC power connector
MIN. PRF switch
STORAGE switch
GATE OUTPUT connector
Rear-panel Controls and Connectors - Continued
Functional operation
Three-prong male connector for ac
power cable.
grounding meets NEC and UL
requirements.
Selects minimum prf.
to 50 Hz position.
counter will measure very low prf
signals but reading will not auto-
matically reset when signal is
removed.
Controls display update.
ON; in OFF position front-panel
display updates continuously during
measurement cycle.
Provides gate pulse representing
actual time at which measurement is
being made. Used in frequency
profile measurements.
Third conductor
Normally set
In 0 position,
Normally
11
12
INPUT INHIBIT connector
ACCESSORY POWER OUT
connector
Connector for external pulse input
for use in frequency profile
measurements.
Provides +5, -5.2, +12, and -12 Vdc
for accessories used with counter,
such as EIP Model 400 Delay
Generator.
Section II. PREVENTIVE MAINTENANCE CHECKS AND SERVICES
2-3.
mind
your
mind
your
form
Troubleshoot with proper equipment.
Report any deficiencies using the proper
forms.
General Instructions.
Before you operate.
a.
the CAUTIONS and WARNINGS. Perform
before (B) PMCS.
b.
While you operate.
the CAUTIONS and WARNINGS.
during (D) PMCS.
After you operate.
c.
your after (A) PMCS.
d.
If your equipment fails to operate.
See TM 38-750.
Always keep in
.
Always keep in
Perform
Be sure to per-
2-4.
be performed at specific intervals.
These checks and services are to maintain Army electronic equipment in a
combat serviceable condition; that is,
in good general (physical) condition
and in good operating condition. To
assist operators in maintaining combat
serviceability, the chart indicates what
to check.
"Equipment is not ready/available if:"
column,
PMCS Procedures.
Table 2-3 outlines the functions to
If any entry appears in the
appropriate corrective
2-5
TM 11-6625-3031-14
maintenance
restore the
condition.
2-5.
table 2-3, remove dust and loose dirt
with a clean soft cloth.
Cleaning Instructions.
a. At the interval specified in
—
action must be taken to
counter to an operational
Table 2-3.
Operator Preventive Maintenance Checks and Services
Within designated interval, these checks are
to be performed in the order listed.
B-
Before
D
- During
A
- After
NOTE
CAUTION
Do not use any solvent except
water or a mild detergent to
clean the plastic front panel of
the counter.
damage the panel.
b.
Clean external surfaces with a
clean soft cloth moistened with clean
water.
more effective cleaning.
A mild detergent may be used for
W-
Weekly
M-
Monthly
Other solvents may
Item
No.
1
2
3
4
5
6
B
x
x
Interval
DxA
WxM
Item to be
inspected
Completeness
Power cable
.
Controls and
hardware
Exterior
x
surfaces
Nameplate
x
Operational
capability
Procedures -
check for and have
repaired or adjusted
as necessary
Power cable connected
to counter.
Cuts or cracks in
outside jacket;
damage to connector
pins.
Missing or loose
knobs or hardware
Clean exterior
surfaces.
Legibility.
Perform self-test,
para 2-7 b (2).
Equipment
is not ready/
available if:
Power cable is
missing.
Power cable is
defective.
Self-test
indications
are incorrect.
2-6
TM 11-6625-3031-14
Section III. OPERATION
2-6.
carton for signs of damage before opening.
request that the shipper’s agent be pres-
ent when the counter is unpacked.
Visible and concealed damage claims
against the carrier or shipper can only
be filed if the agent is present or
waives his rights.
instrument supports and packing
materials.
counter.
Without applying power, check the mechan-
ical operation of all controls and
switches.
are selection of either 115 Vac or 230
Vac line voltage and connecting the
power cable to the instrument.
ready for operation from a 115 Vac power
line, with a 1.5 ampere slow-blow fuse
installed.
voltage selector card (6, fig. 2-2),
visible through the window in the fuse
cover,
volts.
Assembly and Preparation for Use.
a. Unpacking.
—
(1) Visually inspect the shipping
If there is any apparent damage,
(2) Open the carton, removing
Carefully lift out the
Inspect the counter for damage.
b. Assembly
—
(1) The only assembly requirements
Be sure only the specified power
cable is used.
is provided with a 3-wire cable
which grounds the instrument
cabinet.
be inserted in a socket outlet
provided with a protective ground
contact.
should not be negated by the use
of an extension cord without a
protective ground conductor.
(2) The counter is normally shipped
to be certain that it reads 115
The FUSE FULL lever attached to
the body of the power module
housing does not come off.
This cable should only
This protective action
Check the marking on the line
The instrument
CAUTION
Firm
UNDER USUAL CONDITIONS
lifting up on the FUSE PULL lever and
check that it is a 1.5 ampere fuse.
with one of the correct value and con-
nect the power cable to the ac power
connector.
operation,
slide the fuse cover to the left and
remove the fuse by lifting up on the
FUSE PULL lever; see CAUTION above.
selector card.
appropriate marking (115 or 230 volts)
will be visible when the card is
inserted into the card slot.
but firmly insert the card into the
slot, being careful not to cant or tilt
the card while inserting.
seating by sliding the fuse cover from
left to right.
seating, slide the fuse cover back to
the left to gain access to the fuse
clip.
the correct value (1.5 amperes for 115
Vat, 0.75 ampere for 230 Vac) in the
fuse clip;
puller does not obstruct the fuse cover
by sliding the fuse cover to the right.
the ac power connector.
special procedures are necessary if the
counter is used as a stand-alone test
instrument.
ing the signal to the selected connector and selecting the desired switches
and controls is all that is required.
but careful rotation of the fuse
puller will lift up one end of the
fuse so that finger force can re-
move the fuse. Failure to heed
this caution by exerting too much
force may damage the plastic pivot
of the built-in fuse puller.
(3) Remove the installed fuse by
(4) Reinstall or replace the fuse
(5) To change the line voltage
proceed as follows:
(a)
On the rear of the counter,
(b)
Extract the line voltage
(c)
Rotate the card so that the
Carefully
Check the
After checking the card
(d) Insert a slow-blow fuse of
check that built–in fuse
(e)
Connect the power cable to
c. Preparation for Use.
—
(1) Stand-alone Operation. No
Applying power and connect-
2-7
TM 11-6625-3031-14
(2) GPIB Operation. Installation
of the counter in a GPIB-controlled
system will vary with console or rack
hardware.
cedures can be suggested.
counter are 3.5 inches high by 16.75
inches wide by 19 inches deep.
mounting kits are available from the
manufacturer of the counter to mount
the instrument in a standard 19 inch
width rack-mount cabinet or console.
Ventilation of the counter is through
the rear panel so it is not necessary
or desirable to remove the top and bot-
tom covers for cooling.
covers should remain in place secured
by screws to retain RFI integrity.
required to control selector switches
and the GPIB address switches.
panel ventilating louvers and blower
should not be blocked off from free air
flow.
sources to—the counter front-panel con-
nectors should be as short as possible.
A common ground bus should tie the
counter to other instruments and the
GPIB controller.
cable is not critical but the supplied
cable should be retained and plugged
into a powerline strip.
interface cable should be as short as
feasible and should be shielded against
RFI to reduce data transmission con-
tamination.
program controller may be connected,
provided that the controller meets IEEE
Standard 488/1975.
2-7.
Instrument.
a. Operating Modes.
three principal modes of operation:
automatic, manual, and externally enabled.
MHz) is automatic;
(925 MHz matic or manual.
operation covers specific measurement
techniques.
Therefore only general pro-
(a)
The dimensions of the
Rack
Top and bottom
(b)
Access to the rear panel is
The rear
(c) Leads from frequency
The length of power
(d)
The length of the GPIB
Any keyboarding or fixed
Operation as Stand-alone
The counter has
Operation on Band A (300 - 950
operation on Band B
18 GHz) may be either auto-
Externally enabled
Signals may be connected to
both the BAND A and BAND B inputs at the
only the input frequency selected by the
appropriate BAND pushbutton switch on
panel switches as follows.
ADDRESS SWITCH 7 to 0 (top of switch
depressed).
light and the internal cooling fan
should operate.
of the two RESOLUTION switches and
release it, so that neither switch
remains in a depressed position.
digits in the display should indicate
zero.
switch.
88 888.88 while the switch is held in.
Release the switch.
switch.
200.00, with the two leading zeros
blanked (unlighted), while the switch is
held in.
switch and again hold the TEST 200 MHz
switch in.
200.0, with the two leading zeros
blanked.
digit immediately above the switch
which has been depressed, and any digit
by repeating step (b).
same time,
the front panel.
b. Preliminary Procedures.
—
(1) Rear-panel Switches. Set rear-
(2) Self-test.
turn on the counter. The display should
switch in turn and note that the display
to the right, is blanked.
c. Band A (300 -
Peak power applied to the BAND A
input connector should be between
-10 and +10 dBm for normal operation.
but the counter will display
(a)
GPIB IEEE STD 488/1975
(b)
MIN. PRF switch to 50 Hz.
(c)
STORAGE switch to ON.
(a) Press the POWER switch to
(b)
Partially depress either
All
(c) Press the TEST DISPLAY
The display should indicate
(d)
Press the TEST 200 MHz
The display should indicate
Release the switch.
(e)
Press the right RESOLUTION
The display should indicate
Release the switch.
(f)
Press each RESOLUTION
(g)
Unblank all display digits
950 MHz) Operation.
CAUTION
Peak input must not
2-8
exceed +27 dBm or damage to the
counter may result, even if the
counter is turned off.
(1) Perform the preliminary proce-
dures of step b.,
(2) Connect the signal source to
the BAND A input connector.
(3) Depress the BAND A switch.
(4) Depress the desired RESOLUTION
switch.
(5) If the input signal level is
high enough for counting, both the LEVEL
and LOCK indicators will light, and the
measured frequency will be displayed.
The REDUCE SIGNAL indicator is
inoperative on Band A.
(6) Turn the SAMPLE RATE control to
provide the desired display update rate.
The GATE indicator will flash in accord-
ance with the sample rate.
control is set to its switched HOLD
position,
last reading.
desired, press and release the RESET
switch.
d. Band B (925 MHz - 18 GHz)
Operation.
Peak power applied to the BAND B
input connector should be within
the following ranges for normal
operation:
925 MHz - 10 GHz: -10 to +10 dBm
10 -
The peak input power must not ex-
ceed +30 dBm or damage to the
counter may result, even if the
counter is turned off.
procedures of step b above.
to the BAND B input connector.
the display will retain the
18 GHz:
(1) Initial Procedures.
(a)
(b)
(c)
above.
NOTE
If the
If a new reading is
CAUTION
-5 to +10 dBm.
Perform the preliminary
Connect the signal source
Depress the BAND B switch.
RESOLUTION switch.
is high enough for counting, both the
LEVEL and LOCK indicators will light.
If the REDUCE SIGNAL indicator lights,
the input signal power is approaching
the maximum safe operating level and
should be reduced.
matic mode,
input signal by sweeping from a start
frequency which is 105 MHz above a preset frequency.
SWEEP switch to AUTO SWEEP. For full
search,
switches to 00.0 GHz.
speed, the sweep start frequency may be
set by means of the START SWEEP thumb-
wheel switches.
which can then be acquired and displayed
will be 105 MHz above the switch set-
tings; erroneous readings may be displayed if the frequency of the applied
signal is less than 105 MHz above the
switch settings.
control as described in paragraph
2-7 c (6).
mode,
reducing the acquisition time. However,
the signal frequency to be measured
must be between 105 and 325 MHz above a
preset frequency.
SWEEP switch to MANUAL SELECT.
thumbwheel switches so that they indi-
cate a frequency 105 to 325 MHz lower
than the signal frequency. For example,
if the frequency to be measured is ex-
pected to be 12.35 GHz, the thumbwheel
switches should be set to indicate 12.2
GHz, which places the input frequency
105 to 325 MHz above the preset frequency.
played if the frequency of the applied
signal is outside the preset range.
control as described in paragraph
2-7 c (6).
TM 11-6625-3031-14
Depress the desired
(d)
(e)
If the input signal level
(2) Automatic Mode. In the auto-
the counter searches for the
(a)
Set the MANUAL SELECT/AUTO
set the START SWEEP thumbwheel
(b)
To improve acquisition
The lowest frequency
(c)
Adjust the SAMPLE RATE
(3) Manual Mode. In the manual
the search sweep is inhibited,
(a)
Set the MANUAL SELECT/AUTO
(b)
Set the PRESET FREQUENCY
Erroneous readings may be dis-
(c)
Adjust the SAMPLE RATE
2-9
TM 11-6625-3031-14
2-8.
panel INPUT INHIBIT connector makes
possible a class of measurements known
as dynamic frequency
measurements made at a specified point
in time on a signal whose frequency is
some repetitive function of time.
a high emitter-coupled-logic (ECL) level
is applied,
from making a measurement. Thus a signal at the INPUT INHIBIT connector can
be used as an enable signal to make a
measurement at a desired time.
width of the enable signal determines
the duration of the measurement, typi-
cally 30 nanoseconds less than the
applied pulse.
INPUT INHIBIT circuit is designed to be
compatible with either a 50 ohm imped-
ance pulse generator or ECL devices.
An internal termination of 50 ohms
returned to -2 volts makes this dual
compatibility possible.
level signal (-0.8 to -1.1 V) will
inhibit measurement, while an ECL low
level signal (-1.5 to -2.0 V) will
enable measurement.
designed to drive 50 ohm lines without
reflections when the lines are termi-
nated with 50 ohms returned to -2 V.
The direct compatibility with a 50 ohm
pulse generator results from the fact
that zero volts from a 50 ohm source
will produce
(inhibiting the counter), while a -1 V
signal into 50 ohms will produce -1.5 V
at the INPUT INHIBIT thus enabling the
counter.
2-9.
Externally Enabled Operation.
a.
Function.
b.
INPUT INHIBIT Requirements.
Pulse Profile Measurements
The use of the rear-
measurements -
the counter is inhibited
An ECL high
ECL devices are
-1 V at the INPUT INHIBIT
The
When
The
ments of these characteristics are
easily made with the counter and a
delaying pulse generator (see fig. 2-3).
The SIGNAL THRESHOLD OUTPUT of the coun-
ter is used to trigger the pulse genera-
tor. The generator’s output pulse is used
as an enable input to the counter. As the
pulse delay is varied, the measurement
window can be “walked” through the pulse.
A plot of frequency versus delay gives
the frequency-versus-time profile of the
pulse directly as shown in fig. 2-4. The
width of the measurement window is deter-
mined by the width of the pulse genera-
tor output.
nanoseconds or less can be used, although
wider windows yield higher accuracy.
b. Measurement Technique. Measure-
Figure 2-3.
Measurement Test Setup
Measurement windows of 50
Pulse Profile
a. Purpose.
ments can determine the average fre-
quency of a pulse.
however,
necessary.
tron may exhibit substantial frequency
shift near the leading and trailing
edges of the pulse, or a pulsed Gunn
diode oscillator may exhibit frequency
shift during a pulse due to peak power
thermal effects.
2-10
additional information may be
Automatic pulse measure-
In some cases,
For example,
a pulse magne-
Figure 2-4.
Pulse Profile Measurement
TM 11-6625-3031-14
2-10.
Varying Signals.
not pulses at all but simply continuous
signals whose frequency varies repetitively with time. One example is the
measurement of the response of a device
such as a voltage-controlled oscillator
(VCO).
tuning voltage will produce a response
curve of frequency versus time, allowing
measurement of various settling times
such as post-tuning drift.
sible application would be the measure-
ment of linearity and amplitude for
frequency-modulated radar altimeter
signals.
shows a test setup designed to make
measurements on time varying signals.
It is similar to the pulse profile test
setup, except that in this case, since
there is always a signal present, a
trigger must be obtained from the modulating source.
pulse generator which controls the
measurement.
2-11.
Measurements.
ment is that of a repetitive sequence of
pulses differing in frequency. In this
Dynamic Characteristics of Time
a.
Purpose.
A square wave applied to the
b. Measurement Technique.
Multiple Pulse Signal
a.
Purpose.
Figure 2-5.
Measurement Test Setup
Many complex signals are
Another pos-
Fig. 2-5
This will trigger the
Another type of measure-
Time Varying Signal
measurement window is the period during
which the gate is actually open to enable the counting of a signal.
gate width will typically be 30 nanoseconds narrower than the pulse applied
width of the gate is always an integral
number of clock periods (5 nanoseconds).
For applications where the measurement
window needs to be known to an accuracy
better than 20 nanoseconds, it is rec-
ommended that the GATE OUTPUT on the
rear panel be observed directly on a
high speed oscilloscope. The desired
gate width may then be set by varying
the INPUT INHIBIT pulse width.
accurate pulse representation, the
oscilloscope input should be terminated
in a 50 ohm load.
necessary to measure the signal frequency at a precise point in time, the
internal delays of the measuring instrument can be significant. The total
delay between the time a signal is
applied to the counter input connector,
and the time it is available to be
case, it is desirable to measure the
frequency of each pulse in the sequence
separately.
b. Measurement Technique. The same
test setup as shown in fig. 2-5 is
required, with the trigger pulse syn-
chronous with the sequence.
measurement,
simply to discriminate between pulses.
The enabling pulse can be slightly
wider than the pulse to be measured.
The counter will automatically restrict
the measurement window entirely within
the pulse.
the enabling pulse,
the sequence can be separately measured.
2-12.
internal timing within the counter is of
no concern to the user.
applications where a few nanoseconds are
significant,
operation are important.
two areas:
and internal timing delays.
b. Measurement Window Width. The
to the INPUT INHIBIT connector.
c.
Timing Considerations.
a.
General.
Internal Timing Delays.
the INPUT INHIBIT is used
By shifting the delay time of
each input pulse of
Under most circumstances,
some details of internal
measurement window width
In this
However, in
These involve
This
The
For
When it is
2-11
TM 11-6625-3031-14
counted,
The SIGNAL THRESHOLD OUTPUT on the rear
panel typically occurs 20 nanoseconds
after the signal is applied.
OUTPUT at the rear panel occurs at the
measurement time with virtually no
delay.
time positioning of a signal is required,
it is necessary to consider that the
GATE OUTPUT signal,
measurement period, is actually making
a measurement of the signal which
appeared at the input connector 60 nano-
seconds earlier. If the SIGNAL THRESHOLD OUTPUT is used as an indication of
input signal, then it occurs 40 nano-
seconds prior to measurement.
shows the relative timing of these signals for a pulsed input signal.
however, is not a function of input signal characteristics.
2-13.
a. General Considerations.
—
measurement accuracy is generally speci-
fied as time base accuracy ±1 count.
This means that the frequency measurement is in error by the same percentage
as the time base reference oscillator.
The maximum error in the time base is
the sum of various possible errors,
such as aging rate, temperature, etc.
count, is derived from the relative
timing of gate and signal.
stated, if an event occurs every 400
milliseconds,
Figure 2-6.
is nominally 60 nanoseconds.
The GATE
In other words, when absolute
which represents the
Fig. 2-6
Timing,
Accuracy.
(1) In a cw frequency counter,
(2) The second type of error, ±1
Simply
a counter could measure
Internal Timing Delays
either 2 or 3 events in a one second
interval,
signal and the gate are asynchronous.
error in a cw counter is gate error.
A gate is supposed to represent a precise number of reference oscillator
cycles.
in the rise and fall times of various
circuits,
be a fixed amount wider or narrower
than desired. If this error is less
than one period of the maximum input
frequency, no counter error will occur.
Thus a 300 MHz counter needs a gate
accurate to about 3 nanoseconds.
error can contribute to the overall
error In pulse frequency measurements.
In fact for narrow pulses, the second
and third sources of error, which are
usually ignored in a cw counter, become
the dominate sources of error in a
pulse counter.
error in the time base reference oscillator results in a proportional frequency measurement error.
sources of time base error are aging
rate and temperature. The temperature
compensated crystal oscillator (TCXO)
reduces temperature instability to less
than 2 x 10-6.
frequency standard, this error can be
made less than one count, and thus
becomes insignificant.
obtain high resolution, the frequency
of a number of measurements is averaged.
Each individual measurement has a ±1
count uncertainty as previously noted.
If N measurements are made, then an
uncertainty of ±N counts is possible,
but very unlikely.
averaged measurement will follow the
rules of statistics, in that succes-
sive measurements will vary randomly
to a certain degree.
of the readings (63 percent) will fall
between ± counts; this is called
the rms averaging error.
number of gates required to accumulate
100 microseconds or 1 millisecond of
gate time.
since the processed input
(3) A third possible source of
Due primarily to differences
the actual gate will usually
(4) Each of these three sources of
b.
Time Base Errors. A frequency
Two main
By calibration against a
c.
Averaging Error. In order to
The resultant
In fact, most
N is the
The gate is typically
2-12
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