Racal Instruments 1994 User manual

PUBLICATION NO. 980601
Bi
UNIVERSAL TIMER/COUNTERS
Racal Instruments
RacaS Instruments, Inc.
4Goodyear St, Irvine, CA 92718-2002
Tel: (800) RACAL-ATE, [phone], [phone]; FAX: [phone]
Racal Instruments Ltd.
480 Bath Road, Slough, Berkshire, SL1 6BE, United Kingdom
Tel: [phone]; FAX: [phone]
Racal Systems Electronique S.A.
18 Avenue Dutartre, 78150 LeChesnay, France
Tel: [phone]; FAX: [phone]
Racal Systems Elettronlca Sri
Strada 2-Palazzo C4, 20090 Milanofiori Assago, Milan, Italy
Tel: [phone]; FAX [phone]
Racal Elektronik System GmbH
Frankenforster Strasse 21, 51427 Bergisch-Gladbach 1, Germany
Tel: [phone]; FAX: [phone]
PUBLICATION DATE: JULY 1991
Copyright© 1991 by Racal Instruments Inc. Printed in the United States of America. All rights reserved.
This book or parts thereof may not be reproduced in any form without written permission of the publishers.

WARRANTY STATEMENT
Products sold by Racal Instruments, Inc. are warranted to be free from defects in workmanship or
materials. Racal Instruments, Inc. will, at its option, either repair or replace any hardware products
which prove to be defective during the warranty period. You are avalued customer. Our mission is
to make any necessary repairs in areliable and timely manner.
Duration of Warranty
The warranty period for all Racal Instruments, Inc. hardware is one year, except software and
firmware products designated for use with Racal Instruments, Inc. hardware are warranted not to fail
to execute their programming instructions due to defect in materials or workmanship for aperiod of
ninety (90) days from the date of delivery to the initial end user.
Return of Product
Authorization is required from Racal Instruments before you send us your product. Call Customer
Support at 1-800-722-3262. You will be given repacking instructions. You will be required to return
your product prepaid UPS. Racal Instruments will pay the shipping costs back to you UPS Ground.
Limitation of Warranty
Racal Instruments, Inc. shall be released from all obligations under this warranty in the event repairs
or modifications are made by persons other than authorized Racal Instruments, Inc. service personnel
or without the written consent of Racal Instruments, Inc.
Racal Instruments, Inc. expressly disclaims any liability to its customers, dealers and representatives
and to users of its products, and to any other person or persons, for special or consequential damages
of any kind and from any cause whatsoever arising out of or in any way connected with the
manufacture, sale, handling, repair, maintenance, replacement or use of said products.
Representations and warranties made by any person, including dealers and representatives of Racal
Instruments, Inc. ,which are inconsistent or in conflict with the terms of this warranty (including but
not limited to the limitations of the liability of Racal Instruments, Inc. as set forth above), shall not
be binding upon Racal Instruments, Inc. unless reduced to writing and approved by an officer of Racal
Instruments, Inc.
Except as stated above, Racal Instruments, Inc. makes no warranty, express or implied (either in fact
or by operation of law), statutory or otherwise; and except to the extent stated above, Racal
Instruments, Inc. shall have no liability under any warranty, express or implied (either in fact or by
operation of law), statutory or otherwise.
PROPRIETARY NOTICE
This document and the technical data herein disclosed, are proprietary to Racal Instruments, and shall
not, without express written permission of Racal Instruments, be used, in whole or in part to solicit
quotations from acompetitive source or used for manufacture by anyone other than Racal Instruments.
The information herein has been developed at private expense, and may only be used for operation and
maintenance reference purposes or for purposes of engineering evaluation and incorporation into
technical specifications and other documents which specify procurement of products from Racal
Instruments.

FOR YOUR SAFETY
Before undertaking any maintenance procedure, whether it be a
specific troubleshooting or maintenance procedure described herein or
an exploratory procedure aimed at determining whether there has been
amalfunction, read the applicable section of this manual and note
carefully the WARNING and CAUTION notices contained therein.
The equipment described in this manual contains voltage hazardous to
human life and safety and which is capable of inflicting personal
injury. The cautionary and warning notes are included in this manual to
alert operator and maintenance personnel to the electrical hazards and
thus prevent personal injury and damage to equipment.
If this instrument is to be powered from the AC line (mains) through an
autotransformer (such as aVariac or equivalent) ensure that the
common connector is connected to the neutral (earthed pole) of the
power supply.
Before operating the unit ensure that the protective conductor (green
wire) is connected to the ground (earth) protective conductor of the
power outlet. Do not defeat the protective feature of the third
protective conductor in the power cord by using atwo conductor
extension cord or athree-prong/two-prong adaptor.
Maintenance and calibration procedures contained in this manual
sometimes call for operation of the unit with power applied and
protective covers removed. Read the procedures carefully and heed
Warnings to avoid ’’live'1circuit points to ensure your personal safety.
Before operating this instrument:
1. Ensure that the instrument is configured to operate on
the voltage available at the power source. See
Installation Section.
2. Ensure that the proper fuse is in place in the instrument
for the power source on which the instrument is to be
operated.
3. Ensure that all other devices connected to or in proximity
to this instrument are properly grounded or connected to
the protective third-wire earth ground.
If at any time the instrument:
—Fails to operate satisfactorily
—Shows visible damage
—Has been stored under unfavorable conditions
—Has sustained stress
It should not be used until its performance has been checked by
qualified personnel.

Amendment to
Racal Instruments Model 1994
Instruction Manual, Publication No. 980601
May 15, 1995
This amendment updates the drawing and parts list located in Sections 7and 8.
1. Page 7-4, 7-5, Chassis Assembly, 404391
a. Add "Note 8: Item 9to be soldered to bottom of Item 7
during test".
b. Change Revision letter to "F".
2. Page 7-17, PCB Assy, GPIB, 401760
a. No corrections. Change Revision letter to "G".
3. Page 7-18, Schematic, GPIB, 431760
a. Change Revision letter to "C".
b. Change Sheet 1, Zone B6 from "was" to "is" as shown below:
Was Is
4. Page 7-22, PCB Assy, BNC, 401762
a. No corrections. Change Revision letter to "F".
5. Page 7-25 Option 04A, Oscillator Assy, 404392
a. No corrections. Change Revision letter to "C".
6. Page 7-26, Oven Oscillator, 404397
a. Delete "9444" from drawing title.
b. Change Revision letter to "C".
7. Page 7-27, Option 04E, Oscillator, 404384
a. No corrections. Change Revision letter to "D".
8. Page 7-29, Cable Assy, Oscillator, 404691
a. Replace with assembly drawing on Page 3of this amendment.
9. Page 7-33, Option 41, Channel C, 404398
a. No corrections. Change Revision letter to "B”.
10
.
'
11.Page 7-35, Schematic, Channel C
a. Replace with Schematic on Page 4of this amendment.

12. Page 8-3, Chassis Assy Parts List, 404391
a. Add Lem 9, RI P/N R- 18- 1239, Screen, FSC 21793,
Manufacturer's P/N R- 18- 1239.
b. Revision letter is now "F".
13. Page 8-18, BNC Assy Parts List, 401762
a. Change Item 20 to RI P/N 601970, Terminal, Feed-thru,
Insulated, FSC 98291, Manufacturer's P/N 011-2103-000-
479.
b. Revision letter is now "F".
14. Page 8-20, Oscillator Assy Parts Lists, 404397
a. Change Item 1to RI P/N 92 1124, Oscillator, 5MHz, Fallout,
FSC 21793, Manufacturer's P/N 921124.
b. Revision letter is now "C".
15. Page 8-2 1,Cable Assy, Oscillator, Parts List, 40469
1
a. Change Item 22 to RI P/N 602094-900, Polarization Plug,
FSC 22526, Manufacturer's P/N 65307-001.
b. Change Item 23 to RI P/N 611311, Terminal, Crimp, FSC
22526, Manufacturer's P/N 48251-000.
c. Change Item 24 (J14) to RI P/N 602193-005, Connector,
Cable, Recept. 5-Pin, FSC 22526, Manufacturer's P/N 65039-
032.
d. Revision letter is now "E".
16. Page 8-23, Option 41, Channel CParts List, 404398
a. Change Item 7to RI P/N 616315, Screw, Metric, M3X6(2
Required).
b. Revision letter is now "B"
17. Pages 8-24 to 8-26, Channel C, PCB Parts List, 404389
a. Change C19 and C46 to RI P/N R-21-1779, Cap Chip, 2.2
PF, 50V, -f/-.25 PF, FSC 95275, Manufacturer’s P/N
VJ1206A2R2CXA.
b. Change D8 and D9 to RI P/N 210090, Diode, Silicon, FSC
50434, Manufacturer’s P/N 5082-2800.
c. Change IC3 to RI P/N R-22-5155, IC, AB6456A, FSC 21793,
Manufacturer's P/N R-22-5155.
d. Change Q4 to RI P/N R-22-6278, Transistor, AT-42035, FSC
24539, Manufacturer's P/N AT-42035.
e. Change R36 to RI P/N R-20-5763, Cap, Chip, 18 Ohm, 1/8
W, 5pet, FSC 65940, Manufacturer's P/N MCR18-18 Ohm-5
pet.
f. Revision letter is now "H ".

CONNECTOR

ADDENDUM
RACAL INSTRUMENTS MODEL 1994, OPTION 01
Addition to p. 1-15, Table 1.1 Specifications:
Option 01, Rear Panel Inputs
Inputs Aand B
Sensitivity at rear panel inputs is as specified on pp, 1-6 and 1-7.
Sensitivity at front inputs is not specified and will be degraded.
The following statement must be added to the following procedures:
p. 6-21, under NOTE in step (6) of paragraph 29
p. 6-23, under NOTE after step (7) of paragraph 33
p. 6-26, step (2) of paragraph 44
p. 6-27, step (1) of paragraph 45
p. 6-27, step (2) of paragraph 47
p. 6-28, step (1) of paragraph 48
p. 6-31, step (1) of paragraph 56
p. 6-32, step (2) of paragraph 58
p. 6-35, step (2) of paragraph 62
Procedure must be performed on rear inputs when Option 01 is installed.

TABLE OF CONTENTS
Section Title Page
1GENERAL INFORMATION .,T]~i
1.1 Introduction i_i
1.2 Measurement Functions
1.2.1 Frequency Aand B..i-i
1.2.2 Frequency Ci_i
1.2.3 Period Ai-i
1.2.4 Time Interval i-i
1.2.5 Total Aby Bi_i
1.2.6 Ratio A/B 1-9
1.2.7 Ratio C/B 1-9
1.2.8 Rise/Fall A1-9
1.2.9 Pulse Width A1-9
1.2.10 Phase Arel B1-9.
1.2.11 Check 1-9
1.3 Signal Input Channels 1-9
1.4 Low-Pass Filter 1-3
1.5 Math Computation 1-3
1.6 Special Functions 1-3
1.7 Error Indication 1-3
1.8 External Arming
1.9 Display Format .... t1-3
1.10 Hold 1-4
1.11 Gate Time and Resolution 1-4
1.12 External Frequency Standard Input 1-4
1.13 Standby Mode 1-4
1.14 GPIB Interface 1-4
1.15 Options Available 1-4
1.15.1 Rear Panel Input (Option 01)
1.15.2 Frequency Standards (Options 04 Aand 04 E)
1.15.3 Reference Frequency Multiplier (Option 10) 1-5
1.15.4 1.3 GHz Input C(Option 41)
1.15.5 Fixed-Mount Rack (Option 60)
1.15.6 Slide-Mount Rack (Option 65)
1.16 Safety 1-5
1.17 Specifications 1-fi
2INSTALLATION 9-1
2.1 Introduction 9-1
2.2 Unpacking and Inspection
2.3 Reshipment and Instructions
2.4 Bench Operation 2-1
2.5 Equipment Rack Installation
2.5.2 Fixed-Mount Option 60 Installation
2.5.3 Slide-Mount Option 65 Installation 2-3
2.6 Miscellaneous Option Installation 2-11
2.6.1 Ovened Frequency Standards 404392
iii

TABLE OF CONTENTS (Continued)
Section Title Page
2.6.2 Frequency Standard Multiplier 404399 (Option 10) 2-11
2.6.3 1.3 GHz Input C404398 (Option 41) 2-14
2.7 Power Connections .2-15
2.7.2 Line Voltage Selection 2-15
2.7.3 Power Cord and Grounding 2-16
2.7.4 Line Fuse .2-17
2.8 Storage and Temperature 2-17
2.9 Functional Check 2-17
2.9.1 Introduction 2-17
3LOCAL OPERATION 3-1
3.1 Introduction 3-1
3.2 General Operating Information 3-1
3.2.2 Power-On and Self Test 3-1
3.2.3 Home State 3-1
3.2.4 Main Display 3-2
3.2.5 Keyboard Organization 3-2
3.3 Panel Descriptions 3-3
3.3.1 Front Panel Features 3-3
3.3.2 Rear Panel Features 3-16
3.4 Operating Procedures 3-19
3.4.1 Measurement Functions 3-19
3.4.2 Trigger Level Setting 3-35
3.4.3 Display Resolution 3-37
3.4.4 Gate Time 3-38
3.4.5 Stop Arm Delay (Hold Off) 3-39
3.4.6 Math Function (R-X) Y/Z 3-40
3.4.7 Memory Function 3-41
3.4.8 Peak Level Recall 3-41
3.4.9 100 AVG Function 3-41
3.4.10 Special Functions 3-41
3.4.11 Error Codes 3-45
4SYSTEM OPERATION 4-1
4.1 General Purpose Interface Bus (GPIB) 4-1
4.1.1 Introduction 4-1
4.2 GPIB Description .4-3
4.2.3 GPIB Handshake 4-6
4.3 GPIB Address Assignment 4-8
4.4 GPIB Functional Check 4-11
4.4.1 Introduction 4-11
4.4.2 Remote and Local Check 4-12
4.4.3 Local Lockout and Clear Lockout Check. 4-13
4.4.4 Data Output Check 4-14
4.4.5 SRQ and Status Byte Check 4-15
4.4.6 Device Clear and Selected Device Clear Check 4-16
4.4.7 IFC Check 4-17
4.4.8 Talk-Only Selector Check 4-17
iv

TABLE OF CONTENTS (Cont<d)
Section Title Page
4.5 Interface Message Repertoire and Response 4-17
4.5.1 Introduction 4-17
4.5.2 Listen and Talk Address Commands 4-18
4.5.3 Addressed and Universal Commands 4-18
4.6 GPIB Operating Modes 4-20
4.6.1 Introduction 4-20
4.6.2 Talk-Only Mode 4-20
4.6.3 Addressed Mode 4-21
4.7 Output Message Format (Talker) 4-21
4.7.1 Introduction 4-21
4.7.2 High-Speed Data Output Mode 4-23
4.8 Service Request (SRQ) 4-27
4.9 Status Byte 4-27
4.10 Input Commands (Listener) 4-28
4.10.1 Introduction 4-28
4.10.2 Device-Dependent Commands 4-29
5GENERAL THEORY OF OPERATION 5-1
5.1 Introduction 5-1
5.2 Functional Blocks 5-1
5.3 Theory of Operation by Block 5-3
5.3.1 Channel A/B Block 5-3
5.3.1.1 Functional Description 5-3
5.3.1 .2 Circuit Description 5-4
5.3.2 Channel CBlock 5-5
5.3.2.1 Functional Description 5-5
5.3.2.2 Circuit Description 5-6
5.3.3 Measurement Block 5-6
5.3 .3.1 Functional Description 5-6
5.3 .3 .2 Circuit Description 5-8
5.3.4 Display Block 5-10
5.3.4.1 Functional Description 5-10
5.3. 4.2Circuit Description 5-11
5.3.5 Keyboard Block 5-12
5.3. 5.1 Functional Description 5-12
5.3.5.2 Circuit Description 5-13
5.3.6 Microprocessor Block 5-14
5.3.6.1 Functional Description 5-14
5.3. 6. 2Circuit Description 5-15
5.3.7 Standby and IRQ Block 5-16
5.3.7. 1Functional Description 5-16
5.3. 7.2Circuit Description 5-17
5.3.8 Power Supply Block 5-18
5.3.8.1 Functional Description 5-18
5.3. 8.2 Circuit Description 5-19
5.3.9 Internal Frequency Standard Block 5-20
5. 3. 9.1 Functional Description 5-20
5.3. 9.2 Circuit Description 5-20
v

TABLE OF CONTENTS (Contd)
Section Title
5.3.10 GPIB Interface. 5_2l
5.3.10.1 Introduction **5.21
5.3.10.2 Address Setting and Recognition !!!!!!!!!!!! 5-21
5.3.10.3 Reading from the Bus 5_22
5.3.10.4 Writing to the Bus .!!!!!!!!!!! 5-22
5.3.10.5 Serial Poll eo-j
5.3.10.6 Data Transfer Between Microprocessors 5-23
6
7
8
MAINTENANCE
DRAWINGS ....
PARTS LISTS...
vi

LIST OF ILLUSTRATIONS
Figure Title Page
1.1 Model 1994 Universal Timer/Counter ix
2.1 Fixed-Mount Angle-Bracket Detail .2-2
2.2 Rear Corner Foot, Side Panel, and Handle DetaiF 2-4
2.3 Loading the Alignment Blocks 2-4
2.4A/B Slide-Mount and Bracket Assembly 2-6
2.5 Rear End Slide-Mount Rack Dimensions 2-8
2.6 Slide Mount and Instrument Assembly (with inset) 2-10
2.7 Options 04A/04Eand 10 Installation 2-13
2.8 Option 41 Installation 2-15
2.9 AC Line Voltage Selection 2-16
3.1 Trigger Level Setting 3-35
3.2 Use of Stop Arm Delay 3-39
3.3 Special Function Register Display 3-41
4.1 GPIB Connector (Rear Panel) 4-1
4.2 Interface Signal Pin Assignments 4-2
4.3 Handshake Sequence ,,...4-6
4.4 Handshake Flow Chart 4-7
5.1 Simplified Overall Block Diagram 5-2
5.2 Channel A/B Block Diagram 5-3
5.3 Channel CBlock Diagram 5-5
5.4 Measurement -Block Diagram 5-7
5.5 Basic Recipromatic Counting Technique 5-8
5.6 Display -Block Diagram 5-11
5.7 Keyboard -Block Diagram 5-13
5.8 Microprocessor -Block Diagram 5-14
5.9 Standby and IRQ Block Diagram .5-16
5.10 Power-Supply -Block Diagram 5-19
5.11 Internal Frequency Standard Block Diagram 5-20
6.1 AFault Finding Flowchart 6-8
6.2 GPIB Troubleshooting Flowchart 6-16
6.3 Location of R149 and R192 6-20
6.4 Connections for Input ASystem Adjustment 6-21
6.5 Location of R150 and R193 6-22
6.6 Connections for Input BSystem Adjustment 6-22
6.7 Connections for Input CAssembly Adjustment 6-23
6.8 Connections for Internal Frequency Standard Adjustment 6-24
6. 9AConnections for Input ASensitivity PVP (D 6-26
6.9B Connections for Input ASensitivity PVP (II) 6-27
6. 10 AConnections for Input BSensitivity PVP (I) 6-28
6.10B Connections for Input BSensitivity PVP (EL) 6-28
6.11 Connections for Input CSensitivity PVP 6-29
6.12 Connections for 10 MHz Standard Output Level PVP 6-31
6.13 Connections for Minimum Time Interval PVP 6-31
6.14 Connections for External Arming PVP 6-32
6.15 Connections for Trigger Level PVP (I) 6-33
6.16 Trigger Level Waveform 6-33
6.17 Connections for Trigger Level PVP (n) 6-34
6.18 Connections for Internal Frequency Standard PVP 6-35
vii

LIST OF TABLES
Table Title Page
ii1QQ4 Snppi fionti one 1-6
Xf_L
3.1
3.2
Front Panel Controls, Indicators, and Connectors
Rear-Panel Controls and Connectors
Ui>onnonpu MooeiirPmPnf
3-4
3-16
3-20
o9o
^4PprirvH Moocnrompnt 3-22
Tima Tntorvol Mpaeljrpmpnt 3-24
wW
Qfi TV'i+al Ahv RMpflciirpm^nt 3-26
0,0
3.7
raManual Totalize Measurement
Ratin A/R and P./R MPfleiirpmpntc 3-29
3-30
0.0
a9Rico /Fall AMpflctirpmpnts 3-32
0,«7
qinPnlcp Width AMpflflippmpnt 3-33
0,x u
*3 11 Phacp Arpl RMpfl^ippmpnt 3-34
ojl
qioT3
q
evil ntiAn onH fin tp Timp 3-38
Oflu
Q1Q3-43
Vw
314 Fi'pnr Podpe 3-45
4.1
49IEEE-488-1978 Standard Interface Subset Capability
1QQi (~L DTP AHHpocq Acci'crrs mpnt
.a4—4
,a... 4-9
*,M
4.3
44Addressed and Universal Commands
dintniit Mp««flo*P Fftpmftt
..4-18
4-22
4SPunpHnn TptfPr<5 4-23
4fi Wttrh Snppd Ontniit Mndp Format 4-24
*x*u
47Statue RvtP Fnrmflt 4-27
48Pormittpd T*pr rnina tore 4-29
49Tnctm imont Prpcpt Prtdp 4-29
410 Wnmpi*ipfll Tnnut Format 4-30
X,«tw
41
1
Mooenromont Fnnotinn Porips .4-31
412 Mtimoi>ipfl1 Tnnut Rancrpe 4-32
413Rpeolntion Splection 4-33
414 Tnnut Pnntrnl d’ndpe 4-33
41SMAQoni»oniAnt PnnfTrtl P.ivIps ............ 4-34
41fi Stnrp and RppqTI d’ndpe ..................a.. 4-35
X,Xw
417Snooiol Pi motion C’ndpe 4-35
418Sani/ipp Rpniipct f'ndpe ..................a 4-36
*t«x o
4IQ A!r\H ohatir% T.ict rtf Prtm mflfirj 4-36
*X ml O
R1Prtntml Tv'lcrio T.PVPle hv Function 5-10
fi 1PcrmmoH Toct FmitnmPflt 6-2
u*x
fi 96-5
u,«
fi ^Cnooinl Piinotinn Frror dnHp<! .6-6
o,o
fi 4Tn^axnol Frmianpit Standard AnPllfflPV ............... 6-25
6fiA Trim iTASoncitivitu ill 6-26
u,on
fi SR Tnntif ASpn<5itivitv (TT^ 6-27
6fiA Tnnut RRpneitivitv (0 6-28
u,on
fi fiR 6-29
o,uu
67Tnm 11C' Rpneitivitv 6-30
U, i
fi fl Tn+rti»rtol Qtan/iorH Apf'llPfl^V 6-35
0.0
8.1 List of Suppliers *8-2
viii

Figure 1-1 -Model 1994 Universal Timer/Counter
IX
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a
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*
CMWjl o

SECTION 1GENERAL INFORMATION
1.1 INTRODUCTION
1.1.1 The Racal Instruments Model 1994 timer/counter is amicroprocessor-con-
trolled instrument offering high accuracy measurements with acomprehensive range of
capabilities. The 1994 can be provided with Option 41 Input C, extending frequency
measurement to 1.3 GHz. 8My
1.2 MEASUREMENT FUNCTIONS
1.2.1 Frequency Aand B
1.2. 1.1 Frequency Aand Bare used to measure the frequency of the signal applied
to Inputs Aand B, respectively. Aresolution of 9digits is available with a1-second gate
time.
1.2.2 Frequency C
1.2.
2.1
Frequency Cis available as Option 41. Aresolution of 9digits is available
_with a1-second gate time.
1.2.3 Period A
1.2. 3.1 Period Ais used to measure the period of the waveform applied to Input A.
Aresolution of 9digits is available with a1-second gate time.
1.2.4 Time Interval
1.
2.4.1
Time Interval provides single-shot measurements of the time interval
between:
1. Separate Mode: An event occurring at Input Aand alater event at
Input B
2. Common Mode: Two events occurring at Input A
1.
2.4.2
The arming of the stop trigger circuit can be delayed to prevent the
measurement interval being stopped prematurely by spurious pulses, such as those caused
by contact bounce.
1.2.5 Total Aby B
1.2. 5.1 Total Aby Bpermits events occurring at Input Ato be totalized. The
counting interval can be controlled by:
1. Electrical start and stop signals applied to Input B(Total Aby B)
2. Successive operations of afront panel key accumulating counts
(Manual Totalize)
1.2. 5. 2Delayed arming of the stop circuit to prevent spurious triggering is available
in the Total Aby B mode.
1-1

1.2.6
1.2.6.1
1.2.7
Ratio A/B
Ratio A/B is used to measure the frequency ratio between Inputs Aand B,
Ratio C/B
1.2. 7.1 When Option 41 is installed, Ratio C/B is used to measure the frequency
ratio between Inputs Cand B.
1.2.8 Rise/Fall A
1,2. 8.1 Rise Aand Fall Aare automatically measured using positive and negative
slope selection, respectively.
1.2.9 Pulse Width A
1.2, 9.1 Positive and negative Pulse Widths Aare automatically measured using
positive and negative slope selection, respectively.
1.2.10 Phase Arel B
1.2.10.1
Phase Arel Bis used to measure the phase difference between the
waveform applied to Inputs Aand B. The phase difference is displayed in degrees, and
indicates the phase lead at Input A.
1.2.11 Check
1.2.11.1
The Check function enables anumber of functional tests of the instrument's
circuits to be made without the use of additional test equipment. For example, the 1994
can measure its own 10 MHz internal reference standard. Although these tests do not
check the instrument's performance to published specifications, they can be used to
verify that the equipment is operating correctly following receipt or transportation to a
new location. The Check function can be extended using special functions (see
Subsection 3.4.8) to provide acomprehensive range of self tests.
1.3 SIGNAL INPUT CHANNELS
1.3.1 Inputs Aand Bare fully independent, but provision is made for connection of
Input A's signal into both channels (common mode). When this is done, Input B's socket is
isolated from Channel B.
1.3.2 Both Inputs Aand Bare provided with independent controls to permit
selection of:
1.
2.
3.
4.
5.
AC or DC input coupling
1M12 or 5012 input impedance
XI or X10 input attenuation
Positive or negative-slope trigger
Manual or automatic setting of input trigger level
1-2