UNCLASSIFIED

AD NUMBER

ADB001372

NEW LIMITATION CHANGE

TOApproved for public release, distributionunlimited

FROMDistribution authorized to U.S. Gov't.agencies only; Test and Evaluation[01-75]; Jan 1975. Other requests shall bereferred to the OIC and AssistantCommander, NSWC/DL, Dahlgren, VA.

AUTHORITY

USNSWC ltr, 11 Sep 1975

THIS PAGE IS UNCLASSIFIED

NSWC/DL TECHNICAL REPORT TR-3212ýý'hnuary 1i97S

INITIAL SOFTWARF FOREMPASS EP-3A DIGITAL SYSTEM

Be'?nntt S. P'almer

D

iTDB x`opnjh 3

Li!L

Z-I

Distribution limited to U.S. Go,:'t agencies only; Test andEvaluation (01-75). 0)1er requests for this document mustt~e referred to the 0CC --. I Asst. Commander, Naval SurficaWeansons Center DahIgri4- L';!Oiritory, Da-hlgran, Va. 22448.

NAVAL SURFACE WEAPONS CENTERDAHLGREN LABORATORY

Dahlgren, Virginia22448

C. J. Rorie, Cap_., ISN Dr. J. S. di Rende

,)!C, ind Assistan• Commander Deputy Technical Dirccto1

SJanuary 1975

iz

NSINITIAL SOFTWARE FOR EMPASS i IEP-3A DIGITAL SYSTEM

by

Alice J. CampbeliBennett S. Palmer

Advanced Systems Department

Distribution limited to U. S. Government agencies only;Test and Evaluation (January 1975). Other requests forthis document must be referred to OIC and AssistantCommander, NSWC/DL.

NAVAL SURFACE WEAPONS CENTER.Dahlgren LaboratoryDahlgren, Virginia

E3I

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FOREWORD

S ~~The work reported herein was accomplished as part of the Electromagneltic;i

S~~Performance of Air and Ship Systems Project at the Naval Surface Weapons•S~Center, Dahlgren Laboratory. The task was performed in the Systems "!' -~Development Branch, Electromagnetic Systems Division, Advanced Systems

Department. •

A special acknowledgement is made to Mr. E. R. Whalen for his- ~~~~~guidance in the design of this system a-Ld for his leadership in theesalhmnofarud-sdlbrtryfrotwedvlpet.

':: This report was reviewed and approved by:

L. M. Woodward, Head, Systems Development Branch, Electromagnetic:? ~Systems Division ,

!: R.L. Schmidt, Head, Electromagnetic Systems Division :

S~Released by:

•J. .4 MILLS, JR., ad

S• nced Systems Department

.4

? &

2 Ii I

[I;I

•FOREWOR

• • , , , , , i ...... -I' 'i: •'''I .. . 1 -•i ... i"

I ABSTRACT

A digital system developed to support the Electromagnetic Performance ofAir and Ship Systems (EMPASS) Project at NSWC/DL is reported. The air-borne system consists of RF receivers and antennas with special relays andinterface units which allow a UNIVAC 1830A computer to interrogate andcontrol them. Aircraft position, RF signal, and system status measurementsare recorded digitally on magnetic tape while operator displays are providodfor some immediate data analysis and system monitoring. The software forthis data acquisition system was designed and developed at NSWC/DL and iscurrently being used on test and measurement missions of the EMPASSaircraft.

iii

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F R W R .... . .". . ." •. .' ."•• ) . ., . .I

ABSTfhACe . .. .. ..

III

TABLE OF CONTENTS

I ~ ~Page _:

FO BSREWRA ...................................... iABSRAC...........................................1

SLIST OF ILLUSTRATIONS................................v

INTRODUCTION ................... ........................ 1

DESIGN GOALS .................... ........................ 2DATA RECORDED .................. ...................... 2DATA DISPLAYED .... ......................... . ...DATA SIMULATION ................ ..................... 9

SOFTWARE STRUCTURE ............... .................... 10EXECUTIVE ............. ......................... . .. 11NAVIGATION DATA INPUT ...................... 12RECEIVER POSITION 1 (INPUT AND CONTROL) .......... ... 14RECEIVER POSITION 2 (INPUT AND CONTROL) .......... ... 19SYSTEM STATUS INPUT .......... ................... ... 19OPERATOR INPUT ............ ...................... ... 20GENERAL DISPLAY PROCESSING ..... ............... .... 25SPECIAL DISPLAYS ............ ..................... ... 25

BIBLIOGRAPHY .............. ........................ ... 32

DISTRIBUTION ........................................ ... 33

11I

i- 1

LIST OF ILLUSTRATIONS

1 EMPASS Block Diagram ........ .............. 1

2 EASY 100 Flow Diagram ....... .............. 3

3 Pulse Parameters ......... ................. 4 .i

4 Data Rates ............. .................... 4

5 Navigation Parameters ....... ............... 5 5

6 Status Data. . ................... 6

7 Data Buffer .......... .................... 7

8 Device Availability Table ....... .............. 9

9 Executive Routine..... . .. ................. 11

10 Navigation Data Input Task ................ .... 13

11 Table EVCON ...... ................... ... 15

12 Table ERECV ....... ................... ... 15

13 Receiver Input/Control ................. 18

14 ASA 70 ....... ...................... ... 21

15 Matrix Select and Multifunction Switches .... ...... 23

16 Monofunction Switches ................... .... 24

17 Sample Antenna Pattern (Polar) .............. ....

18 Sample Time vs Power Plot ................ .... 28

19 Sample Statistical Summary ...... ............. 29

20 General Purpose Display .... .............. ... 30

21 Special Display (Polar) ......... ............ 31

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S. . . . . . . . . . .. . ... 7.:. -::.':. ..-T '" . . 2--. . . . . .. . . .

II

INTRODUCTION

The Naval Surface Weapons Center, Dahlgren Laboratory (NSWC/DL), inits Electromagnetic Performance of Air and Ship Systems (EMPASS) Project,has developed an airborne measurement system to evaluate the electromagneticperformance of the Navy's airborne, shipboard, and ground-based systemsin their operating environment. A UNIVAC 1830A computer interrogates andcontrols RF receivers and antennas through special interface units to digitallyrecord aircraft position, RF signal, and system status information (Figure 1).The CDC 6700 computer system is utilized for analyzing the recorded dataand producing graphical test results.

SYSTIhI 1- _ I-

"F DICITALANALX &I . -_ .. V1'I .. A.i L- J I

. F -.,T -I.__. -- --- <T•,,,,-.,>__ 7_ ___ 7--V /

I J L IM~

[Z GTI ALTMlII

STATUS/ I dl, ]ALCONTROL L • ..

UNIT

RECLIVLRS AA 1-1J1.iANTENNAS "T"RF SWITCULS &II;rAVIDEO SWITCIIE --CAL SYSTSEM I NI XREC OP a AO -kl-O 1

Figure 1. EMPASS Block Diagram

This report describes the software developed for the airborne dataacquisition function, including the design goals for the recording of rawdata on a pulse-to-pulse basis; the on-line displays provided for operator

1 .•

control, system monitoring, and data analysis: and the provisions for datasimulation. A section on software structure describes how these design goalsare implemented in the initial system. Graphical radiation patterns and asample statistical summary of pulse information are presented as examples oftest results.

DESIGN GOALS

The program. EASY 100, wa. designed for general puspose data acquisition(Figure 2). The design criteria were to store digital RF signal pulse para-meters on magnetic tape compactly, to provide real-time analysis for operatoruse, and to be as reliable or fail-safe as possible in this data acquisitionmission.

DATA RECORDED

To allow versatility in EMPASS test capability, digital RF signal data isrecorded on a pulse-to-pulse basis, providing actual pulse streams for lateranalysis (Figure 3). The slow magnetic tape units impose a maximum datarate of 1 KHz on the system, but special provisions are made for cases whereall pulses cannot be recorded during a sample interval, The operator selectsthe sample interval, and may choose a fixed sample size of 256 pulses orallow the sample size to be a function of the data rate and sample interval. Inthe latter case, data exceeding the maximum rate is recorded by segmentingthe sample interval and recording pulses in bursts, so that short pulsestreams are obtained throughout the selected interval and gaps are reduced(Figure 4).

Aircraft navigation parameters and system status information are recordedwith each sample of signal data (Figures 5 and 6) . Rather than recordingthe different data types as separate short records or buffering largeramounts of each data type, all inputs are allowed to flow directly into thelarge output buffer. This automatically achieves a chronological ordering,reduces processor time required for data handling, and achieves efficiencyin tape start/stop operations. Further, in the event of tape error causingonly a portion of the tape to be recovered, the data accessible will bemeaningful.

Space in a 4096-word output buffer is allocated dynamically as an inputarea. The space is identified by data type, sample size, and current time,and it is linked to space allocated previously for the same data type(Figure 7). The input operation is then initiated and the processor freed,possibly to handle other requests for space. When there is not enough

2

SLI L'LVICL AVAILABILITY TAILL

START

INIUT XE.UTIVL SYSTbN OUTPUINL~tJ1 ~ RTdUr UrTILITIES I NT ERRU TRO IIS PRCEDUIRE ROUJTINES

NAV 4

WA1TDATA

IOROPERATOR

REC 1--DATA r- -

REC I A Nt TSIEVENT'I tWTROL RI INPUT/CONTRUL

REC 2ý _TABLL

DATA R P2 INPITT/CONTROL.

EVENT STATUIS INPU`I' TASKcoNTROL IITABLE IOPERATOR INPUT TASK ---------

DATA PROCESS DIISP'LAY 6 -CNROLSY

PROCESS DISPLAY SPECIAL

OPERAT~t ILALT N, RNITO CALINPUTS EKLYBOARI'1

ALL iLCI

,LkLTT

SPICIAL PURPOSE1RI DISPLAY BUirILV I/ Of !

RZ DISPLAY DUFFER ARO 1UFE BUFFER

jL;1RA-1_PUW_-S:__ DISPLAY

DISPLAY BUFFUR I ARS

DISPLAYED Allkli.IARY UISPLAY/KIBOARL) RECORDEDDATA DISPLAYS F(UR ON-LINE MNOFITOR DATA

Figure 2. EASY 100 Flow Diagram

3

R 0 0P 4 1w s _m Or.- q--- _oF-- A

T-FCKIVLIt I 'Mit, 1IQAI

29 28 27 A8 25 24 1 ' I 1% IsI 14 Ii h) o e

WOIID 0 0a INE IMEBETWE SAMPLES I L'L> AI Vii 1.1111,

-1 W In 1 sPrLT.ANAL.n 'LIT . 14 . 1 -1111IO

WORD 2 Li1~ I1I1RECTIONOF ARRIVAL.kj silm NITS CONTENTS 01-sil 1t 1 IIi Ot -• I

"F 0 cS Ap l tiplcd.'5 b 4(,• 14 ,.+• c ci- 4( t ic-t,7 +•.. c0 82 %" ctu AAMyPe I Iptud., %'%11 Wýil 0-'•',I

1-28 Ti t. Sauoplr m 1A

29 - I

0-15 PSeI mantises cc-•I.c16-17 PSI Chaedt erlstit - I

- 00. Moltip . (0-15) y .01 Ic i. 14 .s. 1"- 0 .*M ltip.y {0-15) by ,i t, ft-It, I .c.

- 10I Multiply (0-I )) by 1.8 ccc- l t•?$l.,C 7-,4 .. ;.418-27 SpectruCm Analyzer pll- Itud I 54 11 V lt c-5 .- It,

25 - 1. CWJfor o.A n29 - 1

2 0-9 Pulse Width Mantissa 0i- 10.10-Figuree Width CharPeterlaet mtr

- 011, multiply (0-5) by '01- 01. Multiply (0-5) by .ItnrII? c~c

- 10, Multiply (0-5) by .414 si '- t1>.'

2-23 DIrectatot of Arrival or ? 5 0 I 3 So5 0-12-24 1 PM froquearcy 11-23 Imill. 2c iii Htnl i M25 * 1, WJ-1140 1.6oc on2b - I, ts tK requenCry Chcang, 521 I. IPX Pulse Cucldnr1".'TieDI os W rims

Ii

Figure 3. Pulse ParametersrFOR SAMPLE INTERVAL =1/1 SIC

Input Rate (KHZ) 1 2L 3 4 5 10 20 iZ Data Recorded 100 50 33 25 20 10 5

Time Data Recorded (MS5) 256 128 84.8 64 51.2 25.6 12.8

Time Data Lost (M4S) 0 128 171.2 192 204.8 230.4 243.2 iMax. Gap (KS) 0 16 21.4 24 25.6 28.8 30.4

Figure 4. Data Rates

4ji4 1!

J29 .'J -2 2 ZI-120 ]'. 18 17)91 t, 14 1 112 131 91097 h ~4 32

1 ~ ~ ~ LOik9 I I ---- *-.-----'. X

(KAM VIp F .1L9 I rR ACK AN !.\'i I1

WORD s WFI-S VELOCITY IN -1S iI'LAP(;

WOR ~ ACA B 9 f ( j\RIN( k-~ I~ AA AIK) CUILAS 111.I)IN ~1Al I I Il-Ill-.

(OKU 11TItS C08 O 'NI tS 1 SI (IiI II MS3i (tI;l) WAil:

o I __ -', _- t i t 1i 'kl (I'AS- 1001 ,7 ~ 1. i k~ I2" o to ') I 0

1 12 -29 L.ong! 11,v iii\M"-) 9'"0 (3* 0. to~ I h'SVI2 1 1 l1%kk Ang1v *uI * i2 'Im' 0I ~ to * sU,

I U- '9 Li st \'-1uclty 1 WI k I 4w).(' k28) o1 to 81 - 1,1. II' lo 29 wc*d %,Ioý it I KI t II -101.v o Is ii I~ !'. .' I

1 4 - 1 Poll II I !it)I)'.I1 t 0 t1 1 ski*

4 19-21 11 Pit"11O 0o~ ,3) 1 Icani Ran?, V I NA I I0~ Nki(I ~j to ..I9. N'-I

5 17-2 1 l ca 1 ' R tr I Tg .090 I I I m" I .'., I . t '()

1, 3-1 AI \t it 11I 20 Ft S3 ~ ~ Fl 0 9 11 to IC l IL

IIIr,!i~t' Sip~l bijt t'1-I, )I~, j to) 1, ylitIsril n'I t I OI 9 - I'S

IN Ju I tnd vs waLrn~ing hit for plr 'c6111x~ V I -)'' Il~l 91-HNll)

X II Il Vc:1 IC; tiVIId 11,t k1011L) Inidicaites fie'ld i'ý ;wills I)I lfld iceýi litVld iN ilw~iY'i IA Indicurcs altinirctur typec (03 1~'hrti radoar

Figure 5. Navigation Paramneters

I-!

Vi - I

t:,CL hATr L0N SYSTEM

29 25 0

0 0 0 0 Calibration Frequency (7 high-order digits)

14 13 7

'Calibration Frequency Selection

0 0 0 i1 3 low-order digits Indicators

I 11 16115 4 •

"0 0 1 0 Calibration Calibration" Attenuation S Power Meter

R 22 15 R 11

0 0 1 1 N ClbainN Calibration PRIG_ _ 22 Pulse Width

ANTENNA CONTROL SYSTEM

9 2 25 16 15 8 7 0

010UTail Angle Wing AngleI0100 -•

RLCEIVER POSITIuN 2

29 26 25 11 10 4 3 0

0 i U I Selection Indicatur5 Equalizer Line

.',ttenuation Attenua.

0 1 1 0 Selection Indicators

21

0 1 i I Slection indicators

RECEIVER POSITION I

29 26 25 11 10 4 3 0

Line1 0 00 Selection Indicators Equalizer kttenua-

Attenuation tion

1 0 0 i Selection Indicators

Figure 6. Status Data

6

. ~ ~~~.......... .....

151Buffer Number

I Buffer Start Time

2 RelativL Address ofnext Available Space

Relative Address of Relative Address of3 First NAV Data Most Recent NAI! Data

Relative Address of Relative Address of Most4 First Rec. I Data Recent Rec. 1 Dats

Relative Address of Relative Address of Most5 First Kee. 2 Data Recent Rec. 2 Data

Relative Address of Relative Address of Most6 First 5tatus Data Recey-t Status Data

New Rec. I PC ur reLnt Roe. Relative Address of Rec. 17 Event No. I Event No. Eivent Label, if present

New flee, 2 Current Roe. Relative Address of Rec. 28 Event No, 2 Event No. Event Label, if present

N telative Address of Relative Address ofLast Data This Type Net aa hi yp INPUT

Sample Size Dats Type Input Time -Buffer Start ITEM

-- - j HEADERAdditional information About Data

Data Sample Wd.i)

INPUTData Sample Wd.l ITEM

Data Sample WD.N

Figure 7. Data Buffer

7

buffer space remaining to honor a request, the output operation is initiatedand the alternate buffer used for allocating input space. In this way it ispossible to have as many as four input operations and an output operationoccurring simultaneously while the computer is free to perform the on-lineprocessing needed for the operator.

DATA DISPLAYED

The Easy 100 system displays information to the operator through twomedia--the ASA 70 16-in. -diameter multipurpose display and the ARO,an auxiliary readout unit containing a 20 X 20 character display. Thegeneral display on the ASA 70, used for total system monitoring, is up-dated every second. The date, time, and lapsed time are presentedalong with all the information from the interface to the LTN-51 inertialnavigation system. Items showing the status of receivers, antennas, andrelay systems are given and flashed if there is a disagreement with theoperator selection. Up to 40 characters from the operator's keyboardmay also be displayed to allow comments to be formatted before recording,and program detected error conditions are made apparent. In addition tothis system monitoring information, the general display contains a rec-tangular plot for each receiver position. Up. to 180 points of signal ampli-tude data are displayed for each receiver, in volts (0 -5) or computercalibrated in lO-dBm steps. The abscissa is normall, in seconds and isupdated every other second. After the display is filled, it may wraparound or shift points as the operator chooses.

The operator may change the two ieceiver plots independently to selectpower versus azimuth argle, distance, elevation angle or frequency.These plots are always updated, even if not displayed. When a new even'tis started for a receiver, the plot area for that receiver is cleared, butwhen an event is ended the data remains on display until another eventbegins using that receiver. The operator has many options for datadisplayed, Amplitude displayed may be either the average, the maximum,or the first in a data sample. Azimuth angle (direction from the emitterto receiver) may be calculated from either a TACAN bearing or trackangle of the aircraft. Amplitude at a certain ang'e may be either thelast one received at that angle or the maximum value received at thbtangle. The latter option is useful in finding main beams, peak power,or excluding noise.

In addition to the general display with the optionai receiver data plots,the operator may choose a special display containing a large poiar plotof either receiver data. Thi3 may be used to display a radiation patternas the aircraft flies around a fixed source.

Bc

The ARO displays the date, time, navigation, and receiver parametersnormally seen on the ASA 70 monitor display, but the operator may selectan event history, an error history, frequency control data files, or anon-line monitor capability used in conjunction with the ASA 70 keyboard.These displays provide the operator with additional system information anda means of monitoring the system in the event of ASA 70 display failure.

DATA SIMULATION

The EASY 100 system was designed and developed to include a datasimulation for each of its inputs. This allowed for program developmentbefore some hardware became available, -t allows for tests to be "pre-flown"without the expense of operating the aircraft, and it provides some backupoperation in the event that a device develops problems during a test.

At program initiation, the operator establishes a system configuration ora device availability table (Figure 8) which indicates the manner in whicheach input and each output is to be handled. System inputs include navi-gation data, receiver position I data, receiver position 2 data, system statusdata, and operator inputs. Each data input may be from the proper inter-face unit, from an 1840 magnetic tape unit, from a 1540 magnetic tape unit,or from core memory, while operator inputs may be from ASA 70 control

panel, from an SST keyboard, from a standard teletype keyboard, or from acore memory table of "canned" start--up information.

29 27 ON-LINE 24 3 DISPLAY 21 20 CONTROL 18 17 TAPE is

MONITORk OUTPUT OUTPUT OUTPUT

0 NO MONITOR 0 = ASA 70 INTF 0=CS INTF 0 = 1840 MT

I = TEKTRONIX 1=I = BYPASS OUTPUT2 Y 1S32 2 BYPASS OUT- 2 BYPASS OUT- 7 1S-10 MI

.1 PUT' 3 Pill 3 W • 'Ass OU11 |11

14 OPERATOR INPUT 12 11 STATUSINPUT 9 8 EC2 INPUT 6 5 RECI INPUrITF 3 2 NAV INPUT -0

2 = TTY 1532 2 FAKE INPUl 1 1840 MTU2 2 = 1540 MTU4 2 - 1540 MTU33 ý FAKE INPUF 3). 2 = 1540 MT1U4 3 w FAKE INPUT 3 = FAKE INPUT

3 = FAKE INPUT

Figure 8. Device Availability Table

System outputs include raw data storage, control information, a general"purpose operator display, an auxiliary operator display, and an on-linemonitor for system evaluation and testing. The data storage may be to an

L

1840 magnetic tape unit, to a 1540 magnetic tape unit, 'or it may be bypassed.Other outputs are to the proper interface units or bypassed. The on-linemonitor uses a teletype or a TEKTRONIX display/keyboard unit for itsoperation.

Off-line piograms are available to produce the tapes of simulated data 'Whengiven flight plans and data specifications. Programs are being developed toretrieve data from completed tests for later use in the simulation mode.

SOFTWARE STRUCTURE

The EMPASS acquisition system known as EASY 100 is essentially atime-sharing system of priority-ordered tasks with a controlling executiveroutine. These tasks may be classified as data input tasks, control tasks,or processing tasks. The input and control tasks initiate data input or issue

control output messages and relinquish control, after setting the time theywish to be called again. Program interrupt occurs at the completion of theI/O operation and automatically accesses an interrupt routine unique to theI/O channel to perform necessary bookkeeping functions before returningcontrol to the point of interrup: . Other processing tasks operate in asegmented fashion sc. control may be shared among the 10 tasks in the systemdesign. Seven of these tasks are implemented in the initial system.

Input of aircratt navigation data is considered to be the highest prioritytask since other data is position relative. Control and input from the tworeceiver positions and system status input tasks follow in that order, whilethe tasks of communicating with a human operator are performed on a lower

priority basis. Separated into an operator input task and two display updatetasks, these procedures allow operator controls over the data acquisitionhardware and software while providing on-line processing for immediatedata display.

Common to all tasks are two large I/O buffers used for data input and out-put and the procedures which initialize these buffers, allocate buffer spacedynamically to requesting input tasks, link data samples of the same typewithin a buffer, and write a full buffer to magnetic tape while the alternatebuffer is used for input.

EXECUTIVE

The executive routine (Figure 9) performs the required initialization and

start-up functions. During the start-up phase, it permits the operator toestablish:

1. System configuration (a device availability table which gives thesystem some flexibility in the event of peripheral failure).

10

L t -

EEASY EXECUTIVE

INITIALIZATIONAND STA.TUPROCEDURES

W WAIT

FOROP SIGNAL1V SAV

CONTATT ATL TOPS TFATA

NO TIMEuTTOTGALL

YES HANE ALLR NOTASToT-

TEOOKNATD NIEAT

ENDT ATRTY

SETIFORLEDSTOR

Figur 9.O ExctieRotn

L D F1R

,TERMIATION

2. Current date and time, which allows all data to be uniquely labeled.

3. A starting event number, which allows each test or measurement tobe uniquely labeled.

4. Which tape unit is ready to be used for recording data.

When start-up is completed, the executive polls a priority-ordered tableof task call times, comparing each call time with the computer's real-timeclock. When the clock exceeds the call time, the task is initiated. Each

task resets its call time before returning so that it may be called again onthe next poll, after some fixed time delay, or, if call time is set to amaximum value, it will not be called again. The executive computes andstores the amount of time that each task consumes as well as its own "idle''time; i.e., the amount of time between the last task execution and the nextcall time in the table. An on-line monitoring procedure can be used to makethese and other system values available to the operator.

When an operator request to halt the system has been processed by theoperator input task, the executive communicates the need for an orderlytermination to each task in the system. When all tasks have set their calltimes to maximum value, indicating termination, the executive executesthe instructions that will stop the system in a state ready for restart at theoperator's signal.

NAVIGATION DATA INPUT

The navigation data input task (Figure 10) is the highest priority taskin the time-sharing system, but it is also the shortest task, both in runningItime and in coding required. It consists of an input-initiate procedure,NAVIN, and an input-complete interrupt procedure, ENSINT. If simulatednavigation data is being used, the magnetic tape interrupt procedure ESMTIPperforms the input-complete functions, and if no navigation data input isavailable, there is no interrupt function.

"The input-initiate procedure is called by the executive when the computer'sreal-time clock exceeds the entry for the navigation task in the table of taskcall times. It obtains space in the I/O buffer linked into the navigation datalinks, and consults the device availability table *n determine how navigationdata input is being handled.

"If the unit which interfaces the inertial navigation system is available,the procedure simply initiates an input from that device, resets its call timeaccording to the current operator-established navigation interval, and returns

* control to the executive.

j: 12

Lw'

O0BTAIN SPACE

1,BUFFER LINKE

NOT PRIMULATS NES

NINO RI YES

USYSTE

FLAG TAPE UNIT

NAV DATAIN i

INITIJATE INT

MOSE NNITEVA

SAPE INSO 1/0 ERNOBUFFERTAP INTERRUPTLERi

CERINPUT-IN-PROGRESS UETP FLAG TOP

I/O BUFFER

____CEA IPT-N-RGRS

NTERRUPTLA RETFLGOANYPENI

TIIINITIAEE INPDT

SHTSIGNA OPERPERTOR

INTERRUPTI-POGES R SET DTAP TLAG E TOTTAEDFLAG~~~~CURE ON NA TM NDTEMN ATO

FigERure 10.I Navgaio Dat Inu Task I

13-

If simulated navigation data is being obtained from a magnetic tape unit,the procedure waits for a flag to indicate that the tape is riot busy, sets theflag to signal that the tape unit is busy reading navigation data, and thenaddresses the proper tape unit with a read command before resetting calltime and returning.

If navigation data is not available at all, the procedure calls a routine tomove a prestored sample of navigation data into the buffer space and clearthe input-in-progress flag. It then resets the call time and returns controlas above.

When a data sample has been completely read in, the input-in-progressflag on the item header in the I/0 buffer must be cleared. This function isperformed by the interrupt procerdure accessed when the input is completed.If the input is from the navigation interface unit, the interrupt procedureENSINT is accessed to perform this function. If the input is from a magnetictape unit, the interrupt procedure ESMTIP i3 accessed. This.procedure usesthe system tape flag to determine what type of tape action has occurred andwhat interrupt processing is needed. When it finds the flag set to indicate anavigation data read, it clears the input-in-progress flag on the navigationitem. This procedure also checks the status from the proper tape unit,signals the operator if a bad read has occurred, and rewinds the navigationdata tape when an end of file is encountered. When all registers have beenrestored, it clears the system tape flag to indicate that the tape unit is nolonger busy, and returns control to the point of interrupt.

RECEIVER POSITION 1 (INPUT AND CONTROL) IThe second highest priority task in the EASY 100 system involves receiver

position 1 . When the computer's real-time clock exceeds this call tableentry, the procedure RECIIN is called to determine what processing isneeded at this position. For each receiver position, procedures are availableto allow input of signal data, control of the calibration system, control ofthe spectrum analyzer, control of the receiver frequency, or control of theantenna position. *

When the operator enters a request to start an event involving receiver

position 1, he may select any one of the controls available. This controlrequest is passed to the receiver task through the event control table*EVCON (Figure 11). For each of 100 possible receiver 1 events, this

table stores event start time, controls selected, length of time the eventwas in progress, and the number of signal data samples recorded, thusproviding a history of operation of the receiver position during a programrun.

* The last three control procedures are not implemented in the initial system.

14

i.

I:VIENT" SI'ARI I IMI IN SL'ONI'S CONIROI.S SEI-LCThED 0i-OR Til1s EVE:NT

"2! EVENT 1RAlON I -iI NI Nt'MIRI OF I "AA S"IA. S REICORDED INPOSITION I TII FVENTONE ____ _ENTRI ES

11)0 ENlIR I.

" EVENI SIAKIT lkiMI V4N"S ,WN6 CONT'ROI.S SEILECTIEDFOR "I'IIS F-VENT

RFCEI IVER 29 EVENT DIURA'I ION I'M" 7 IINUMBR 511 01: I'ATA SA, [LES RECORIDED0

POSITION IN TIllS FVENT

TWOENTRI ES

Figure 11. Table EVCON

Another table, ERECV (Figure 121, contains information about the event inprogress and is used for communication between the various proceduresoperating within the task, On each initial call to this task (i.e., in responseto operator's input of start event), this table is set to contain only thecurrent event number and a procedure selection switch of zero, whichcauses RECIIN to initiate a call on the procedure RDATA.

2 RLCELVER ONI. 154 14 CURRENT RECEIVER ONE

W. I0 PRILOIURE SI.VC1 ION 10 i S 'I EVENT NIUBER

DATA INTERIACE. 12R• Hi III DATA R:C4IVER ONE--CURRENT

Wd. I SELECT CODE - RATE FLAG _ RAMPLE SIZE

Wd. 2 PRI V'A1.III !:ROM LAST RICl DI'A SA•?4'LL

29 0Wd. S CONTROL INFoRMATION FOR RECIIVER POS;TION ONE

29 RECFIVER TWO iF 14 CURRENI RECEIVER TWO

'Wd. 0 PROCEDURF SEECTION SWITClH 1 I V'N1 NUMBUE:2

ýDATA INTERFACE 2" 4 1 7

R2 Ill "1I'AIw 14 RICEIVI-R TWO--CURRENT 0ITEM I 1 SELECT CODE - RATE ILAG 1S7PlE SItE

.Wd, 2 _ I'Rl \,Ai.III HIOM LAST RI:U 2 DATA SAMPLE29

Wd 32 CONTROl INIORmATION FOR RIL'I-\ER POSITION TWO

Figure 12. Table ERECV

15

Receiver Data Input

The procedure RDATA is common to both receiver tasks. It is responsiblefor entering data in the I/O buffer, linked into the proper receiver datalinks. It determines which receiver position task has called it, obtains theevent number from the table ERECV, and accesses the proper entry in thetable EVCON. Sensing the beginning of an event, it sets start time in theF EVCON entry and causes an event start label to be linked into the I/Obuffer, storing all information a',ailable on the status of the system at thetime the event begins. It then tests the selected controls stored in theEVCON entry to see what procedure should be called on the next call to thistask.

If no controls are requested on a receiver event, the procedure selectionswitch in the table ERECV will rt-main zero, and each call on this task willresult in a call on RDATA (Figure 13). This procedure will initiate inputof receiver data according to the device availability table and monitor thenumber of data samples linked into the I/O buffeirs. Control is relinquishedas soon as the input has been initiated and the next call time established.

If data is input from the receiver data interface unit, the interrupt pro-cedure EDATAlINT is accessed when the input is complete. Under normal

data input operation, this procedure simply clears the input-in-progressflag on the data item and issues a return to the point of interrupt.

If data is input from a magnetic tape unit, this function is performed bythe procedure ESMTIP which determines from the system tape flag thatsimulated receiver position 1 data has been read in from tape. Thisprocedure also signals the operator if a bad read status is detected, andrewinds the tape if an end of file is detected.

If data is simply moved from a prestored sample in core memory, nointerrupt routine is accessed.

The procedure PDATA also attempts to determine the proper size for areceiver data sample. On each call after the initial daxa input, if no controlsare in effect, it calls a routine to examine the last data sample stored andestimate the number of pulses expected in the current operator-establishedsampling interval, If the last data sample obtained indicates that the datarate is too high to record all pulses emitted in a sample interval, then ahigh data rate flag is set in the table ERECV and special processing isbegun.

16

- Ii

When the RF signal data being recorded exceeds the maximum of 256 pulsesper sample interval, the ih.lerval is segmented to avoid collection of allpulses at the beginning of the interval. Sensing the high data rate flag set,the procedure which initiates the data input requests buffer space for thefull sample, but initiates input of only one-eighth of the pulses desired. Itthen sets the computer countdown clock to cause a program interrupt whenone-eighth of the sample interval has elapsed.

but the interrupt routine EDArAIINT does not clear the input-in-progress

flag until the eighth group is complete.

The countdown clock interrupt routine, ECDTIMER, is accessed whenone-eighth of the sample interval has elapsed. It initiates the input requestfor the next group of pulses and sets the countdown clock for the nextinterrupt. When the last segment of the sample interval has expired, theclock interrupt routine disables the clock processing, terminating thesample input,

If the data rate remains high, the next call on the receiver data inputtask will begin another segmented sample and again start the countdownclock processing. The time-between-samples value on the data beingrecorded makes it possible to reconstruct the actual time of arrival of eachpulsc, identifying and measuring the data gaps within the samxple interval.

Calibration Control

When control of calibration is selected by the operator, the procedureselection switch will be set to 1 after the event start label has been linkedinto the I/O buffer. This means the second call on the task will causeRECIIN to call the procedure RCAL (Figure 13) to calibrate the receiverselected, This procedure, common to both receiver tasks, will read instatus information to obtain a power meter reading and the amount ofattenuation which the receiver operator has set for the maximum powerlevel. It then issues control messages to the calibration attenuator increasingattenuation in 5-dB steps. After each control message, it sets the procedureselection switch to zero, resets its call time to wait a full second beforethe next call on this task, av.d returns. When the task is called again,control passes to RDATA to obtain a sample of signal data at the prescribedattenuation. Absolute power, passed through the table ERECV, is storedin the I/O buffer with the signal data.

Calls on the receiver task, then, initiate alternate calls on the RCAL andRDATA procedures. RCAL examines each sample of receiver data todetermine the average amplitude in volts at each power level. It passesthis information to procedures which update the operator's display and also

17

INTO1 110 Ill1111*111

FUR All I ANAL I

LII IATA IRLU~ A]/

N~~~~~~~n~[ 1 N1 411 AIRUA l il ] /.1 11!7Il

NJ III 111

RITATA

NO Z OF Sill? %I jI 2VENT11 IlS AAII ,;

L ILK DATA LINK EVENT FIC DAITl I.TO LABIEL WITH STATIIS i~ S.

0/ NUIFER INI0Ni4ATIlO4 INTO . , 1 .. ~.- /'?i1li"FIRlilA

Nil LATE ]Nl1ITIl TI I I l l X'IIli 1IIC V ATA I 11111 / I lC ATA~Rl IIPU AI I IOl AD I N 1.5T11ACO NUI[11 N1411fF TAIl)

AVAVAI 1 ITY--JI

SNIT PtII (IRIjI4,1, L11T.1- 1111111C1 RI, I -m-ý' N

014T51101 SUUVt I Rol

DAK

Figure 13. Reeie InpA, Conro

18

uses it to determine when the attenuation is too great to receive a measur-able signal. At this point or when the attenuation exceeds an upper limitof 129 dB, the calibration is considered complete. The next call on thetask causes the RDATA procedure to store an event end label in the I/Obuffer and set the maximum call time so the task will be termindLed.

RECEIVER POSITION 2 (INPUT AND CONTROL)

The third highest priority task in the EASY 100 system involves receiverposition 2. When the computer's real-time clock exceeds this call table entry,the procedure REC2IN is called to determine what processing is needed atthis position. The procedures available for receiver position 1 are alsoavailable to receiver position 2. Since the tasks are executed serially andall storage items are separate for receiver 1 and receiver 2, the two positionsmay be operated completely independently. All information presented abovefor receiver position 1 also applies to receiver position 2.

Hardware is not yet available for operation of receiver position 2, butdata simulation from this position and fake input operations have both beenimplemented, recording data in the receiver 2 links and producing on-linedisplays for operator analysis.

SYSTEM STATUS INPUT

The fourth task in the EASY 100 system is the input of system status infor-mation. This data maintains a record of all changes in system controls,provides a vehicle for entering opcrator comments at any time, and allowsan on-line error detection capability.

The procedure SYSTEMSTAT is called by executive at intervals establishedby the operator. This procedure obtains space in the I/O buifer linked intostatus data links and consults the device availability table to determine howthis input is being handled. If the control and status interface unit is avail-able, a utility procedure, STATUSlN, is called to initiate input of statusdata from the entire system. If the interface unit is not available, a sampleof status information is moved from core into the buffer space.

A system flag set by the operator input task indicates when a keyboardbuffer contains an operator comment to be stored in the I/O buffer alongwith system status data.

On-line error detection is provided by examining the system statusdata and comparing it with the relay commands which have been issued.Any discrepancies are called to the operator's attention by flashing itemson the status display provided.

19

OPERATOR INPUT *

Operator input can come from one of three sources--an ASA 70, an SST or

a teletype. The latter two merely simulate inputs in ASA 70 format. Duringinitialization, one selects the input medium. The chosen device is inter-rogated constantly via a pending input with monitor. When an input occurs,Ii an interrupt routine, KINT, saves the input code and partially decodes it. Ifthis happens during initialization, the input is part of either the date, time,event number or tape number. These values are accumulated and formattedfor the displays. Otherwise, the partially decoded input is stored to beprocessed and executed at a later time by KIM, which calls the necessaryprocessing routine and checks for illegal codes. A new input is requestedimmediately, even when the old one is still waiting to be processed. Ifthe SST is chosen, the inputs are used in combination to form all possibleASA 70 inputs.

The ASA 70 (Figure 14) has been used as the primary input-output mediumfor the computer operator. The ASA 70 consists of an 1830A computer inter-face, a control tray, at least 100 labeled switches (48 of which are active),a 16-in.-diameter multipurpose display, and a ball-type cursor. The inter-face includes a test option for manually setting and sending up t( three wordsto the control tray.

Possible inputs from the ASA 70 are switches, keyboard characters, andcursor changes. The program is controlled by the pressing of the switches."Matrix Select" switches choose a set of 12 interdependent options on the"Multifunction" switches (Figure 15) . "Monofunction" switches select aspecial independent function (Figure 16) . The matrix and monofunctionswitches have green and amber background illumination. They have beenprogrammed to light amber if and only if the associated function is selected.A unique set of 12 legends automatically appears on the multifunctionswitches with the depression of each matrix select switch, except for the lastone, which clears all switches. Through the use of the 12 matrix select and12 multifunction switches, there is a choice of 132 functions. There are 24

monofunctions, not all of which light. Tue labels and functions of thoseimplemented are given below. In order to light the monofunction switch

lamps, onue sends the cur-ent status of either the upper 12 or lower 12 to thecontrol tray. Therefore, any combination can be lit at any one time. How-ever, only 12 actually have amber lights.

The- tracking control ball assembly places the cursor (hook) symbol at anylocation on the CRT. The trackball sends over a pair of changes in x and ypositions every 50 ms, whether or not there has been any change. Moreover,the input consists of the absolute value of the change, plus a sign bit. Theprogram saves the trackball Ay in a special word if it senses a Ax.

The keyboard assembly is similar to a typewriter and consists of 44alphabetical, numerical, and special character keys. These keys are

20

B!

11 c 1 9 7 1 N= _

INDEX RlEPlNO. NAME DESIG FUNCTION

OFF LINE/ANALOG AIS2 Permits the dtspl•y of fou, ch-nrelt. CIHAN I thru CHAN 4.swithO end CHAN l 4 of nidvn , Ie ' h-rnce of certain digital Input

signels. when unod ir. _nn}uocton with the mode selector switch.

CHAN I Provides sean convert,,, i tdwrCHAN 2 Provides low itght level teevston (LLLTV)CHAN 3 Spare, c.n conv,-L _rCHAN 4 Provides functio ,, nroo,,.c, l.ijl •.eCHAN 1 ,4 .Permit% supnr, i t_ d ly of channels 1 5 4

2 CHAN 2 BRIGHTNESS AlR3 Adjusts brightness of displayed video. channel 2control

3 CIAhN 3 SRIGHTNBSS AtIR3 Adjusts brightness of displayed video. channel 3control

4 vERr CENTERING ARIR54 Adjusts relattve -vntie po-itioning of display on tube face

5 CHAN 4 BRIGHTNESS AIR6 Adjusts brighl•tc. of displayed video. cho.nnel 4control

a VECTOR BRIGHTNESS AIR22 Adjusts brightness of displayed v-ctorscontrol

7 Monoflunctuon Enables operator to comeunicate with computer. Both singleswtch indlcators and double lamp switches ore used. Single lamp switches are

always lighted green and cannot be ;ighted by the computer. Thedouole temp esowhtChei are green and amber. Green is thenormal background and amber is the computer lighted response.

a Metrix These 31e lwu-poeltiott owitchb- mety be illuminated green or amberswitch Indicators end have several legends that may be projected on their surface."rh. digital data computer sendos inftnation to the operator via

these legende. end the opertor noes the switch futcttton to sendinformation to the computer.

9 Matrix select Pasetilts tnformation to compioer when pressed by operator.switch Indicators Indicatore ore double )cml, pu.hbubton switches. one switch

for each PRO In the three metricee. A, B. and C. The greenlamp is on at all times while the amber lamp comes on onlywhen computer responds I)v lighting the corresponding PROIn adjacent mastri

Figure 14. ASA 70 JL 21

+ .'g .

1 2 34 56 7

19U

18.

H4 907

137)12 89 11 7 10

INDEX RSP!NO- NAME nESI FUNCTION

ISKeyboard Allows operotor is communicate w Ith computer, koysore A to Z. U to i, REPEAT. MACE. EOM. Minus. Pius,NEXT LINE. Period, SACK. uod CANCEL.

15 Tracking hail control Provides signals which cs. respond to position of manuanlly positionedball. ibis sinormatison in used by UPS sod csotputer to neisct cursor(hook) Isaymbol uoad disploy illsn locainon corrasponding to positionof irsolsing boll.

12 Time totatizing rooter Mi Indicate elapsod boors of oIeation

13 Lamp intensity Enshiro upersitir to adjost hrtghtnesu of Indicator switches and controls.controls 121 Otto cootrol adjusts matrix A. B. and C PRO switch-indicator brightness:

sen moorted ruottr lell side of runlrol trap.-

14 TEST indicator AItiS3 Indicates MODE SELFOTOR switch in not ON LINE position

15 OVERFLOW Indinsta AllIS4 Indioate.s : .osnov. islorwullu for dispisy lube

ig CHARACTER Alit)) Adjoust rnghiptnless of displayetd charactersBRIGHNTESS control

17 CHAR S BRIGHTNESS AIR)) Adjusts brightneson of displayed video. channel 1

Is NORI ' CENTERING ANS11tI Adjusts relative horizontal positioning of dioplay on tube facecontrol7

1s MODE SELECTOR AlE) Permits d-eytay of video In absence of terrain digits) Input signals whenswitch crd to canojecticn with OFF LINE/ANALOG swritch. Also controls

I lilumlostlon of TEST indicstor.

ON LINE _____ Parmit, normal on line operation

MATRIX TEST Di Gi1vduitest caerts,

REGISTRATION TEST _______ regij~j storation lost ns:6ternVECTOR TEST ____ fjp5genrtaotln

TYP TST ____ Displaye lope2 teat palternFU.NCTION DEN TEST Dlp____ Is nctlait ensotn or ta to etitizOFF LINE/ANALOG 7.v__ uiYy teeison test potlern

Figure 14. ASA 70 (Continued)

22

0

zz

0z z z

P 0- > >

u-. 0 > r

c4 m

z I-

00

c.- I-' I-'

wL U4 f-

C- ~ ~ ~ P C- Cr - D O-

cc0l c

U 23

NO. EASY NAME CODES LAMPS

i ~1 1S12 17

i I3 20

4 215s 22

S6 23 x-i i7 24 X

1 0 25 x11 15 x

12 HALT/RESTART 3 x13 CLOCKWISE 7

S14 CROSSWISE 10i'15 TAPE 2 READY 2S16 POINTWISE 617 TAPE 1 READY 1 x

0TAPE 2 READY

21 END TAPE 12 x22 HALT/RESTART 26 x

S23 CW DATA 13!24 HOOK 14.2 5 MAX 11

26 27 x27 30 x

30 END TAPE 431 END TAPE 4

IFigure 16. Monofunction Switches

I used to construct messages for display, and to initiate and control tacticalsituations. During the initialization procedure, EASY requests date, time,

and event numbers for identifying the run. These are converted, for-matted, and displayed on the MPD and ARO as they are received. Duringthe test, keyboards are buffered and displayed in a line (of up to 40characters) on the bottom of the MPD. Control characters have theirnormal meaning, except LINEFEED which will clear and start a new linewith the next character. After a message has been composed, the EOMkey must be pressed in order to transfer the message buffer. (The keysin this assembly are in series with the inonofunction switches in thecontrol tray.) During the input of data for EMCON files, all the for-matting is done automatically; i.e., the operator does not have to typeblanks and periods.

24

25MAA1[ 26J27-,

R i

Pressing a switch results in a call on the procedure KSWPROC whichdetermines the type of switch and illuminates the correct lamp. For arnonofunction switch, a flag is merely set. For a matrix select switch,the matrix number is saved in order to interpret any multifunctionswitches, which actually call the processing routines.

Receiver data collection is controlled by two matrices, one for eachreceiver. After choosing either the receiver 1 or 2 matrix switch, all onemust do in order to start recording receiver data is to press "START".This starts a new event which continues until "STOP" is pushed. If onedesires other data to be recorded along with or in place of receiver data,one must push "CAL", "S/A", "DOA", "ANT", "IFM", or "POL" before"START". A display of time versus power is given unless a differentoption is selected by a "DISPLAY" matrix switch, These may be changedat any time during data acquisition.

GENERAL DISPLAY PROCESSING

The displays are updated every second through the task table by EUPDATEin four subtasks on a shared-timed basis. Date and time are always updated,i.e., every 1/4 sec. AUPDATE handles the information from the navigationinterface which goes at the top of the ASA 70 and on the ARO. AURECupdates the normal time versus power rectilinear plots alternating betweenthe two receivers. It looks in the buffer for the last receiver item, cal-culates the average (or maximum) amplitude and stores a point in thedisplay buffer. UPSTAT displays the system status and checks for con-sistency. AUM1SC updates miscellaneous information such as event numberand error messages.

The time dependent display information is updated by AUREC whichalternates between receivers on successive calls. First of all, it callsALASTREC which searches for the last receiver item in the buffer, movesit, and averages the amplitudes. If no pulses are present, ALASTRECreturns with the flag AINT set to inhibit plotting. This routine alsoaverages crudely the frequency, PRI, and PW for digital display. Itwould be helpful to sort and display them graphically here, but this wouldimply a logarithmic plot or the operator setting a window.

The average amplitude is scaled down to display size (0-177 octal) andoffset for the receiver. If the buffer is full and a moving display isdesired, the set of points is shifted to the left. This has the effect ofhaving the newest value always being added to the right. A mark appearsto indicate the elapsed event time. Neither of these operations arestraightforward since there is a discontinuity at zero.

25

-'l - . . -

SPECIAL DISPLAYS

Special displays are all handled through one task in the executive tasktable. They involve correlation of receiver and navigational parameters.

The most interesting display is an antenna pattern, which is a polar plot

of average (or maximum) received power versus azimuth angle. Optionaldisplays are rectangular plots of power versus azimuth angle, powerversus range, power versus elevation angle, and power versus frequency.

Figures 17, 18, and 19 show some off-line hard-copy results for a typicaldata tape produced by EASY 100. On-line displays are similar. Figure 20is a picture from the general display. A polar antenna pattern from theASA 70 multipurpose display is illustrated in Figure 21.

26

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- Iz *; . h ; w aI , , z 1*a 1 0* - cI a

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X A 1. 4 .- , 13 -

292

Figure 2J. General Purpose Display

30

r -� - - � � � -.- .. , - -- -- - -- - -

I

jI

IaI

3 1

L. � -� -- �*- -------- �'-----* - - -> - -

BIBLIOGRAPHY

1, Systems Development Branch, Advanced Systems Department,"EMPASS' EP-3A Digital Sy %item Planning ," Naval Surface WeaponsCenter/Dahlg-en Laboratory, ')ahlgren, Virginia, 8 Novenber 1973.

2. Sperry Rand UNVAC. BIG LOO( Final Equipment Test Specificationfor the ASA-70 Subsystem. PTM-2-6, St, PaJA, Minnesota, 1 February1971.

3. Sperry Rand UNIVAC, BIG LU, 0K Final Equipme:t Test Specificationfor the HSP and Keyboard Subs- stein, PTM-180, St, Patil, Minnosota,1 July 1970.

4. Naval Air Systems Command, AN /ASA-70 Tactical Data Dfisý.la' Group,Maintenance Instructions Organ i:,t:onal, Aircraft Model P-3C,Technical Manual NAVAIR 01--75PAC-2-5-3, Washington, L C,15 February 1971.

5. W. J. Peters, Memorandum FEA: WJP: kjh, dated 6 December 19'3,Subject: "EUquipment Status for the EMPAS3 Data Acquisition Syý*e.r,,"

6. W. J. Peters, Memorandum FEA:WJP; kjh, dated 10 October '.972,Subject: "Data Interface; Preliminary Specification for."

7. W. J. Peters, Memorandum 7EA:WJP: kjh, dated 8 November 1972,

Subject: "Computer Code Words for the Data Interface.

8. B. S. Palmer and A. J. Campbell, EMPASS EP-3A In'tial SoftwareDesign, Naval Surface Weapons Ceiter/Dahlgren LaboratoryTechnical Note TN-F-160/74, Dahlgr:'n, Virginia (to be published).

32

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CommanderNaval Air Systems CommandWashington, D. C. 20360ATTN: AIR-53364D

AIR-5105A2 •A111-5331746 .

Conimand,.rOperational Test and Evaluation ForceNaval BaseNorfolk, Virginia 23511

CommanderFleet Electronic Wai fare Support GroupNaval Air StationNorfolk, Virginia 23511

Center for Naval AnalysisSystems Evaluation Group1401 Wilson BoulevardArlington, Virginia 22209

Defense Documentation CenterCameron StationAlexandria, Virginia 22314 (2)

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UNCIASSIFIED $SECURITY CLASSIFICATION OF THIS PAGE (When Dalte Entered)

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSBEFORE COMPLETING FORMI. REPORT NUMBER t2. GOVT ACCESSION NO, 3. RECIPIENT'S CATALOG NUMBER

TR-3212L. TiTLE (end Subrltle) S. TYPE OF REPORT & PERIOD COVERED

INITIAL SOFIWARE FOR EMPASS EP-3A DIGITALS~SYSTEMSYSTEM 6. PERFORMING ORG. REPORT NUMBER

7. AUTHOR(.) S. CONTRACT OR GRANT NUMBER(a)

Alice J. CampbellBennett S. Palmer §

. PERFORMING ORQANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK

Naval Surface Weapons Center AREA 8 WORK UNIT NUMBERS

Dahlgren LaboratoryI Dahlgren, Virginia 22448 _

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January 197513- NUMBER OF PAGES

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Distribution limited to U. S. CGov't agencies only; Test and Evaluation(1-75). Other requests for this document must be referred to the OICand Asst. Cormmander, Naval Surface Weapons Center/Dahlgren laboratory,Dahlgren, Virginia 22448.

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IS. SUPPLEMENTARY NOTES

I1. KEY WORDS XConlinue on reverse side If necesesa7 and Identify by block numbe') I20. ABSTRACT (Contie an .ide if. ,,.e... nd Ientify by block n.ib.r)

; ~A digital system develope•d to suppor't the Electrom.agnetic PerformanceS~of Air and Ship Systems (E4PASS) Project at NSWC/DL is reported. The

airborne system consists of RF receivers and antennas with special relays_" A and interface units which allow a UNIVAC 1830A computer to interroqate and

Fcontrol them. Aircraft position, RF signal, and system status measurementsare recorded digitally on magnetic tape while operator displays areprovided for some immediate data analysis and system monitoring. The

DD ,O`. 1473 EDITION OF I NOV65 IS OBSOLETE/N 0001-0 UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE (Reite Date MIntor)

.UNCIASSIFnD_,LL.UMITY CLASSIFICATION OF THIS PAGE(When Deta fMceoed)

software for this data acquisition system was designed and developed at

NSW)/DL and is currently being used on test and measurement missions of.ti!e EMPASS aircraft.

SECURITY CLASSIFICATION Of THMS PAAE(WhMm DOMa SnIffn0

........ . ...........