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https://ntrs.nasa.gov/search.jsp?R=19730018388 2020-06-17T12:19:06+00:00Z

VANGUARD/PLACE EXPERIMENT SYSTEMDESIGN AND TEST PLAN

SUMMARY

This document defines the system design, and describes an operational testplan, for demonstrating and testing the NASA-GSFC Position Location and Air-craft Communications Equipment (PLACE), at C band, using NASA's ship, theUSNS Vanguard.

The Maritime Administration (MARAD), U. S. Department of Commerce,is a co-experimenter on board the Vanguard, having installed an ExperimentalMaritime Satellite Navigation/Communication (pseudo-random noise navigationcode) System for a side-by-side comparison with the PLACE sidetone-rangingsystem.

The Vanguard/PLACE Experiment is the result of a "crash" in-houseprogram to implement, and begin operational testing of the PLACE system in aperiod of time less than six months after inception. A pacing factor for theexperiment was the March 28, 1973 departure date for the Vanguard, from PortCanaveral, Florida. The Vanguard's departure date was met by a sufficientmargin that permitted operational-readiness checkout tests between the Rosman,N. C. Station, the Vanguard, and the ATS-5 satellite, as early as March 5, 1973.

The Vanguard/PLACE Experiment is divided into two phases: a Sea Test(approx. 30 days duration) to evaluate the position-location, 2-way voice, and2-way data communications capability of PLACE; and a Trilateration Test(approx. 60 days duration) to position-fix the ATS-5 satellite using the PLACEsystem.

Preceding page blank ]iii

VANGUARD/PLACE EXPERIMENT SYSTEMDESIGN AND TEST PLAN

ACKNOWLEDGMENTS

The NASA-Goddard Communications and Navigation Division (Code 750)originated the concept of employing NASA's ship, the USNS Vanguard, to demon-strate and test the Position Location and Aircraft-Communications Equipment(PLACE) at C band. In particular, Mr. James L. Baker made the initial sugges-tion to use the Vanguard for this purpose.

The Bell Aerospace Company, Buffalo, New York, manufactured the PLACEelectronic hardware for the Rosman, N. C. and Mojave, California stations, andthe PLACE equipment for the Vanguard, under the direction of Messrs. E. Rupp,Karl R. Gohlke and Steve Martin. Bell Aerospace also provided field-supportpersonnel for the Rosman and Vanguard terminals.

Mr. Harry Feigleson, Program Manager, of the Maritime Administration(MARAD), U. S. Department of Commerce, provided planning assistance as aco-experimenter, and supplied the 2.5-ft-diameter dish antenna, including aC-band receiver, for the Vanguard. This was accomplished under the directionof Mr. Michael W. Mitchell, Applied Information Industries (AII), Moorestown,New Jersey (MARAD Contract).

The loan of the TRANSATEL, C-band, transmitter terminal, from theGeneral Electric Company (Valley Forge, Pa.) for use at NASA's station atRosman, N. C., is appreciated. Also, the helpful comments made by Mr. Roy E.Anderson, Project Manager, General Electric Company (Schenectady, New York),in the review of the Vanguard/PLACE Test Plan, are acknowledged.

The ATS Project Office (Code 460) is commended for their overall coordina-tion of the satellite and ground-station support for the Vanguard/PLACE Experi-ment; the ATS Operations Control Center (ATSOCC) was especially helpful inthis regard.

The indispensable operational support provided by the NASA-GoddardNETWORKS DIRECTORATE (CODE 800), at the Rosman, N. C., Vanguard andMojave, California terminals, is deeply appreciated.

Preceding page blank v

The effort of the Network Engineering Division (Code 810), Antenna SystemsBranch (Code 811), and RF Systems Branch (Code 813) is appreciated for thefeed modification of the 15-ft-dish antenna, and for installation of the 4-GHzMonitor Link at the Rosman Station.

The satellite-ephemeris data provided by the Mission Support Computingand Analysis Division (Code 580) is also appreciated.

The operational aspects of the Vanguard/PLACE Experiment were directedby Mr. Richard Waetjen, Program Manager (Code 752); Mr. Walter K. Allen(Code 752) is the Principal Investigator for the PLACE Experiment; and Mr.Sheldon Wishna (Code 752) was Technical Officer for the procurement of thePLACE aircraft modems used in the experiment.

Dr. Ahmad Ghais, Mobile Applications (Code 752), Messrs. C. A. White(Code 750), and Dean Bonnell (Code 861.2) provided coordination between NASAand MARAD.

Vanguard/PLACE personnel on board the Vanguard, for the Sea Tests,include:

* Mr. Sheldon Wishna, NASA/GSFC, Code 752

* Mr. James Christo, NASA/GSFC, Code 752.

* Mr. Karl R. Gohlke, Bell Aerospace Company

* Mr. Richard Snyder, Bell Aerospace Company.

The information contained in Appendix 8, "Voice Tests, Vanguard/PLACEExperiment," was prepared by Messrs. S. Wishna and W. Risley, of NASA/GSFCCode 752. Also, the information in Appendix 9, "Satellite Trilateration Theoryand Computations" was provided by Mr. H. Winter, Bell Aerospace Co., Buffalo,New York.

Finally, the individual and corporate contributions made by the following"Key Personnel" were invaluable.

vi

LIST OF KEY PERSONNEL

FOR

VANGUARD/PLACE EXPERIMENT

NASA/GSFC CODE 460:

H. PedolskyA. J. Yudd

L. NicholsonR. Moore

P. McCeney

NASA/GSFC CODE 700:

J. Baker (750)R. Waetjen (752)W. Allen (752)C. A. White (750)D. Nace (751)

W. Risley (752)

A. Ghais (752)R. E. Taylor (752)S. Wishna (752)J. Christo (752)F. Long (752)

NASA/GSFC CODE 800:

D. Bonnell (861.2)R. Tagler (813.2)H. Kingman (813.2)W. Hughes (811.4)T. Keating (811.0)J. Kueberth (811.2)P. Kushmeider (814.2)

C. Parker (852.1)E. Zink (824.2)R. Covington (863.2)A. Durham (811.0)E. Ferrick (861.0)D. Tinari (820.0)G. Dennis (810.0)

USNS Vanguard:

O. Thiele, Station DirectorJ. Heasley, Operations SupervisorS. Liptak, Telemetry EngineerJ. Martin, SATCOMM. McClain, SATCOMS. Martin, Bell Aerospace Company

vii

E. Zink, NASA/GSFC Code 824.2

NASA/GSFC ATS Operations Control Center (ATSOCC):

F. Kissel

Bendix Field Engineering Co.:

D. Fink

NASA - Rosman, N. C. Station:

J. C. Jackson, Station DirectorE. Taylor, ATS Station DirectorD. Andersen, Supervisory EngineerD. Fabans, Operations ManagerR. Griswald, Systems SpecialistJ. Graham, Staff EngineerT. Buckley, Systems EngineerL. Wyant, ATS Operations ManagerW. Howard, Systems Engineer (PLACE)R. Singleton, Bell Aerospace Co.W. Alabran, Bell Aerospace Co.R. R. Roesler, Bell Aerospace Co.J. Allison, Bell Aerospace Co.J. McChesney, Bell Aerospace Co.

viii

CONTENTS

Page

I. Introduction .................................... 1

II. Vanguard/PLACE Experiment System Design ..... I........ 3

III. Vanguard/PLACE Experiment Test Schedule .. ............ 12

IV. Vanguard/PLACE Experiment Instrumentation, Sea Tests ...... 13

A. PLACE-System Instrumentation On-Board Vanguard ....... 13B. PLACE-System Instrumentation at Rosman Station ........ 14C. VHF Backup Link Using ATS-3 ...................... 15

V. Vanguard/PLACE Experiment Test Plan, Sea Tests .......... 15

A. Operations - Readiness Tests ...................... 15B. Sea-Test Scenario ........................... .. 16

VI. Data Reduction and Analysis, Vanguard/PLACE Experiment .... 17

VII. Satellite Trilateration Tests ......-................... 19

Appendix 1 - ATS-3 and ATS-5 Characteristics, C-Band FrequencyPlan, and RF-Link Budget Calculations ............ 22

Appendix 2 - Rosman and Vanguard Equipment Configurations,Vanguard/PLACE Sea Tests; Rosman, Vanguard andMojave Configurations, ATS-5 Trilateration Tests ..... 26

Appendix 3 - Vanguard/PLACE, ATS-3/-5, Satellite-Support Time,Sea Tests; ATS-5 Support Time, Trilateration Tests . . . 32

Appendix 4 - Vanguard and Rosman-Station Instrumentation,Vanguard/PLACE Experiment, Sea Tests ........... 33

Appendix 5 - VHF, Backup, RF-Link Budget Calculation ... ....... 47

Appendix 6 - Operations-Readiness Tests, Vanguard/PLACEExperiment ............................... 51

ix

CONTENTS (Continued)

Page

Appendix 7 - Sea-Test Scenario, Vanguard/PLACE Equipment ...... 57

Appendix 8 - Voice Tests, Vanguard/PLACE Experiment ......... 63

Appendix 9 - Satellite Trilateration Theory and Computations ...... 71

x

VANGUARD/PLACE EXPERIMENT SYSTEM DESIGN AND TEST PLAN

I. INTRODUCTION

This Center originated a mar i t ime experiment to tes t the GSFC Position Location and Aircraft Communications Equipment, Reference 1, (PLACE), at C-band (due to lack of mar i t ime L-band capability), with NASA's ship, the USNS Vanguard (Figure 1), and the Applications Technology Satellite(s) (ATS), ATS-3 and ATS-5, now in orbi t . The Vanguard/PLACE Experiment (Reference 2) was designed to give a pre l iminary evaluation of the PLACE concept one year in advance of i ts scheduled tes t s with ATS-F , scheduled for launch in April 1974.

Quoting direct ly from Reference 3: "The experiment proposed in your le t te r dated November 20, 1972, using PLACE equipment on the USNS Vanguard is approved."

Figure 1. NASA Ship, USNS VANGUARD, Showing Locat ion of 30-Ft .

& 2.5-Ft , C-Band, Dish Antennas for Place Experiment.

1

The principal functions of the Vanguard/PLACE Experiment are as follows:

* Real-time Position Location of Ship, by two-way sidetone ranging,through two synchronous satellites (ATS-5 and ATS-3).

* Duplex (two-way) Voice Communication (shore-to-ship and ship-to-shore).

* Duplex (two-way) Data Transmission.

* Data and Voice Multiple Access

* Trilateration Tests to Accurately Position-Fix ATS-5 Satellite.

The principal objectives of the Vanguard/PLACE Experiment are:

(1) Early Demonstration of PLACE Concept in a Maritime Environment.

(2) Offer the U. S. Maritime Administration (MARAD), Reference 4, anAlternate System, which includes Duplex Voice.

(3) Determination of Position-Fixing Error for a Mobile User (Vanguardship), compared to on board, precision, Navigation Instrumentation.

(4) Early Demonstration of Duplex-Voice Communications, Duplex-DataTransmission, and Mobile-User Multiple-Accessing Techniques.

(5) Demonstration of PLACE Trilateration Capability for Position-Fixinga Synchronous Satellite (ATS-5) by Means of Sidetone-Ranging Measure-ments from three, Earth-Based, Trilateration Stations.

The Vanguard/PLACE Experiment has been divided into two phases: (1) aSea Test (approx. 30 days duration) using C-Band links (4/6 GHz) between theVanguard ship, the ATS-5 and ATS-3 satellites, and the NASA-Tracking NetworkStation located at Rosman, North Carolina, and (2) a Trilateration Test (approx.60 days duration) to position-fix the ATS-5 satellite, with the PLACE system inthe Trilateration Mode, using C-Band links between three trilateration stationsincluding the Vanguard, Rosman and Mojave (California) stations. The Vanguardship will be docked at Mar Del Plata, Argentina, South America, during theTrilateration Test Phase.

The first documentation on the PLACE system originated from NASA-Goddard in April 1967 which was later updated - a recent update is Reference 1.In early 1970, a hardware contract for several aircraft transponders (L-Band

2

Transmitter/Receiver and Modem, Reference 5) was initiated with the BellAerospace Company; consequently, in mid-1971, a similar contract, (Reference 6)was placed for PLACE Ground Equipment (PGE), for an approved PLACE Ex-periment on the ATS-F satellite.

In the Fall of 1972, members of the NASA-Goddard Communications andNavigation Division (Code 750) originated the concept of employing the Vanguardto demonstrate the PLACE system at C-Band (4/6 GHz), a frequency-spectrumregion free of propagation anomalies including ionospheric delay and scintillation.

A crucial factor was the realization that the Vanguard's 30-ft-diameter dishantenna had sufficiently high effective-radiated-power (ERP) to employ the ATS-5satellite's, omnidirectional, C-Band antenna (transmit and receive) which madepossible a complete PLACE Experiment - including ship position-fixing, 2-wayvoice communications and 2-way data communications. Utilization of the omni-directional antenna circumvents a number of problems due to satellite spin;both ATS-5 and ATS-3 satellites are spinning and the directive C-band radiationpattern thus also spins.

However, in order to make the Vanguard/PLACE Experiment viable, aminimal amount of additional PLACE hardware electronics was required on theVanguard - this equipment, contained in a single rack, was subsequently procured.

In addition, the availability of the NASA-Vanguard ship allowed the MaritimeAdministration (MARAD), U. S. Department of Commerce, to become a co-experimenter by deploying a MARAD Ship Terminal (Reference 4) on the Vanguardfor a side-by-side comparison with the NASA-PLACE system. Furthermore,this had the advantage of reducing costs for the NASA-PLACE Experiment sinceMARAD's C-Band, 2.5-ft., dish antenna, and C-Band Receiver, could be timed-shared on the Vanguard by both experimenters.

A pacing factor in the milestone schedule (Table 1), for the joint NASA-MARAD Experiment with the Vanguard ship, was the Vanguard's March 28, 1973sailing date (from Port Canaveral, Florida) in support of the NASA PIONEER-Gmission.

II. VANGUARD/PLACE EXPERIMENT SYSTEM DESIGN

The primary function of the NASA-PLACE system is to provide simultaneoussurveillance and position-fixing for up to 250 mobile users, in addition to pro-viding 2-way voice communications and 2-way data communications between aground station and the mobile users.

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In order to obtain an independent position-fix for a mobile user (e.g., aircraftor ship), three range measurements are required: (1) range from satellite 1(ATS-5) to the mobile user, R1 , (2) range from satellite 2 (ATS-3) to mobile user,R2 , and (3) range from the Earth's geocenter to the mobile user, R3 . R1 andR2 are computed directly from sidetone-ranging measurements made by thePLACE system; whereas the location of the geocenter is known a priori - itremains only to measure the height (altitude in case of aircraft) above sea level, h.A real-time printout of each user's position is made at the PLACE controlCenter (PCC); a typical format is shown in Table 2.

Having thus available specific values of R1 , R2 and R3 for a given mobileuser, the PLACE system computes (in real time) two independent Line-of-Positions* (LOP 1 and LOP 2, Figure 2) for that mobile user; two possible userpositions are determined - the actual position, P1 , and an ambiguous position,P2 , the latter being resolved by a priori information. Surveillance and Ranging(S & R) is performed by a single S & R channel to ATS-5 which consists of fourrange tones and a DPSK, 600 bps, Low-Rate-Data signal, Figure 3(a). The S & Rtransmission from Rosman to the Vanguard, via ATS-5, is continuous; however,the Vanguard counts time to an assigned time slot and replies with an S & Rsignal burst which includes the returned ranging tones. Timing synchronizationis established through 600-bps data transmissions, in the S & R channel.

A second set of range tones, consisting of only three tones, is transmittedfrom the Rosman Station to the ATS-3 satellite, Figure 3(b). The NASA-PLACEequipment on the Vanguard contains three digital phase-lock loops, phase lockedto range tones intermittently received from ATS-3, which recover and reproducecontinuous (but delayed) replicas of the original range tones.

The two sets of range tones, Figure 3(a) and 3(b), each contain a high range-tone frequency, at 8575 Hz, which is used for "fine" range measurements. Thefirst set of rangetones, Figure 3(a), provide a low-difference frequency of 25 Hzwhich is sufficient for completely unambiguous ranging; whereas the second setof rangetones, Figure 3(b), provide a low-difference frequency of 175 Hz, whichwillgive a range ambiguity of only 467 n mi. (one way). However, the Vanguard's,on board, navigation measurements will be used to eliminate the ambiguity at467 n mi.

The reply S & R channel from the Vanguard to ATS-5 is operated in a time-division-multiplex (TDM) Mode, Figure 4, in order to handle sequentially up to250 mobile users. The update rate is once per 64 sec., for each user; an optionalupdate rate of 10 data points per 64 sec (approx. 1 minute) is also available.

*An LOP is generated by a range measurement from one satellite to a user (e.g., Ri), andrange to geocenter, R3 .

6

LEGEND:

SS - SUBSATELLITE POINTLOP - LINE OF POSITIONPi - POSITION OF MOBILE USERP2 - POSITION AMBIGUITYR - RANGE,C - CIRCLE F

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Figure 2. Mobile User Position Fixing By Direct Ranging to Two Spacecraft

The TDM slot assignments for the three trilateration stations (Rosman,Mojave and Vanguard), for the ATS-5 Trilateration Tests, are also shown inFigure 4; an update rate of 10 ranging measurements per 64 sec will be used.

The PLACE frequency channels, for the 4 GHz and 6 GHz RF links betweenRosman, ATS-5 and the Vanguard, consist of a single S & R channel, three voicechannels, and three High-Rate Data (1200 bps) channels, Figure 5(a) and 5(b).The voice and data channels are frequency-division multiplexed (FDM). Thevoice channels employ an adaptive, narrowband, frequency-modulation (NBFM)technique; whereas the data channels use differentially coherent phase-shift-keyed (DPSK) modulation.

However, the PLACE Aircraft Modem on board the Vanguard can transmitonly one voice and one data channel simultaneously (e.g. V1 and D1 ), but canreceive up to 3 voice and 3 data channels.

The Vanguard/PLACE Experiment utilizes the Rosman Station, the Vanguard,and the ATS-5 and ATS-3 satellites for the Sea Tests; the Mojave, Californiastation is required only for ATS-5 Trilateration Tests (Figure 6).

7

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Various characteristics for the ATS-5 and ATS-3 satellites, an ATS-5,C-Band Frequency Plan, and C-Band RF-Link Calculations are given in Appen-dix 1 (Tables 1-1 thru 1-4, Figure 1-1 and Figure 1-2). The weakest RF link isfrom ATS-3 to the Vanguard; however the peak value of 50.6 dB-Hz, Carrier-to-Noise Power Density, C/No, is sufficient for a viable PLACE experiment (Table1-4). For a fully-loaded PLACE spectrum, the C-band links will operate atsignals only several decibels above threshold.

The equipment configuration for the Rosman Station (Figure 2-1, Appendix 2),for the Vanguard/PLACE Sea Tests, contains both a 6 GHz and a 4-GHz RF linkbetween Rosman and the ATS-3 satellite. The function of the 4-GHz RF link isto monitor transmissions from ATS-3 to insure that the narrow, 3 dB, beamwidth(0.70) of the 15-ft. dish antenna is always pointing toward ATS-3, which driftsapproximately ±3° in latitude over a 24-hr. period, and to insure a constantfrequency of 4.1100 GHz from ATS-3 to the Vanguard.

Vanguard/PLACE equipment for the Vanguard's Sea Tests is shown inFigure 2-2 (Appendix 2) which includes functional interconnections between theVanguard's SATCOM system, NASA-PLACE equipment, and the MARAD, 2.5-ft,C-Band, Dish Antenna and C-Band Receiver.

The equipment configurations for the Rosman Station (Figure 2-3), for theVanguard (Figure 2-4), and the Mojave Station (Figure 2-5) are shown in Appen-dix 2 for the Trilateration Tests, Vanguard/PLACE Experiment.

A major function of the Vanguard/PLACE Experiment is to compute thereal-time position of the Vanguard, during the Sea Tests, with the "on-line"PDP 11/20 computer which is a part of the PLACE Control Center (PCC) atRosman. The return ranging signals from the Vanguard to the Rosman computerare processed through the PLACE-Interface-Logic Unit (ILU) which takes thetwo sequential replies and calculates the two ranges through the satellites(ATS-5 and ATS-3). A typical format of the Rosman-PLACE, PGE/PCC, lineprinter (real-time) printout (Table 2) includes the roundtrip range to Satellite 1(ATS-5) and roundtrip range to Satellite 2 (ATS-3).

The real-time position of the Vanguard will be computed by the RosmanPLACE system with an accuracy better than ± 1 n. mi., the PLACE instru-mentation capability. NASA-derived ephemeris data from both satellites willbe entered into the computer, appropriate for the time period covering eachparticular test. The Vanguard's, on-board, "truth", navigation systems willprovide an averaged position of the ship within ± 0.1 n. mi. which will be com-pared to the ship's position as determined by the NASA-PLACE system.

12

IIIo VANGUARD/PLACE EXPERIMENT TEST SCHEDULE

The Vanguard/PLACE Experiment will be conducted while the Vanguard isat sea, en route to the PIONEER Test Support Position (TSP) from Port Canaveral,Florida, and during the sailing time from the PIONEER TSP, while en route toMar Del Plata, Argentina. There are approximately eight sailing days from PortCanaveral to PIONEER TSP; whereas an additional 9 or 10 days are required forthe voyage from PIONEER TSP to Argentina (Figure 7).

U.S.A.

PORTCANAVERAL

O SAILING 3000 2 DAYS

*-SAILING DAY 34 20° ISCHEDULED FORVANGUARD/PLACE EXPERIMENT. 8 10° 0

z

GDOP - GEOMETRICAL DILUTION PIONEER 2OF POSITION. · 2

TSP@ T0SAILING - 10°

DAY GDOP S.A. I

-__ 20 °1 0.38 00D2 ------- 0.46 6 3 -- … 0.52 7 30

4 ------- 0.65 MAR DEL PLATA 3085 - -- - - 0.70 - 4006 - - 0.80 407 1.0

8 - PIONEER TSP - 2.0

Tj+ 1 …-- 5.0+2 - - ---- 4.0+3 ------- 3.0 800 600 400 300 W+ 4 ------- 2.0 LONG.+5 -- ---- 1.5+6 ------- 0.9+7 ------- 0.75+ 8 --- -- 0.60+9 ------- 0.48

+ 10 ------- 0.42

Figure 7. Vanguard Route, Sea Tests, Vanguard-Place Experiment

13

The Vanguard's voyage extends over both northerly and southerly latitudes,providing an excellent opportunity to measure GDOP (geometrical dilution ofposition) for 'the PLACE system. GDOP is a measure of the user's-position-location error magnification; a GDOP of "one" results in an error in position ofone standard deviation. Maximum values of GDOP occur near the equator (0°

latitude).

Considering satellite-support time for MARAD, and other U. S. Governmentagencies, Table 3-1 (Appendix 3) is a composite compilation of ATS-3/ATS-5satellite support time expressed in Greenwich Mean Time (GMT), or Zulu time,for the NASA/Vanguard/PLACE Experiment (Sea Tests), Table 3-1 includesweekend support time which accounts for the fact that 59,0 hours of ATS-3/ATS-5satellite support time were allotted for the Vanguard/PLACE Experiment; anadditional 9.5 hours of ATS-5 support time has been assigned, not accompaniedby ATS-3 support time.

In the Experiment Test Plan, which follows, the ATS-3/ATS-5 satellitesupport time has been reserved mainly for Vanguard/PLACE position-locationmeasurements, requiring both satellites; whereas the additional ATS-5 supporttime will be used for 2-way voice communications, 1200-bps data communicationexperiments, and single-satellite, 2-way, ranging measurements.

The ATS-5 satellite support time, required for the Vanguard/PLACETrilateration Tests, in Table 3-2 (Appendix 3), is planned for May and June1973.

IV. VANGUARD/PLACE EXPERIMENT INSTRUMENTATION, SEA TESTS

A. PLACE-System Instrumentation On-Board Vanguard

As mentioned earlier, it was necessary to fabricate a rack of PLACEhardware, over-and-above that PLACE hardware already committed for theATS-F/PLACE Experiment, for installation on the Vanguard. The necessaryVanguard instrumentation, including the additional PLACE rack is shown inFigure 4-1, which indicates the interconnections with the Instrumentation-Recording System (FR-600 Recorder), the Vanguard's SATCOM Terminal andthe on-board, C-band, receiving system (Reference 7) supplied by MARAD. Asimplified system block diagram is shown in Figure 2-2, Appendix 2.

The complement of channel track assignments for the FR-600 recorder,for the Vanguard/PLACE Experiment on board equipment, is shown in Table4-1, Appendix 4.

14

The Vanguard/PLACE equipment on the Vanguard relays 2-way rangingsignals, 2-way voice communications, and 2-way data (1200 bps, High-Ratechannel) communications back to the Rosman Station via the ATS-5 satellite.In addition, the Vanguard receives PLACE ranging signals, also originating atthe Rosman Station, from ATS-3; these ranging signals are in turn relayed backto the Rosman Station, via the Vanguard's SATCOM Terminal, and the ATS-5satellite.

The PLACE ranging signals received from the ATS-5 and ATS-3 satellitesare transmitted back to the Rosman Station, via ATS-5, in appropriate timeslots within the time-division-multiplex (TDM) matrix (see Figure 4) for thePLACE Surveillance and Ranging (S and R) channel.

B. PLACE-System Instrumentation at Rosman Station

The PLACE system located at the Rosman Station originates 2-way rangingsignals, 2-way voice communications, and 2-way data (1200 bps, High-Ratechannel) communications for transmission to the Vanguard's SATCOM Terminalvia the ATS-5 satellite. A 21-ft-dish antenna (Mobile Terminal), located at theRosman Station, is utilized for this purpose.

In addition, the PLACE system originates a second Range-Tone Set, contain-ing 3 range tones, Figure 3(b), for transmission to the ATS-3 satellite via a15-ft-dish antenna terminal (Figure 4-2, Appendix 4), also located at the RosmanStation.

The PLACE system (Figure 4-2, Appendix 4) contains an "on-line" PDP-11/20 computer, including a Central-Processor Unit (CPU), a DEC writer,Master and Slave Tape Units, and a 132-column-wide Line Printer.

The PDP-11/20 computer calculates in real time (on line with a Kalman-type filter) the position of the Vanguard, during the Sea Tests, in terms oflatitude and longitude coordinates according to the format shown in Table 2.Satellite, a priori, ephemeris data, for both the ATS-5 and ATS-3 satellites, isinputted to the PDP-11/20 computer from a magnetic tape whose source dataoriginated from the NASA-Range and Range Rate (RARR) system (see Table 3-1,Appendix 3, for RARR schedule).

An updated position of the Vanguard is computed "off line", from recordingsof ranges from the PDP-11/20 Tape Units (Figure 4-2, Appendix 4), at a timewhen "updated" (post-measurement) RARR data becomes available for the ATS-5and ATS-3 satellites.

15

An Audio Tape Recorder is contained within the PLACE system at theRosman Station for transmitting and receiving voice communications with asimilar Audio Tape Recorder (Figure 4-1, Appendix 4) on board the Vanguard.

Two-way, data communication (1200 bps High-Rate, HR, channel) is main-tained between the Vanguard and the Rosman Station by means of a Frederick600 Data Test Set, located both on board the Vanguard and at Rosman (Figures4-1 and 4-2, respectively, Appendix 4). The performance of the 1200-bps datachannel is determined from measurements of carrier-to-noise power density(C/No) and bit error rates measured by the Frederick 600 Data Test Set. Inaddition, raw 1200 bps data signals, and a 1200 bps clock signal, are recordedboth on the Vanguard, and at Rosman, for playback later.

The complement of channel track assignments for the FR-600 instrumentationrecorders are shown in Table 4-1 and Table 4-2, Appendix 4, which includes achannel containing raw bit-error pulses from the Frederick 600, used fordetermining bit-error rates in the 1200 bps data channel.

C. VHF Backup Link Using ATS-3

The primary purpose of the VHF Backup Link is to provide an emergencybackup link, as an option, for the Rosman C-band link to ATS-3, the secondsatellite. Appendix 5 describes the VHF Backup Link, and includes an RF-linkcalculation, which utilizes the omnidirectional, VHF, transmit/receive antennaon the ATS-3 satellite (Table 5-1).

Vo VANGUARD/PLACE EXPERIMENT TEST PLAN, SEA TESTS

A. Operations - Readiness Tests

The primary purpose of the operations-readiness tests (ORT) is to determinethe operational status of the Rosman station and the NASA/PLACE equipment onthe Vanguard, including the MARAD C-band equipment (i.e., 2.5-ft-dish antenna,and C-band receiver) employed for receiving PLACE-ranging signals from theATS-3 satellite, prior to the departure of the Vanguard from its docked positionat Port Canaveral, Florida.

The ORT-test phase utilizes the satellites and ground terminals. The threeoperational modes (Modes A, B & C) for the ATS-3 and ATS-5 satellites, at bothC-band and VHF, are given in Table 6-1 which includes six station configurations(1 thru 6) for the Vanguard and Rosman terminals.

16

As listed in Table 3-1, Appendix 3, the ORT-test schedule begins on March 5,1973, and extends through March 26, 1973; Table 6-2, Appendix 6, lists detailedPLACE equipment checkout tests scheduled for the ORT-test phase.

B. Sea-Test Scenario

The most significant part of the Vanguard/PLACE experiment is the Sea-Test Phase. Primary emphasis will be given to the PLACE, sidetone, rangingmeasurements, through the ATS-5 and ATS-3 satellites, in turn utilized tocompute the position location of the Vanguard; the sea-test scenario (Appendix 7,Table 7-1) was structured to this end.

Whereas ranging through two satellites produces two indpendent line-of-positions (LOP) for locating the ship, two-way ranging through only one satellite(ATS-5) produces a single LOP, which when combined a single earth coordinate(e.g., ship's latitude from on-board navigation systems), also produces usefulinformation for position fixing the ship.

Ordinarily, the geometrical dilution of positionL (GDOP) for a single LOPdegrades when the user is positioned in equatorial regions, for a synchronousequatorial satellite. However, for the Vanguard Sea Tests the degraded accuracyaffects only one earth coordinate (i.e., latitude in the case of the ATS-5 satellitepositioned at 1050 W, and the Vanguard's route over the equator, Figure 7),whereas the accuracy of the remaining coordinate (ship's longitude) is unaffected.

Therefore, an excellent position fix for the ship can be obtained at all timesfrom a single LOP measurement, by means of two-way ranging through ATS-5,when combined with the ship's latitude derived from the on-board navigationsystems. Such a position fix, for the Vanguard, will be computed (off line) foreach ranging measurement point. The utilization of a single LOP, combined witha single earth coordinate passing through the Vanguard, increases the effective-satellite support time for ship position-location statistics.

Secondary emphasis will be placed upon two-way, voice, communicationmeasurements (i.e., ship-to-shore and shore-to-ship) between the Vanguardand Rosman terminals. Voice tests will be conducted for at least 18 hours(Appendix 8, Tables 8-1 and 8-2).

Five voice-test tapes have been prepared for voice transmissions (Appendix 8,Table 8-2), which include typical maritime and air-traffic-control messages.As a part of voice testing, a telephone-network free-conversation test has beenplanned, at which time personnel on the Vanguard will contact parties in thecontinental United States; an appropriate rating sheet will be prepared by partic-ipating personnel (Table 8-3, Appendix 8).

17

A smaller percentage of time has been scheduled for the various, remaining,miscellaneous tests that are required to evaluate fully the PLACE system. Theseinclude two-way, 1200-bps (H-R), data communications testing, the measurementof intermodulation products, and the evaluation of the multiple-access capabilityof PLACE (Appendix 7, Table 7-1).

VI. DATA REDUCTION AND ANALYSIS, VANGUARD/PLACE EXPERIMENT

The data reduction and analysis (DR&A) phase includes both "on line" and"off line" data processing. The primary data, of course, is the position-locationinformation for the Vanguard, computed initially "on line" by the PLACE PDP-11/20 computer at Rosman (Appendix 4, Figure 4-2), from two-satellite, sidetone-ranging measurements. However, the Vanguard's position-location data will beupdated later, "off line", as a part of the DR&A phase when updated ATS-3/-5satellite-ephemeris data becomes available.

If all goes well, the following maximum amount of position-location datawill be obtained from the Vanguard/PLACE experiment:

o 2-Satellite LOP Measurements - - - - - - - - - - - -59.0 hours

* 1-Satellite LOP Measurements - - - - - - - - - - - -9.5 hours

*Total 68.5 hours

Assuming that all PLACE-ranging measurements will be made at the high rateof ten ranging points per minute, this results in 600 ranging points per hour, or agrand total of approximately 41,000 ranging points for the total 68.5 hours available.

It is envisioned that the position-location data will be plotted, in hourlyincrement sets, wherein each ranging point appears in a latitude/longitude-coordinate** system along with a calibration curve of the Vanguard's true positionobtained from on-board navigation systems. To further aid the analysis, anrms-position error will be computed for each hourly increment set of data,with GDOP computed for data sets.

The basic-source ranging data, used in the DR&A phase, will be derivedfrom magnetic tapes recorded by the PLACE, TM-11A, Tape Units located atthe Rosman terminal.

*Includes satellite/ground-station support over weekends.**Mercator projection chart giving latitude and longitude in equal distance.

18

The analysis of the voice tapes will be performed "off line", both by playbackto a listening audience, and by playback to a computer. These tests will be clas-sified as follows:

(1) Live-Audience Analysis

· Intelligibility Test (IT)

e Modified-Rhyme Test (MRT)

· Phonetically-Balanced Test (PBT)

(2) Computer Analysis

· Articulation Index (AI)

(3) Free-Conversation Telephone Test

The voice test results including IT, MRT, PBT and AI will be plotted versuschannel carrier-to-noise power density C/No , expressed in dB-Hz.

The analysis of the 1200-bps, H-R, data-channel tests will be performed"off line", both on data from the Frederick 600 Data Test Set, and from "raw"1200-bps signals (and clock) recorded by the FR-600 tape recorder on theVanguard (Appendix 4, Figure 4-1), and at the Rosman terminal (Figure 4-2).The objective is to obtain bit-error probability performance versus C/No .

The secondary source of data will come from the FR-600 tape recorder,both on the Vanguard and at Rosman, for the track inputs given in Tables 4-1,and 4-2, Appendix 4.

Analog strip-chart recordings will be made from magnetic tapes obtainedfrom the FR-600 recorders, and these in turn analyzed during the DR&A phase.The following approximate quantities of magnetic tape (10" reel, 1-mil tape@ 3-3/4 in./s speed) will result from the Sea Tests:

* Vanguard FR-600 Tapes - - - - - - - - - - - - - -35 ea.

* Rosman FR-600 Tapes - - - - - - - - - - - - - - -35 ea.

Total (Approximately) 70 ea.

A strip-chart playback speed of 2 mm/s is suggested for data processing.

19

VII. ATS-5 SATELLITE TRILATERATION TESTS

Satellite-ephemeris data for the ATS-3 and ATS-5 satellites is a necessaryinput to determine the position location of the Vanguard during the Sea-TestPhase. In effect, the satellite-ephemeris data provides the unknown value of therange from the Rosman station to the ATS-5 satellite, and similarly the rangefrom Rosman to the ATS-3 satellite. Having provided both these ranges as apriori information (up-dated, post-measurement, ephemeris data is also satis-factory), the value of the range from ATS-5 to the Vanguard, R1 , and similarlythe range from ATS-3 to the Vanguard, R2 , can be computed from the roundtriprange measurements made by the PLACE system at Rosman (Figure 2). Ofcourse, after determining values for R1 and R2 , the position location of theVanguard can then be computed.

Therefore, to determine the ranges R1 and R2 requires a knowledge of thesatellite's position for the Vanguard/PLACE Experiment. However, in theforthcoming ATS-F/PLACE Experiment, the satellite's position will be deter-mined independently of external data. To accomplish this, the satellite's positionwill be determined by a geometrical-trilateration method by placing a transponderat each of three known station locations, and performing sidetone-ranging meas-urements. Satellite trilateration tests, for the ATS-5 satellite, will be performedin the Vanguard/PLACE Experiment for station locations shown in Figure 9-1,Appendix 90

The unique location of the Vanguard, while docked at Mar Del Plata, Argentina,provides unusually long baselines with the Rosman, N. C. and Mojave, Californiastations for accurate trilateration measurements with the ATS-5 satellite. Sincethe ATS-5 satellite has a rather stable orbit, the trilateration tests from theVanguard/PLACE Experiment should provide an excellent data base for updatingATS-5 ephemeris data.

The necessary trilateration equations for computing the dynamic, geocentriccoordinates for the ATS-5 satellite, as well as the corresponding ranges r1,r2 and r 3 (Figure 9-11, Appendix 9) from the three ground terminals, is includedin Appendix 9 (private communication, Reference 8, received from the BellAerospace Company), These equations are based upon the assumption of randommotion of the satellite, rather than knowledge of satellite orbital motion.(i.e., orbital elements)o

Necessary inputs for trilateration computations include the locations of thethree ground stations, within an accuracy of about 15 m, as well as the measuredroundtrip ranges from the Rosman station to the Vanguard and Mojave stations,through the ATS-5 satellite0

20

C/

A Kalman-type filter is used for the computations: H. Winter (Reference 8)provided a typical case shown in Table 9-1, Appendix 9, for the ATS-5 satellitelocated approximately at 1050 W. longitude. The data rate is assumed as oneranging measurement per minute; however, the Vanguard/PLACE TrilaterationTests will be conducted at the higher update rate of ten ranging measurementsper minute for greater accuracy.

In closing, a series of trilateration tests with the ATS-5 satellite have beenproposed (Table 3-2, Appendix 3), which include PLACE, sidetone-rangingmeasurements extending over a 24-hour interval.

At the suggestion of Mr. Roy E. Anderson, General Electric Company,Corporate Research and Development, Schenectady, New York, the Vanguard/PLACE Trilateration Tests will be conducted concurrently, and compared with,trilateration tests on ATS-5 to be jointly conducted by the General ElectricCompany (GE). Reference 9 describes GE's method for making satellite trilater-ation measurements at VHF and L-band frequencies.

Certain limitations in ground station and spacecraft resources are outlinedas follows. First, the ATS-5 satellite does not contain a VHF-relay transponder,but does have an L-band transponder. Second, only one of the General Electricstations (Radio-Optical Observatory, Schenectady, N. Y.) has L-band capability.Finally, spacecraft primary-power considerations restrict L-band transmissionsfrom the ATS-5 satellite to 10 minutes per hour, maximum, when operating overa 24-hour interval; continuous operation may extend up to several hours, if thenterminated. However, both the C-band and L-band transponders in ATS-5 maybe operated simultaneously, with the C-band transponder operating continuouslyfor 24 hours if desired.

A joint NASA/GE trilateration experiment is outlined as follows. First, com-pute (on line) ATS-5's latitude/longitude and altitude (distance from geocenter)coordinates vs GMT, at C-band, by means of the three NASA/PLACE trilaterationstations located at Rosman, N. C., Mojave, California, and Mar Del Plata, Argen-tina (Vanguard). Second, conduct simultaneously with the C-band experiment2-way ranging measurements, at L-band, between ATS-5 and GE's Radio-OpticalObservatory, Schenectady, N. Y. Third, for the same time interval, recompute(off line) the latitude/longitude and altitude coordinates of the ATS-5 satelliteusing C-band data for two of the NASA/PLACE trilateration stations (e.g., Mojaveand Vanguard), but substituting GE's ranging measurements, at L-band, taken bythe Radio-Optical Observatory, Schenectady, N. Y., for the third station (e.g., inlieu of Rosman station). Various other combinations of stations could be tried,resulting in a direct comparison of L-band and C-band performance, with thelarger error being attributed to L-band performance.

21

REFERENCES

1. Allen, Walter K., Ralph E. Taylor, Eugene J. Feinberg, "Position Locationand Aircraft Communications Equipment (PLACE)", Revised Proposal,NASA/GSFC, Report No. X-752-72-132, May 1972.

2. "NASA-USNS Vanguard/PLACE Experiment at C-Band Using ATS-5 andATS-3 Satellites", Nov. 20, 1972, letter from NASA/GSFC (Code 750) toNASA HDQTS, Office of Applications (Mr. C. W. Mathews).

3. Dec. 4, 1972, letter from NASA HDQTS, E/Associate Administrator forApplications (C. Wo Mathews) to NASA/GSFC Dr. J. F. Clark, Directorand Mr. Jo Baker.

4. "Maritime Satellite Navigation/Communication Program Phase II -Experiment System Development and Operation, System Design Plan,Revised Configuration", August 11, 1972, U. S. Department of CommerceReport No, MAR 594-M-005; Applied Information Industries, Moorestown,New Jersey, Uo S. Dept. of Commerce Contract No. 1-35594; RevisedConfiguration, dated August 11, 1972.

5. "PLACE Airborne Equipment, Detailed Design Review Agenda", Report No.6203-945004, Aug. 1971, Bell Aerospace Co., Buffalo, NY NASA ContractNAS5-21120,

6. "PLACE Ground Equipment, Critical Design Review Report," Rev. 1, Vol.1 of 6, Report Noo 6225-933003, Sept, 1971, Bell Aerospace Co. Buffalo, NYNASA Contract NASA5-21619o

7. "Maritime Satellite Navigation/Communication Program Phase II -Experiment System Development and Operation, Ship Terminal DesignReport", U. SO Dept. of Commerce, Maritime Administration Report No.MAR 594-R-015, Sept. 15, 1972, Applied Information Industries,Moorestown, N. Jo

8. December 13, 1972 letter from Mr. Ho Winter, Principal Scientist, AdvancedAvionic Systems Research (C84), Bell Aerospace Company, Buffalo, NewYork 14240,

9. "Final Report on Phase 3 ATS Ranging and Position Fixing Experiment",NASA Contract No. NAS5-11634, 19 March 1971 to 1 December 1972, pre-pared by General Electric Company, Corporate Research and Development,Schenectady, New York, Roy E. Anderson, Project Manager.

22

APPENDIX 1

ATS-3 AND ATS-5 CHARACTERISTICS,

C-BAND FREQUENCY PLAN,

AND RF-LINK BUDGET CALCULATIONS

23

Table 1-1ATS-5 and ATS-3 Satellite C-Band Transponder Characteristics

ATS-3 ATS-5

TRANSPONDER #1 #1CHARACTERISTIC

TWT's 1 2 1 2

Antenna Polarization Linear Linear

*Transmit Antenna Gain, dB 16.2 16.7

*Receive Antenna Gain, dB 16.2 16.3

Effective Radiated Power (ERP), dBw 22.2 24.6 21.4 24.4

TWT Power, Watts 4 8 4 8

Transmit Network Loss, dB 0 -. 6 -1.3 -1.3

Antenna Noise Temperature, °K 290 290

Receiver Noise Temperature, °K 890 890

Receiver Noise Figure, dB 6.1 6.1

Receive Effective Noise Temp, °K 1183 1183

Receiver Network Loss, dB -0.4 -0.4

Uplink Frequency, MHz** 6212.094 6212.094

Uplink Space Loss, dB -199.8 -199.9

Downlink Frequency, MHz** 4119.599 4119.599

Downlink Space Loss, dB -196.2 -196.3

*OMNIDIRECTIONAL antenna (ATS-5 only) has 1,3 dB gain, above isotropic.**Band Center of 25 MHz passband (Frequency Translation, FT Mode).

24

Table 1-2ATS-5 Link Budget

30-Foot SATCOM Receive Antenna on Board ShipUSNS VANGUARD

21-Foot Transmit Antenna at Rosman

Rosman to ATS-5to Ship

Parameter6-GHz 4-GHz

Up Link Down Link

Transmit Antenna Gain (dB) 48.5 1.3Transmit Network Loss (dB) - 1.0 - 0.4

Transmitter Power Out (dBW) 34.8 6.0*ERP (dBW) 82.3 6.9Receive Antenna Gain (dB) 1.3 48.0Receive Network Loss (dB) - 0.4 - 0.2

Free Space Loss (dB) -199.9 -196.3Atmospheric Loss (dB) - 0.2 - 0.2Polarization Loss (dB) - 0.8 - 3.8S/C Antenna Point Loss (dB) - 0.5 - 0.5

Ground Antenna Point Loss (dB) - 0.2 - 1.0

Net Propagation Loss (dB) -201.6 -201.8S/C Modulation Loss (dB)_ - 3.5

Received Carrier Power (dBW) -118.4 -150.6

Receive Effective Noise Temperature (°K) 1183 100Receive Antenna Noise Temperature (oK) (290)Noise Power Density (dBW/Hz) -197.9 -208.6

Carrier/Noise Power Density C/N

o

(dB-Hz) 79.5 58.0

* Two TWT's are used on ATS-5 for total of 8-watts (9.0 dBw); however, assume twoequal-level signals which power share the repeater output power.

25

Table 1-3ATS-5 Link Budget

30-Foot Transmit Antenna on Board ShipUSNS VANGUARD

21-Foot Receive Antenna at Rosman

Ship to ATS-5to Rosman

Parameter6-GHz 4-GHz

Up Link Down Link

Transmit Antenna Gain (dB) 52.0 1.3Transmit Network Loss (dB) - 0.5 - 0.4

Transmitter Power Out (dBW) 35.0 6.0*ERP (dBW) 86.5 6.9Receive Antenna Gain (dB) 1.3 45.0Receive Network Loss (dB) - 0.4 - 0.4

Free Space Loss (dB) -199.9 -196.3Atmospheric Loss (dB) - 0.2 - 0.2Polarization Loss (dB) - 3.8 - 3.8

S/C Antenna Point Loss (dB) - 0.5 - 0.5

Ground Antenna Point Loss (dB) - 0.2 - 1.0

Net Propagation Loss (dB) -204.6 -202.0S/C Modulation Loss (dB) - - 3.0

Received Carrier Power (dBW) -117o2 -153.5

Receive Effective Noise Temperature (°K) 1183 135Receive Antenna Noise Temperature (°K) (290)Noise Power Density (dBW/Hz) -197.9 -207.3

Carrier/Noise Power Density, C/No (dB-Hz) 80.7 53.8**

* Two TWT's are used on ATS-5 for total of 8-watts (9.0 dBw); however, assume twoequal-level signals which power share the repeater output power.

** 53.8 dB-Hz is minimum C/N0 required (see Reference 6, pp. 111o78, -79 & 82) for transmittinga fully-loaded PLACE spectrum consisting of S and R channel (600 bps data and 4 range tones),3 voice channels, and 3 high-rate (1200bps) data channels (Frequency-Translation Mode).Thresholds for individual channels in the composite signal are defined as:

S and R ................ 42 dB-HzHR (1200 bps) Data ..... 42 dB-HzVoice ................. 46 dB-Hz.

26

Table 1-4ATS-3 Link Budget (#1 Transponder)15-Foot Transmit Antenna at Rosman

2.5-Foot Receive Antenna on Board ShipUSNS VANGUARD

Rosman to ATS-3to Ship

Parameter6-GHz 4-GHz

Up Link Down Link

Transmit Antenna Gain (dB) 46.0 16.2Transmit Network Loss (dB) - 0.5 - 0.5

Transmitter Power Out (dBW) 24.8* 9.0ERP (dBW) 70.3 24.7Receive Antenna Gain (dB) 16.2 27.3Receive Network Loss (dB) - 0.4 - 1.0

Free Space Loss (dB) -200.0 -196.5Atmospheric Loss (dB) - 0.2 - 0.2Polarization Loss (dB) - 0.8 - 3.0S/C Antenna Point Loss (dB) - 0.5 - 0.5Ground Antenna Point Loss (dB) - 0.2 - 1.0

Net Propagation Loss (dB) -201.7 -201.2S/C Modulation Loss (dB) _ - 3.0

Received Carrier Power (dBW) -115.6 -153.2

Receive Effective Noise Temperature (°K) 1183 300Receive Antenna Noise Temperature (oK) (290) (100)Noise Power Density (dBW/Hz) -197.9 -203.8

Carrier/Noise Power Density C/No (dB-Hz) 82.3 ** 50.6 Peak)

*Assumes 300 watts, minimum, total power; however, GE's TRANSATEL Terminal provides anominal power of 2.5 kW.

" *Reduces to 47.6 dB-Hz at the 3dB-down point on the ATS-3 antenna pattern. For a modulationphase deviation of 1 radian rms, each of 3 range tone sidebands are down 5.3 dB below totalsignal power, resulting in C/N

O= 42.3 dB-Hz (42 dB-Hz threshold, see Table 1-3).

27

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APPENDIX 2

ROSMAN AND VANGUARD EQUIPMENT CONFIGURATIONS,

VANGUARD/PLACE SEA TESTS;

ROSMAN, VANGUARD AND MOJAVE CONFIGURATIONS,

ATS-5 TRILATERATION TESTS

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VANGUARD/PLACE, ATS-3/-5, SATELLITE-SUPPORT

TIME, SEA TESTS; ATS-5 SUPPORT TIME,

TRILATERATION TESTS

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40

APPENDIX 4

VANGUARD AND ROSMAN-STATION INSTRUMENTATION,

VANGUARD/PLACE EXPERIMENT, SEA TESTS

41

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Table 4-1Vanguard/PLACE Experiment, Sea Test, Vanguard

FR-600 Recorder-Channel Allocation

FR-600 Record IRIG IRIG FrequencyMeasured Parameter

Track # Module Subcarrier # Response (Hz)

1 FM 1200-bps clock

2 Direct 10-kHz StandardReference Frequency(±2 volts, peak)

3 FM 1200-bps Raw Datafrom Modem

4 1 6 Ship's pitch signal(±9.6 volts)

multi- 3 11 Ship's Roll signal~~~~~~~plexed ~(±9.6 volts)

on 5 20 UnassignedDirectChanecl 7 35 UnassignedChannel

8 45 ATS-3 Coherent -AGC (0 to +3.5 volts)

13 220 C/No Voltage, ATS-5AGC (0 to -1.0 vdc)

5 Direct Raw Bit-Error pulsesfrom Frederick 600(0 to -12 vdc)

6 Direct GMT Time NASA Code36-Bit, BCD, 1/sec.,1 KHz carrier(0 to 2.5 vdc)

Edge of Voice AnnotationTrack

Tape Speed: 3-3/4 inches/sec. (3 hrs./reel)Type Tape: 1-mil tape, 10-in. reel.

44

Table 4-2Vanguard/PLACE Experiment, Sea Tests, Rosman

Station FR-600 Recorder-Channel Allocation

FR-600 Record IRIG IRIG Frequency Measured ParameterTrack # Module Subcarrier # Response (Hz)

1 FM 1200-bps clock

2 Direct 10-kHz standardreference frequency(±2 volts, peak)

3 FM 1200-bps Raw Datafrom Modem

4 Multi- 7 35 Unassigned

plexed 13 220 C/N Voltage ATS-5

onDiect AGC (0 to -1.0 vdc)DirectChannel

5 Direct Raw Bit-Error pulsesfrom Frederick 600(0 to -12 vdc)

6 Direct GMT Time Code, 36-bit, BCD, I/sec.,1 kHz carrier(0 to 2.5 vdc)

Edge of Voice AnnotationTrack

Tape Speed: 3-3/4 inches/sec. (3 hrs./reel)Type Tape: 1-mil tape, 10-in. reel

45

APPENDIX 5

VHF, BACKUP, RF-LINK BUDGET CALCULATION

PRECWDING PAGE BLANK NOT FLM)E

47

OPTIONAL FORM NO. 10MAY Im1 EDITIONGSA FPMR (41 CPR) 101-11.6

UNITED STATES GOVERNMENT

MemorandumTO : H. Pedolsky DATE: February 15, 1973

ATS Project, Code 460

FROM : Ro E. Taylor

Navigation & Data Collection Branch, Code 752

SUBJECT: VHF-Backup Link for VANGUARD/PLACE Experiment

It is requested that a VHF-backup link, from Rosman-to-ATS-3 and down tothe Vanguard, be made available for the VANGUARD/PLACE Experiment. Theprimary purpose of the VHF link is to provide a backup link as an option for theRosman C-band link to ATS-3, the second satellite. The VHF link should beavailable from March 5, 1973, until the Vanguard docks at Mar Del Plata,Argentina.

Discussions with E. Ferrick, Code 861.0, indicate that the SCAMP antenna (new9-element Yagi, 17 dB gain @ 149.220 MHz), and 2.5 kw VHF transmitter, canbe made available at Rosman for the subject tests. Also, discussions with theTelemetry Engineer on the Vanguard (Steve Liptak) indicate that a Quad-DipoleArray, VHF preamplifier, and TR 102 VHF Receiver are available on the Vanguardfor the subject tests. Code 750 will provide the necessary IF converter to trans-late the 30 MHz IF output, from the TR 102 Receiver, up to a 70 MHz IF requiredfor the VANGUARD/PLACE electronics.

Attached is an ATS-3 VHF Link calculation, for Rosman to the Vanguard path,for the subject test. The 135.600 MHz downlink (100 KHz bandwidth) is the weakerlink, but the carrier-to-noise power density value of 49.5 dB-Hz, out of the TR102 receiver, is sufficient for the PLACE ranging tones.

Unique problems for VHF operation, compared to C-band, include larger valuesof time delay in the satellite transponder, VHF transmitter and receiver; andincreased ranging bias and variance due to the ionosphere. However, the increasedtime delay is a matter of calibration whereas, the ranging bias due to the iono-sphere can be removed from the data. Paul Schmid, Jr., Code 591, estimatesthat the residual range bias, after correction, is to to 100 meters rms at 136 MHz.This value compares with that expected for C-band operation.

ATS-3 operation at VHF, when scheduled, will be required for GMT times pre-viously established for NASA/VANGUARD by ATSOCC.

Ralph E. TaylorNavigation & Data Collection Branch

Attachment

Buy U.S. Savings Bonds Regularly on the Payroll Savings Plan

48

Table 5-1ATS-3, VHF, RF-Link Calculation for VANGUARD/PLACE

Experiment (Rosman to Vanguard)

149.220-MHz 135.575-MHzUplink Downlink

Transmit Antenna Gain (dB) 17 0Transmit Network Loss (dB) - 1 - 1

Transmitter Power Out (dBW) 34 (2.5 kW) 14 (25 W)ERP (dBW) 50 13Receive Antenna Gain (dB) 0 8 (CP)Receive Network Loss (dB) - 2 - 0.5

Free Space Loss (dB) -167 -166Atmospheric Loss (dB) 0 0Polarization Loss (dB) - 3 - 3.0S/C Antenna Point Loss (dB) 0 0Ground Antenna Point Loss (dB) - 1 - 1

Net Propagation Loss (dB) -171 -170

Received Carrier Power (dBW) -123 -149.5

Receive Effective Noise Temperature (*K) 435 (4 dB) 290 (3 dB)Receive Antenna Noise Temperature (0 K) 700 600Noise Power Density (dBW/Hz) -198.0 -199.0

Carrier/Noise Power Density C/N o (dB-Hz) 75.0 49.5

49

APPENDIX 6

OPERATIONS-READINESS TESTS, VANGUARD/PLACE

EXPERIMENT

PECEDING PAGE BLANK NOT FUlMD

51

Table 6-1Satellite Modes and Station Configurations,

Vanguard/PLACE Sea Tests

A. SATELLITE MODES:MODE A (ATS-5):

* C-band omnidirectional antenna (orthogonal-linear polarization,transmit and receive)

* 2 TWT's

* #1 Transponder

* Frequency-Translation (F T) Mode

MODE B (ATS-3):

* C-band directive antenna (co-linear polarization, transmit andreceive)

* 2 TWT's

* #1 Transponder

e FT Mode

MODE C (ATS-3 Backup):

* VHF Mode (100 KHz BW)

* ERP 43 dBM (full power) @ 135.575-MHz carrier frequency

* 8-element omnidirectional antenna

B. STATION CONFIGURATIONS:CONFIGURATION 1 (Rosman 21-ft. Mobile Terminal):

* Up-link carrier frequency - 6220.075 MHz to ATS-5

· Transmitter power (total) - 2 kw

· Down-link carrier frequency - 4127.575 MHz

* Antenna-polarization: orthogonal-linear, transmit and receive

52

Table 6-1 (Continued)

CONFIGURATION 2 (Vanguard, 30-ft. SATCOM Terminal):

· Up-link carrier frequency - 6210.00 MHz to ATS-5

· Transmitter power - 3 kw (total)

· Down-link carrier frequency - 4127.575 MHz

CONFIGURATION 3 (Rosman - VHF Transmit):

· SCAMP antenna to ATS-3

· Transmitter power - 2.5 kw (total) @ 149.22 MHz

CONFIGURATION 4 (Vanguard - VHF Receive):

* Down-link carrier frequency - 135.575 MHz from ATS-3

* VHF, Quad-Dipole, Array receive antenna

CONFIGURATION 5 (Vanguard, Marad, 2.5 ft., C-band Terminal):

* Down-link 4110.00 MHz from ATS-3

· 2.5 ft. dish antenna pointing at ATS-3

* C-band preamp., Frequency down-converter, and receiver

· Antenna polarization-circular

CONFIGURATION 6 (Rosman, 15-ft., Dish-Transmit Terminal):

* Up-link carrier frequency - 6202.5 MHz to ATS-3

· Transmitter power - 2 kw (total)

* Down-link carrier frequency to Vanguard - 4110.0 MHz

· Antenna polarization - Linear (adjustable).

Note: All frequencies listed above, in Table 6-1, refer to the S and R Channel Center Frequency,f0 (see Figures 3 and 5).

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APPENDIX 7

SEA-TEST SCENARIO, VANGUARD/PLACE EQUIPMENT

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APPENDIX 8

VOICE TESTS, VANGUARD/PLACE EXPERIMENT

gpi1ING PAGE BLANK NOT FHlA

63

/

Table 8-1Schedule for Voice Tests, Vanguard Place Experiment

Date: 31 March 73..........

Zulu Time(Hrs.-Min.)

0400-04020402-04190419-04240424-05110511-05160516-05280528-0530

1.5 hrs.

Item

Set UpTest Tape #2Set UpTest Tape #3Set UpTest Tape #4No transmission

Date: 3 April 73 ...................................

Alternate

2.0 hrs.

Zulu Time(Hrs.- Min.)

0400-05040504-05090509-0556

Item

Telephone Net TestSet UpTest Tape #2

Zulu Time(Hrs.- Min.)

0400-04020402-04490449-04540454-05410541-0600

Item

Set UpTest Tape #1Set UpTest Tape #2

I Command and Execution

Date: 4 April 73 ...........

Zulu Time(Hrs.- Min.)

0400-04020402-04490449-04540454-05410541-0600

....................... . ..2.0 hrs.

Item

Set UpTest Tape #4Set UpTest Tape #5Command and Execution

64

Table 8-1. (continued)

Date: 10 April 73 .

Zulu Time(Hrs.- Min.)

0330-03320332-04190419-04240424-05110511-05160516-05280528-05330533-05450545-0600

Item

Set UpTest Tape #2Set UpTest Tape #3Set UpTest Tape #4Set UpTest Tape #5Command and Execution

Date: 11 April 73 .

Zulu Time(Hrs.-Min.)

0330-03320332-04190419-04240424-05110511-05160516-05280528-05330533-05450545-0600

Item

Set UpTest Tape #1Set UpTest Tape #2Set UpTest Tape #4Set UpTest Tape #5Command and Execution

Date: 12 April 73 ..................................

Alternate

Zulu Time(Hrs.- Min.)

0330-04340434-04390439-05260526-05310531-05430543-05480548-0600

Item

Telephone Net TestSet UpTest Tape #1Set UpTest Tape #4Set UpTest Tape #5

Zulu Time(Hrs.- Min.)

0330-03320332-04190419-04240424-05110511-05160516-05280528-05330533-05450545-0600

65

Item

Set UpTest Tape #3Set UpTest Tape #1Set UpTest Tape #4Set UpTest Tape #5Command and Execution

2.5 hrs.

2.5 hrs.

2.5 hrs.

Table 8-1 (continued)

Date: 13 April 73 .

Zulu Time(Hrs.-Min.)

0330-03320332-04190419-04240424-05110511-05160516-05280528-05330533-05450545-0600

........................ 2.5 hrs.

Item

Set UpTest Tape #2Set UpTest Tape #3Set UpTest Tape #4Set UpTest Tape #5Command and Execution

Date: 14 April 73 .......... .. ... ...... . 2.5 hrs.

Zulu Time(Hrs.-Min.)

2100-21022102-21492149-21542154-22412241-22462246-22582258-23032303-23152315-2330

Item

Set UpTest Tape #1Set UpTest Tape #2Set UpTest Tape #4Set UpTest Tape #5Command and Execution

Voice Testing (total) ................................. 18.0 hrs.

66

Table 8-2Definitions for Voice-Test Tapes

TAPE # 1: 47 MINS

A-5 50 WORDS OF MRT10 SCIM SIGNALS50 WORDS OF PB APOLLO # 22410 SCIMA-6 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 26410 SCIMF-3 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 21410 SCIMF-4 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 354

TAPE # 2: 47 MINS

E-1 50 WORDS OF MRT10 SCIM SIGNALS50 WORDS OF PB APOLLO # 24410 SCIME-2 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 25410 SCIMB-1 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 28410 SCIMB-2 50 Words of MRT10 SCIM50 WORDS OF PB APOLLO # 274

TAPE # 3: 47 MINS

C-3 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 31410 SCIMC-4 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 32310 SCIMD-5 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 28310 SCIMD-6 50 WORDS OF MRT10 SCIM50 WORDS OF PB APOLLO # 21310 SCIM

TAPE # 4:

12 MINUTES OF MARITIME MSGS

TAPE # 5:

12 MINUTES OF A.T.C. MSGS

Legend: MRT - Modified Rhyme TestPB - Phonetically BalancedSCIM - Speech Communications Index MeterA.T.C. - Air Traffic Control

67

Table 8-3Telephone Network Free-Conversation Test Form

EXPERIMENT

NAME

ADDRESS

NASA/VANGUARD

TE LE PHONE #

TELEPHONE COMPANY

DATE OF TEST

TIME OF TEST

1. CONVERSATION INTELLIGIBILITY (Please check one of the following)

Understood Complete Conversation

Understood Complete Conversation With Moderate Difficulty

Understood Complete Conversation With Appreciable Difficulty

Understood Most Of The Conversation With Appreciable Difficulty

Understood Little Or None Of The Conversation

2. TRANSMISSION LINE QUALITY (Please check one of the following)

Background Completely Free Of Noise

Background Slightly Noisy

Background Very Noisy, But Understood Conversation Completely

Background Very Noisy. Do Not Understand ConversationCompletely Because of Noise Masking

Background Noise Extremely High. Understand Little Or None OfThe Conversation Because Of Noise Masking.

68

Table 8-3 (Continued)

3. VOICE QUALITY STATISTICS (Check appropriate box)

Recognized Person Speaking Yes No

Voice Distorted Yes No

Voice Appeared To Fade Yes No

4. BACKGROUND NOISE STATISTICS (Check appropriate box)

Noise level heard should be compared to the loudness of the voice heard.

Noise Type

Static NONE LOWER _ SAME HIGHER

Hum _ NONE _LOWER _ SAME _ HIGHER

Ringing _ NONE _ LOWER - SAME HIGHER

Putt Putt NONE LOWER SAME HIGHER

Typewriter NONE _ LOWER SAME HIGHER

Somebody Talking NONE LOWER _ SAME HIGHER

Other

5. GENERAL STATEMENT (Check only one)

Based on my previous experience with long distance calls I would say thatthe overall service provided was:

Excellent

Acceptable

Not Acceptable

6. COMMENTS

Please state any comments that you may have with respect to this experiment.

69

APPENDIX 9

SATELLITE TRILATERATION THEORY AND COMPUTATIONS

py;.i)]lGW PAGE BIut N0J l[l

71

ATS-5SATELLITE - --

POSITION - '

r/ r 2 r 3

1r1 s,. r3MOJAVE, VANGUARD

CALIFORNI 2 MAR DEL PLATA,ARGENTINA

ROSMAN,NORTH CAROLINA

Figure 9-1. ATS-5 Satellite-Trilateration Tests

SATELLITE TRILATERATION EQUATIONS

The state variable in the satellite-trilateration equations will be a six-dimensional vector:

xT = (L A r/ro L A r/r0),

where

L = satellite longitude, positive west,

X = satellite latitude, positive north,

r = satellite distance from earth's center,

r = nominal value of r,o

72

with distances in earth radii, angles in radians, and time in polling intervals(approximately minutes). The symbol ^ over a letter will indicate its estimatedvalue; thus,

xk/l = estimate of x at time k, using information up to time 1.

The following equations will be instrumented:

Rk/k-l =- Zk-l/k-1 '

where

3 I3/

I3/

13 = 3 x 3 identity matrix,

03 = 3 x 3 zero matrix;

X/ 0 = (Lo 1 00 0),

L o being the nominal satellite longitude (e.g., 1050 W.);

Xk/k = Xk/kI + Kk (rik - rik/k-l ) '

where

rik = measured range from ground station i at time k (i = 1, 2, 3),

rik/k- - -2 k/k- rgi [sin Ag i sin Xk/k_1 +

cos Agi cos Ak/k-l COS (Lgi -Lk/kl)] + r 2 . }i)/2

rk/k-1 = ro (P/rO)k/k- 1 '

73

kgi = geocentric latitude of ground station i,

Lg. = longitude of ground station i,gl

rgi = distance of ground station i from earth's center, and the groundstations are numbered

1 - Mojave, California

2 - Rosman, North Carolina

3 - Mar del Plata, Argentina.

The gain matrix at the first polling time, K1 , is computed as follows:

1. Compute nominal ranges from the ground stations to the satellite:

rio = [r 2 - 2 ro rgi

cos Xgi cos (Lgi - Lo) + r 2 i] /2;0 gi gi gi gi

2. Compute a 3 x 3 matrix H, whose elements are

hil = - (ro rgi/ri0) cos Xgi sin (Lgi - L0 )

hi 2 = -(ro rgi/ri0) sin Xgi

hi3 = (r 0 /riO) [r 0 - rg i cos Xgi cos (Lgi - Lo0 )];

3. Find the inverse of H;

4.

(K°< )

74

The gain matrix at each subsequent polling time,only of the estimated satellite longitude:

Kk for k > 2. is a function

-1.

.15

-.12Kk = *33

0.

-. 03

.9

-. 7

+ .002 Lo

+ .0007 Lo

.2 - .002 Lo

.26

-. 24

.073 - .00057 Lo

where in this expression only L0 is in degrees.U

75

.1\

.5

.07

.07

.24

.04

Table 9-1Satellite Trilateration-Error Computation for ATS-5 at 1050 West Longitude

Magnitude of Semi-Axesof Error Ellipsoid

(km)

1.8490.5630.058

Velocity Error(km/min.)

0.5960.5960.596

1.3580.5330.059

0.7820.6540.547

1.2760.5440.059

0.8410.6400.539

1.3120.5450.059

0.8340.6270.538

Direction Cosines of Each AxisReferenced to East/North/Vertical

Coordinates *

0.900 -0.434 -0.0490.435 0.901 0.0120.039 -0.032 0.999

Kalman-Filter Gain**

1.000 0.0 0.00.0 1.000 0.00.0 0.0 1.000

0.895 -0.444 -0.0480.445 0.895 0.0120.038 -0.032 0.999

0.890 -0.453 -0.0480.454 0.891 0.0140.037 -0.034 0.999

0.889 -0.456 -0.0480.457 0.890 0.0080.039 -0.030 0.999

0.896 -0.441 -0.0480.441 0.897 0.0050.041 -0.026 0.999

0.890 -0.453 -0.0480.454 0.891 0.0080.039 -0.029 0.999

0.897 -0.439 -0.0490.440 0.898 0.0110.039 -0.032 0.999

76

t= 1 Min.:

t= 2 Min.:

t= 3 Min.:

t = 4 MiV.:

**

**

**

**

Table 9-1. (continued)

Magnitude of Semi-Axesof Error Ellipsoid

(km)

1.3420.5430.059

Velocity/Error(km/min.)

0.8070.6220.538

1.3500.5430.059

0.7830.6210.538

1.3460.5420.059

0.7680.6200.538

1.3400.5420.059

0.7610.6200.538

Direction Cosines of Each AxisReferenced to East/North/Vertical

Coordinates *

0.892 -0.449 -0.0480.449 0.893 0.0090.039 -0.029 0.999

Kalman-Filter Gain**

0.894 -0.444 -0.0500.446 0.895 0.0150.038 -0.035 0.999

0.893 -0.447 -0.0480.448 0.894 0.0090.039 -0.030 0.999

0.891 -0.452 -0.0500.453 0.891 0.0150.038 -0.036 0.999

0.893 -0.448 -0.0480.448 0.894 0.0090.039 -0.030 0.999

0.888 -0.457 -0.0500.458 0.889 0.0150.038 -0.036 0.999

0.893 -0.448 -0.0480.449 0.893 0.0090.039 -0.030 0.999

0.887 -0.459 -0.0500.460 0.888 0.0150.038 -0.036 0.999

77

t= 5 Min.:

t= 6 Min.:

t = 7 Min.:

t= 8 Min.:

**

**

*

**

**

**

Table 9-1. (continued)

Magnitude of Semi-Axesof Error Ellipsoid

(km)

Direction Cosines of Each AxisReferenced to East/North/Vertical

Coordinates *

t= 9 Min.:

t = 10 Min.:

Velocity Error(km/min.)

0.7590.6200.538

1.3330.5420.059

0.7580.6200.538

0.892 -0.449 -0.0480.450 0.893 0.0090.039 -0.030 0.999

Kalman-Filter Gain**

0.887 -0.459 -0.0500.460 0.888 0.0150.038 -0.036 0.999

0.892 -0.449 -0.0480.450 0.893 0.0090.039 -0.030 0.999

0.887 -0.458 -0.0500.460 0.888 0.0150.038 -0.036 0.999

Assumptions:

(1) Trilateration stations @Rosman, Mojave and Mar Del Plata (Position surveyed to an ac-curacy of 10 m).

(2) Ranging-Measurement Error is 10 0-m, rms.(3) Random Satellite Motion: 42 0-m initial position error, each direction, and 25km/hr. velocity

error; disturbances of 420 m and 25 km/hr. (all rms values) between ranging measurementsmade @ 1-minute intervals (i.e., t = 1, 2, 3, 4 min., etc.).

78

NASA-GSFC

1.3350.5420.059

**

**