astsyshansatlauvehsec7and8_073007090052

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Astrionics Systemi

S e c t i on

CHAPTER 7TRACKING SYSTEMS

TABLE OF CONTENTS

PageSATURN TRACKING INSTRUMENTATION . . . . . . . . . . . . .. . 7 . 1 - 1C-BAND RADAR . . . . . . . . . . . . . . . . . . . . . . . . .. . . 7 .2 -17 . 3 . 1 A z u s a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 . 3 - 17 . 3 . 2 G l o t r a c . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 7 . 3 - 5O D O P T R A CK I NG S Y S T E M . . . . . . . . . . . . . . . . . . . . . . . . . 7 . 4 - 1S-BAND TRACKING (To b e s u p p l i e d at a l a t e r d a t e ). . . . . . . . . 7 . 5 - 1


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Astrionics SystemSection 7. 1

SECTION 7.1

SATURN TRACKING INSTRUMENTATION

The purpose of r adi o track ing is the deter-mination of the vehi cle's traje cto ry. Tracking dat ais used for mission control, range safety, and post-flight evaluation of veh icle performance.

The Saturn vehicles car ry seve ral trackingtrans pond ers as listed in Table 7.1-1. A combina-tion of tracking dat a fro m different tracking syst emsprovides the best possible trajectory information andinc rea sed reliability through redundant data. Thetracki ng of th e Saturn Launch Vehicle may be dividedinto 4 phas es: (1) powered flight into earth orb it, (2)orbita l flight, (3) injection into translunar trajectory,and (4) coast flight after injection.

Continuous tracking is required during poweredflight into eart h orbit. Because of the long burningtim e (700 seconds) of th e 3-stag e Saturn V LaunchVehicle, the end of the powered flight phase cannotbe co vered sufficiently fro m land-based trackingstations. Therefore, a tracking ship will be locatedin the Atlantic to obtain the v ery important trackingdata during insertion which is required for orbit de-termination. Figure 7.1-1 shows tracking stationsused during the powered flight into ear th orbit. Thenumber of statio ns which can "see" the vehicle de-pends on the launch azimuth. Station visib ilitie s ar eindicated in Figure 7.1-2 fo r launch azimuths of 72. 5deg ree s and 105 degrees. Accuracy of position andvelocity measurem ents obtained from combinedtrack ing information ar e shown in Figure 7.1-3. BothFigu res 7.1-2 and 7.1-3, a re based on a typicalSaturn V powered flight trajectory.

In addition, the Saturn Launch Vehicle will betracked from S-band stations at Cape Kennedy and onthe Atlantic tracking ship. These s tations have dualtracking capability; i. e. , hey can simultaneouslytra ck t he two S-band transponders on the vehicle (onein the IU and the othe r in the Apollo Spacecraft). The

S-band station on Bermuda has only a single capabilityand will tra ck th e Apollo Spacecraft transponde r.

During orbital flight, tracking is accomplishedby S-band st ations of t he Manned Space Flight Networkand by C-band radar stations listed in Table 7.1-2.The S-band stat ions , including the Deep Space Instru-mentation Facility, can track th e Apollo Spacecraftto the moon and will also be involved in tracking afterinjection. Tracking information collected during orbi-ta l flight may be used to update the Saturn guidancesyste m before injection.

In addition to land-based stations, five track-ing ships, equipped with C-band ra da r, and S-bandstatio ns, will be available. One of these ships willbe used fo r ins ertion tracking in the Atlantic.

Tracking requirements fo r the launch vehicleduring second burn of the S-IVB Stage and during theflight period following injection have not been com-pletely defined. Stations list ed in Tab le 7.1-2 willparti cipat e in thi s operation. The DSIF and MSFNstations have essentially the sa me capabilities. AllS-band tracking stations will be equipped for recep-tion of PCM te leme try at VHF and UHF.

Table 7.1-1 Saturn Tracking InstrumentationI

Tracking SystemS-bandC4an d radar (2)AZUSA/GLOTRACODOP

Transpond er LocationSaturn I B

-

IUIU

S-IB Stage

Saturn VIUIUIU

S-IC Stage


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7. 1

Figure 7 . 1 - 1 Launch Phase Tracking Stations7.1-2

Number Loca tion Tracking System1. Cape Kennedy, C-Band Radar

Florida ODOPAZUSA/GLOTRAC

2. Patrick , C-Band RadarFlorida

3. Val karia, (N ot used presentlyFlorida for Saturn tracking )

4. Cherry Point, GLOTRAC ReceiverNorth Carolina

5. Wallops Island , C-Band RadarVirginia

6. Gra nd Bahama C-Band RadarIsland AZUSA

Numbe r Loca tion Tracking System7. Eleuthera Island GLOTRACK Receiver

8. Bermuda Island C-Band RadarGLOTRAC Transmitter& Receiver

9. Grand Turk C-Band RadarIsland GLOTRAC Receiver

10. Anti gua C-Band RadarGLOTRAC Transmitter& Receiver

11. Atl an tic Ship C-Band Radar(Position dependson launch azimuth)

IBM B73


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70(deg) Elevation

60S-I VB CutoFF

I

50

40a-mac0 304-0>-W

20A Z I M U T H O F 72.5 DEGREES

10

0 0Flight Time (sec)

60(deg) Elevation

50

400-m Grand Bahama4r 30-0>-W

20

A Z I M U T H O F 105 DEGREES10

0 0 200 400 600 800Flight Time (sec)

I B M B7

Figure 7. 1 -2 Station Visibility for Saturn V Powere d Flight7 . 1 -


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7. 1

Table 7.1-2 Orbita l Tracki ng Stations

( To be supplied at a la ter date )

Name and Location

CapeKennedy, FloridaBermudaAntigua IslandCanary IslandAscension IslandCanarvon, AustraliaHawaii, USAGuaymas, MexicoWallops Island, USAGuamTex as Station, USACanberra, Australia

Goldstone, USAMadrid, SpainGoldstone, USAMadrid, SpainCanberra, AustraliaPoin t Aguello, USAWhite Sands, USA1 Ship (Atlantic )4 Ships

9 .2 m=30f t

Figure 7. 1-3 Accura cy of Posi tio n and VelocityMeasurements

C-BandRadar

XXXXXXX

XXXX

S- BandSingleDual

DSSSDDDSDDSD

DDDDD

DS

Ant.Dia

"

""

"I'

"

""

"

26 m

""

"""

2 6 m=8 5 f t

Tracking

9.2mMSFN11

I.I 1

I 1

I f

I

I t

I t

11

TI

DSIF/J P L

11

11

MSFNI

It


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7/34

Astrionics SystemSection 7.2

Semiconductors a re used in all c ircuitry, with Table 7.2-2 Radar Ground Station Chara cter istic sthe exception of th e local osc ill ato r and magnetron.The charact eris tics of the transponder a re given inTable 7.2-1.

The r ada r ground stations determine the posi-tion of th e vehic le C-band tran sponder by measurin grange , azimuth angle , and elevation angle. Range isderived fr om pulse trav el time, and angle tracking isaccom plish ed by amplitude-compar ison monopulsetechniques. As many as four rada r stations maytr ac k the beacon simultaneously. Some data aboutthe AN/F'pS-16 and AN/FPQ-6 rada r is listed inTable 7.2-2.

AN/FPS-16 AN/FPQ-6Frequency band (MHz) . . 5400-5900 5400-5900Pea k power (mw) . . . . . . 1.3 3.0Antenna size (meters). . . . 3.9 9.2Antenna gain (db) . . . . . . 47 52Receiver noise figure (db) . 6. 5 8Angleprecision(units) . . . 0.15 0.1Range precision (m eters). . 4.5 3.0

Table 7.2-1 C-Band Radar Tran sponder, Model SST-135CReceiver Characteristics

Frequency (tunable extern ally) 5400 to 5900 MHz (set to 5690 *2 MHz)Frequency stability i2 .O MHzBandwidth ( 3 db) 10 MHzOff -freq uency rejection 50 db image; 80 db minimum, 0.15 to 10,000 MHzSensi tivity (99% reply) -65 dbm over entir e frequency range and all

environmentsMaximum input sig nal +20 dbmInterrogation code Single o r double pul sePuls e width 0.2 to 5.0 us (single pulse), 0.2 t o 1.0 us

(double pulse)Pulse spacing Continuously se ttable between 5 and 12 us (s et to 8

&O. 05 us )Decoder limits i0. 25 us accept, *0.85 us reje ct (5 to 12 us )

Transmitter Characteristics IFrequency (tunable externally)Pea k power outputPuls e widthPulse jitterPulse ri se time (10% to 90%)Duty cycleVSWR of loadPulse repetition rate

5400 to 5900 MHz (set to 5765 *2 MHz)400 watt s minimum, 700 watt s nominal1.0 * 0 .1 us0.020 u s maximum fo r signals above -55 dbm0.1 us maximum0.002 maximum1. 5 :1 maximum10 to 2000 pps; overinterrogation protectionallows interrogation a t much higher r at es withcount-down; re pl ie s during overinterrogationmeet all requirements

Transponder CharacteristicsRecovery time 50us single pulse, 62 us double pulse maximum

for input signal levels differing by up to 65 db(re cove rs to full sensitivity with no change intransmitter reply power or frequency with multipleradars interrogating simultaneously)

Fixed delay Settable 2 * 0.1 and 3.0 to 0.01 us (set to3.0 * 0.01 us )

Delay variati on with signal level 50 nanoseconds maximum from -65 dbm to 0 dbmPower requirements 24 to 30 voltsPrimar y current drain 0.7 amp ere standby; 0.9 amp ere at 1000 ppsWeight 2. 5 kg (5.5 lbs)


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Astrionics System, Section 7.

SECTION 7.3AZUSA/GLOTRAC

7.3.1 AZUSAAZUSA i s an inter fero mete r tracking sys tem

which det erm ine s the position of a vehic le-b ornetransponder. Two AZUSA station s a r e in operation,one s tat ion (MK 11) at Cape Kennedy and the oth erstation (MK I) at Grand Bahama Island. The AZUSAsyste m provides real- time tracking data used forrange safety impact prediction and post flight trajec-tory analysis. AZUSA stations cover only a portionof the Saturn V powered flight trajectory.

The position of the vehicle ( tran sponde r) isdeter mined a t the AZUSA ground stations by me asur -ing range (R) and two direction cosines (1, m) withres pec t to the antenna baselines. The antenna lay-out of the AZUSA MK II station, shown in Figure7. 3-1, consi sts of two cro sse d baselines (at rightangle) with three antenna pairs each. The transmit-ter antenna (T) radiates a CW signal at 5 GHz to thevehicle. This signal i s offset by 60 MHz in the tra ns -ponder and retransmitted to the ground station receiv-ing antennas. The direction cosine, with resp ect toa baseline, is obtained fr om the measu rement of thephase difference between signals received at spacedantenna pa ir s along thi s baseline. The range to thetransponder is found by measuring the phase differ-ence between trans mitte d and received signal. Forrange ambiguity resolution, the transmitted carrieris modulated with se ve ra l low frequencies.

X

Y

LxI : osa s -- Rrn = cosp = I 5R

T: Transmitter AntennaDF: Dire cti on Finder Antenna (Receiving)XF, XR, YF, YR: Rec eiv ing AntennasL: Distance between antennas

IBM B n

Direction cosine me asurement is accomplishedby using the antennas in pa ir s to provide baselines of5 met ers , 50 meters, and 500 met ers a s indicated inthe table of F igu re 7. 3-1. A conical scan antenna(DF) yields unambiguous direction measurement andfurnis hes ambiguity resolution for the 5-meter base-lines. The 5-meter ba selines resolve ambiguity forthe more accur ate 50-mete r baselines , and the 500-me te r base lines supply information fo r computingcosine rat e data. The direction finder antenna DF(conical scan antenna) provides pointing informationfor all other antennas.

Measurements

Intermediate cos aFine cos aRate cosaIntermediate cospFine cospRate cos p

Antennas

DF - X1XF l - XF2XFI - XRDF - Y1YF2 - YF lYF2 - YR

Figure 7.3-1 AZUSA (MK 11) Ground Station Layou

BaselineLengthLx r Ly

5 rn50 rn

500 rn5 rn

50 rn500 rn


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The signa ls recei ved at the two spaced anten-f an antenna pai r have a phase difference caus edof the antennas. Thi s phase differen ce is mea-

They of the m easurem ent incr ease s with increa s-

g baseline length, but data becomes ambiguous andmeasurements a re nec essary for ambiguity

Range is determine d at the ground station bycomparing the instantaneous phas e of the tra nsmi ttedmodulation signal to that of th e rece ived modulationsignal. The resulting phase difference is directlyroportional to the propagation time f rom the ground

station to the trans ponder and back to the groundstation. In other words, phase difference is propor-tional to range. Using a high range modulation fre-quency to obtain fine resolution, res ult s in output datathat a r e ambiguous, the number of ambiguities is pro-portional to the modulation frequency.

The ambiguities in range measurement ar eresolved by using three modulation frequencies thata r e obtained by the frequen cy division of a single,prec ise, frequency sourc e at the ground station. Thephase shift is mea sure d for each one of the se harmon-ically related frequencies. The lower frequency phasedata is used t o resolve the ambiguities in the nexthigher frequency phase data. This arrangement has,a s advantages, the resolving power of the highest fr e-quency signal and the extended unambiguous rangedata provided by the lower dat a frequency. The modu-lation signal s used for range measurement ar e 157.4Hz, 3.934 kHz, and 98.356 kHz. The fin e rangemodulation signal, 98.356 kHz, rem ain s ON at alltim es s o the transponder can "lock-on1' with theground station. Higher resolution range data is ob-tained by coherent ca rr ie r phase comparison.

The coherent transponder includes a phase-control loop in which the 98.356 kHz fine range modu-lation frequency is multiplied by a fa ctor of 612 toestablish the transponder offset frequency (60.194MHz) and a frequency and phase-co herent resp onsesignal (5000 MHz).

At the ground station, the 98.356 kHz frequencyi s al so multiplied by 612 to equal the transponder off-se t frequency (60.194 MHz). Both, the 5000 MHz sig -nal recei ved from the transponder and the data signal,a re heterodyned with a local oscillator signal to ob-tain approxima tely 5 MHz. Data and refe renc e sig-nals a r e then fed into a discrimina tor which providesone pulse (count) output for each 360-degree phase

differenc e (1 cycle) in the input circuit. Plu s andminus pulses a r e fed on sepa rate lines to a bidirec-tional counter. The coherent car ri er range data isthen fed to an IBM 7090 Computer with the directio ncosine dat a (1, m) and modulation-derived slan t rangedata. The computer, using 20 input sam ple s pe r sec -ond, sol ves the equat ions for the position of th e vehicle.AUTOMATIC FREQUENCY CONTROL LOOP

The AZUSA Type-C Transponder used in theSaturn Vehicles is a par t of the overa ll AFC loop inthe AZUSA sys tem (Fi gur e 7.3-2). Upon transpo nderactivation, t he klystron tran smi ts a 5060.194 MHzsign al which is swept *2 MHz by a 1 5 Hz int erna lsweep generato r. This enables the ground stationand the trans ponder to find a common frequenc y s othat lock-on can occu r. When freq uency lock-onoccu rs, the 5060.194 MHz signa l tran smit ted by theground st ation will be shifted slightly by AFC actionso that, afte r the transponder receive s the signal andretransmits it, the frequency received by the groundstation re ce ive rs will be 5000 MHz. The 5060.194MHz (plus Doppler) signal entering the t ransponderreceiver is mixed with a fra ctio n of the re tra nsm itt edsign al to prod uce a 60.194 MHz offset frequency. Afrequency discriminat or i s used to maintain the offsetfrequency within 30 Hz.

Pha se lock between the transponder and groundstation is establis hed by multiplying the fine r angemodulation fre quency (98.356 kHz) recei ved f ro m theground station and using it as a reference for a phasediscrimi nator. This phase discrimina tor has higheroutput gain than the freque ncy loop disc rimi nato r andholds the transponde r offset frequency (60.194 MHz)cor rec t to within a fra ctio n of a cycle. The Type-CTransponder us es this combination frequency-phasediscrimina tor t o obtain maximum stabil ity in bothAFC and APC loops. Thi s coherent condition in thetransponder enables phase me asureme nts to be madeat the ground station between the received 5000 MHzsignal and the 5060.194 MHz transmitted signal(heterody ned to 5000 MHz) to obtain high -res olut ionincremental range data. Similarly, phase comparisonof the tra nsm itt ed and receiv ed 98.356 kHz modula-tion signals produces non-ambiguous ra nge data.

Before lock-on, the transm itte r loc al AFCloop and the local ov er-a ll AFC loop ar e used to keepthe ground station transmitter frequency at 5060.194MHz. When the ground station and the transp ondera r e frequency locked, a 5 MHz signal fro m the groundstation range receiver IF amplifier controls the over-al l AFC loop. This high-gain loop ov er ri de s both thelocal over-al l AFC loop and the tra nsm itt er AFC loop


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Transponder7

. ....... . x12 t-

. ........: :. ..

Local Overall AFC Loop

From Receiver System':Oscillatort--................... ... . "... ...........................................Motor ..A * .Overall AFC Loop Azusa Mark I 1 Ground Station

IBM ~

Transml tter LocalAFC Loop

Figure 7. 3-2 AFC Loops, Ground Station and Tran sponder7.3-


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Astrionics SystemSection 7. 3(Fi gure 7.3-2). Should the re tur n signal received fr omthe tra nsponde r devia te from 5000 MHz a t the groundstation receiver, the ground station recei ver will de-tect the e rr or and cause the ground station transmit-te r frequency to shift slightly in a direction to corre ctthe er r or (through AFC action). The transponder re -ceiver detects the frequency or phase change and cor-re ct s the return frequency s o that the offset frequencyremains exactly 60.194 MHz (through the transponderAFC and APC loops). Thus, t he vehicle-to-groundlink maintains a constant f requency (5000 MHz) a t theground station r ece iver s despite systematic frequencydrift and Doppler shift.

TRANSPONDERIn the trans ponder (Figure 7.3-3), the

5060.194 MHz inte rrogat ion s ignal and the 5000MHz klystr on local o scill ator signal produce a 60.194MHz IF, o r offset frequency, in the cryst al mixer.This signal is mixed with a 55.2 MHz second localoscillator signal. The sec ond IF (4.994 MHz) is am -plified and fed to the re ceive r frequency discriminatorwhere the range signal s which modulate the groundstation ca rr ie r ar e detected. This range modulation(98.356 kHz) is fed to the compensation network. The4.994 MHz IF sig nal is als o fed to the phase networkand to one s ide of the frequency-phase discriminator.

A 4.994 MHz re feren ce signal for phase lockis provided as follows: The 98.356 kHz range signa lis direc ted through the compensation network, anamplifier, and two cryst al fil ter s, to a frequencymultiplier circuit. Here the signal is multiplied to60.194 MHz. (One cr ys ta l fi lt er is in the compensa-tion network subassembly and one is in the sweep os-cillator subassembly. ) The 60.194 MHz signalent ers the phase network and is mixed with 55.2 MHzfrom the receiver second local oscillator to obtainthe 4.994 MHz refe rence fo r the phase discrimina tor.

In the compensation network, the phase andfrequency discriminator e rr or voltage from the phasenetwork ove rri des the output from the sweep oscillator.It is then combined with the 98.356 kHz range modula-tion and fed to the modulator. In the modulator thesesignals a r e superimposed on the klystron anode volt-age. The dc er r or signal maintains phase lock be-tween the 5060..194 MHz received signal and the 5000MHz re spon se signal. The 98.356 kHz is used tomodulate the response signal. The 98.356 kHz phaseshift in the transponder is held to an absolute minimumso that phase compar ison of the receive d signal andtrans mitte d signal a t the ground station will indicateactual range t o the transponder.

The waveguide subassembly is designed withtwo bandpass fi lt er s internally connected to a symmet-

r

5060.194MHz+ Duplexer 60.194 ~ e c e i v k 4.994 MHz

r L zo Antenna + 000 MHz Assembly I . -100 H Z to I 55.2 MHz5000 MHz 100 kHz

Phase Error PhaseOscil lator Network

Modulation 60.194 MHz28Vdc Power Frequency

Regulator MultiplierControl

28Vdc Power

6.3 + 15-905Vac Vdc Vdc

To Al l Act ive AssembliesIBM B7 9

Fig ure 7. 3-3 AZUSA Transponder Block Diagram7.3-4


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Astrionics System, Section 7.

r ical Y section. This arra ngement permits the us e ofa single rece iving- transmitti ng antenna. The klystronoutput is ca rr ie d to the 5000 MHz filt er by coaxialcable. The signal pa ss es through a 3-section filter,the symmetrical Y, and a waveguide-to-coaxial tr an -sition and is ca rr ie d to the antenna by coaxial cable.A 5060.194 MHz signal entering the antenna pa ss esthrough the sa me coaxial cable into the waveguide. A2-sec tion fi lt er pass es the incoming 5060.194 MHzsignal and a sma ll amount of the 5000 MHz signalpresent in the symmetrical Y to a crystal mixer whichproduces a 60.194 MHz offset frequency.

The Type-C Transponder us es tran sis tor s inal l circ uitry except for the klystron. The Type-CTransponder operat es a lso with GLOTRAC stat ionsdescr ibed briefly in the following paragraphs. Table7.3-1 li st s the cha rac ter ist ics of the AZUSA system.7.3.2 GLOTRAC

GLOTRAC (GLObal TRACking) was originallyplanned as a global tracking s ystem , but changes inpr ogr am s rest ric ted th e number of ground stations.GLOTRAC us es the AZUSA Type-C Transponder inth e vehicle. GLOTRAC ground stat ions a re equippedwith either a transmitter or a receiver o r both asindica ted in Figu re 7.1-1. Both existing AZUSA sta-tio ns may be considere d as pa rt of GLOTRAC. Thetransponder in the vehicle is interrogated by anAZUSA ground stat ion or by a GLOTRAC tran sm it te rsite. The transponder offsets the received frequencyand re tra nsmi ts the signal to GLOTRAC receivingsi te s where the Doppler shift is measured by compar-ing the received signal with the transmitter signal(i f receiver is located near the transmit ter) or witha local frequency source . The meas ured Dopplershift provides the range sum sim ilar to ODOP (refe rto Section 7.4). At GLOTRAC sta tions equipped withboth a transmitte r and receive r, the range to thetransponder is meas ured by phase comparison betweenthe trans mitte d and recei ved signals. The AZUSAType-C Transponder can also be interrogated byC-band r ad ar s for r ange and angle determination.

The range rat es measured at thre e receivingstations yield the vehicle velocity, and by integratinthis velocity, the position is obtained. Initial condi-tions for integration a r e obtained from ra dar rangemeasurements. Data measured at all stations istransmitted to the computer at Cape Kennedy. Accura cy of GLOTRAC measu rem ent s i s 30 met er s (98.4feet) in position and 0.15 meters/ secon d (0.49 fee t/second) velocity.

Table 7.3- 1 AZUSA CharacteristicsTransponder Type- C

Receiver frequency.. .. 5060.194 MHzTransmitt er frequency. 5000.000 MHzR F power output ...... 2. 5 wattsInput voltage ......... 28 Vdc.........nput cur ren t -5 amp ere sReceiver input sig nal .. -12 to -90 dbmWeight.. ............. 8.74 kg (19.3 lbs)Size ................. 0.006 meters3(372 inches3)

AZUSA Ground Station Mark I1Transmitted power.. .. 2 kwTran sm it te r frequency. 5060.2 MHz *0.75 MHzRanging modulation. ... 157.4 Hz, 3.934 kHz,

98.351 kHzReceiver frequency.. .. 5000 MHzReceiver sensitivity.. , -145 to -147 dbmRece iver antenna gain 33 db (MK n)Accuracies:

Range.. ........... 3.05 meters.............ngle 1 x l o -5 in cosine data


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i

SECTION 7.4

The ODOP (Offset-OPpler) tracking systemi s essen tial ly the &me a s the UDOP sys tem used formany years at the Atlantic Missile Range, but ODOPoperate s at different frequencies. It is a phase-coherent, multistation Doppler tracking syst em whichme asur es posit ion of a veh icle equipped with the ODOPtransponder. ODOP stations ar e located at and aroundCape Kennedy. The ODOP transponder is carr ied inthe first stage (S-IB o r S-IC) of the Saturn Vehiclesand, th erefore, ODOP tracking data is limited to theflight of the fi rs t stage only. The ODOP trackingsys tem provides data immediately following lift-offwhile other tracking sys tem s cannot "see" th e vehicleor their accuracy is reduced by multipath propagationduring the ear ly phase of the flight.

The basic op eration of th e ODOP sys tem isillustrated in Figure 7.4- 1. The ground transmitt erradia tes a CW signal of 890 MHz to the transponder inthe vehicle. The transpo nder shifts the received signain frequency by 70 MHz and ret ransm its it to thereceiving stations (R l, R2, R3). The signal fro m thetransponder received at the ground stations containsa 2-way Doppler shift f J) which is extracte d by mix-ing the received signal ( ,f = 960 MHz + f D)with thereference frequency ( f = 960 MHz) de rived fr om th etran smit ter frequency. Actually, a refe renc e fr e-quency of 5 3 . 3 3 MHz is transmitt ed over a VHF linkto each tran smit ter station and then multiplied by afa ct or of 18, yielding 959.94 MHz. When th is fr e-quency is combined with the signal received f rom t he

Vehicle

--------I-----&----I

R1, R2, R3 :Receiving Stations* ** f4..,,,...* f ~3 f D 1 , f D2 , f ~3 : Doppler FrequencyRecelved a t R Station

f R :Reference Frequency ( 53 .33 MHz )I B M B80

Figure 7.4- 1 ODOP System Configuration7.4-1


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7. 4transponder, the Doppler shift is obtained with a 60kHz bi as fr equenc y (60 kHz +fD). The UDOP systemused a t ra nsmi tt er frequ ency of 450 MHz which wasdoubled in the transponde r (900 MHz). The higherfrequency in the ODOP system (890 MHz versus450 MHz) is le ss affected by the ionosphere and theresult is increased tracking accuracy.

The Doppler frequencies , f D, (includingthe bias frequency) from a ll receiving stations ar etransmitted t o the central station and recorded onmagnetic tape. Integration of the Doppler frequ encyreceived at a particula r station provides the rangesum, i. e. , he distance transmitter-transponder-receiver. At least three range sums (for thr ee dif-fere nt stations) a r e neces sary to compute the posi-tion of the vehic le (transponde r). The ODOP sys temuse s 20 re cei ver stations around Cape Kennedy for

redundancy and optimum tracking geometry. ODOPtracking data is not available in re al t ime but is ob-tained fro m post-flight evaluation.

A block diagram of th e ODOP transponder isshown in Figur e 7.4-2. It is a modified vers ion ofthe transponder used by the Jet Propulsion Laboratoryin the Ranger Vehicles. Separate antennas a r e usedfor the receiver and the transm itter. The transpon-der consi sts of a double superheterodyne rec eiv er(890 MHz) and a tra nsm itt er (960 MHz). The signa ltransmitted fr om the transponder is phase-coherentwith the signal recei ved by the transponder. Pha secoherence i s accomplished by an automatic phasetracking loop. The transponder is completely tran -sistorized.

The char act eri sti cs of the ODOP trackingsystem ar e listed in Table 7.4-1.

Figure 7.4- 2 ODOP Transponder Block Diagram

*J50 M H zIF Amplifier

& Mi xerFrequencyConverter

10 M H z 10 AmplitudeMHz IF AmpliFier M H z * Detector -- >

890M H zInput

50 @M H zA 4

+

Av

AG CDC Amplifier

i

M H z 60

RFPreselector Phase FrequencyDetector Divider vA A G C T LM

vLoop SP E TLM LockM H z LP Fi l ter -) Indicator

L -840

x 42FrequencyMul t ipl ier- Output

x 16 960 PowerFrequencyMultiplier MH z * Amplifier --

IBM B 81

*0M H z

Voltage ControlledRF Oscillator & 20x 3 Mul t i p l i e r MHz 960 M H z

A


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16/34


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Astrionics Systemi

CHAPTER 8POWER SUPPLY

ANDDISTRIBUTION SYSTEM

TABLE OF CONTENTS

Section Page8. 1 GENERAL DISCUSSION. . . . . . . . . . . . . . . . . . . . . . . . . 8.1-18.2 IU POWER AND DISTRIBUTION SYSTEM . . . . . . . . . . . . . . . 8.2-1

8.2.1 Power System . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2-18.2.2 The IU Distribution. . . . . . . . . . . . . . . . . . . . . . . 8.2-28. 2. 3 IU Grounding System . . . . . . . . . . . . . . . . . . . . . . 8.2-38. 3 BATTERIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3-18. 4 56 VOLT POWER SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . 8.4-18. 5 5 VOLT MEASURING VOLTAGE SUPPLY. . . . . . . . . . . . . . . 8.5-1


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Astrionics System,Section 8 . 1

SECTION 8.1GENERAL DISCUSSION

The power supplies fo r the Sa turn Launch Ve-hicles provide the electrical power necessary to oper-ate the various onboard electronic and electromechan-ical components. Each vehicle stage contains batteries,power supplies, cables, connectors, and distributors.The distribution system interconnects these units.Figure 8. 1-1 ill ust ra tes the arrangement of the powerand distribut ion sy stem components within eachSaturn V Stage.

While the component interconnection is similarin each stage, the grounding scheme dif fers betweenstages. The IU grounding system is discussed late rin this chapter.The Power Distributor is the only distributionsystem component whose basic function may not beobvious. Essentially, i t is a junction box which pro-vides quick acces s to stage c ircu itry and overallstage and vehicle logic. Such a device becomesnecessary because of the impact on airborne and

ESE hardware which is crea ted by the variety ofmission r equi rements assigned to the Saturn Vehicles.The Power Distributors are equipped with terminals,relays, resis tors , and diodes. These componentpar ts a r e eit her har d mounted or mounted on printedcircuit boards to permit rapid acces s to the distribu-tion, switching, and isolation networks.An illustration of the power and distributionsystem is shown in Figure 8.1-2. The figure rep-resents a smal l portion of the actual logic involved,and only the IU system is detailed.Functions provided by the power supply anddistribu tion system include the following:

Prima ry power is fed to high c urre ntcapacity buses in the Power Distributor.Components which r equ ire high cu rrentlevels a r e supplied directly from thesebuses.

Each stage is equipped with a powertransfer switch to select a power sourceeither inte rnal or external to the ve-hicle. During normal checkout opera-tions, a ground power source will beused in place of the airborne batteri es.A detailed explanation of power transferis provided in Section 8.2.

Each power source generally suppliesat lea st one bus in each distributor.

Buses a r e provided to other stag es forevent logic and EDS signal transmission.

a Power requirements, other than thatsupplied by the airborne batteries, a r eusually provided by a special powersupply (e. g., power sou rce for com-ponent D in Figure 8. 1-2).

Distributor switching facilitates check-out operations and is essential fo r con-trol of certain flight events. Figure8. 1-2 illustrates how both intra-stageand inter-stage switching is accom-plished.During prelaunch operations, manyswitching operations ar e possible fro mthe ESE. Figure 8. 1-2 i llus trat es howPower Distributor relays K1 and K2 a r eutilized to control the power to compon-ents C and D when the power transferswitch is in the exte rnal position. TypicSwitch Selector contro l of power application and discr ete event transmission isillu stra ted by the configuration of r ela ysK3 and K4.


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AstrionicsSe

I

Power Transfer Switch- - - - - - - - - - - - - - - - - - - - - - - - -

Figure 8.1-2 Parti al Schematic of the Power and Distribution8.1


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SECTION 8.2

The following paragraphs discuss the powersupplies and distribution system within the IU Stageof the vehicle. The operation of the other sta ges i ssomewhat si mi la r to that of the IU, and detailed dis -cuss ions of these st age s will not be presen ted.8.2.1 POWER SYSTEM

The IU power components may be divided into3 groups:Pr im ar y 28 Vdc power s our ces (i nternaland external)Inertial Platform sys tem powerInstrumentation syste m power

PRIMARY POWER SOURCES

To switch to the internal o r external powerstat e, an ESE command (28 Vdc) is sent to one ofthe drive-motor field coils. The motor switches themake-before- break contacts to the desire d position.The switch will rem ain in that position until anothe rESE command is generated.

During prelaunch testing, the power tran sfe rswitch will be actuated se ver al times. Figure 8.2-4ill ust rat es how the ESE generate d power is used tosimulate the airbo rne battery. As shown in the figure,the pr ima ry 28 Vdc (external) power is normallyrouted through an umbilical to the IU Power Distributor.The battery simulator shunts the internal and externalbuses in the Power Distributor to provide power toboth input contacts of the tr an sf er switch. During anumbilical plug drop test , a tes t cable is used to main-tain continuity when the umbilical circ uit i s opened.INERTIAL PLATFORM SYSTEM POWER

The total IU power requirements vary accord-ing to mission assignment. The initial S-IB vehicleswill use four IU Stage batteries. As the vehicle loadrequirements decrease, 3 batteries will normally beused. Load profiles a r e illus trat ed in Figur es 8. 2-1and 8.2-2. The figur es show the absolute and relativediff eren ces of IU Stage cur ren t dra ins between S-IBVehicles , SA201 and 205.

As s tate d in Section 8. 1, each stage is equip-ped with a power transfer switch which is used tosele ct either an internal or an external power source.During normal checkout operations, power fro m theESE will be use d in place of the vehicle batter ies. Adisc ripti on of the b att eri es will be found in Section8. 3.

Approximately 30 seconds prio r to lift-off, apower transfer sequence (to internal power) is initiated.This action is accomplished by the power transferswitch which is simil ar to the switch illustrated inFigure 8.2-3.

The Inertial Platform system requires seve ralunique voltages. These ar e provided by the ST-124-MPlatform AC Power Supply and the 56 Volt PowerSupply. See Fig ure 8.2-5. The AC Power Supplyis defined as a part of the Inertia l Platfor m syst emand i s presented in Chapter 14. Deta ils of the 56 VoltPower Supply a r e contained in Section 8. 4.INSTRUMENTATION SYSTEM POWER

The instrumentation system require s spe cialexcitation and reference voltages for t rans ducer sand signal conditioning equipment. The power flowfor this system is shown on Figure 8. 2-6.

The 5 Volt Measuring Voltage Supply generatesa highly regulated 5 Vdc output for use a s a signal conditioning r efer ence voltage and as excitation fo r som etransducers. Trans ducer excitation voltages, otherthan the 5 Vdc supplied by the Measuring VoltageSupply, a r e generated in the Measuring Racks.


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Astrionics SystemSection 8.2

1

8.2.2 TH E IU DISTRIBUTION SYSTEMThe IU distri bution syst empr ovi des the follow-

ing :Power switching to large loadsPower switching to medium loadsSwitching of low-power logic signalsP r -'per interconnection of all el ectr ica lequipment

The Power Distributor performs the requiredswitching of high-c urren t loads. Medium-currentload switching is accomplished by the Control Dis-tribu tor and two Auxiliary Distributors. The lar genumber of unique requ ire men ts presented by theemergency detection and instrumentation systemsnecessit ates sep arate dist ributo rs for each of thesesyst ems . The rem ain der of the logic switching isperfo rmed by the Control Distr ibuto r and, to a limi tedextent, by the two Auxiliary Distributor s.

The placement of the Control, EDS, andAuxiliary Distributors is illust rated in Figure 8.2-7.In general, components which requi re high-currentswitching are mounted near the Power Distributor,and components requiring numerous logic switchinga r e located near the Control Distributor. The dis-tri butor mounting, relat ive to other components,provides fo r a minimum amount of cabling.

Certai n hardware configuration problemsaris e where it is impractical to alter o r redesignexisting components just to provide correct signalrouting. In cas es such a s this, a device called aPlug-type J-box is used. The J-box is a standardplug used a s an adapter.

Redundancies in circuit design provide aninc reas e in vehicle reliability. Certain componentsreceive primary power f rom three separate batteriesa s a precaution against a pri mar y power failure.

Measuring Distr ibutor s route the numerousairborne measurements to thei r respective destina-tions. A measur ement originates in a transd ucer orwithin another component and is routed either directlyto the telemet ry syst em o r indirectly through Meas-uring Rack signal conditioning equipment and a Meas-uring Distributor.

The lar ge number of t elemet ry signals andnumerous configuration changes require several

Measuring Distributors. The Measuring Distr ibuto rsprovide the routing, voltage division, and cu rr en t -limiting networks to ensu re compatability betweenthe measuring and telemetry systems. Throughthe ir switching capabilities, the Measuring Dis-tri butors can change the selection of measurementsmonitored by the telemetry system. The switchingfunction transf ers certain measurements to channelswhich had been allot ted to expended functions. Lf i twer e not for th is switching, these channels wouldnormally be "wasted" for the remainder of the flight.The Measuring Distributor also provides the optionof using RF l ink or PCM (DDAS) coaxial cable tr an s-mission during checkout operations for a mor e thoroughand comprehensive system test evaluation.

The EDS Distributor contains the relay logicneeded to monitor and interpr et emergency indica-tions and to issue the approp riate commands. Sincethe EDS Distributor is an integral pa rt of the EDS,a mor e thorough description wi ll follow in Chapter 9,Emergency Detection System.

8.2.3 IU GROUNDING SYSTEMIN-FLIGHT ELECTRICAL GROUNDING

All Instrument Unit grounding is referencedto the oute r skin of the stage. The methods used toaccomplish IU grounding are illustrated in Figure8.2-8. Each are a will be described separately.Power System Grounding. The power sys tem isgrounded by means of har dwire s routed fro m the6D COM bus in the Power Distributor to the 601E1ground stud attached to the stage skin. This con-nection provides the single-point ground for thepower system. All 6D COM buses in the variousdis tri butors a r e wired back to the 6D COM bus inthe Power Distributor. The common buses, fo rthe most part, ar e isolated from the chassis of thecomponents in which they a r e enclosed. Isolatingpower supplies a r e utilized in some instances t oaccomplish this. The close proximity of the PowerDistributor, batter ies, and outer skin power groundtermination point (601E1) assu re s that a relativelylow potential difference will be developed by theirrespective ground levels.Ele ctr ical o r Black Box Grounding. Grounding ofindividual boxes and components i s accomplished bydirect metal-to-metal contact of the black box andcold plate or stage skin. All common re tur n linesare isolated from the component chassis except in a


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A s t r i o n i cS

I

BATTERY D10 BATTERY D20

IU Command Rece iver and I U Command Decoder,-/ ISecure Range Safety 0.2 A +18? seconds

+I60 seconds40 - +I884 !t-Q-EhII 0.5A I

30] C-Band Transponder 0.9 A T \ I35-

301 2 Telemetry 9.2 Aj 3 7Measuring Distrib utor 0.2 A / Mea surin g Racks (2) 4.2 A

25 4 Measurin g Racks (2) 4.2 Aa, I & I Radar Altim eter 2.8 A I2.20 -

L6 I ST-124-M Platform AC Power Supply 5.2 A I56 Vo lt Power Supply 3.4 A +g 20

L

d4Coolin g System Electronics 1 O A~

Coo ling System Pump 2 0.0 A

*2 15 -+6

10 -ST-1 24-M Platform Electronics Assembly 1.6 AEDS Dis trib uto r 0.1 Af Flig ht Control Computer 3.8 A

I LVDA 7.1 A I5-0 I I I I I I I I0 5 10 15 20 25 30Mission Time (minutes).vContro l Signal Processor and Rate Gyro Package 1.4 A /

" I I I I I I0 5 10 15 20 25 30Mission Time (minutes)BATTERY D30

+1000 seconds+I6 0 seconds BATTERY D40615 seconds4 0 1 I I

35 IAzusa Transponder 4.8 A

35 -+I844 secondsI

m ~ o n t r o n i m lccelerometers 0.7 AMeasuring Rack 2.1 AT +675 seconds1I Mistrarn I . , n o ,

PCM Telemetry 6.8 A

30 -

6 I F1 Telemetry 9.1 A I

Transponder 5.0 A

+@ 20-3u+ 1 -+.

-i 004

-TM Calibra tor 0.4 A -/*S1 Telemetry 8.6 A

12

610-

4EDS Distributor 0.1 A Flig ht Control Computer 3.8 A6 .

10 - EDS Dis trib uto r 0.1 A2 Flig ht Control Computer 3.8 A

5-I LVDA 7.1 A IIControl Signal Processor and Rate Gyro Package 1.4 A 5-

0 1 I 1 I I I0 I5 10 15 20 25 30I Mission Time (minutes)

@Control Signal Processor and Rate Gyro Package 1.4 A

0 t I 1 I 10 5 1 I I10 15 20 25 30Mission Time (minutes)1

F i g u r e 8. 2 -1 B a t t e r y L o a d P r o f i l e s fo r


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8 . 2ry few instances (e. g., some part s of the telemetry

Grounds Inte rnal to Black Boxes. Internalre connected directly to black box c hass is

f metal-to -metal contact.4Grounds fo r Cabling System. Cable Shields

r e grounded by 2 methods. They a re as follows:

a Most shie lds a re connected to the 6DCOM bus in one of the d ist ributo rs.This is accomplished by extending theshield through the la st s mall contact ofthe distributor connector where it isrouted to the 6D COM bus. Whereseve ral cables ar e connected in series ,the cable shields a re routed through thela st sm al l contact of the interconnectingconnector. This method is used in orderto keep the cable shielding continuousfro m the black boxes through each inter -connecting cable to the distributor.

a When the shielded cables ar e routedbetween two black boxes and do notterminate a t a distributor, a secondmethod of termina ting cable shielding

must be utilized. In this case , onlyone end of the shield is grounded. Theshield is routed through the last smallconnecto r contact on one of the com-ponents and terminated a t the chassis.The black box chassis is groundednormally (as outlined ear lie r). Whereseveral shielded cables ar e connectedin s er ie s from black box to black box,the cable shield is made continuous byrouting the shield through the last s mal lcontact of the interconnecting connectors.

RF Grounding. RF grounding of components is effectedby means of me tal to metal grounding. Refer to theparagrap h on ele ctr ica l o r black box grounding. RFconnectors and cables a r e grounded through the sh ellof the connector t o the black box.PRELAUNCH GROUNDING

The IU and ESE common syste ms a re ref er-enced to earth ground prio r to launch. Shortly afterengine ignition, the umbilicals ar e ejected. To as -su re the IU rem ains a t earth potential until all umbil-icals a r e ejected, two single-wire grounding cablesa re connected to the IU. They a re the final conductorsto be disconnected from the IU Stage. One of thesecables is connected to the ESE 6D COM bus. Th iscable is routed through a single-conductor connectorlocated below the umbilical plate and is terminated a t

Figure 8 . 2 - 3 Pa rt ia l Schematic of the IU Power Transfer Switch

8 . 2 - 6

POWER DISTRIBUTOR Internal Power Bussr, C J CI O L

int pTB--- ---- --- - -- tcExt Int Ext-ATransfer to Internal Command A A A As v v,VLoadsTransfer to External Command IBM B M O


26/34

Astrionics System, Section 8.2

sta ge single-point ground termi nal, 601E1. Cablesrouted from the ESE ac ro ss the swing ar ms to thestage umbilical have an overall RF shield to avoidinduced signal s fro m local tracking antennas. Theseshield s ar e terminated by a second single-conductorcable which is routed fr om the ESE side of the umbil-ical through a one-pin connector to stage skin termi nal601E2. This connector is also located below the um-~i l i ca l la te .

Test Cabler----------"-'--------------------------------1I II I

DISTRIBUTOR-------Power Tmnsfer------

ESE POWER SUPPLY

* This facility i s provided tosimulate airborne batteryI power during the umbilicalJ plug drop test.L-------------

IBM B201

Figu re 8.2-4 Ground Checkout Configuration of IU Power Derivation


27/34

8 .2

Figure 8.2-5 Inertial System Power Flow

56 Vdc b

28 Vdc

5 VoltMeasuring EquipmentVoltage

5 Vdc Signal Conditioning ,eferenceo Measuring5 Vdc Racks(SignalExcitat ion- onditioning)IBM B203

AccelerometerSignalConditioner

Figure 8.2-6 Instrumentation System PowerDistribution

f

56 Vol tPowerSupply

56 Vdc -

t

2 0 V - 1.92 k H zI

201:-6k~z---i ;ELI (ESE) II IL,A

IBM B 20 2

20 V - 4.8 kHzIUBattery

ST-1 24- MInert ialPlatformAssembly

ST-1 24-MPlatformElectronicsAssembly28 Vdc 28 VdcT28 Vdc

26 V400 H~ - 34w56 VdcI 26 VST-1 24-MPlatform

ACpowerSupply

400 Hz - 3 620 V - 4.8 kHz

I


28/34


w

IBM B20Figure 8.2-7 IU Distribution Equipment Layout


29/34

AstrioniS

1

ES E 6D CO M

IE3 - Stage Skin Ground Terminal

Shields to) ~ e s ~ e c t i v eComponents 2

K 01E2 - Stage Skin Ground TerminalI Cable . 1

Shields to(7%T+* Respective Components 26D COM

EDS Distributor

NOTE:f enotes shield termination points.-

IFigure 8.2-8 IU Grounding System for Saturn IB and


30/34


SECTION 8.3BATTERIES

Three or more 28 Vdc batteries ar e used inthe IU to provide the primary power for all electricalcomponents. Each sourc e is a dry-charged, alkalinesilver-z inc, primary battery. During launch count-down, the batteries a re activated by adding a potassiumhydroxide (KOH) electrolyte.

A primary battery contains 20 series-connectedcel ls, each producing a nominal 1. 5 volts. Occasion-ally, the full 20-cell output voltage may exceed thespecified tolerance. In such cases , 18 or 19 cel ls

may be selected by varying the configuration ofbattery connector J / P ~ .

To prevent an excessive internal pressu rebuildup, a relief valve is provided. The valve ventsinternal pressure s in excess of 69,000 meter^ g(10 psig).

Table 8.3-1 summarizes the major IU batterycharacteristics.


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Table 8. 3-1 IU Battery Characte risti csBattery Type MAP 4240 - Dry chargedCells

Number 20 (with provisions fo r selecting 18 or 19cells if required)

Nominal voltage p er cell 1. 5 VdcMaterial Alkaline silver-zi nc

Electro lyte Potassium hydroxide (KOH)output

Voltage +28 k 2 VdcCurrent 35 amp ere s for a 10-hour load period

(if used within 72 hours after activation)Measurements available Curr ent output

Internal temperatureCooling Sys tem Cold plateAmbient Temperature Range +lOC to +48.gC

(+50F to +120F) for proper operationHeat Transfer Characteristics

Dissipation 0.07 w/cm2 (0.47 in?)Surface are a 2074 cm2 (321.4 in?)Total dissipation 150 watts

Physical CharacteristicsActivated weight 75 kg (165 pounds)Dimensions

Length 65.5 cm (25.4 in )Width 26. 9 cm (10. 6 in. )Depth 23. 1 cm (9. 1 in. )

Volume 40, 164 cm3 (2450 in.?)


32/34


SECTION 8.4

56 VOLT POWER SUPPLY

Figure 8.4-1 illus trate s the technique usedto develop a regulated 56-volt output. A 2-kilohertzblocking oscillator develops a square wave which istransformer coupled to a magnetic control amplifier.The signal is then passed through 2 stage s of ampli-fication to a rect ifie r bridge and filter network whichprovides a low-ripple, 56 Vdc output. The ref erencebridge regulates the output voltage by changing theamplification in response to voltage variations sensedat the output.

The 56 Volt Power Supply provides operating Table 8.4-1 56 Volt Power Supply Elec tri cal

A summary of performance cha racteristic sof the power supply is pre sented in Table 8.4-1.

voltage to the ST-124-M gyro and acce lero mete rservoloops. The voltage is also used in the Acceler-omete r Signal Conditioner. Input Voltage 24 to 32 VdcOutput Voltage

0 to 1A load 56+0. 5 Vdc1.1 to 8 A load 56 *2. 5 Vdc8.1 to 10 A load 56* 3. 5 Vdc

Output LoadMinimum continuous load 0. 5 AMaximum continuous load 3.0 A

Output Ripple0 to 5 A load 0.2 5 V peak-to-peak

Range of Output Setting 56 rt 0.5 VdcEfficiency 75 percentWarm up Requirement 2 minutesOperating Temperature Range -25 "C to +I00"C

(-13F to +212"F)

Characteristics

Figure 8.4-1 56 Volt Power Supply Block Diagram8.4-I/8.4-2

- ReferenceBridge

56 Vdc

v2 kHz

BlockingOsci I ator

28 Vdc

t 4 A Ar

+

OutputFilter - - - VoltageInput+ - Limiter

IBM B 206

Mag AmpControl

t - --) -)

-Rectifier Filter --+IBridge

i

High-PowerAmplifier

4

Low-PowerAmplifier -)


33/34


SECTION 8.55 VOLT MEASURING VOLTAGE SUPPLY

The 5 Volt Measuring Voltage Supply provides The chara cter isti cs of the 5 Volt Measuringexcitation voltage for the various vibration, tempera- Voltage Supply are presented in Table 8. 5-1.ture, pressu re, and engine position tranducer s withinthe IU instrumentation system. The measuring supplyis also used to provide a refe rence voltage for in-flight calibration of c erta in telemetry channels. Table 8. 5-1 5 Volt Measuring Voltage Supply

The power supply consist s of the followingmajor elements:

Preregulator circuitrySquare-wave oscillatorStepdown transformer - rectifierSeries regulator - output filte r

Figure 8. 5-1 is a block diag ram of the 5 VoltMeasuring Voltage Supply. The pre regu lato r opera-tion is analogous to a serv o amplifier. The filt eroutput is compared with a constant reference voltageand the resulting e rr or voltage is applied to anamplifi er which var ie s the duty cycle of the pulse-width modulator. Th e output of the pulse-widthmodulator is a square wave whose period is a func-tion of the er ro r voltage detected in the comparator.A fi lt er cir cui t follows the pulse-width modulator toprovide an average dc value of the modulator outputThe square-wave oscillator output voltage is reducedin the stepdown tran sfor mer and is rectified andfiltered prior to entering the se ri es regulator. Thefinal stage of regula tion is accomplished by varyingthe conduction acr os s the se ri es regulator controlelemen t which is a transistor. The conduction of th istransistor is controlled by the magnitude of the e r ro rvoltage sensed by the comparator.

An overload protection circuit is provided tolimit the seri es regulator curr ent to a safe level inthe event of a n overload a t the output.

CharacteristicsPhysical Characteristics

Weight 0.7 kg (1. 5 pounds)Dimensions

Length 11. 5 cm (4. 5 in. )Width 12. 6 cm (4. 9 in. )Depth 5. 1 cm (2. 0 in. )

Input Characteristic sVoltage 28 6 4 VdcCurrent 0.6 A (max)Power 14.4 W (max)

Output CharacteristicsVoltage 5.000 i 0.005 VdcRange of output adjus tment i 0.050 VdcC ur rent O t o l APower 5 W (with 1 A output

Cooling Cha racteris ticsCooling Cold pla teHeat transfer surface ar ea 142. 6 cm2 (22.1 in?Heat tr an sf er of mounting

area 0.05 w/cm2(0. 32 in?)


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8. 5

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