The Space Congress® Proceedings 1967 (4th) Space Congress Proceedings

Apr 3rd, 12:00 AM

HDRSS- A High Data Rate Storage System for Nimbus B

R. Curry Astra-Electronics Division, Radio Corporation of America, Princeton, N. J.

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Scholarly Commons Citation Curry, R., "HDRSS- A High Data Rate Storage System for Nimbus B" (1967). The Space Congress® Proceedings. 3. https://commons.erau.edu/space-congress-proceedings/proceedings-1967-4th/session-13/3

This Event is brought to you for free and open access by the Conferences at Scholarly Commons. It has been accepted for inclusion in The Space Congress® Proceedings by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. HDRSS -A HIGH DATA RATE STORAGE SYSTEM FOR NIMBUS B R. Curry Astra-Electronics Division Radio Corporation of America, Princeton, N. J.

Summary The heart of the HDRSS is a 5-channel tape recorder which stores and reproduces digital data and analog The high data rate storage system ( HDRSS) is video signals for transmission to NIMBUS ground sta­ being developed to provide storage and reproduction tions. During an orbital revolution the signals from of data aboard the NIMBUS B Satellite. The system two sensors and a clock are transmitted in real time uses a 5-channel 2-speed tape recorder and a 5-· to local stations and simultaneously stored in the tape channel frequency division multiplexer. The system recorder. Later, as the spacecraft passes over a is tested using a bench checkout unit, which simulates ground station, the data is read from the recorder at spacecraft signals and ground station processing a rate 32 times that at which it was recorded. The functions. signals from the five tracks are frequency multiplexed and transmitted to earth via an S-band FM communica­ Introduction tions link.

The high data rate storage system ( HDRSS) Functional Description (Fig. 1) is being developed by RCA for NASA to pro­ vide storage and replay of sensor data aboard the The tape recorder (Fig. 3) operates in two modes: NIMBUS B satellite. NIMBUS B is the third satellite record and playback. The modes of operation are con­ to date in the NIMBUS series. trolled by the record end-of-tape switch (reverts to off), the playback end-of-tape switch (reverts to re­ The NIMBUS program involves stabilized, ex­ cord ) and the record on, playback on, and off com­ perimental meteorological satellites designed to mands. Both recording systems may be operating circle the earth in a 600-nmi, near-polar, sun­ simultaneously; alternatively, the two recorders may synchronous orbit with an orbital period of approxi­ be operated sequentially to provide greater storage mately 107 minutes. The NIMBUS television and in­ capacity. frared sensors provide complete coverage of every point on the earth's surface once in daylight and once Five signals are recorded in the HDRSS: The image in darkness every 24 hours. During each orbital dissector (JD) video signal ( 0 to 1, 600 Hz); the high revolution, continuous infrared mappings and 31 resolution infrared radiometer ( HRIR) signal ( 0 to single-frame television photographs are made. 360 Hz); the infrared interferometer spectrometer (IRIS) signal, a biphase 3, 750-bit Is data signal; the On NIMBUS I, orbital coverage photographs were medium resolution infrared ( MRIR ) signal, a biphase obtained using a rapid-readout ( 6. 4 seconds) auto­ data signal at a rate of 1, 600 bits/s; and the timing matic vidicon camera system (AVCS) and a tape re ­ signal, a 2, 500-Hz carrier, amplitude modulated by corder with a 1:1 record-playback speed ratio, re­ the 100 - bit/s NASA Mini track pulse width modulated sulting in a video bandwidth of 60 kHz for an 800-line ( PWM) time code. picture. This bandwidth, suitable for transmission to the ~o high-gain command and data acquisition Recorder Electronics ( CDA) ground stations, is too large for the smaller weather stations provided around the world for use Before the ID and HRIR signals are recorded, they with TIROS automatic picture transmission (APT) are converted from video to frequency modulated sub­ satellites. The APT camera readout time is 208 carrier signals in the tape recorder electronics. The seconds, resulting in a video bandwidth of 1. 6 kHz. time- code, IRIS, and MRIR signals are amplified and are then recorded directly without further processing. To provide the capability both for real-time transmission to the local stations and complete or­ Tape Transport bital readout at the CDA station, the tape recorder speed-up concept was adopted. The HDRSS (Fig. 1) The FM modulators and the input amplifiers are consists of redundant spacecraft tape recorders and located on an electronics module in the tape recorder multiplexers, ground station demultiplexers, sub­ assembly but are not contained in the transport en­ carrier demodulators, digital decoders and video closure. The transport enclosure, which is pressur­ display equipment. Some of the ground station equip­ ized to 2 psig with an inert gas, contains the drive ment was designed during the NIMBUS I and II pro­ motors, the record heads and head driving a:mplifiers, grams; the spacecraft equipment was designed specifi­ the playback heads and differential playback pre­ cally for NIMBUS B. The spacecraft subsystem amplifiers, and some of the motor control relay cir­ (Fig. 2) weighs 32 pounds and requires a power of cuits. The playback phase equalizers (digital tracks) 23 watts. and the playback limiters are located on the electronics

13 - 37 module outside the transport enclosure. The HRIR In the ground station demultiplexer (Fig. 6 ), the and ID channels have only playback amplifiers and IRIS channel consists of a low-pass filter and an equal­ limiters. izer which corrects the phase response of the cas­ caded multiplex-demultiplex filters to with ±1 µ s. The HRIR signal, at playback speed, is a fre - quency modulated wave with a center frequency of Timing Signal 87. 5 kHz with a frequency deviation of ±13. 75 kHz at a maximum modulating frequency of 11. 5 kHz. The The second channel is the timing channel with a ID signal, at playback speed, is a frequency modulated passband from 171 to 203 kHz. The input signal con­ wave with a center frequency of 96 kHz, a peak fre­ sists of an 80-kHz carrier, amplitude modulated by quency deviation of 24 kHz and a maximum modulating a PWM time code which has a pulse repetition fre­ frequency of 51. 2 kHz. The timing signal is an 80 quency of 3. 2 kHz and pulse durations of 60 and 180 µ s kHz carrier, amplitude modulated by a 3. 2 -kilobit/s for O and 1, respectively. The timing signal is heter­ PWM waveform. The IRIS and MRIR playback chan - odyned with a 267-kHz local oscillator; the difference nels are amplitude and phase equalized and are ampli­ frequencies are selected by the 171 - to-203-kHz band­ tude limited. They contain biphase data at 120 and pass filter. 53.3 kilobit/s, respectively. The ID, HRIR, and tim­ ing signals from the recorder go directly to the multi­ At the demultiplexer, a 171-to-·203-kHz filter plexer; while each biphase signal first passes to a selects the timing signal; no further heterodyning is repeater which removes some of the high frequency required as the signal is passed directly to the time jitter introduced by flutter in the tape recorder. code detectors and the flutter discriminator at 187 kHz. Biphase Repeater MRIR Signal The two biphase repeaters (Fig. 4) are identical except for the data and clock bandwidhts. The incom ­ The MRIR signal is placed in channel 3 of the ing signal and noise are amplified, band limited, and multiplexer. The MRIR biphase data, at a rate of amplitude limited. The output of the limiter is then 53. 3 kilobits/s, modulate a 300-kHz local .oscillator. processed simultaneously on two separate paths: a The resulting double-sideband AM signal is passed timing extraction path and a data path. In the timing through a 235-to-365-kHz filter. The equivalent extractor the incoming data is differentiated and used basebandwidth is :1:65 kHz, or approximately ±1. 2 to drive a one -shot pulse generator. The standardized times the bit rate. pulses from the one-shot are combined with the out­ put of a voltage controlled (saw tooth) oscillator ( VCO) At the demultiplexer, the signal is selected by a in a multiplier. The output of the multiplier is filtered filter with a passband from 235 to 365 kHz and is heter­ to develop an average bias voltage which controls the odyned with a 475-kHz local oscillator. The difference frequency of the VCO. The output of the VCO (the frequencies are selected by a low-pass 270-kHz filter extracted timing) is used to sample the incoming sig­ and are passed through a phase corrector having a nal in the data path. Additional flip-flop stages are passband from 110 to 240 kHz. This channel, used in used to generate pulses during tape dropouts so that NIMBUS I for an FM video subcarrier, is phase­ the decoder at the ground station will not lose synchro­ equalized to within ±5 µs of constant time delay. At nism. If this feature were not provided, the ground this point, the signal is a double-sideband AM wave station decoder would lose data during reacquisition with a center frequency of 175 kHz. This signal is of timing in addition to the data lost during the drop­ envelope detected to recover the biphase MRIR data out. The output of the IRIS repeater, a square wave which is then passed to a bit synchronizer for timing digital data signal, still in biphase-level format at extraction and conversion to nonreturn-to-zero format. 120 kilobits/s ( 53. 33 kilobits/s for MRIR) is passed to the spacecraft multiplexer. ID Signal

Multiplexing The ID signal uses channel 4 of the multiplexer, with a passband from 400 to 530 kHz. The input sig­ The IRIS, MRIR, HRIR, timing, and ID signals nal from the tape recorder is an FM wave with a cen­ are fed to the multiplexer (Fig. 5) where they are ter frequency of 96 kHz and a peak deviation of ±24 heterodyned, filtered, and added to form a composite kHz at a maximum rate of 51. 2 kHz. This signal is signal with a frequency spectn1m ranging from DC to frequency doubled and heterodyned against a 640-kHz 700 kHz. The input signal amplitudes are approx­ local oscillator; the difference terms are then passed imately 3 volts peak-to-peak, while the composite through a bandpass filter having -3 dB points of 400 output signal amplitude is 5. 5 volts peak-to-peak. and 530 kHz. The bandwidth is such that the signal received at the demultiplexer and demodulator is a IRIR Signal "single-sideband" FM carrier for certain combina­ tions of peak deviation and modulating frequencies. The IRIS signal is assigned the lowest frequency For example, for video signals superimposed on a multiplexer channel, covering the range from DC to white ( 120 kHz) average field, the signal becomes 132 kHz (within -3 dB). No heterodyning is required SSB-FM for any modulating frequency, since all upper for the signal; this multiplexer channel consists sidebands corresponding to the video signal are re­ simply of a low-pass filter. moved by the multiplexer filter which cuts off at 400 kHz.

13-38 At the demultiplexer, an input filter with a pass­ Ground Stations band from 400 to 530 kHz, selects the signal which is then heterodyned with a 640-kHz local oscillator; the Two command and data-acquisition stations pro­ difference frequencies are selected by a 270-kHz low­ vide coverage for nearly 93% of the NIMBUS orbital pass filter and are fed to an equalizer having a pass­ passes at an altitude of 600 nmi. The Alaska station band of 110 to 240-kHz, which corrects the phase re­ is located at Gilmore Creek near Fairbanks, Alaska; sponse of the cascaded multiplexer-demultiplexer the other, Rosman, is located at Rosman, North filters to within ±5 µs of constant delay. At the de­ Carolina. The Alaska station acquires the spacecraft multiplexer output, the signal is an FM wave, with a on an average of 10 out of 14 orbital passes each day. center frequency of 192 kHz and a peak frequency Rosman acquires the spacecraft on an average of two deviation of ±4~ kHz at a maximum rate of 51. 2 kHz. orbital passes a day of the four missed at Alaska, and two orbital passes for back-up. Both stations have 85- foot-diameter parabolic antennas to track and command HRIR Signal the spacecraft. Data transmitted by the spacecraft are received at Alaska and Rosman and are relayed over The HRIR signal uses channel 5 of the multiplexer. long lines or a wideband microwave link to Goddard The incoming signal is an FM wave with a center fre­ Space Flight Center and to the Weather Bureau at quency of 87. 5 kHz and a peak deviation of ±13. 7 kHz Greenbelt, Maryland. at a maximum rate of 11. 5 kHz. This signal is fre­ quency doubled, then heterodyned against an 805-kHz As the S-band signals are received, they are con­ local oscillator and the difference frequencies are se­ verted to VHF, FM-detected, demultiplexed, and lected by a filter with a passband from 565 to 695 kHz. passed to their respective subsystems for further processing. The ID signal is fed to an FM demodulator At the demultiplexer, after mixing with the 805- and then to a kinescope display unit, while the HRIR kHz local oscillator, the HRIR signal is phase cor­ signal is recorded on a facsimile recorder. An on­ rected to within ±5 µ s and passed to an FM discrim­ line computer is used to assist in the analysis of the inator. At the demultiplexer output the HRIR signal data and to provide latitude and longitude grids for the is an FM wave with a center frequency of 175 kHz sensory data. The ID subcarrier is demodulated and and a peak deviation of ±27 kHz at a maximum rate the video is applied to the kinescope electronics and of 11. 5 kHz. to a kinescope monitor for visual observation. In the kinescope electronics the horizontal arid vertical sync RF Link pulses are detected and applied to a deflection gener­ ator. The output of the deflection generator provides The five HDRSS signals, translated to their se­ sweep voltages to the kinescope in the kinescope re­ lected frequency slots and combined in the multi­ corder. The video signal is amplified and displayed plexer, are used to frequency modulate an S-band on the kinescope. transmitter having an output of power of 5 watts at a frequency of 1710 MHz. An 85-foot antenna and a The timing signal is fed to an envelope detector 3-MHz receiver are used at the ground station. The to recover the time code; an index computer uses the overall carrier-to-noise ratio ( CNR) for the RF time code to generate a numerical print out on the ID link is 18. 1 dB. For a given CNR and fixed band­ picture. The raw timing signal is also fed to an FM widths, the detected signal-to-noise ratio for a par­ demodulator which generates a flutter correction sig­ ticular channel is determined by the fraction of the nal. This signal is applied to the ID kinescope sweep total RF deviation which is allocated to that channel. circuits to compensate for the effects of tape recorder The amplitudes of the five signals are adjusted in the flutter on the video-time base. multiplexer to provide the appropriate RF deviation to each channel. The HDRSS signal frequency devia­ The video displayed on the kinescope is projected tions and the resulting signal-to-noise ratios are onto the 70-mm film in the film processor with unity given in Table I. magnification. At the end of the picture, a decimal readout from the ID index computer is illuminated and TABLE I. HDRSS SIGNAL FREQUENCY focused onto the film below the video display. The DEVIATIONS AND SIGNAL- TO­ picture size is approximately 2 by 2 inches with a NOISE RATIOS vertical sweep period of 6. 5 seconds and a horizontal sweep rate of 128 lines per second. Each picture contains approximately 800 lines. At the end of each Peak RF Channel Baseband decimal-display exposure, the film is automatically Signal Deviation No. SNR (dB) advanced. As successive pictures are taken, the film (kHz) is developed, fixed, and dryed. In approximately one 1 IRIS Data 100 34. 0 (P/RMS) minute the film is processed and displayed in the view­ 2 Timing 75 er. A take-up reel collects the completed pictures. Time Code 15. 4 (RMS/RMS) Flutter 30. 0 (RMS/RMS) The HRIR signal, along with the timing signal, 3 MRIR 400 28.2 (P/RMS) is recorded on a MINCOM recorder, and played back 4 ID 300 34. 4 (B-W/RMS) at one quarter of the record speed. The slow-rate 5 HRIR 200 47.0 (B-W/RMS) HRIR is fed to an FM demodulator and then to a Westrex facsimile recorder. The slow-rate timing Total Peak RF Deviation 1, 075 kHz signal is enveloped detected and used to drive the

13 - 39 facsimile recorder motor. The PWM time code is The bench check unit includes a link simulator also passed to the HRIR index computer which gen­ in which shaped noise is added to the HDRSS-RF Link erates time data to be impressed on the facsimile interface to simulate the noise of the FM communi­ record. cation link. In addition, noise is added to each of the signal inputs and the power supply to verify HDRSS The two biphase digital signals, IRIS, and MRIR, ope ration under realistically noisy conditions. are passed to bit synchronizers (Fig. 7) where they are filtered, bit timing is extracted, and the data is Operation of the ID video channel is demonstrated converted to non-return-to-zero format by a sampling by recording a simulated test pattern signal in the detector. The bit synchronizers are commercially HDRSS and playing it back for display in the bench available units selected for their flutter tracking cap­ check unit kinescope assembly. A hard copy of the ability and low bit error rate in the presence of FM displayed picture is also made in the kinescope re­ noise. corder as a permanent record of test results. In addition, quantitative measurements are made of Bit timing for the biphase data is extracted by a system linearity, drift, frequency response, transient phase-locked loop which is synchronized with the zero response, and signal-to-noise ratio. crossings of the incoming data stream. The extracted timing pulses are then used to sample the polarity of The HRIR infrared channel operation is similarly the incoming data. demonstrated by quantitative measurements of overall system parameters, and photographic records of the The decoder has three selectable phase-locked­ channel output signals. loop bandwidths to ensure optimum performance for various operating conditions. Tne maximum per­ Timing channel operation is demonstrated by missible frequency modulation ot the bit rate for which detection of the simulated Minitrack time code with lock can be maintained with a PCM transition density an acceptable bit-error-rate and by a subjective evalu­ of 50%, for various bandwidths, is presented in Fig. 8. ation of the HDRSS flutter correction capability as ob­ These curves determined the maximum flutter which served on the kines cope display. The IRIS and MRIR could be exhibited by the HDRSS tape recorder while biphase data channels are tested by generating and working with this decoder. recording a pseudo-random code on the HDRSS tape recorder. The code is then played back and passed The bit error rate of the HDRSS biphase decoder, through the multiplexer, the simulated RF link, and operating with FM noise, is shown in Fig. 9. The the demultiplexer. The received signal is decoded biphase channels of the complete HDRSS have been and compared bit by bit with the original sequence demonstrated to have a bit error rate ot 1 x 10-5 from while a count is kept of the number of errors. The tape recorder input to decoder output wm1e subjected bench check unit also contains detectors which in­ to simulated power supply noise, sensor noise, and dicate whether the phase-locked-loop timing extractor RF-link noise. has fallen out of lock.

The decoded IRIS and MRIR data are provided, Certain parameters, such as tape recorder flutter, along with the extracted timing signal, to a NASA limiting level, intersymbol interference, harmonic interface for transmission over the microwave link distortion, etc., are measured on the subsystems be­ and further data processing at the Goddard Space fore the bench check unit is used to test the HDRSS at Flight Center. the system level.

System Checkout Acknowledgement

The HDRSS performance is verified at the sys­ The author, in writing this paper, has reported tem level using the HDRSS bench check unit. This the work of a large team of people many of whom have unit simulates all spacecraft-HDRSS interfaces, in­ made very significant contributions to the HDRSS pro­ cluding signals, commands, power, and telemetry, gram. The team included several design groups, Test and provides quantitative measurement of all spec­ Engineering, the NIMBUS Program Office, and Space ified parameters for the HDRSS. All subsystem in­ Communications System Engineering. While it is not terfaces are simulated and brought to breakout boxes possible to list here the specific contributions, it is a to facilitate fault isolation to the subsystem level. pleasure to acknowledge the total effort made by each person involved in helping to bring the HDRSS to its present state of development.

13- 40 SPACECRAFT GROUND STATION

MRIR 81 T SYNCHRONIZER HRIR ,---, HRIR FACSIMILE . I TAPE RECORDER RECORDER L J 4 : 1

ct: ct: ct: w r- w )( J..., 0 w m: )( w TIME I 0 w r-' "' -, ....J I u ....J Q. INDEX I Q. TC w ;~, ~ 'COMPUTER m: ~ ....J L __ _J w ....J :> Q. :> L _\,__ I \._j :E 2 Cl UJ FLUTTER ~ TRANSMITTER RECEIVER 0 CORRECT I ON AND r---, TIMING TIME I INDEX I COMPUTER I 10 L_I_J - -, KINESCOPE I I DISPLAY I TIME i.....-----~ CODE ~---1

IRIS BIT SYNCHRONIZER

Figure 1. High Data Rate Storage System, Block Diagram

13-41 TAPE TRANSPORT ELECTRONICS MODULE

TAPE RECORDER

BIPHASE REPEATER MULTIPLEXER

Fig. 2

Figure 2. Spacecraft Subsystem of the High Data Rate Storage System

13-42 I ------, PRESSURIZED I TAPE TRANSPORT I CONTAINER I I HRIR VOLTAGE RECORD PLAYBACK COIHROLLED PRE- LIMITER AMPLIFIER OSCILLATOR AMPLIFIER

MRIR PLAYBACK LIMITING RECORD PHASE PRE- AMPLIFIER AMPLIFIER AMPLIFIER EQUALIZER

LIMITER

IRIS LIMITING RECORD PLAYBACK PHASE PRE­ AMPLIFIER AMPLIFIER EQUALIZER AMPLIFIER

LIMITER

ID VOLTAGE RECORD PLAYBACK CONTROLLED AMPLIFIER PRE- UM ITER OSCILLATOR AMPLIFIER

TIME PLAYBACK INPUT RECORD OUTPUT PRE- AMPLIFIER AMPLIFIER AMPLIFIER AMPLIFIER

400 Hz CLOCK ------1-. AMPLIFIER TO MULTIPLEXER • COMMANDS COMMAND MOTOR CONTROL I POWER RELAYS 28VDC I CIRCUITS I L ______J

Figure 3. HDRSS Tape Recorder, Block Diagram

13-43 II PHASE PATA LOW-PASS BUFFER LIMITER FILTER

DC ONE SAMPLER AMPLIFIER SHOT DRIVER AND LOOP SHAPER

SAWTOOTH BUFFER OSCILLATOR (TWICE BIT RATE)

RECONSTITUTED FLIP-FLOP FLIP-FLOP FLIP-FLOP DATA

ONE SHOT

Figure 4. Biphase Repeater, Block Diagram

.. . 1'' " '11,1 t

13-44 CHANNEL I IRIS FILTER 0 T0132 KHZ

CHANlllEL 2 TIME CODE DOUBLE BANDPASS - BALANCED - FILTER MODULATOR 171 TO 203 KHz

j

LOCAL OSCILLATOR 267 KHZ

l l CHAllllllEL 3 MRIR BALANCED BAlllDPASS ADDER - Fl LTER ~ MODULATOR AMPLIFIER ..... 235 TO 365 KHI

j

LOCAL OSCILLATOR 300 KHz

CHAlllNEL 4 ID FREQUElllCY DOUBLE BANDPASS - ~ BALAlllCED FILTER - DOUBLER ~ MODULATOR 400 TO 530KHz '

LOCAL OSCILLATOR 640 KHz

CHANlllEL 5 HRIR DOUBLE BANDPASS - FREQUENCY ~ BALAlllCED FILTER DOUBLER MODULATOR -- 565 TO 695KHZ '

LOCAL OSCILLATOR 105 l

Figure 5. Multiplexer, Block Diagram

13-45 1 CHANNEL1 FILTER PHASE --R_i_s_..- DC TO ~ CORRECTOR 132 KHz

CHANNELTIMING 2_ 171Fl L KHzTER L------~ TO .....-~ 203KHZ

CHANNELJ FIL TEA LOW-PASS DOUBLE MR IA -- 235kHz FILTER PHASE ~ BALANCED TO ~ DC TO ~ CORRECTOR DEMODULATOR 365KHI 270KH1

j

LOCAL ENVELOPE OSCILLATOR ~ - 47SKHz DETECTOR'

CHANNEL 4 FIL TEA DOUBLE LOW-PASS ID _.,, 4001

LOCAL ..__ _.... OSCILLATOR 640KHz

CHANNEL 5 FILTER LOW-PASS HAIR !56!5KHZ .. DOUBLE FILTER PHASE ~ TO BALANCED ~ DEMODULATOR DC TO i-. CORRECTOR 695KHz 270 KH l

LOCAL OSCILLATOR 80!5KHz

Figure 6. Demultiplexer, Block Diagram

13-46 Bl PHASE DATA INPUT INPUT -- AMPLIFIER r ------, TIMING EXTRACTION CIRCUITS

PHASE LIMITER I~ FILTER ~ L SHIFTER 2 2 l • w PHASE PHASE .... LI MITER ~ SENSITIVE ~ SENSITIVE DETECTOR DETECTOR -

I

VOLTAGE 90- DEGREE LOOP CONTROLLED CLOCK ~ FILTER ...... OSCILLATOR BINARY CLOCK OUTPUTS L ------__J -1- . SPLIT-PHASE 0-DEGREE CLOCK ~ CLOCK RESET Bl NARY

I - ..... I I ------, I - I I I I PHASE DC .._. ~ I SENSITIVE ..... FILTER RESTORER' I DETECTOR I I n I - I I I I BIT CODE LIMITER I I ...... DECISION ~ CONVERTER' I ' I I I I l PCM DATA I OUTPUT OUTPUT I - I AMPLIFIER - I DECODING CIRCUITS I L ------·- -- - J

Figure 7. Biphase Decoder, Block Diagram

13-47 0 0- > ...... iii 0 Zz In "'"'~o "'c... "'z er a..o 0 i= in- 0 ...... II) z N CD c ~ ct: 0 ...... 0 ...... >- z u1&.1 zl- "'u II.IC ct: ~a:: "'CL. ll'I 01- 0 11.1- ! a:: m ....% k. k. a zO !a N a ~ ..... z 0 t-Z c Cl&.I CD -u CL. - >a:: 0 0 II.I Ill 0_, OG.- 0 ll'I "'¥ 0 u 0 0_,

..., N "'c 0 % 0 CL

0 N ~ tD co • N oci +I +t +I +• +I +t (l.Hflt J.18 ~O J.Nl:>ltld) NOIJ.YIAlO

Figure 8. Maximum Lock Hold-in Range of HDRSS Biphase Decoder

13-48 1 10 5

2

162 5

l&J 2 ~ 4 3 a:: 10 a:: 5 0 a:: a:: 2 l&J 164 ~ m 5

2

16 5 5 NOTE: NOISE BANDWIDTH IS 2 8 TIMES BIT RATE 16 6 L-~.L-~....L-~....L-~-'-~...... 0 2 4 6 8 10 CA RR I ER-TO- NOISE RATIO (DB)

Figure 9. Bit Error Rate as a Function of Carrier­ to-Noise Ratio for HDRSS Biphase Decoder

13-49