Space Technology GSFC 5 Tomorrow s Technology Today Section

Space Technology GSFC 5 “Tomorrow’s Technology Today” Section 11. 0 Communications Subsystem Victor J. Sank Communications Lead Engineer ST 5 PDR June 19 -20, 2001

GSFC Agenda • Key Requirements • Documentation • Allocations • Transponder, Diplexer and HPA Layout • System Concept Design • Link Budgets • Antenna • Block Diagram • Development • Testing • Issues • Back-up Slides ST 5 PDR June 19 -20, 2001 11 - 2

GSFC System Requirements • S/C shall implement X-band communications link with the ground. (MRD 10104040) • The spacecraft shall be able to downlink telemetry and receive uplinked commands. (MRD 10303060) • The transponder system shall be capable of decoding “special/hardware" commands from the uplink without the use of the CDH or FSW and execute discrete pulse signals to other units on the spacecraft. (MRD 10303062) • The spacecraft shall have two, ground selectable, downlink data rates; 1 Kbps and 100 Kbps. (MRD 10303063) • The spacecraft shall be able to support 2 -way radiometric Doppler tracking. The system radiometric Doppler tracking accuracy shall be sufficient to support ground antenna pointing at distances of 2 to 5 Re. (MRD 10301010 and MRD 10301011) • The spacecraft shall provide a minimum RF output power of 1. 5 W, measured at the antenna port of the diplexer. (MRD 10303067) ST 5 PDR June 19 -20, 2001 11 - 3

GSFC Derived Requirements • 10 MB HK and Science data playback plus RT HK in -30 min contact 25 • 11 m Ground Antenna (minimum) • Convolutional coding on telemetry , r = 1/2, K = 7 – Due to the use of 1/2 rate convolutional encoding, the necessary symbol rate (in kilosymbols per second, Ksps) is twice the required data rate (in kilobits per second, Kbps). • Coherent RF turn around using CCSDS recommended ratio • Stable oscillator ST 5 PDR June 19 -20, 2001 11 - 4

GSFC Documentation ST 5 PDR June 19 -20, 2001 11 - 5

System Allocations GSFC • Mass – – Transponder Unit Front End Unit (Dplxr & HPA) Antenna System Total . 198 Kg. 210 Kg. 120 Kg. 528 Kg • Volume – Transponder Unit – Front End Unit – Antenna 187. 5 cm 3 80. 0 cm 3 157. 5 cm 3 • DC Power – Rcvr Only – Rcvr and Xmtr 4 W 12 W • Thermal Operate – Transponder, HPA & Dplxr – Antenna Survive -20 to 50 °C -40 to 60 °C -60 to 40 °C -80 to 80 °C ST 5 PDR June 19 -20, 2001 11 - 6

GSFC Transponder, Diplexer and HPA Layout Scale: 3” Transponder (2. 95 x 2. 45 x 1. 97 in) Diplexer HPA (3. 0 x 1. 5 x 0. 6 in) (3. 3 x 1. 1 x 0. 5 in) ST 5 PDR June 19 -20, 2001 11 - 7

GSFC Communications System Design Concept (1 of 2) • Performance – Two Data rates baselined; 1 and 100 Kbps – At <5 Re Data transfer of 100 Kbps with a BER of <1 X 10 -5 – Two-way, Coherent Doppler Tracking is baseline – One-way Doppler will provide backup orbit determination • Other Attributes – 5 V transponder, excluding HPA – HPA mount point minimizes thermal variation at Oscillator – X-band Uplink and Downlink – 3 d. B margin in Telemetry link budget – >20 d. B in Command link budget ST 5 PDR June 19 -20, 2001 11 - 8

GSFC Communications System Design Concept (2 of 2) • Frequency and Spacecraft ID Registration (MRD 30104000) – NTIA Frequency allocation approval; currently Stage 2 • X-band 8470. 000 MHz downlink, 7209. 125 MHz uplink • S-band 2263. 000 MHz, 2084. 000 MHz – CCSDS GSCIDs assigned; minimum Hamming distance 4; (used to uniquely identify spacecraft in CCSDS frame header) • ST 5 -1 • ST 5 -2 • ST 5 -3 0011100000 0001011110 0010011011 E 0 5 E 9 B – SOMO/CSOC SCIDs assigned (for ground handling of data) • ST 5 -1 • ST 5 -2 • ST 5 -3 0100011 0100100101 23 24 25 ST 5 PDR June 19 -20, 2001 11 - 9

GSFC 1 2 3 4 5 6 7 8 9 10 11 12 Link Budget: X-band Space – Ground (1 of 2) Transmitter Power (W) 1. 9 2. 79 d. B Antenna gain (d. B) 0. 00 SC Antenna beamwidth (°) 40. 00 FWHM Passive Loss (d. B) 1. 0 cables, etc. EIRP (d. BW) 1. 79 31. 79 d. Bm Freq. (MHz) 8470 Range (km) 32000 5 Re Space loss (d. B) 201. 11 Atmos, Scint, Rain Att (d. B) 0. 9 high elevation Polarization loss (d. B) 1. 5 Rcvd power den (d. BW/m 2) -162. 01 Rcvd PSD over 4 KHz -181. 91 convo coded ST 5 PDR June 19 -20, 2001 11 - 10

GSFC Link Budget: X-band Space – Ground (2 of 2) 13 Ground antenna size (m) 11 36. 09 ft 14 Antenna gain (-surf loss)(d. B) 56. 92 55% eff 15 Antenna beamwidth (deg) 0. 22 FWHM 16 Power Received (d. Bm) -115. 00 Bkg Temp 40 K 17 Antenna to LNA Loss (d. B) 1. 00 diplexer Temp 75. 09 18 LNA gain (d. B) 25 N=1. 2 d. B, T=92. 29 K 19 System temp (deg K) 231. 28 23. 64 d. B K 20 System G/T (d. B/K) 33. 27 L 14 - L 19 21 C/No (d. B-Hz) 59. 86 L 12 + L 20 + 228. 6 22 Data rate (bps) 100000 50 d. B (N = -154. 96 d. Bw) 23 Implementation loss (d. B) 2. 4 Rcvr and BS 24 Avail Eb/No (d. B) 7. 46 L 21 - L 23 - L 24 25 Eb/No required (d. B) 4. 4 10 E-5 coded (4. 2 ideal) 26 Avail margin (d. B) 3. 06 Line 24 - Line 25 ST 5 PDR June 19 -20, 2001 11 - 11

GSFC 1 2 3 4 5 6 7 8 9 10 11 12 Link Budget: X-band Ground – Space (1 of 2) Transmitter Power (W) 5. 0 6. 99 d. B Antenna gain (d. B) 55. 8 11 m SC Antenna beamwidth (°) 0. 26 FWHM Passive Loss (d. B) 1. 0 cables, etc. EIRP (d. BW) 61. 79 91. 79 d. Bm Freq. (MHz) 7209. 125 Range (km) 32000 5 Re Space loss (d. B) 199. 71 Atmos, Scint, Rain Att (d. B) 1. 40 Polarization loss (d. B) 1. 0 Rcvd power den (d. BW/m 2) -102. 21 Rcvd PSD over 4 KHz -102. 11 ST 5 PDR June 19 -20, 2001 11 - 12

GSFC Link Budget: X-band Ground – Space (2 of 2) 13 Space antenna size (m) omni 14 Antenna gain (-surf loss) 0. 0 15 Antenna beamwidth (deg) 40 FWHM 16 Power Received (d. Bm) -110. 69 Bkg Temp 40 K 17 Antenna to LNA Loss (d. B) 1. 00 diplexer Temp 75. 09 18 LNA gain (d. B) 25 N=3 d. B, T=288. 63 K 19 System temp (deg K) 315. 45 Bkg 40. d. B K 20 System G/T (d. B/K) -24. 96 L 14 - L 19 21 C/No (d. B-Hz) 62. 82 L 12 + L 20 + 228. 6 22 Data rate (bps) 1000 30 d. B (N = -173. 43 d. BW) 23 Implementation loss (d. B) 2. 4 incl mod & diff coding 24 Avail Eb/No (d. B) 30. 42 L 21 - L 23 - L 24 25 Eb/No required (d. B) 9. 6 10 E-5 uncoded 26 Avail margin (d. B) 20. 82 Line 24 - Line 25 ST 5 PDR June 19 -20, 2001 11 - 13

GSFC ST 5 Quadrafilar Helical Antenna Beamwidth +20 to +60º from ecliptic Receive Gain 0 d. B Transmit Gain 0 d. B Operating Frequency: 8. 47 GHz LHCP Diameter: 0. 150 inches Length: 1. 125 inches Turns: 1 Trace: copper Dielectric core: Ecco. Stock Lo. K (Dielectric Constant =1. 7) Notes: There are four traces in the dielectric core. Traces are 90° apart from each other. Traces do not touch each other. Drawing not to scale. ST 5 PDR June 19 -20, 2001 11 - 14

GSFC Antenna Gain (Stand alone) 180 160 140 120 100 80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 5 0 -5 -10 -15 -20 -25 -30 -180 (Gain in d. B) ST 5 Quadrifilial Helical Antenna Angle (Deg) LHCP ST 5 PDR June 19 -20, 2001 RHCP 11 - 15

GSFC Antenna Gain with Choke Rings ST 5 Ideal Antenna with Choke Ring 10 170 145 120 95 70 45 20 -5 -30 -55 -80 -105 -130 -155 -10 -180 Gain (d. B) 0 -20 -30 -40 -50 Degree LHCP ST 5 PDR June 19 -20, 2001 RHCP 11 - 16

GSFC Transponder Functional Block Diagram Auxiliary Command Inputs LNA Up. Link Lock to C&DH Cmd Decoder Receiver Command C&DH Clock Special Cmd reset Coherent Reference Rx Statu s Status/Control X-band Up/Down C&DH Data Special Command Detector Diplexer Transponder Controller Control Rx/Tx Status Output to C&DH Transponder Mode Control from C&DH Tx LO Generator Oscillator Downlink Clock to C&DH HPA Front End Units Transmitter Downlink Telemetry from C&DH Telemetry Transponder +7. 2 Vdc +5 Vdc ST 5 PDR June 19 -20, 2001 11 - 17

BPF LPF DRV Loop Filter TX I C&DH INTERFACE C&DH 244 TX DATA SPECIAL COMMAND DECODE DIPLEXER C& DH HPA Loop Filter 6121. 5 MHz 636 TX Q 2348. 5 MHz RX DATA 8470. 0 MHz VECTOR MODULATOR TRANSMITTER TX CONDITIONING Transponder RF Block Diagram SPLITTER LNA C-BAND SYNTHESIZER BPF 7209. 125 MHz BPF 113 DUAL SYNTHESIZER VGA 1087. 625 MHz TRACKING Front-End Assembly SYNTHESIZER LOCK DETECT REFERENCE TUNING RX Q RX I RX CONDITIONING FROM BASEBAND PROCESSOR Loop Filter 1087. 625 MHz 9. 625 MHz TCVCXO ZERO-IF RECEIVER GSFC ADC AGC RECEIVER BASEBAND PROCESSOR Electronics Unit ST 5 PDR June 19 -20, 2001 11 - 18

GSFC L, C and S-band Synthesizers ST 5 PDR June 19 -20, 2001 11 - 19

GSFC Transponder Digital Block Diagram Soft Reset 6 -8 bit DAC or Resistor Ladder To Modulator IC Radio status To Synth. Q from Tuner IC Loopback Special Commands Master Clock LPF, 2 k. Hz 1 MHz Out RX Clock Hard & Soft C&DH Reset C&DH Cmd & Status Parameter change / status read Commands / Status (2 rates, and set-to-nominal) RX Clock TX Clock Data Clock Generation RX Data Bit Lock Data out RX Data Carrier Detect Oscillator Commands Control / Status AGC +/- ó õ To AGC I from Tuner IC ó õ Special Command Data Decode RX Commands C&DH Command / Radio Discrete Command Status interface Interface. C&DH interface Synthesizer setup & other commands 9. 625 MHz VCO TX Data In TX Conditioning Data Out Lock Indication & other status Xpdr. Reset ADC Clocking 8 bit ADC I in I out RX Conditioning Q in Q out I in Tracking Signal Detect Q in ST 5 PDR June 19 -20, 2001 11 - 20

GSFC Communications System Development • Transponder System Development – Transponder being designed under phase 2/3 SBIR • Will result in breadboard/test unit and Qual unit – Firm fixed price (FFP) contract expected for flight units – After Transponder CDR, Aug 2001, contract for flight units will be issued – No Heritage; New technology, 5 volt, digital, single reference oscillator – New development. Requires full qualification • Antenna Development – In progress at GSFC Code 567 • Feed blanks under contract with Emerson & Cuming • Polyflon to lay traces on blank feeds • Have prototype Choke Ring Assembly; needs final design and fab ST 5 PDR June 19 -20, 2001 11 - 21

GSFC Communications System Technology • Technology Characteristics – Receiver and transmitter will use common frequency synthesis (common to any transponder) – Under development by Aero. Astro – Technical Readiness Level is currently about 3/4 • Untested conventional design, Hardware prototyping ST 5 PDR June 19 -20, 2001 11 - 22

GSFC Testing and RFGSE • Test Program is under Development per ST 5 -495 -007, Component Test Requirements and Guide Lines – Will include compatibility and performance characterization • RFGSE – One RF Rack to include • • • PSK Modulator/Xmtr (µdyne TSS-2000) S-band Receiver (µdyne MRB-1200 or 700) Upconverter (Miteq UP-25020) Downconverter (Miteq DN-25020) Spectrum Analyzer (HP 8596 E) Oscilloscope (HP 54602 B) Plotter/Printer/PC Power Meter (HP 4418 A) Power Meter Heads (HP 8481 A, H) Bit Error Rate Test Set (FBD-6000 A or Bit. Alyzer 26, 400, 622) ST 5 PDR June 19 -20, 2001 11 - 23

GSFC Risk Mitigation (1 of 2) • Risk – Oscillator; 40 weeks ARO for flight units – HPA 1. 5 W DC to RF efficiency not confirmed – Diplexer transmit filter may have high insertion loss • DSNBand stop filter may be required that adds to insertion loss ST 5 PDR June 19 -20, 2001 11 - 24

GSFC Risk and Mitigation (2 of 2) • Mitigation – GSFC is working with Aero. Astro to specify and buy the transponder oscillator. GSFC will provide for screening and qualification of the oscillator flight with the chosen vendor and deliver it to Aero. Astro for integration and qualification of the transponder. To mitigate scheduling risk, Aero. Astro is building a non flight oscillator for the EM unit. The Qualification Transponder Unit will be fully tested and flight qualified, enabling it to be utilized for flight. – A backup/replacement amplifier has been built by Aero. Astro. Its 1. 5 W output does not meet the 2. 0 W HPA output requirement, but it can be utilized by ST-5, lowering the risk from mission critical to a performance (data rate) issue. – Use of a low insertion loss Diplexer may require an additional band stop/ band reject filter (BRF). The filter needs to have steep cut-off characteristics at the band edges and high selectivity or Q factor and low insertion loss inband. Even though BRF may not be needed, specifications are being drawn up and filter will be ordered. ST 5 PDR June 19 -20, 2001 11 - 25

Space Technology GSFC 5 “Tomorrow’s Technology Today” Back-up Slides Communications Subsystem ST 5 PDR June 19 -20, 2001 11 - 26

GSFC ST 5 Mission Overview • S/C - Mission Configuration – Satellite constellation technology mission (3 satellites) – GTO orbit, Spin stabilized – < 25 Kg, < 25 watts – X-band space to ground; S-band space to space – Magnetometer • Space - Ground Communication – Aero. Astro transponder is 1 of 8 technologies to be demonstrated – Orbit determination via 2 way coherent Doppler – S/C Position Accuracy for pointing 11 m antenna: 10 Km – 1 Kbps to 100 Kbps downlink rate, CCSDS format – 1 Kbps to 8 Kbps uplink rate, BPSK on X-band carrier ST 5 PDR June 19 -20, 2001 11 - 27

GSFC Transponder Tracking Block Diagram ST 5 PDR June 19 -20, 2001 11 - 28

GSFC SINDA/G Thermal Analysis S/C 25 °C Radio Board S/C 40 °C Max board Temp (°C) Max Board Temp(°C) Baseband 45 60 Synthesizer 69 84 Up/Down converter 57 72 Oscillator 45 61 ST 5 PDR June 19 -20, 2001 11 - 29

GSFC 1 2 3 4 5 6 7 8 9 10 11 12 CCNT Link Budget: S-band Space - Space Transmitter Power (W) 1. 0 0. 00 d. B Antenna gain (d. B) 0. 00 SC Antenna beamwidth (deg) omni FWHM Passive Loss (d. B) 1 cables, etc. EIRP (d. BW) -1. 0 29. 0 d. Bm Freq. (MHz) 2265 Range (km) 1000 Space loss (d. B) 159. 55 Atmos, Scint, Rain Att (d. B) 0. 0 Polarization loss (d. B) 0. 2 Rcvd power den (d. BW/m 2) -132. 70 Rcvd PSD over 4 KHz -102. 11 convo coded ST 5 PDR June 19 -20, 2001 11 - 30

GSFC CCNT Link Budget: S-band Space - Space 14 15 16 17 18 19 20 21 22 23 24 25 Antenna gain (-surf loss)(d. B) 0. 0 55% eff Antenna beamwidth (deg) omni FWHM Power Received (d. Bm) -131. 25 Bkg Temp 40 K Antenna to LNA Loss 1. 10 diplexer Temp 75. 09 LNA gain (d. B) 20 N=3. 5 d. B T=359. 23 K System temp (deg K) 399. 23 26. 01 d. B K System G/T (d. B/K) -27. 11 L 14 - L 19 C/No (d. B-Hz) 40. 23 L 12 + L 20 + 228. 6 Data rate (bps) 1000 30 d. B (N = -172. 59 d. Bw) Implementation loss (d. B) 2. 4 incl mod & diff coding Avail Eb/No (d. B) 7. 83 L 21 - L 23 - L 24 Eb/No required (d. B) 4. 4 10 E-5 coded (4. 2 ideal soft) 26 Avail margin (d. B) 3. 43 ST 5 PDR June 19 -20, 2001 L 25 - L 26 11 - 31

GSFC Transponder PDR Review Actions • SCR Held May 10 -11, 2000 – 8 actions assigned, all closed with originator • Transponder PDR October 19, 2000, PDR January 31, 2001 56 RFAs written, 39 closed, 17 Open until Transponder CDR – 2 – 3 – 10 CDR – 11 – 13 – 16 CDR – 17 – 29 – 31 – 35 CDR – 36 – 47 CDR – 49 CDR – 50 CDR Compliance matrix AA Close, fill by CDR Incomplete items AA Open, close by CDR Present signal characteristic to electrical systems ST 5 Done, close by Mechanical, thermal, electrical interfaces AA Done, close by CDR Define resets ST 5/AA Done, close by CDR Work with electrical systems on C&DH interface AA/ST 5 Done, close by Provide parts list AA Done, close by CDR Parts qualification and testing AA Open, close by CDR Plan for reduced magnetic signature AA Open, close by CDR Specify transponder-C&DH command telemetry AA Done, close by above plus special commands ST 5/AA Phase noise vs tracking accuracy ST 5/AA Specify limit on spurs to meet system requirements Done, close by CDR Open, close by CDR AA Open, close by Show that Cmd format is supported by ground stations. ST 5 Open, close by Define testing for development and compatibility Open, close by ST 5 PDR June 19 -20, 2001 AA/ST 5 11 - 32