section 11.0 communications subsystem victor j. sank communications lead engineer 5 space technology...
TRANSCRIPT
Section 11.0
Communications Subsystem
Victor J. SankCommunications Lead Engineer
5Space Technology
“Tomorrow’s Technology Today”GSFC
ST5 PDR June 19-20, 2001
ST5 PDR June 19-20, 2001
GSFC
11 - 2
Agenda• Key Requirements
• Documentation
• Allocations
• Transponder, Diplexer and HPA Layout
• System Concept Design
• Link Budgets
• Antenna
• Block Diagram
• Development
• Testing
• Issues
• Back-up Slides
ST5 PDR June 19-20, 2001
GSFC
11 - 3
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; 1Kbps and 100Kbps. (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)
ST5 PDR June 19-20, 2001
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Derived Requirements• 10MB HK and Science data playback plus RT HK in
25-30 min contact
• 11m 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
ST5 PDR June 19-20, 2001
GSFC
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DocumentationCommunicationSubsystem
Specification
ST5-495-023 Preliminary
X-Band Transponder SOW
ST5-495-004 21DEC00
X-Band TransponderSpec
ST5-495-003 14MAR01
X-Band TransponderMechanical ICD
ST5-495-041 Preliminary
X-Band TransponderElectrical ICD
ST5-495-042 Preliminary
X-Band Antenna ICD
ST5-495-047 Preliminary
ST5 PDR June 19-20, 2001
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System Allocations• Mass
– Transponder Unit .198 Kg– Front End Unit (Dplxr & HPA) .210 Kg– Antenna .120 Kg– System Total .528 Kg
• Volume – Transponder Unit 187.5 cm3
– Front End Unit 80.0 cm3
– Antenna 157.5 cm3
• DC Power– Rcvr Only 4 W – Rcvr and Xmtr 12 W
• Thermal Operate Survive– Transponder, HPA & Dplxr -20 to 50 °C -40 to 60 °C – Antenna -60 to 40 °C -80 to 80 °C
ST5 PDR June 19-20, 2001
GSFC
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Transponder, Diplexer and HPA Layout
Transponder
(2.95 x 2.45 x 1.97 in)
Diplexer
(3.3 x 1.1 x 0.5 in)HPA
(3.0 x 1.5 x 0.6 in)
Scale: 3”
ST5 PDR June 19-20, 2001
GSFC
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Communications System Design Concept (1 of 2)
• Performance
– Two Data rates baselined; 1 and 100 Kbps
– At <5Re Data transfer of 100Kbps with a BER of <1X10-5
– Two-way, Coherent Doppler Tracking is baseline
– One-way Doppler will provide backup orbit determination
• Other Attributes
– 5V transponder, excluding HPA
– HPA mount point minimizes thermal variation at Oscillator
– X-band Uplink and Downlink
– 3 dB margin in Telemetry link budget
– >20 dB in Command link budget
ST5 PDR June 19-20, 2001
GSFC
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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)
• ST5-1 0011100000 E0• ST5-2 0001011110 5E • ST5-3 0010011011 9B
– SOMO/CSOC SCIDs assigned (for ground handling of data)• ST5-1 0100011 23• ST5-2 0100100 24• ST5-3 0100101 25
ST5 PDR June 19-20, 2001
GSFC
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Link Budget: X-band Space – Ground (1 of 2)
1 Transmitter Power (W) 1.9 2.79 dB2 Antenna gain (dB) 0.003 SC Antenna beamwidth (°) 40.00 FWHM4 Passive Loss (dB) 1.0 cables, etc.5 EIRP (dBW) 1.79 31.79 dBm6 Freq. (MHz) 84707 Range (km) 32000 5Re8 Space loss (dB) 201.119 Atmos, Scint, Rain Att (dB) 0.9 high elevation10 Polarization loss (dB) 1.511 Rcvd power den (dBW/m2) -162.0112 Rcvd PSD over 4 KHz -181.91 convo coded
ST5 PDR June 19-20, 2001
GSFC
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Link Budget: X-band Space – Ground (2 of 2)
13 Ground antenna size (m) 11 36.09 ft 14 Antenna gain (-surf loss)(dB) 56.92 55% eff15 Antenna beamwidth (deg) 0.22 FWHM16 Power Received (dBm) -115.00 Bkg Temp 40K17 Antenna to LNA Loss (dB) 1.00 diplexer Temp 75.0918 LNA gain (dB) 25 N=1.2dB, T=92.29K19 System temp (deg K) 231.28 23.64 dB K20 System G/T (dB/K) 33.27 L14 - L1921 C/No (dB-Hz) 59.86 L12 + L 20 + 228.622 Data rate (bps) 100000 50dB (N = -
154.96dBw)23 Implementation loss (dB) 2.4 Rcvr and BS24 Avail Eb/No (dB) 7.46 L21 - L23 - L2425 Eb/No required (dB) 4.4 10E-5 coded (4.2
ideal)26 Avail margin (dB) 3.06 Line 24 - Line 25
ST5 PDR June 19-20, 2001
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Link Budget: X-band Ground – Space (1 of 2)
1 Transmitter Power (W) 5.0 6.99 dB2 Antenna gain (dB) 55.8 11 m3 SC Antenna beamwidth (°) 0.26 FWHM4 Passive Loss (dB) 1.0 cables, etc.5 EIRP (dBW) 61.79 91.79 dBm6 Freq. (MHz) 7209.1257 Range (km) 32000 5Re8 Space loss (dB) 199.719 Atmos, Scint, Rain Att (dB) 1.4010 Polarization loss (dB) 1.011 Rcvd power den (dBW/m2) -102.2112 Rcvd PSD over 4 KHz -102.11
ST5 PDR June 19-20, 2001
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Link Budget: X-band Ground – Space (2 of 2)
13 Space antenna size (m) omni14 Antenna gain (-surf loss) 0.015 Antenna beamwidth (deg) 40 FWHM16 Power Received (dBm) -110.69 Bkg Temp 40K17 Antenna to LNA Loss (dB) 1.00 diplexer Temp 75.0918 LNA gain (dB) 25 N=3 dB, T=288.63K19 System temp (deg K) 315.45 Bkg 40. dB K20 System G/T (dB/K) -24.96 L14 - L1921 C/No (dB-Hz) 62.82 L12 + L 20 + 228.622 Data rate (bps) 1000 30dB (N = -173.43 dBW)23 Implementation loss (dB) 2.4 incl mod & diff coding24 Avail Eb/No (dB) 30.42 L21 - L23 - L2425 Eb/No required (dB) 9.6 10E-5 uncoded26 Avail margin (dB) 20.82 Line 24 - Line 25
ST5 PDR June 19-20, 2001
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ST5 Quadrafilar Helical Antenna
Operating Frequency: 8.47 GHzLHCPDiameter: 0.150 inchesLength: 1.125 inchesTurns: 1
Trace: copperDielectric core: EccoStock LoK(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.
Beamwidth +20 to +60º from eclipticReceive Gain 0dB Transmit Gain 0dB
ST5 PDR June 19-20, 2001
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Antenna Gain (Stand alone)
ST5 Quadrifilial Helical Antenna
-30
-25
-20
-15
-10
-5
0
5
Angle (Deg)
LHCP RHCP
(Ga
in in
dB
)
-180
-160
-140
-120
-100
-8
0
-6
0
-4
0
-2
0
0
2
0
4
0
6
0
8
0
100
120
140
160
180
ST5 PDR June 19-20, 2001
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Antenna Gain with Choke Rings
ST5 Ideal Antenna with Choke Ring
-50
-40
-30
-20
-10
0
10
-180
-155
-130
-105 -80
-55
-30 -5 20
45
70
95
120 145
170
Degree
Ga
in (
dB
)
LHCP RHCP
ST5 PDR June 19-20, 2001
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Transponder Functional Block Diagram
Downlink Telemetry from C&DH
Transponder Mode Control from C&DH
Rx/Tx Status Output to C&DH
UpLink Lock to C&DH Cmd Decoder
Auxiliary Command Inputs
C&DH Data
C&DH Clock
+7.2Vdc +5Vdc
Diplexer
Transponder Controller
Special Command Detector
Receiver
TransmitterHPA
Tx
RxCoherent Reference
Telemetry
Status
Control
Command
Status/Control
Front End Units Transponder
LO Generator
Oscillator
X-band Up/Down
LNA
SpecialCmd reset
Downlink Clock to C&DH
ST5 PDR June 19-20, 2001
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Transponder RF Block Diagram
113
244
636
LoopFilter
LoopFilter
LoopFilter
9.625 MHzTCVCXO
DIPLEXER
SP
LIT
TE
R
DR
V
LNA VGABPF BPF
BPF LPF
VE
CT
OR
MO
DU
LA
TO
RZ
ER
O-I
FR
EC
EIV
ER
BASEBAND PROCESSOR
6121.5 MHz
2348
.5 M
Hz
1087
.625
MH
z
2348.5 MHz8470.0 MHz
7209.125 MHz 1087.625 MHz
AGC
RX I
RX Q
TX Q
TX I
FROM BASEBANDPROCESSOR
Front-EndAssembly
TRANSMITTER
RECEIVER
C-BAND SYNTHESIZER DUALSYNTHESIZER
RX
CO
ND
ITIO
NIN
G
TR
AC
KIN
G
REFERENCETUNING
TX
CO
ND
ITIO
NIN
G
C&DHINTERFACE
SPECIALCOMMANDDECODE
TX DATA
C&DH
RX
DA
TA
SYNTHESIZERLOCK DETECT
ADC
ADC
HP
A
Electronics Unit
C&
DH
ST5 PDR June 19-20, 2001
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L, C and S-band Synthesizers
ST5 PDR June 19-20, 2001
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Transponder Digital Block Diagram
TrackingRX
Conditioning
Data ClockGeneration
SpecialCommandDecode
C&DHCommand /
StatusInterface
LPF,2kHz-1MHz
LPF,2kHz-1MHz
I fromTuner IC
Q fromTuner IC
I in
Q in
RX DataData out
9.625MHzVCO
To Synth.
MasterClock
Lock Indication& other status
OscillatorControl
I in
Q in Q out
I out
RX Clock
TX Clock
RX Data
Commands/ Status
Commands/ Status
Parameter change / status read
ADCClocking
SpecialCommands
TXConditioningData Out Data In
Synthesizer setup &other commands
Radiostatus
RadioCommand
C&DHinterface
Discreteinterface
Hard & SoftC&DH ResetC&DH Cmd& Status
CommandsOut RX Clock
RX Data
RX Clock
TX Clock
TX Data6-8 bitDAC or
ResistorLadder
To Modulator IC
To AGC AGC +/-
Loopback
(2 rates, andset-to-nominal)
8 bitADC
8 bitADC
XpdrResetSoft Reset
Bit Lock Bit Lock
CarrierDetectSignal Detect
ST5 PDR June 19-20, 2001
GSFC
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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
ST5 PDR June 19-20, 2001
GSFC
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Communications System Technology
• Technology Characteristics
– Receiver and transmitter will use common frequency synthesis (common to any transponder)
– Under development by AeroAstro
– Technical Readiness Level is currently about 3/4
• Untested conventional design, Hardware prototyping
ST5 PDR June 19-20, 2001
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Testing and RFGSE• Test Program is under Development per ST5-495-007,
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 8596E)• Oscilloscope (HP54602B)• Plotter/Printer/PC• Power Meter (HP4418A)• Power Meter Heads (HP8481A, H)• Bit Error Rate Test Set (FBD-6000A or BitAlyzer 26, 400, 622)
ST5 PDR June 19-20, 2001
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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
ST5 PDR June 19-20, 2001
GSFC
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Risk and Mitigation (2 of 2)• Mitigation
– GSFC is working with AeroAstro to specify and buy the transponder oscillator. GSFC will provide for screening and qualification of the oscillator for flight with the chosen vendor and deliver it to AeroAstro for integration and qualification of the transponder. To mitigate scheduling risk, AeroAstro 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 AeroAstro. 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 in-band. Even though BRF may not be needed, specifications are being drawn up and filter will be ordered.
Back-up Slides
Communications Subsystem
ST5 PDR June 19-20, 2001
GSFC 5Space Technology
“Tomorrow’s Technology Today”
11 - 26
ST5 PDR June 19-20, 2001
GSFC
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ST5 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
– AeroAstro 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
ST5 PDR June 19-20, 2001
GSFC
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Transponder Tracking Block Diagram
ST5 PDR June 19-20, 2001
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SINDA/G Thermal Analysis
6145Oscillator
7257Up/Down converter
8469Synthesizer
6045Baseband
Max Board Temp(°C)
Max board Temp (°C)
Radio Board
S/C 40 °CS/C 25 °C
ST5 PDR June 19-20, 2001
GSFC
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CCNT Link Budget: S-band Space - Space
1 Transmitter Power (W) 1.0 0.00 dB2 Antenna gain (dB) 0.003 SC Antenna beamwidth (deg) omni FWHM4 Passive Loss (dB) 1 cables, etc.5 EIRP (dBW) -1.0 29.0 dBm6 Freq. (MHz) 22657 Range (km) 10008 Space loss (dB) 159.559 Atmos, Scint, Rain Att (dB) 0.010 Polarization loss (dB) 0.211 Rcvd power den (dBW/m2) -132.7012 Rcvd PSD over 4 KHz -102.11 convo coded
ST5 PDR June 19-20, 2001
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CCNT Link Budget: S-band Space - Space
14 Antenna gain (-surf loss)(dB) 0.0 55% eff15 Antenna beamwidth (deg) omni FWHM16 Power Received (dBm) -131.25 Bkg Temp 40K17 Antenna to LNA Loss 1.10 diplexer Temp 75.0918 LNA gain (dB) 20 N=3.5dB T=359.23K19 System temp (deg K) 399.23 26.01 dB K20 System G/T (dB/K) -27.11 L14 - L1921 C/No (dB-Hz) 40.23 L12 + L 20 + 228.622 Data rate (bps) 1000 30 dB (N = -172.59dBw)
23 Implementation loss (dB) 2.4 incl mod & diff coding24 Avail Eb/No (dB) 7.83 L21 - L23 - L2425 Eb/No required (dB) 4.4 10E-5 coded (4.2 ideal
soft)
26 Avail margin (dB) 3.43 L25 - L26
ST5 PDR June 19-20, 2001
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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, 200156 RFAs written, 39 closed, 17 Open until Transponder CDR
–2 Compliance matrix AA Close, fill by CDR–3 Incomplete items AA Open, close by CDR–10 Present signal characteristic to electrical systems ST5 Done, close by CDR–11 Mechanical, thermal, electrical interfaces AA Done, close by CDR–13 Define resets ST5/AA Done, close by CDR–16 Work with electrical systems on C&DH interface AA/ST5 Done, close by CDR–17 Provide parts list AA Done, close by CDR–29 Parts qualification and testing AA Open, close by CDR–31 Plan for reduced magnetic signature AA Open, close by CDR–35 Specify transponder-C&DH command and telemetry AA Done, close by CDR–36 above plus special commands ST5/AA Done, close by CDR–46 Phase noise vs tracking accuracy ST5/AA Open, close by CDR–47 Specify limit on spurs to meet system requirements AA Open, close by CDR–49 Show that Cmd format is supported by ground stationsST5 Open, close by CDR–50 Define testing for development and compatibility AA/ST5 Open, close by CDR–53 Develop plans for false and self lock testing AA Open, close by CDR–54 Generate plans for packaging AA Open, close by CDR