Transcript Document

Communication Systems
Jason A. Soloff
NASA/GSFC Code 567
August 16-17, 2005
NASA’s Goddard Space Flight Center
Section Number - 1
Lunar Reconnaissance Orbiter (LRO)
Communication System Document List
Level 2
431-SPEC-000008
431-OPS-000042
431-REQT-000004
431-SPEC-000091
Level 3
431-REQT-000137
451-RFICD-LRO/LN
LRO Electrical Systems Specification
LRO Mission Concept of Operations
LRO Mission Requirements Document
General Thermal Systems Specification
Communication System Requirements for the Lunar Reconnaissance Orbiter
Radio Frequency Interface Control Document (RFICD) Between the Lunar Reconnaissance Orbiter
(LRO) and the Lunar Network (LN)
Derived (Level 4)
431-SPEC-000121
431-SPEC-000138
431-SPEC-000178
431-SPEC-000179
431-SPEC-TBD
431-SPEC-TBD
431-SPEC-TBD
431-SPEC-TBD
Performance Specification for the LRO S-Band Transceiver Subsystem
Performance Specification for the LRO Ka-Band Modulator
Performance Specification for the LRO Ka-Band Traveling Wave Tube Amplifier
Performance Specification for the LRO High Gain Antenna System
Performance Specification for the LRO Ka-Band Isolator
Performance Specification for the LRO Omnidirectional Antennas
Performance Specification for the LRO S-Band Hybrid
Performance Specification for the LRO S-Band Isolator
Derived (ICD)
431-ICD-TBD
431-ICD-TBD
431-ICD-TBD
431-ICD-TBD
LRO High Gain Antenna ICD
LRO Omnidirectional Antenna Mechanical ICD
LRO S-Band Subsystem ICD
LRO Ka-Band Subsystem ICD
Derived (I&T Procedures & Plans)
431-PLAN-TBD
LRO S-Band Subsystem Integration & Test Procedure
431-PLAN-TBD
LRO Ka-Band Subsystem Integration & Test Procedure
NASA’s Goddard Space Flight Center
Section Number - 2
Lunar Reconnaissance Orbiter (LRO)
Communication System Level 2 Flow Down Key
Requirements
431-REQT-000137
Communication System Requirements for the Lunar
Reconnaissance Orbiter
Level 2 Req.
Paragraph
Concept/Compliance
Requirement
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CONOPS-9.2.2
CSR-3
The spacecraft shall include a S-Band transmit system capable of
supporting S-Band telemetry in all flight conditions.
Provides S-Band downlink data
capability for telemetry function
MRD-119
(TT&C)
MRD-121
(Radiometrics)
MRD-123
(TLM D/L)
CSR-1
The spacecraft shall include a S-Band transmitter with an output
frequency of 2091.3967 MHz +/- 2.5 MHz.
Frequency assignment per GSFC
Spectrum Management office.
MRD-119
(TT&C)
MRD-121
(Radiometrics)
MRD-122
(CMD U/L)
CSR-2
The spacecraft shall include a S-Band receiver with an operating
frequency of 2271.2 MHz +/- 2.5 MHz
Frequency assignment per GSFC
Spectrum Management office.
MRD-119
(TT&C)
MRD-121
(Radiometrics)
CSR-10
The spacecraft transponder shall support STDN compatible operation.
STDN provides S-Band TT&C,
including the capability for
radiometric measurement.
NASA’s Goddard Space Flight Center
Section Number - 3
Lunar Reconnaissance Orbiter (LRO)
Communication System Level 2 Flow Down Key
Requirements
431-REQT-000137
Communication System Requirements for the Lunar
Reconnaissance Orbiter
Level 2 Req.
Paragraph
Concept/Compliance
Requirement
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CONOPS-9.2.2
CSR-15
The spacecraft transponder shall support downlink subcarrier
modulation of data at rates up to 273 kbps (791.7 Kilo-symbols/sec
after FEC coding). Telemetry data shall be PSK modulated on a 1.7
(TBD) MHz subcarrier.
Provides S-Band downlink data
capability for LRO nominal and
unusual attitude telemetry data
rates per CONOPS.
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CONOPS-9.2.2
CSR-16
The spacecraft transponder shall support direct carrier modulation of
data at rates up to 2.186 Mbps (5 Msps). Telemetry data shall be
OQPSK modulated at baseband on the downlink carrier.
Provides S-Band downlink data
capability for LRO telemetry data
rates during high rate
contingencies per CONOPS
MRD-119
(TT&C)
MRD-122
(Radiometrics)
CSR-11
The spacecraft transponder receiver shall receive and demodulate
command uplink data at a rate of 4 kbps. Command data shall be
PSK modulated on a 16 kHz subcarrier.
Provides S-Band uplink capability
for TT&C function at LRO
command data rates per
CONOPS
NASA’s Goddard Space Flight Center
Section Number - 4
Lunar Reconnaissance Orbiter (LRO)
Communication System Level 2 Flow Down Key
Requirements
431-REQT-000137
Communication System Requirements for the Lunar
Reconnaissance Orbiter
Level 2 Req.
Paragraph
Concept/Compliance
Requirement
MRD-39
(Radiometric Tracking)
MRD-41
(Orbit Determination)
MRD-121
(Radiometric)
MRD-146
(Mission Planning)
CSR-18
The spacecraft transponder shall support radiometric
measurement.
Radiometric measurement
provides range and range-rate
(Doppler) data to the FDF and
LRO Flight Dynamics team.
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CSR-5
The spacecraft shall include a S-Band transmit system with a
radiated EIRP of not less than 34 dBm through the omnidirectional
antennas.
Sufficient EIRP to meet LRO
telemetry requirements during offnominal flight as described in
CONOPS
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CSR-9
The S-Band transmit gain over of the combined omnidirectional
antenna system shall not be less than 0 dBi over 90% (TBD) of the
spherical radiation pattern, including losses due to the
omnidirectional antenna hybrid.
Provides antenna visibility for
TLM/CMD during off-nominal
attitudes & spacecraft
contingencies.
MRD-119
(TT&C)
MRD-123
(TLM D/L)
CSR-4
The spacecraft shall include a S-Band transmit system with a
radiated EIRP of not less than 55 dBm through the high gain
antenna.
Sufficient EIRP to meet LRO
telemetry requirements during
nominal flight as described in
CONOPS
NASA’s Goddard Space Flight Center
Section Number - 5
Lunar Reconnaissance Orbiter (LRO)
Communication System Level 2 Flow Down Key
Requirements
431-REQT-000137
Communication System Requirements for the Lunar
Reconnaissance Orbiter
Level 2 Req.
Paragraph
Concept/Compliance
Requirement
MRD-119
(TT&C)
MRD-123
(TLM D/L)
MRD-124
(High Rate D/L)
CSR-25
The spacecraft downlink telemetry shall be FEC coded using
concatenated CCSDS Reed-Solomon, interleave level 8, and rate ½
convolutional codes.
FEC coding provides necessary
coding gain to ensure required
link BER and link margin.
MRD-119
(TT&C)
MRD-121
(Radiometrics)
MRD-122
(Command Link)
CSR-31
Ground stations in the LRO Ground System shall provide an S-Band
transmit EIRP of not less than 79 dBW.
Allocation to ground station in link
budget.
MRD-119
(TT&C)
MRD-121
(Radiometrics)
MRD-123
(TLM D/L)
CSR-32
Ground stations in the LRO Ground System shall provide a station SBand G/T of not less than 20.3 dB/K, including full lunar noise.
Allocation to ground station in link
budget.
NASA’s Goddard Space Flight Center
Section Number - 6
Lunar Reconnaissance Orbiter (LRO)
Communication System Level 2 Flow Down Key
Requirements
431-REQT-000137
Communication System Requirements for the Lunar
Reconnaissance Orbiter
Level 2 Req.
Paragraph
Concept/Compliance
Requirement
MRD-124
(High Rate D/L)
CONOPS-9.2
CSR-33
The spacecraft shall include a transmitter with an output frequency of
25.650 GHz +/- 200 MHz.
Frequency assignment per GSFC
Spectrum Management office.
MRD-124
(High Rate D/L)
CONOPS-9.2.1.3
CSR-34
The Ka-Band transmitter shall modulate a Ka-Band carrier using
OQPSK, direct carrier modulation, at data rates up to 100 Mbps (229
Mega-symbols per second including all FEC encoding).
OQPSK is required to support
LRO’s downlink data volume
within the allocated spectrum.
MRD-124
(High Rate D/L)
CSR-35
The spacecraft shall include a Ka-Band transmit system with an EIRP of
not less than 54 dBW.
Sufficient EIRP to meet LRO high
rate telemetry requirements
during nominal flight as described
in CONOPS
MRD-124
(High Rate D/L)
CSR-40
The high speed science data shall be encoded using concatenated
CCSDS Reed-Solomon, with interleave level 8, and rate ½ convolutional
encoding.
FEC coding provides necessary
coding gain to ensure required
link BER and link margin.
MRD-124
(High Rate D/L)
CSR-49
Ground stations in the LRO Ground System shall have a Ka-Band
receive G/T of not less than 45 dB/K in the presence of full lunar noise
under clear sky conditions.
Allocation to ground station in link
budget.
NASA’s Goddard Space Flight Center
Section Number - 7
Lunar Reconnaissance Orbiter (LRO)
Communication System Block Diagram
S-Band TT&C Subsystem
50Ω
TT&C Omni
Test Port
50Ω
Omni
A
TT&C Serial
TLM / CMD
RS-422
COUP
TT&C TX I CH CLK/DATA
RF from HGA & Omnis
2.5 Msymbols/sec
RS-422
ISO
2.5 Msymbols/sec
RS-422
TT&C
Transponder
COUP
TX
BRF /
Diplexer
20dB
Coupler
3dB Hybrid
RX
TT&C TX Q CH CLK/DATA
IN
COUP
IN
OUT
OUT
6dB
Coupler
Omni
B
OUT
TT&C RX CLK/DATA
TX to Omni
4 KSps
RS-422
Isolator
IN
TX PA
RX
50Ω
TX to HGA
TX
BRF /
Diplexer
20dB
Coupler
IN
TT&C
HGA
Test Port
NASA’s Goddard Space Flight Center
OUT
COUP
50Ω
TT&C Omni / HGA RF Switch
Discrete
H
G
A
Section Number - 8
Lunar Reconnaissance Orbiter (LRO)
Communication System Block Diagram
Ka-Band High Rate Downlink Subsystem
High Rate Serial
TLM / CMD
RS-422
HIGH RATE I CH CLK/DATA
115 Msymbols/sec
LVDS
HIGH RATE Q CH CLK/DATA
High Rate
Modulator
115 Msymbols/sec
LVDS
TWTA RF Control
NASA’s Goddard Space Flight Center
WG
TWTA
High Voltage
Tube Power
WG
WG
H
G
A
TWTA
EPC
Section Number - 9
Lunar Reconnaissance Orbiter
Communication System
Preliminary Verification Approach
• Communication System Analysis
–
–
–
–
–
–
–
S-Band frequency spectrum interference analysis
S-Band link budget calculation
Ka-Band link budget calculation
HGA RF field calculation and modeling
Omnidirectional antenna RF phasing analysis
Navigation signal accuracy analysis
Mini-RF interference analysis
• Flight Module Testing
– Performed at vendor and as part of LRO I&T
• Comm System Verifications
–
–
–
–
RF compatibility test (RF Compat Lab, TURFTS)
Antenna radiation pattern measurement (GEMAC)
End-to-end communication link BER measurement
EMI/EMC compliance testing with Mini-RF
NASA’s Goddard Space Flight Center
Section Number - 10
Lunar Reconnaissance Orbiter
Communication System Summary
• LRO Communication driving requirements are defined
– COMM preliminary architecture developed in accordance with
defined driving requirements
– COMM system functional allocation of requirements completed
– COMM system component specifications in development
– Interfaces being defined between the following elements at Level 3
• S-Band / C&DH interface
• Ka-Band / C&DH interface
• HGA / Mechanisms interface
– Driving requirements still in development
• Information assurance based on no encryption requirement
The Comm Subsystem is ready for Preliminary Design
NASA’s Goddard Space Flight Center
Section Number - 11