GSFC/JPL

5Space Technology

“Tomorrow’s Technology Today”

Section 15.0

Constellation Communications &

Navigation Transceiver (CCNT)Jeffrey Srinivasan,Yoaz Bar-Sever,Allen Farrington of JPL

ST5 PDR June 19-20, 2001

ST5 PDR June 19-20, 2001

GSFC

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Agenda•Key Requirements

•Power, Mass, Volume Budgets

•Review History and Status

•Design Details

– H/W

– Analysis Planned

– S/W

• Integration & Test Flow

•Operations/Validation Plan

•Mission Data Flow

•Risks and Mitigations

ST5 PDR June 19-20, 2001

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Key Requirements

•The S/C shall measure relative position knowledge to within 0.1% accuracy (1 sigma) (MRD 3020200)

– 4.4.1.3 Inter-S/C Ranging: CCNT shall meet the following performance requirements for Inter-S/C Ranging:

• Operational range 100 - 1000 km

• Ranging Accuracy 5 meters

Full Compliance (CBE: <4m @ 100km & 5 s avg w/worst case specs)

•The S/C shall acquire on-board GPS data for ground processing and orbit determination (MRD 30201000)

– 4.4.1.4 GPS Receive, Store and Processing Capability: CCNT shall meet the following performance requirements for GPS Receive and Processing Capability:

• Operational Range for Continuous GPS Tracking Below 5000 km altitude

• Maximum Number of single-frequency satellites 12

Full Compliance (CBE: capable of 12 simultaneous GPS tracks)

ST5 PDR June 19-20, 2001

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Key Requirements - cont

•The mission shall demonstrate the concept of Science Event Warnings (MRD 20400000)

•Each S/C shall provide the ability for inter-S/C communications (MRD 30300000)

– 4.4.1.2 Inter-S/C Communications: CCNT shall meet the following performance requirements for Inter-S/C Communications:

• Symbol rate for inter-constellation communications from 100-1000 km range shall be at least 100 bps (TBR)

• Minimum latency for transfer of data (including Space Events) received from local C&DH to remote C&DH shall be less than 50 sec (TBR)

• Full Compliance (CBE: a. 3dB margin w/worst case subsystem specs

b. Approach w/<10 sec latency identified)

ST5 PDR June 19-20, 2001

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Key Environmental Requirements

4.7 ENVIRONMENT The CCNT shall be designed to operate properly in the face of the following environmental requirements. (a) Orbital Parameters

(i) Perigee Altitude: 200 km (ii) Apogee Altitude: 35786 km (iii) Period: 10.2 hrs (iv) Inclination: 28.5 deg

(b) Radiation (i) Total Ionizing Dose (TID): 40 Krads-Si/3 months (including 2x margin) (TBR) (ii) Linear Energy Transfer (LET): 40 MeV-Cm^2/mg

(c) Thermal (i) Operating (°C): Electronics Unit: -10 to 40 All Antennas: -60 to 40 (ii) Survival (°C): Electronics Unit: -30 to 60 All Antennas: -80 to 80 (iii) Transients: Unless otherwise specified the component provider shall assume that the maximum rate of change of any component or mounting interface, when integrated to the spacecraft, will be no greater than 2° C per minute. (iv) Watt-Density: Electronics Unit: 0.18 W/cm2 (v) Life Cycles: 200 Transients

20; Each Axis TBD

per CCNT Performance Specification - ST5-495-008

ST5 PDR June 19-20, 2001

GSFC

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Allocated CBE

Power (Spec-4.3.1b)

Standby 2.6W 3.1W

S-band Rx 8.5W 7.5W

L-band Rx 10.0W 7.8W

S-band Rx/Tx 12.8W 12.3W

Mass (Spec-4.2.1) 1900g 2000g

Volume (Spec-4.2.1)

Elec Unit 18 x 16 x 8 cm 18 x 16 x 8 cm

S Antenna 5.3 x 6.9 x 7cm5.3 x 6.9 x 7cm

L Antenna 7.5 x 7.5 x 1cm7.5 x 7.5 x 1 cm

Budgets

(Allocations above do NOT include 20% reserve against allocation. Half of this reserve is held by the CCNT Project Mgr. and the other is held by ST5 Project Mgr. (MOU-GSFC/JPL))

ST5 PDR June 19-20, 2001

GSFC

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Review History/Plans

• February 15, 2000: JPL Internal Peer ReviewMajor RFAs DispositionUHF cross link is risky in terms of noise & allocation Use S-bandConsider half duplex to get rid of duplexer Descope optionDependence on Mars Network Funding Dependence removedInsufficient budget Revised budget

• October 20, 2000: JPL Internal Conceptual Design and Cost Review

No Major RFAs

• March 15, 2001: Informal Preliminary Design & Cost Review @ GSFC

Major RFAs DispositionAdjust schedule of major deliveries ComplyDeliver 2 FM, 1 flyable WQM Comply

• June 20, 2001: Support ST5 PDR @ GSFC • June 27, 2001: Formal CCNT PDR @ JPL

ST5 PDR June 19-20, 2001

GSFC

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Top-Level Block Diagram

Test 422 Port (w/ skin conn)

Flight Computer 422 Port (Command & Telemetry)

S-band Antenna

L-band Antenna

xmt

rcv

rcv

memory

dsp

µproc

ctrl

Electronics Chassis

Antenna Subsystem RF Subsystem Digital Baseband Subsystem

To Spacecraft Subsystem

DC Power

= procured

= in house

adc

regulators

Science Event Warning (discrete)

Analog Temp Sense

ST5 PDR June 19-20, 2001

GSFC

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• H-frame design • RF half / Digital half • “hot” parts mounted near

or on bottom plate • Connectors on top

• three SMA (RF) • two D-shell (C&DH / Test)

Electronics Unit Chassis

Bottom View

Side View End View

ST5 PDR June 19-20, 2001

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S-band Rx / Tx Supplier: AeroAstro (fab, test), JPL (sys eng, parts), GSFC (parts) Flight Heritage: New Design; derived from ST-5 X-band transponder

L-band Rx Supplier: JPL in-house build Flight Heritage: Flying on CHAMP & SAC-C

Interfaces

CMOS data; 2 Mbps

near-zero IF; 3v peak-to-peak

L-band RF; 0.8 v peak-to-peak

sine wave; +0 dBm

L1 BPF L1 BPF L1 BPF L1 BPF

LNAfrom Antenna rcv RF

+3.9v

CMOS ctrl x 4

regulated DC pwr

unreg. DC pwr

notch #2

notch #1

BP #2

BP #1

X X

diplexerfrom Antenna

xmt data

rcv IF

38.656 MHz

Synthesizer

Dual Synthesizers

DiscreteControl

1 W

LNA

Vector Modulator

+7.2v

Contractor

RF Subsystem

15 - 10

ST5 PDR June 19-20, 2001

GSFC

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Digital Signal Processor (DSP)

Interfaces

Std. S/C +7.2v Power Bus

RS-422 (232c) serial interface; BJDLP packets

Analog-to-Digital Converters

microProcessor

non-volatile memory volatile memory

RS-422 Interfaces

(2)

S/CC&DH

System Controller

Linear Regulators

+7.2v (unregulated)+7.2v

High Speed Digital Signal Processing

38.656 MHz Ref.

Xmt Data to S-band Tx

L-band RF S -band IF to S-band Rx/Tx

+3.9v +3.3v +2.5v +1.8v

L-band: GPS Std.

S -band: CCSDS Proximity-1 data (phys/link layers); Ranging code (GPS C/A)Samp

PWB

DSP PWB

S-band Ctrl x 4

Science Event Warning

Discrete Pulse; RS-422 differential

CMOS Ctrl x4

ST5 PDR June 19-20, 2001

GSFC

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DSP

• Flying on CHAMP and SAC-C

– GPS Receiver algorithms

– BlackJack Data Link Protocol (BJDLP) on C&DH Interface

– L-band A-to-D, 38MHz reference oscillator

• S-band A-to-D will fly on GRACE (Nov. 2001 launch)

• CCSDS Proximity-1 Protocol prototyped on COTS DSP

• Embedded DSP is new design - based on above COTS

– Another JPL instrument has baselined common embedded DSP

• Final Flight Parts List Complete

– Long lead items identified; procurements begin July 2001

ST5 PDR June 19-20, 2001

GSFC

15-13

CCNT to C&DH Interface Details

• C&DH Interface

– Full-duplex, RS-422 differential w/RS-232

– Asynchronous 38.4 kbaud transmit and receive

• CBE vs. channel capacity

– From CCNT: less than 17kbps

– To CCNT: less than 10bps (mostly quiescent)

• Science Event Warning Discrete Interface

– Output Only, RS-422 differential

– Non-periodic, low duty cycle pulse triggers alert to constellation

• C&DH interface signals replicated on Ground Support Equipment Interface

– Available on Direct Access (Skin) connector

• PSE Interface

– Input, +7.2V, unregulated (+1.2V), non-isolated

ST5 PDR June 19-20, 2001

GSFC

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Antenna SubsystemAntenna

Supplier

FlightHeritage

Antenna

53mm

69mm

36mm

S-band L-band

DERA, UK Sensor Systems

Antenna Flying on STRV-1c/d;mission critical gnd comm

Antenna Flying on CHAMP;mission critical GPS

Other Will be deployed by GSFCdesigned/supplied boom[Spec-4.2.2]

Fixed, surface-flush mount

ST5 PDR June 19-20, 2001

GSFC

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S-band Link Details

90

Inter-Spacecraft Link Details

Categories UNITS COMMENTSSimultaneous Nodes in Network 3

MHz 2090

MHz

Each CCNT can rcv and xmt in either band;

Frequency Bands

Modulation BPSK

Pure Tone Capable YesGPS-like

Modulation Index deg 90Data Rate bps 500 Forward and Return Link are symmetricPower Amp WLink BER 10 E-5

Coding Scheme Convolutional (r=1/2, k=7) YesDoppler Offset kHz +/-10Doppler Rate Hz/s 20Range accuracy in 1 second m < 5

SPECIFICATION

1

Scalable in “star” configuration

2270

Ranging Code nominal 2 MChip/second; GPS C/A code

software implementation

suppressed carrier

Protocol CCSDS Proximity-1

TBCTBC

ST5 PDR June 19-20, 2001

GSFC

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Analysis

•Thermal Analysis (SOW-4.3.3 deliver @ CDR)

– JPL Thermal Engineer staffed & analysis begun

– Key Focus:

• 1 Watt Power amplifier placement/thermal path

• Processor/FPGA

•EMI/EMC with magnetics emphasis (Spec-4.3.1)

– JPL magnetics experts staffed & analysis begun

– Design team has experience designing, building & testing on magnetically “clean” S/C with magnetometers

ST5 PDR June 19-20, 2001

GSFC

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Analysis

•Mechanical Design & Dynamics Analysis (SOW-4.3.3 deliver @ CDR)– JPL Mechanical Engineer to be staffed by June 10, 2001

– CCNT Packing Engineer and CAD Engineer work with above to analyze chassis design to ensure compliance with dynamics requirements

•Electrical Analysis (SOW-4.3.3 deliver @ CDR)– Will perform

• Failure Modes Effects analysis for S/C interfaces only

• Electrical Worst Case analysis, including electrical stress

– JPL Quality Assurance Engineer to be added no later than

July 15, 2001, to assist design team with analysis

ST5 PDR June 19-20, 2001

GSFC

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S/W Block Diagram

0

01

N

0Transmit Data + FEC enc + PN Seq. Control

C h a n n e l s

H / W Re c e i v e

C h a n n e l

H / W T r a n s m i t

Data to Transmit

0

1

0

Data Bit FEC dec & Protocols Processing

Control

CCNT System Software and Operation Control Module

Commands

Data Format

and Transmit Control

Data Receive

and Routing

Command Receive

and Decode

C o m p u t e r I N

Sp a c e c r a f t

C o m p u t e r O U T

Sp a c e c r a f t

RTG Module GPS & Range Processing

3

514

8

911

7

12

i

j

k

Constellation State Estimate (TBD epoch)

l

o++

Acquire, Track; Fit and Output ø, R, SNR,

Telemetry

1

G P S

Re c e i v e

Acquire, Track, Fit and Output ø, R, SNR

15 GPS Almanacsm

from all modules

remote data streams (200 bps)

Status & Health (100 bps)

local observable stream (1 sec epoch)

Science Event Alertn 1

GPS observable stream (1 sec epoch)

ST5 PDR June 19-20, 2001

GSFC

15-19

S/W Subsystem• S/W Development Process

– Based on JPL S/W Development Process (D-15378)

• Using “Class B” process for Mission Enabling applications

• Documented in S/W Development Plan (draft complete)

– Applications code written in C++

– RTOS is COTS from GreenHills S/W (in place/running)

– Development System

• Sun/Solaris Workstations (in place)

• GreenHills S/W “MULTI 2000” tool chain (in place); widely used at JPL for Flight S/W development

• Interface with C&DH

– Packet-based interface using BJDLP

• Flying on CHAMP and SAC-C

ST5 PDR June 19-20, 2001

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S/W Subsystem - cont•S/W Design and Prototyping Status

– RTOS, FPGA interface and CCSDS Prox-1 running on COTS DSP

– BJDLP ported to RTOS

– Common system S/W, link protocol and signal tracking modules with another JPL instrument

•CPU and memory margins; heritage-based estimates

CPU 200 MHz 25% utilized

Memory

SDRAM 16 MB 33% utilized

FLASH 8 MB 25% utilized

ST5 PDR June 19-20, 2001

GSFC

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I&T Plan

EM subassembly fabrication/test (2)

EM instrument integration/test (2)

EM functional test/thermal cycling

QM subassembly fabrication/test

QM instrument integration/test

QM functional test

QM qualification dynamics tests

QM qualification TV tests

Delivery to GSFC FlatSat

Delivery to GSFC

Delivery to GSFC for Compatibility test

Return to JPL

FM subassembly fabrication/test (3)

FM instrument integration/test (3)

FM functional test (3)

FM acceptance dynamics tests (3)

FM acceptance TV tests (3)

Delivery to GSFC (2)

Constellation Tests w/ Proto # 2

Upgrade EM @ GSFC w/ RF subsystem &

SW

Constellation Tests w/ Proto #2

EM #2 remains @ JPL

EM Flow QM Flow FM Flow

S/C Integration Support

S/C Integration Support

Constellation Tests w/ other S/C

EM functional test

QM EMI/EMC tests

FM EMI/EMC tests

ST5 PDR June 19-20, 2001

GSFC

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Operations/ValidationA

C

B

ft

fr

• Initially, all constellation elements listen at

• Whoever initiates Comm, transmits at Others then respond on .

• Link is terminated when required task complete

ft

ft

fr

Flight validation of the CCNT shall be implementedas discrete demonstration events for eachfunctional mode of operation (10102010).

3.2 R

Cross Link Experiments

2 R

GPS Tracking

Ground Link possible

0

5

10

15

20

0 3 6 9 12

PerigeePerigee

GPS-based orbit determination

ST5 PDR June 19-20, 2001

GSFC

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Mission Data Flow

ST-5 operations centermakes CCNT data availableto JPL within one hour

CCNT Flight Data Output

CCNT Operations Center

GPS data (time, phase, pseudorange)Crosslink ranging data (time, phase, pr)Crosslink comm dataEstimator data (state, covariance)Engineering data

Software tool: GIPSY-OASIS IIAuxiliary data: Precise GPS orbitsProducts: orbits, clocks, rangesValidation: ranging, data rate, latency, orbit determinationPerformance assessment

ST5 PDR June 19-20, 2001

GSFC

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Risks & Mitigation Plans•Power Consumption

– DSP team actively reducing power in design by lowering clock speeds in microprocessor and FPGA

– Identifying power-driving requirements and considering descopes

• Will consider FPGA-only acquisition design that allows processor to sleep until signal detected

•Delivery of S-band RF subsystem

– JPL actively doing RF system engineering

– Finalizing contract SOW that is appropriate for contractor

– Working with JPL Contracts Office to expedite letting of this contract

– Schedule risk is driver

• Will consider fixed Rx/Tx bands to simplify diplexer and RF switch

• Will consider half-duplex operations to eliminate diplexer

GSFC/JPL

5Space Technology

CCNT Back-up Slides

“Tomorrow’s Technology Today”

ST5 PDR - June 19 & 20, 2001 25

ST5 PDR June 19-20, 2001

GSFC

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CCNT Schedule

ST5 PDR June 19-20, 2001

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Governing DocumentsTop Level Documents (Overriding; GSFC & JPL Generated)

• Statement of Work for CCNT ST5-495-009 Under Final Review• Performance Specification for CCNT ST5-495-008 Under Final Review

ST5 Generated Documents (Subordinate)

• ST5 Mission Requirements Matrix ST5-495-051 Baseline 04/06/01• System Safety and Mission Assurance

Program for the ST5 Mission ST5-495-010 Baseline + 1 09/28/00• ST5 Component Test Requirements

and Guidelines ST5-495-007 Baseline + 2 12/21/00• ST5 Electrical Requirements Document ST5-495-016 In Draft• ST5 Ra diation Specification ST5-495-031 Baseline 12/21/00

JPL Generated for CCNT Documents (Subordinate) *Requires ST5 Approval

• Electrical/Mechanical/S/W ICD * In Draft (Final 11/12/01)• Safety and Mission Assurance Plan* In Draft (Final 06/25/01)• Risk Management Plan In Draft (Final 11/12/01)• Validation Requirements and Implementation Plan* In Draft (Final 11/12/01)• Project Schedule* Under Final Review

• Qualification/Acceptance Test Plan/Procedures* Final 04/02/02• S/W Development Plan * Final 11/12/01• S/W Test Plan/Procedure * Final 11/12/01• CCNT User’s Manual Final 01/07/02

ST5 PDR June 19-20, 2001

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All Top-Level RequirementsRequirements Flow-Down from Project to CCNT subsystem 10102010 Flight validation of the CCNT shall be implemented as discrete demonstration events for each functional mode of operation. 10102020 Failure of the CCNT shall not degrade the operation of the spacecraft 10102040 The CCNT unit shall provide telemetry information, in the form of packets, that includes status information pertaining to the operational state of the unit (i.e., operational mode, sub-component on/off status, processor health, etc.), the RF performance of the unit in both the cross-link transceiver and the GPS receiver configurations (i.e., receive gain, transmit power, tracking status, etc.), the thermal performance of the unit (i.e., oscillator stability, high power amp base plate, etc.) and the communication performance of the unit (i.e., bit errors, message errors, etc.) 10102050 The CCNT shall operate in four basic functional modes of operation 10102051 The [CCNT] sleep/standby mode of operation shall permit the unit to retain local memory and operate spacecraft interfaces but place the unit in the minimum power state. 10102052 The [CCNT] listen only mode shall permit the CCNT to listen for inter-spacecraft communication traffic with a minimum amount of power required to run the cross-link receiver section of the unit and spacecraft interfaces. 10102053 The [CCNT] transmit mode shall permit the CCNT to communicate with the other spacecraft in the constellation for short periods of time in order to transfer information and/or measure relative distance between spacecraft. 10102054 The [CCNT] navigation mode shall permit the CCNT to track the GPS constellation and solve for the spacecraft orbital state. 10502000 The spacecraft shall be designed for a 3 month mission duration. 20102010 The spacecraft shall be designed so that generated electric and/or magnetic fields do not interfere with magnetometer measurements. 20102011 The spacecraft generated magnetic fiel d at the magnetometer sensor shall be less than 0.1 nT from DC to 0.1 Hz and less than 0.05 nT for frequencies between 0.1 Hz and 200 Hz. 20301000 Total science validation data shall not exceed 6 megabytes of total solid state recorder space. 20400000 The mission shall demonstrate the concept of Science Event Warnings (SEW) 20401000 S/C shall be capable of detecting, responding and communicating the occurrence of science events autonomously. 20402000 S/C shall communicate real time science event detection to other S/C in the constellation within 1 sec of occurrence. 20402020 The constellation communication network shall transmit the event detection message upon signal receipt from detecting spacecraft to the receiving spacecraft within 600 msec. 20403000 SEW shall be communicated to all other spacecraft in the constellation using the Cross-link communications capability of the system. 30101010 Spacecraft Relative Separation shall be between 100 – 1000 km at apogee. 30201000 Acquire on-board GPS data for ground processing and orbit determination. 30201010 The GPS data shall be accurate to determine the spacecraft position to within 10m. 30201020 The ability to collect GPS data at both 200 km and 36000 km altitudes shall be possible. 30202000 The spacecraft shall measure relative position knowledge to within 0.1% accuracy (1 sigma). 30300000 Each spacecraft shall provide the ability for inter-S/C communications. 30301000 The spacecraft shall exchange health and safety telemetry via S/C to S/C communications. 30302000 The cross-link communication shall be conducted at S-band frequencies. 30303000 The cross-link communication channel shall implement a reliable multi-point to multi-point communications protocol. 30304000 The CCNT shall be capable of transmitting data between spacecraft in the constellation at a 1Kbps rate at 1000Km separation distances.

ST5 PDR June 19-20, 2001

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Requirements on Mission

10102030 The [Flight Software] system shall provide command and telemetry capability to determine the functionality and performance of the CCNT unit.

10102031 The ability to code CCNT-specific data to the CCNT unit shall be supported on

board the spacecraft. 10102032 The ability to store information packets from the CCNT unit for transmission to

the ground shall be supported on board the spacecraft. 10102033 The ability to send command packets from the ground to the CCNT unit, without

on-board interpretation of the data shall be implemented. 10704000 The mounting and orientation of all instruments and sensors shall provide

unobstructed Fields of View as required. 30304010 The spacecraft shall include structure and mechanisms for deployment of a

cross-link antenna and a GPS antenna.