page 1 satellite to satellite tracking...
TRANSCRIPT
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GOCE Workshop
SATELLITE TO SATELLITE TRACKINGSATELLITE TO SATELLITE TRACKINGINSTRUMENTINSTRUMENT
A. Zin, S. Landenna
A. Conti
DESIGN
PERFORMANCE
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HERITAGE
SSTI instrument is based on the LAGRANGE receiver architecture
LAGRANGE receiver development started in 1998 with Alcatel Alenia Space Italia S.p.A.internal funds
The product is developed, manufactured and tested by the Navigation Department inMilan plant
LAGRANGE X-prototype developed in 1999 with ASI contribution for demonstrative flighton SAC-C satellite
LAGRANGE fully space compatible design completed end 2001
LAGRANGE is onboard the following satellites:n RADARSAT-2 (2 FM’s)
n COSMO SKYMED constellation: 3 satellites (1 EQM + 6 FM’s)
n OCEANSAT (1 EM + 1 FM tailored for Radio Occultation application)
n Soyuz (1 FM)
LAGRANGE was onboard Soyuz mission 10S in April 2005 in the frame of ENEIDEmission
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DESIGN 1/3
Receiver Type: Integrated GPS receiver for
spaceborne applications
Channels: 12 dual-frequency channels
Frequency Band: GPS L1: 1575.42 MHz
GPS L2: 1227.6 MHz
Observables: L1CA, L1P(Y) & L2P(Y) Code
L1CA & L2P Carrier phase
Instantaneous Doppler
Time (Bias, Bias Rate)
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DESIGN 2/3
Receiver Unit: RF/IF Module
Synch Module
AGGA 2 Module
Processor Module
Power Supply Module
+ Motherboard
RYMSA
GPS L1/L2 Antenna
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DESIGN 3/3
DUAL BAND
GPS ANTENNA
DIPLEXER
L1 Band
L2 Band
RF
CA
BL
E
LNA
A/D
LNA
A/D
OCXO5 MHz
L1 BandPLL
L2 BandPLL
SMPLCLK
RF/IF Board
TH TH
TH TH
EMI
FILTERON / OFF
DC/DC
CONVERTERSECTION
+3.3V
+5V
-5V
+12V
-12V
POWER BUS
ON/OFF (R)
ON/OFF (N)
TRMN
ASMN
J01
RSMNDC/DC Relay Sensing
+5V Analog Monitor
Thermistor
RSMN
J02DC/DC Board
AGGA2# 1
AGGA2# 2
AGGA2
# 3
NA
V(0
:3)
DSP21020
PROGRAM
MEMORY
DATA
MEMORY
1553
I/F
AGGA2 Board
1553I/F (N)
J03
1553I/F (R)
CPUCLK
DSP Board
HOUSEKEEPING
ACQUISITION
PPS
SYNCH
J04
J06
J07J08
J09
PPS
PPS
WDEN / DIS
WD E/D (R)
WD E/D (N)
HPC
HPC
HPC
HPC
PWR
PWR
PPS (N)
PPS (R)
HPC
HPC
HPC
HPC
J05
M_EPOCH
1553
1553
WD E/D Relay Sensing
SYNC Board
Receiver Processor Unit
+5V
+12V
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MAIN FUNCTIONALITY
Pseudorange measurements (Code Phase)
n C/A Code, for GPS L1
n P(Y) Code, for GPS L1 & L2
Integrated Doppler measurements (Carrier Phase)
n L1 and L2 Carrier Phase
Signal and Noise measurements
n Signal to Noise Ratio C/No in dB/Hz units evaluated at the tracking loop input
Real-Time Orbit Determination, determined using GPS C/A signalobservations and navigation messages (PVT solution through SPS andNavigation Kalman Filter)
Time measurements, determined from the GPS system
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ELECTRICAL INTERFACES
POWER LINES:
n N° 1 Unregulated Primary Power Supply Interface (connected to Satellite Power Bus)
TELECOMMANDS:
n N° 8 High Power ON/OFF Command (HPC) (Nom + Red for Receiver ON, Nom + Red
for Receiver OFF, Nom + Red for Watch Dog Enabling, Nom + Red for Watch Dog
disabling)
TELEMETRY:
n N° 2 MIL-STD-1553B I/F (Nominal + Redundant)
n N° 1 Temperature Sensing Monitor I/F (TSMN) (Thermistor on the DC/DC Board)
n N° 1 Analog Single Ended Monitor (ASMN) (5V Secondary Voltage Monitor)
n N° 2 Relay Sensing Monitor (RSMN) (Unit ON/OFF and Watch-Dog EN/DIS Relays)
SYNCHRONISATION:
n N° 2 External Synchronization Pulse Per Second (PPS) (Nominal and Redundant)
RF INTERFACE:
n N° 1 RF Input (from Antenna)
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PHYSICAL BUDGETS
Mechanical Dimensions
n 250 mm x 200 mm x 190 mm (LxHxW) including mounting feet
n 29.32 mm x 212.1 mm x 225.5 including Diplexer & LNA Cables
Mass:
n Receiver Unit : ~ 5.35 Kg
n Antenna: ~ 490 g
n Cable to antenna: ~ 225 g
Power Consumption:
n ~ 29.3 W (steady state)
n ~ 32.1 W (OCXO warm-up)
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SSTI PERFORMANCE
SSTI Characteristics
n Tight requirements in order to comply with system specifications
n Performance Requirements on three large areas:
!Real-Time Navigation (PVT)
!Raw Measurements (errors, acquisition/tracking thresholds, biases…)
!Robustness
n Temperature Sensors on-board placed on sensitive points of the RF board inorder to allow calibration of Rx-specific biases (IFB)
n Precise Modeling/Testing of errors (Multipath, antenna CoP etc.)
n Peculiar measurement sampling procedure (sample after PPS in input),typical of timing receivers
n Freely drifting Rx time scale, Rx bias bound between ± 10 ms
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SSTI PERFORMANCE
SSTI Performance Test Setup:
Navigation A ntenna
Port
Occ ul ta tion Antenna
Ports
I/O Data Interface
1553-B
Com mands & Da ta
Output D ata
Output Da ta
Com mands & Da ta
PC – GOCE RX
PC – GOCE RX
GSS Sim WS
TE - PC
GOCE RX
Power Supply
Single/Mult i-channel
Simulator
Antenna RF Cables (or simulation)
Optional link (for autom ated tes ts)
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SSTI PERFORMANCE
RT Navigation Testing
n Tested under Selective Availability ON and OFF (major source of RTnavigation error)
n Output tested in different reference frames (ECI J2000, ECI TOD,ECEF)
n Orbital GOCE scenario, usually having a duration of 12 hours
!Period of time representative of GPS orbital period
!GOCE orbit modeled using a 70x70 gravity field model, GPS 8x8
!Drag-free simulation (DFAC compensation), no SRP
!Force model and reference frame basically limited by Spirentimplementation.
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SSTI PERFORMANCE
RT Navigation Scheme
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SSTI PERFORMANCE
Real Time Navigation Requirements:
RT Navigation Results (S/A on):
Results with S/A off (current GPS status) - much better:
NKF Position J2000.0 (3D - 3s): ~ 30.35 m
NKF Velocity J2000.0 (3D - 3s): ~ 0.12 m/s
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SSTI PERFORMANCE
Navigation Results (example)
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SSTI PERFORMANCE
Visibility to GPS (example)
Direction Of Arrival Density Plot
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SSTI PERFORMANCE
Acquisition-Tracking thresholds & Measurements accuracy:
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SSTI PERFORMANCE
n A dedicated test campaign has been carried out to check robustness against
ionospheric scintillation activity
n Ad-hoc test set-up (Test Equipment, SSTI firmware modifications)
n GISM (Global Ionospheric Scintillation Model) simulator by IEEA has been used to
generate the scintillation time series in terms of amplitude and phase errors
n Amplitude fades injected at RF level using a programmable RF attenuator
n Phase errors injected at DSP level in the SSTI (pre-correlators carrier rotation)
n Orbital scenario in the RF simulator, scintillation error applied repeatedly during a pass.
n S4 values from 0 (no effect) up to 0.8. GISM version has S4 & sigma_phi linked
n Analyses in terms of loss of lock on carrier phase in post-processing
SSTI Sensitivity to Ionospheric Scintillation
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SSTI PERFORMANCE
Ionospheric Scintillation Test Setup
Navigation Antenna
Port
Occ ulta tion Antenna
Ports
I/O Data Interface
1553-B
Comm ands & Da ta
Output D ata
Output Da ta
Comm ands & Da ta
PC – GOCE RX
PC – GOCE RX
GSS Sim WS
TE - PC
GOCE RX
Power Supply
Single/Mult i-channel
Simulator
Antenna RF Cables (or simulat ion)
Optional link
(for automated tes ts )
Attenuation P rofi le
Programmable
Attenuator(PA13)
Test Setup
Phase error injection
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SSTI PERFORMANCE
Example of amplitude and phase errors applied:
Characterization in terms of loss of
lock sensitivity to S4 parameter
Scintillation Time Series
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SSTI PERFORMANCE
Example of Results
S4 = 0.6: OK!
S4 = 0.76: Not OK!
SUMMARY:
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SSTI precursor: ENEIDE
n LAGRANGE receiver installed inside the Soyuz
Orbital Module
n GNSS antenna installed outside the Soyuz vehicle
n Laptop installed inside the Orbital Module and
connected with LAGRANGE Receiver via MIL-
BUS1553 data cable
n The Crew MMI provides commanding and
monitoring functions
n All the data acquired by LAGRANGE Receiver
handled by the Laptop Software and stored on the
PCMCIA Hard-Drive
SSTI-Like experience on ENEIDE experiment (May 2005):
different target application (combined
GPS/EGNOS/WAAS tracking from space) but same
technological base of SSTI
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SSTI precursor: ENEIDE
ENEIDE experiment antenna
LAGRANGE
receiver
T. Col. Vittori
ENEIDE
Experiment
Conductor
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SSTI precursor: ENEIDE
All the analyses conducted on the flight data allow to
say that the ENEIDE experiment was carried out
successfully.
ENEIDE proved to be a benchmark for the validation of the AAS-I
receivers of LAGRANGE class, like GOCE SSTI. The different
environmental conditions in which the receiver operated (Sun-pointing
attitude, orbital attitude, peculiar antenna pointing constraints etc.) made
the experiment an important laboratory for different applications like
attitude analysis, atmospheric sounding, space weather, real-time
navigation and control.
Reference:
A. Zin, S. Landenna, A. Conti, L. Marradi, M. S. Di Raimondo, “ENEIDE: an Experiment of a Space-borne, L1/L2
Integrated GPS/WAAS/EGNOS Receiver”, European Navigation Conference 2006, (ENC 2006), May 08-10 2006,
Manchester, UK.
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GOCE SSTI: FACTS
State-of-art GPS space receiver technologyState-of-art GPS space receiver technology
Advanced performanceAdvanced performance
Twelve LAGRANGE flight models built (two SSTI Twelve LAGRANGE flight models built (two SSTI FMsFMs))
Fully qualified for space applications for severalFully qualified for space applications for several
satellitessatellites
Flight provenFlight proven
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Thanks for your attention !Thanks for your attention !