TOPSTAR 3000D GPS RECEIVER

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TOPSTAR 3000D GPS RECEIVER

• PART 1 Requirements for Spatial GPS
• PART 2 TOPSTAR 3000D module
• PART 3 Performances of TOPSTAR module
• PART 4 TOPSTAR 3000D space qualification
• PART 5 TOPSTAR 3000D Testing
• and monitoring

CERN 11-15 April 2005 - AMS-Team - C. Zurbach
GAM Montpellier
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PART 1 spatial GPS requirements

• AMS-02 requirements
• Position accuracy in LEO (Low Earth Orbit)
  few m
• Time transfer or precision accuracy few ?s
• Universal Time Coordinate (UTC)
• Monitoring degradation C/A (Coarse Acquisition)
  signal at L1 frequency

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PART 2 TOPSTAR 3000D Module

• TOPSTAR functional architecture
• RF radio frequency module
• SP signal processing module (ASIC)
• LOC localisation module (Diogene navigator)
• PVT Positioning, Velocity, Time, in output

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PART 2 TOPSTAR 3000D Module

• TOPSTAR core architecture

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PART 3 Spatial GPS performances

• Performances of TOPSTAR 3000D
• Position accuracy in LEO (Low Earth Orbit) lt
  10 m (SA Selective Availability, obsolete
  from 2001)
• Velocity accuracy in LEO lt 1 cm/s
• Time accuracy with TCXO (Temperature Controlled
  Crystal Oscillator) lt 1 ?s (in AMS02)
• Time accuracy with OCXO (Oven Controlled
  Crystal Oscillator) lt 200 ns (not in AMS02)

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PART 3 TOPSTAR3000D Module

• TOPSTAR interfaces overview
• The TOPSTAR 3000D GPS receiver is composed of one
  single GPS core at 10Mhz processing frequency
• It interfaces with GPS antenna, secondary voltage
  lines and on-board computer (through Data
  Interface serial RS422)

DAQ Trigger
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PART 4 TOPSTAR 3000 D space qualification

• TOPSTAR space qualification
• The GPS receiver is manufactured by ALCATEL
• (ISO 9001 and AQAP 110 compliant - ESA CNES
  qualified)

• Requirements of launch
• Test vibrations
• Thermal vacuum
• Radiation
• Long life-duration
• Software development Quality level is ESA PSS-05
  level B (Essential)

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PART 5 TOPSTAR 3000D Test setup CNES Toulouse

• Test bench

Input - Output
RF
RF
RS422
Orbital and antenna simulator (Spirent TM)
PVI 5,2
PVI 6,3
RS232
Monitoring software (Alcatel TM)
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PART 5 TOPSTAR 3000D Data monitoring

• Mode of operation

Two modes of operation selected in initial
command PPS locked or PPS free-running Locked
(exact 1Hz output), standard will be in used in
AMS02 UTC Time Free monitoring of GPS status,
non-standard mode for AMS02
RS422
Monitoring software
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PART 5 TOPSTAR 3000D Data monitoring

• TeleCommand (TC) monitoring

Initialisation Wmode Init Navigation mode
activation Gmess control of transmission rate
of TeleMetry Rtime current GPS time or local
clock initialization (precision gt or 1
second) Rnave or Norbit provides navigation
aiding initial coarse position of the GPS
receiver (orbit, position and velocity) Raleph
provides GPS almanach for the 32 GPS satellites
with date
RS422
Monitoring software
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PART 5 TOPSTAR 3000D Data monitoring

• TeleMetry (TM) monitoring

Data needed in AMS experiment S1chanst
status of the tracking of 14 channels S1/2/3Rawd
raw measurement of the channel output Snavn
computed position and velocity Sreceivst
provides general status of Topstar
receiver Stime corresponding to TC Rtime
command, provides GPS and UTC time of the PPS
signal (output for AMS)
RS422
Monitoring software
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PART 5 TOPSTAR 3000D Data monitoring

• Output Data Structure Stime

Length of data 720 bits Acquisition time less
than 500 ms Validity validity of GPS and UTC
time GPS clock time of PPS week number, second
in the week, second fraction (10-9s), FOM of Time
(accessible only in free mode) UTC time of PPS
week number, second in the week, second
fraction TFOM Time Figure Of Merit after
selection of the best time, between differents
ways of calculation