Demonstration of an integrated AODS based on the MosaicGNSS receiver with the AGGA-2 and complemented by star sensors and optional gyros for multimedia applications.
Higher level signal processing functions and software algorithms (GPS receiver, star sensor and gyro) are centralized on a single DSP.
The common hardware platform for these components is the GPS/AODS Demonstrator Hardware.
Integration of an AODS (Attitude and Orbit Determination System) demonstrator, being a sensor system that provides full state information and having a large degree of autonomy. The system comprises the following components:
- MosaicGNSS receiver that provides position, velocity, time and attitude,
- 3-axis star sensor, inertial 3-axis attitude information can be provided with spacecraft rates up to typically 2 deg/sec,
- Optional gyroscopes for inertial rate measurements.
- Compact integrated AODS, stand-alone unit and slide-in module,
- Portability, Modularity and Flexibility,
- GPS Rx and Star Sensor and Gyro SW share MosaicAODS board:
- Reduction of mass, volume, power consumption costs,
- Easy to implement module interconnections,
- Improvement in robustness,
- Radiation tolerant (up to 100 krad),
- Short initial acquisition,
- Fit for LEO / MEO / GEO missions,
- Relative navigation.
The GPS/AODS demonstrator will consist of three boards:
- MosaicGNSS Receiver Base Board, comprising the DSP with program memory and data memory, a GPS ASIC developed by Astrium for signal preprocessing, board and boot control (BBC) and communication interfaces(UART/HDLC, SpaceWire, MIL-STD-1553), a boot PROM containing the primary boot loader, an EEPROM bank containing the application software. The base board has all the hardware required for a software correlator based GPS signal reception.
- AGGA-2 Extension Board, comprising one AGGA-2. The AGGA-2 is connected to the DSP using the data bus extension of the base board. Four RF front-ends, one RF multiplexer (MUX) and three RF power splitter (PS) will be used to route the RF signals as required for the different modes.
- Power Converter Board with the required DC/DC converters.
Since the GPS receiver as well as the star sensor require significant processor load, the key is the implementation of all functions on a single DSP. This is made even more difficult by the limitation of the DSP clock frequency (20 MHz) due to radiation requirements.
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The MosaicAODS system is composed of the following components:
Project start was the 1st of January 2003. The Baseline Design Review is planned 4 months after the project start. A Mid Term Review (MTR) is planed 11 months after the project start. The Final Review (FR) is planned for December 2005.
Milestones in this activity are:
|Project Start||T0||January 2003|
|BDR:||Baseline Design Review||April 2003|
|MTR:||Mid Term Review||December 2003|
|FP/FR:||Final Review||December 2005|
- Start date of the project was 01.01.2003,
- Successful BDR at ESA/ESTEC in Noordwijk, 28.04.03,
- Successful MTR at ESA/ESTEC in Noordwijk, 08.12.03,
- The system architecture of the GPS/AODS Demonstrator has been revised and a MIL-STD-1553 Bus interface has been added to the system architecture,
- Adaptations of parts of the GPS attitude determination software have been performed,
- The AGGA-2 breadboard has been used for differential phase measurement in full parallel attitude mode and in hybrid-multiplexed mode,
- Adaptations of O/S and Interface SW using the AGGA-2 breadboard have been done,
- GPS/AODS DC/DC converter manufactured,
- RF Multiplexer PCB manufactured,
- AGGA-2 extension board manufactured,
- Successful board level tests and first functional tests,
- Successful environmental and functional tests.