Detailed Description
Launched alongside HealthSat-2 on the September 1993, PoSAT-1 is Portugal's first satellite achieved through a technology transfer program with Surrey Satellite Technology, Ltd. (SSTL). PoSAT-1 was built at the University of Surrey in a collaborative program between a consortium of Portuguese academia and industry LNETI, EFACEC, OGMA, MARCONI, ALCATEL, IST, UBI & CEDINTEC). The Portugese consortium sent 4 engineers to Surrey to participate in on-the-job training. Like KITSAT-1, PoSAT-1 carries a wide range of technology experiments, including earth imaging cameras, DSP and space-radiation experiments. In addition, PoSAT-1 carries the first microsatellite GPS experiment and an ultra-low-cost CCD star sensor. PoSAT-1 is operated jointly by the University of Surrey command station at Guildford and the Portugese command station at Sintra.
Please note - SpaceTrack wrongly identifies this object as EyeSat A
PoSAT was operated on amateur frequencies for several weeks in early 1994. OSCAR News 105 (February 1994, p. 35) carried a letter from CT1DBS reporting that an agreement was signed by AMSAT-PO and the PoSAT Consortium on December 6, 1993 stating "The name of PoSat-1, when in use by the amateur radio community will be PoSAT OSCAR 28, OSCAR 28 or PO-28." Presently, PoSAT-1 is not open for amateur operations.
Star Sensor
The star sensor is based on the same technology as the EIS, but is optimised for imaging the faint light from stars for use as part of the spacecraft's attitude determination system. The star-field image is analysed by the Transputer Data Processing Experiment and the resulting measurement data returned on the On-Board-Computer.
GPS Navigation
PoSAT-1 carries a Global Positioning System (GPS) receiver based on the Trimble TANS-II receiver. The received data is decoded and filtered by the Transputer Data Processing Experiment to provide the satellite position and velocity as well as an accurate on-board time reference. This enables the satellite to generate its own orbital element set, provide scheduling and synchronisation to other on-board computers, and allow groundstations equipped with a GPS receiver to experiment with applications for real-time differential GPS data.
Cosmic Ray Experiment (CRE)
The CRE monitors the space radiation environment experienced in orbit by the satellite and enables analysis of its effect on spacecraft semiconductor electronics. The CRE contains a large area PIN diode and multi-channel analyser capable of detecting energetic particles with a wide range of Linear Energy Transfer to build up a spectrum of observed energies of particles within the spacecraft. Special RADFET's are also incorporated to monitor the accumulated ionising dose. The larger memory devices in the on-board computers are regularly 'washed' to detect and log Single Event Upset (SEU) information.
Digital Signal Processing Experiment (DSPE)
The DSPE consists of two Texas Instruments processors from the TMS320 series, the C25 and C30. The DSPE can be used as a programmable communications modem to modulate the downlink data from, or demodulate uplink data for the OBC, thus enabling experiments with new modulation techniques optimised for Low Earth Orbit satellite mobile communications.
Store and Forward Communications
The main On-Board Computer (OBC), based on an 80C186 8MHz processor with 16MByte of Static RAM, also supports digital Store and Forward communications using AX25 packet protocols and communications links optimised for communications using very low cost, simple and portable groundstations. The Store and Forward system employs a 9.6kbps uplink and 9.6 and 38.4kbps downlink data rates.
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