VITASat Portable Ground-Station (PGS)

Dr. David Palmer of Surrey, England has developed a complete, self contained portable ground-station for use with multiple SSTL-built satellites. The PGS was developed to provide e-mail communications in developing countries to support humanitarian efforts. It is fully automatic and designed to be used by those with no radio knowledge and a minimum of computing experience.

The PGS is designed for unattended uploading and downloading of e-mail messages as the satellites pass overhead. E-mail from the satellites is then downloaded onto the terrestrial e-mail network and automatically sent to its intended recipient. The PGS comes with a Psion palmtop computer to control the radio and perform e-mail functions. The control software automatically switches the equipment on and off according to the satellite pass schedule, thereby minimizing power requirements. The internal 4.5 amp-hour battery has a life expectancy of 8-10 years and can be recharged via the front panel from the supplied switch mode power supply or from a nominal 12 volt 1 amp. solar panel. The PGS is enclosed in a case 270 x 260 x 170mm that is water proof to 20 ft., and is strong enough to drive a light vehicle over. Total weight is less than 6kg. The PGS uses a commercial radio that has been modified to improve transmitter and receiver modulation/demodulation and uses a digital hardware technique to track Doppler frequency shift.

PGS Specifications

Radio: Modified Yeasu FT8100R VHF/UHF Transceiver
Receiver UHF Frequency Range: 380 - 450 MHz.
Transmitter VHF Frequency Range: 140 - 150 MHz
Transmitter Power: 50 watts maximum
Modulation: FSK
Data Rate: 9600 bps
Terminal Node Controller: Kantronics 9612+
Computer: PC or PSION 3mx palmtop
External Interface: RS-232
Antenna: Omni directional dual band Quadrifilar Helix