Satellite Data Collection System at Ku-Band

The paper describes a system dedicated to the collection of low-rate data by small, unattended and inexpensive remote earth stations operating through conventional satellite transponders at Ku-band. The high phase noise and frequency drift environment has been the limiting factor in introducing this kind of system. A system using trellis coded 4-FSK modulation on the inbound link (300 bits/s) and BPSK modulation (2400 bits/s) on the outbound link together with a SHF PLL converter chain, solves these problems. Using dual-shaped off-set Gregorian antennas with diameter 55cm or 90cm, a low-cost and robust system is established.