Preambleless demodulator for satellite communications

A high-performance demodulator capable of demodulating packetized data without preamble sequence in a very low bit-energy-to-noise (Eb/NO) environment is described. The design uses newly developed algorithms for estimating precise input carrier phase and frequency on the basis of a near-maximum-likelihood (ML) estimation strategy. Performance obtained through experiments satisfies a 2.5-dB Eb/NO requirement to demodulate 512-b packetized data at 1*10/sup -2/ packet loss probability. An experimental system that has been built to evaluate system performance, along with very small aperture terminal (VSAT) system parameters, is presented. The results are quite satisfactory, giving prospects for future VSAT applications.<<ETX>>