Research On Satellite Overlap Communication Techniques And Its Applications

Satellite Overlap Communication Technique (i.e. SOCT) is a new technique in satellite communications. Its signal is overlapped, not only in time domain but also in frequency domain, on the signals of another system supported by the same transponder. Moreover, its signal may be non-orthogonal to the others in CDMA meaning, but it can be separated from the latter and demodulated by means of some special methods. Its signal is much weaker than the back ground signals so that it hardly affects the back ground system. Therefore, SOCT is very useful not only in raising channel efficiency, but also in building a hidden communication system for military purpose.Through some research in depth on SOCT, this thesis proposes a scheme of star-type VSAT (very small aperture terminal) network based on overlap back transmission, and do some research on key techniques involved with the scheme and their partial realization with FPGA(field programmable gate array), such as spread spectrum techniques, a non-coherent de-spreading spectrum and demodulation technique and adaptive interference cancel. Some useful conclusions have been obtained in theoretical analysis and computer simulation experiments.Besides, a demonstration system for a simplified satellite communication system model is implemented in a development platform of Borland C++ Builder 5. The demonstration system works well, where the BER of the receiver keeps to 0 even when some AWGN noise exists in the channel.