Frequency selection for dispersion signal in satellite communication lines

Interference produced by a satellite communication system in other communication systems operating at the same frequency band is suppressible by dispersion of the transmitted energy. This method is ised in one channel per carrier systems, which have particularly low interference immunity. Examples are SPADE and SCPC systems, both using pulse-code modulation and phase keying. Selection of the frequency for a dispersion signal requires determination of the maximum allowable interference level in the presence of a fast dispersion signal, the frequency of the latter being either equal to or higher than the scan-line frequency. Here this determination is made analytically, by estimating the error probability in a one channel per carrier channel. The maximum allowable level of dispersion interference is then related to this error probability, assuming that presence of such an interference will increase the error probability from 10 to the minus 7th power to .000001 as a basis.