Adjacent-channel interference effects in shaped biphase-shift keyed satellite communications

The author presents computer simulation results for the effects of adjacent channel interference in shaped biphase-shift-keyed (SBPSK) communications systems. The channel separations and channel filter characteristics used are typical of VHF/UHF military satcom links. Two types of detection methods are used-integrate-and-dump, which is typical of current SBPSK receivers, and maximum likelihood sequence detection, which makes use of the inherent memory of the SBPSK signal to improve performance in the interference environment. The results indicate that, with the possibility of oscillator instability offsetting the desired spectrum within the passband of the channel filter, it is better to go with a wide channel filter and accept more adjacent channel interference than to use a narrow filter and suffer additional degradation due to frequency offsets