The viability of shaped BPSK modulation techniques with 5kHz UHF SATCOM channels.

Abstract

A method of generating constant envelope BPSK compatible modulation formats is described in which spectral containment is achieved via controlled phase rotations. These Shaped BPSK modulations can be considered BPSK/CPM hybrids. The instantaneous phase transitions of BPSK are tempered to become the continuous phase rotations of CPM. The SBPSK modulations described above are compared with classical BPSK as well as a Shaped BPSK modulation specified by the Joint Chiefs of Staff for use with Department of Defense 5kHz UHF SATCOM channels. It is shown that the use of SBPSK modulations can allow significant increases in the data transmission rate without exceeding the spectral "envelope" of a lower rate BPSK signal. Analysis also includes fractional out of band power curves for the modulated signals before and after transmission through a bandpass hard-limited channel. Equivalent SNR's are generated to quantify the simultaneous effects of decreased adjacent channel interference at the expense of I channel energy. Finally, probability of error curves vs SNR are presented for BPSK and SBPSK modulations transmitted through a band-limited and hard-limited channel.