A method of generating constant envelope BPSK-compatible modulation formats is described in which spectral containment is achieved via controlled phase rotations. These SBPSK modulations 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 5-kHz UHF satellite communication 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. The analysis also includes fractional out-of-band power curves for the modulated signals before and after transmission through a bandpass hard-limited channel. Equivalent signal-to-noise ratios are generated to quantify the simultaneous reduction of adjacent channel interference and I channel energy. Probability of error curves are presented for BPSK and SBPSK modulations transmitted through a bandlimited and hard-limited channel.