Abstract: Waveform orthogonality has a direct influence on signal bandwidth and demodulation. The paper obtains orthogonal EBPSK signals and power spectrum by deriving EBPSK correlative expression and power spectrum expression. The best power spectrum condition, duty cycle of one and phase shift of π/2, are given. This is helpful in parameter selection of EBPSK waveform control. As the symbol correlativity is increased, the power is more concentrated but with poorer demodulation performance. On the other side, with symbol correlativity decreased, performance of demodulation is improved, but power becomes more distributed. The best orthogonal power spectrum can reduce line spectrum components, make power concentrated and spectra compressed. Thus bandwidth efficiency is improved and, at the same time, performance of demodulation is also improved for symbol orthogonality. Therefore a good tradeoff between symbol correlativity and demodulation performance is obtained.

Key words: EBPSK, orthogonality, power spectrum, spectrum efficiency