Estimation of delay phase offset in multi-carrier differential phase modulation systems

Propagation delay introduces unwanted delay phase offsets among carriers using different frequencies and deters differential phase demodulation in the hybrid frequency and differential phase modulation systems. Operating on the preamble sequence with two alternately transmitted pulsed carriers, an estimation approach is proposed in this paper to extract the delay phase offsets among carriers using different frequencies. It is shown that delay phase offsets can be reliably estimated when the preamble sequence is sufficiently long.