A DUAL-TONE REFERENCE DIGITAL DEMODULATOR FOR MOBILE DIGITAL-COMMUNICATION

This paper presents a new demodulator applicable to the dual-pilot tone modulation technique. Examination of orthogonal and ISI free pulse shapes leads to the novel demodulator structure. This demodulator is advantageous because the processing is strictly linear, the pilot channel and data channel ideally do not interfere or create self-noise, no differential encoding is required since no phase ambiguity is created with the pilot tone processing, and near ideal bit error probability performance is achieved. This demodulator offers an alternative to the transmitted tone-in-band and the pilot symbol assisted modulation techniques. This paper considers pi/4-QPSK modulation with 33% excess bandwidth in the isotropic time-varying fading channel as a design example.