DIFFERENTIATE AND MULTIPLY BASED TIMING RECOVERY IN A QUADRATURE DEMODULATOR

摘要

Differential and Multiplication Based Timing Recovery in Orthogonal Demodulator. An orthogonally modulated signal is received and the received modulated signal is demodulated by orthogonal mixing with a local oscillator signal. The inphase and orthogonal down-converted signals are sampled. The sampled signal is separately detected to produce a binary number from the symbols delivered by the quadrature modulated signal. Sampling is controlled by a symbol timing recovery signal derived from the in-phase and quadrature down-converted signals. Further, each in-phase and quadrature down-converted signal is differentiated with respect to time, each of the differentiated signals is multiplied with the orthogonal and in-phase signals, respectively, and the multiplied signals are subtracted from each other to produce a differential signal. The difference signal controls the symbol timing circuit in such a manner that a clock signal controlling the timing of sampling is locked to the difference signal.