| 摘要 |
A differentiate and multiply based timing recovery in a quadrature demodulator. A quadrature-modulated signal is received and demodulated by quadrature mixing the received modulated signal with a local oscillator signal. In-phase and quadrature down-converted signals are sampled. The sampled signals are differentially detected to produce binary digits from symbols conveyed by the quadrature-modulated signal. Sampling is controlled by a symbol timing recovery signal derived from the in-phase and quadrature down-converted signal. Thereto, the respective in-phase and quadrature down-converted signals are differentiated with respect to time, the respective differentiated signals are multiplied by the quadrature and in-phase signals, respectively, and the multiplied signals are subtracted from each other so as to produce a difference signal. The difference signal controls the symbol timing recovery in that a clock signal controlling the timing of the sampling is locked to the difference signal.
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