Quadrature - phases demodulator for a wide dynamic range

摘要

PURPOSE:To secure a considerably large dynamic range (about 90dB) by logorithm-converting an input amplitude and separately detecting the amplitude and a phase. CONSTITUTION:A logorithm amplifier 1 logorithm-converts the amplitude of a reception modulation signal which has been band-limited and is outputted. At the same time, an input signal is amplitude-lmited and outputted. The unnecessary high frequency components of the amplitude output which have been logorithm-converted are removed in a filter 2, and are inputted to an A/D converter 3 so as to be digitalized. On the other hand, the output of the logorithm amplifier 1 is limited to a constant amplitude by a limiter 4, and a phase detector 5 detects a phase difference with a reference signal from a reference signal generator 6. The amplitude and the phase detected by the A/D converter 3 and the phase detector 5 are inputted to an arithmetic processing circuit 7. It accumulates the signal of one block (packet) and converts it into a linear amplitude with the maximum value as reference.