Demodulators – Phase shift keying or quadrature amplitude demodulator
Patent
1990-12-18
1991-12-31
Pascal, Robert J.
Demodulators
Phase shift keying or quadrature amplitude demodulator
329307, 375 83, H03D 300
Patent
active
050775316
ABSTRACT:
A PSK signal which is subject to frequency fluctuation and noise is demodulated through a quasi-coherent detection process with a fixed local frequency oscillator (5) noise elimination process using a low pass filter (17,18) after frequency adjustment, and a frequency and phase regeneration process using a PLL circuit (20). The PLL circuit (20) is updated by the estimated center frequency of a received signal by using an FFT (fast Fourier transform) circuit (11), a power spectrum means (12,13,14), and a frequency estimation circuit (15) estimating the center frequency based upon the fact that the modulated signal component exists only on a high level portion of the frequency spectrum.
REFERENCES:
patent: 4912422 (1990-03-01), Kobayashi et al.
"A Method of High Precision Frequency Detection with FFT", Makoto Tabei et al., vol. J 70-A, No. 5, pp. 798-805, May 1987.
"A Calculative Demodulation Method for PSK Signals in Burst Mode", Teruhiko Honda et al., pp. 57-64, Oct. 30, 1987.
"A Demodulation Method by Stored Signal Processing for PSK Burst Signal (I)", Teruhiko Honda et al., pp. 7-12, Sep. 29, 1988.
"A Demodulation Method by Stored Signal Processisng for PSK Burst Signal (II)", Yoshio Takeuchi et al., pp. 13-18, Sep. 29, 1988.
Honda Teruhiko
Takeuchi Yoshio
Kokusai Denshin Denwa Co. Ltd.
Pascal Robert J.
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