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    An FM signal demodulation system
    2.
    发明公开
    An FM signal demodulation system 失效
    系统zur解调冯频率调制。

    公开(公告)号：EP0064819A1

    公开(公告)日：1982-11-17

    申请号：EP82301963.3

    申请日：1982-04-16

    申请人： Oki Electric Industry Company, Limited ,  NIPPON HOSO KYOKAI

    发明人： Ohta, Tomozo c/o Oki Electric Industry Co., Ltd ,  Tsutsumi, Yoshio Oki Electric Industry Co.,Ltd. ,  Konishi, Yoshihiro c/o Nippon Hoso Kyokai

    IPC分类号： H03D3/00

    CPC分类号： H03D3/00 ,  H03G5/24

    摘要： An FM signal demodulation system comprises a signal level detector (1), an adaptive bandpass filter (2), a frequency discriminator (3), amplifiers and amplitude limiters (4,5), and a fixed-bandwidth reference bandpass filter (8). The FM signal is fed to an input terminal (6) and the demodulated output is obtained from an output terminal (7).
    The threshold level for demodulating the FM signal, for example a television picture signal, is improved by restricting the bandwidth of the signal using the adaptive bandpass filter (2), thereby improving the picture quality and/or the signal/noise ratio of the demodulated signal. The adaptive bandpass filter has a wide bandwidth when the signal level is sufficiently higher than the threshold level, but a narrow bandwidth when the signal level is close to or lower than the threshold level. The bandwidth of the adaptive bandpass filter is adjusted according to the total power of the input FM signal, or the carrier signal to noise ratio.

    摘要翻译： FM信号解调系统包括信号电平检测器（1），自适应带通滤波器（2），鉴频器（3），放大器和限幅器（4,5）和固定带宽参考带通滤波器（8） 。 FM信号被馈送到输入端（6），并且从输出端（7）获得解调输出。 ...通过使用自适应带通滤波器（2）限制信号的带宽来提高用于解调FM信号（例如电视图像信号）的阈值电平，从而提高图像质量和/或信号/ 解调信号的噪声比。 当信号电平足够高于阈值电平时，自适应带通滤波器具有宽带宽，而当信号电平接近或低于阈值电平时，具有窄带宽。 根据输入FM信号的总功率或载波信噪比，自适应带通滤波器的带宽进行调整。