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    • 1. 发明授权
    • Digital FM receiver back end
    • 数字FM接收机后端
    • US5903825A
    • 1999-05-11
    • US671385
    • 1996-06-27
    • Steven Howard GoodeJames Clark BakerMichael John Carney
    • Steven Howard GoodeJames Clark BakerMichael John Carney
    • H03D3/00H04B1/16
    • H03D3/006
    • The digital FM receiver back end receives an analog intermediate frequency signal from a radio frequency front end (310) having a heterodyne circuit (312) and an intermediate frequency filter (314). In the receiver back end (307), a digital demodulator (330) having a hard limiter (333), a direct phase digitizer (336), and a phase differential circuit (339) produces a digital phase differential signal from the analog intermediate frequency signal. Next, a digital processor (360) filters and reduces noise in the digital phase differential signal using a bandpass filter (362), a de-emphasis filter (364), and an expandor (366). Finally, a pulse-width-modulation audio amplifier (380) prepares the signal for reproduction on an audio speaker (390). The digital FM receiver back end avoids inherent DC offset problems common to analog FM receivers, and it also offers a reduced complexity, size, and power consumption alternative to conventional digital FM receivers.
    • 数字FM接收机后端从具有外差电路(312)和中频滤波器(314)的射频前端(310)接收模拟中频信号。 在接收机后端(307)中,具有硬限幅器(333),直接相位数字转换器(336)和相位差电路(339)的数字解调器(330)从模拟中频产生数字相位差分信号 信号。 接下来,数字处理器(360)使用带通滤波器(362),去加重滤波器(364)和扩展器(366)对数字相位差信号中的噪声进行滤波和降低。 最后,脉冲宽度调制音频放大器(380)在音频扬声器(390)上准备用于再现的信号。 数字FM接收机后端避免了模拟FM接收机常见的固有DC偏移问题,并且与传统的数字FM接收机相比,还提供了降低的复杂性,大小和功耗。