The apparatus and method reduced for FM receiver noise and handheld communication devices

The apparatus and method reduced for FM receiver noise and handheld communication devices

  • CN 102,668,387 B
  • Filed: 11/16/2010
  • Issued: 08/10/2016
  • Est. Priority Date: 11/17/2009
  • Status: Active Grant
First Claim
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1. during the stereo frequency modulation(PFM) FM received via antenna for reduction broadcasts notThe device of the signal sound wanted, described device includes:

  • Converter, it is configured to the stereo FM broadcast received is converted into intermediate frequency carrierFrequency,Demodulating unit, the FM signal after it is configured to demodulation conversion adds right amplitude to form a left sideModulation AM signal and a left side subtract right AM signal,Wave filter, it is configured to that a left side adds right AM signal and a left side subtracts in right AM signalOne is filtered forming filtered signal, to stop center being introduced by phase-locked loop pllUndesired sound frequency at narrow-band, thus suppression include that a left side for undesired sound adds the right sideAM signal or a left side subtract the sub-band of right AM signal, andSum unit, it is used for that filtered signal and a left side are added right AM signal and a left side subtracts right AMAnother in signal is added to produce stereo audio signal.

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