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FM receiver

A technology for receivers and receiving targets, applied in electrical components, transmission systems, etc., can solve problems such as sound distortion and sensitivity reduction, and achieve the effect of preventing sound distortion and improving adjacent interference characteristics

Inactive Publication Date: 2008-08-27
SANYO ELECTRIC CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

As a result, sound distortion tends to occur in weak electric fields
[0011] As a countermeasure against this problem, conventionally, the sensitivity of detection of adjacent interference in a weak electric field has been reduced.

Method used

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  • FM receiver
  • FM receiver
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Embodiment Construction

[0037] Hereinafter, an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

[0038] FIG. 1 is a block diagram showing a schematic configuration of an FM receiver as an embodiment of the present invention. The FM receiver 50 has its main part configured as an integrated circuit (IC), and is used in, for example, an in-vehicle audio device of an automobile. The FM receiver 50 includes an antenna 52, an RF amplifier 54, a first local oscillation circuit 56, a first hybrid circuit 58, BPEs 60 and 64, amplifiers 62 and 72, a second local oscillation circuit 66, a second hybrid circuit 68, an IFBPF 70, The detection circuit 74 , the S indicator circuit 76 , the impulse noise detection circuit 78 , the AFC (Automatic frequency control) circuit 80 , and the bandwidth control unit 82 .

[0039] RF signal S received by antenna 52 RF After being amplified by the RF amplifier 54 , it is input to the first hybri...

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PUM

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Abstract

An FM receiver that is suitable for reducing a transmission bandwidth W F of a bandpass filter to remove adjacent-channel interference, and increasing W F to prevent audio distortion. A detection output signal S OUT is inputted to an HPF 122 when a reception electric field strength signal S M-DC indicates an intermediate or stronger electric field. In a weak electric field, an AC component signal S M-AC , which is extracted from an intermediate signal S IF1 prior to detection and which has fewer high-pass noise components than S OUT , is inputted to the HPF 122. A control circuit 120 detects a case as an adjacent-channel interference state when a large amount of high-pass components passes through the HPF 122, and reduces W F of an IFBPF 70 in order to remove adjacent-channel interference. When a small amount of high-pass components is transmitted, W F is increased in order to minimize audio distortion. The relative detection output signal has more noise components in weak electric fields and has less noise in AC component signals, so that adjacent interference reliability is enhanced, and bandwidth control based thereon is implemented properly.

Description

technical field [0001] The present invention relates to an FM receiver for receiving FM (Frequency Modulation: FM) signals, and in particular, to the removal of adjacent interference and the suppression of sound distortion when receiving FM broadcast or the like. Background technique [0002] Since the frequency of the carrier wave is changed in the FM signal based on the audio signal or the like, for example, a wider frequency band than that of the AM signal is required for its transmission. Therefore, in an FM receiver, when receiving a target transmission signal, it is susceptible to interference (adjacent interference) from other signals transmitted at a frequency close to its frequency, which affects the quality of the sound signal to be detected. bad influence. The adjacent interference can be reduced by narrowing the frequency band of the band-pass filter for extracting the received target signal. On the other hand, when the FM signal to be received is highly modula...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/10H04B1/26
CPCH04B1/10H04B1/06H04B1/16
Inventor 铃木顺
Owner SANYO ELECTRIC CO LTD
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