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Frequency modulation receiver and its demodulation method

A demodulation method and receiver technology, applied in the direction of improving frequency converters, electrical components, transmission systems, etc., can solve problems such as "condition three" errors, and achieve the effect of overcoming errors, overcoming harsh requirements, and accurate baseband signals

Inactive Publication Date: 2007-06-27
SHANGHAI BEILING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

If "Condition Two" does not hold, then "Condition Three" will produce a large error

Method used

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  • Frequency modulation receiver and its demodulation method
  • Frequency modulation receiver and its demodulation method
  • Frequency modulation receiver and its demodulation method

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Embodiment Construction

[0036] As shown in FIG. 2 , the present invention, that is, an FM receiver, is composed of a Hartely-structured mixer 100 , an image rejection filter 200 , a limiter 300 and a demodulation circuit 400 .

[0037] As shown in Figure 3, it is assumed that the angular frequency of the signal amplified by the LNA is ω RF , the angular frequency of the image signal is ω image .

[0038] In order to remove the image signal, that is, the signal represented by the aforementioned (2) and (4), the most common method is to use a polyphase filter (Polyphase filter) to eliminate the image signal of (2) and (4). A complex filter can also be used to suppress image signals through frequency conversion. That is, the 200 circuit in the figure. 300 is a two-way IF amplifier, or limiter. The IF amplifier 300 outputs two signals I(t) and Q(t).

[0039] The I(t) signal passes through the delay circuit 408 all the way, and the delay time τ is very small. The other I(t) has no delay and is mixed...

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Abstract

This invention relates to a FM receiver and its demoduoation method, in which, the FM receiver is composed of a Hartely structure mixture, an image suppression filter, a limiter and a FM demodulating circuit characterizing that said circuit includes two routes of orderly connected delay circuits, mixing circuits and addive circuits, and an integral circuit connected by a differential circuit and an division circuit, in which, the mixing circuits in the two routes are connected crossly, which realizes demodulation to FM base band signals and overcomes the hard requirement to delay circuit in the traditional FM signal demodulation circuit and the error problem of sine signal approximation.

Description

technical field [0001] The invention relates to a frequency modulation receiver, in particular to a frequency modulation receiver capable of accurately separating baseband signals through its demodulation circuit. Background technique [0002] The superheterodyne radio frequency receiver is still the mainstream scheme of the radio frequency receiver at present. Although the zero-IF (Zero IF) technology has been extensively studied, the RF receiver of the ZIF structure is still only used in low-end RF receivers, such as BP machines (Paging). In order to improve the integration of the radio frequency receiver, some devices outside the chip, such as filters, are integrated into the chip. In the superheterodyne RF receiver, the IF frequency of the IF structure is too high, which limits the IF filter to be placed outside the chip and implemented with discrete devices. In the low-IF structure, the frequency of the IF is very low, and the IF filter can be realized by an integrate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04B1/26H03D7/18
Inventor 陈后鹏
Owner SHANGHAI BEILING