System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system

A frequency modulation signal, digital wireless technology, applied in the direction of digital transmission system, two-way line system station, transmission system, etc., to achieve the effects of digital processing, compatibility, and enhanced anti-interference ability

Active Publication Date: 2011-05-04
HYTERA COMM CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] In the current digital mobile walkie-talkies, FPGA (Field Programmable Logic Gate Array chip) is usually used to realize each functional module, but there is no solution to realize analog FM demodulation based on FPGA hardware platform in the prior art

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  • System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system
  • System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system
  • System and method for performing digital demodulation to frequency modulated signal in digital wireless intercom system

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Embodiment Construction

[0033] The demodulation process of the present invention is as figure 1 As shown, among them, the analog input data is first sampled to obtain the signal to be demodulated, and its representative expression is S FM = A cos [ ω c t + ∫ 0 t k f m ( t ) dt ] , It can be expanded into the difference in the form of the product of two trigonometric functions; from the structure of the input signal, it can be seen that in the demodulation process, the first step is to remove the carrier signal (based on ω c t); then use the arctan (arc tangent) algorithm to obtain the argument angle for the I and Q two-way useful signals after the carrier wave is filtered out, that is, for sin [ ∫ ...

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Abstract

The invention relates to a system and a method which demodulates the frequency-modulation signal, which solves the compatibility issue of analog FM demodulation in digital mobile interphone system, comprising the following steps: firstly, sampling the input analog FM signal by data sampling module; secondly, removing carrier of the FM data by carrier removal module; thirdly, analyzing the removedcarrier signal of IQ dual to revivify the modulated signal by baseband analytic module; finally, outputting the final modulated signal by lowpass module. The functions of clock module, carrier removal module, baseband analytic module and lowpass module can be realized by a FPGA. The invention has an advantage of achieving the compatibility of analog FM demodulation and the digital treatment of analog signal in digital mobile interphone system, so as to enhance the signal anti-interference capability.

Description

technical field [0001] The present invention relates to digital wireless walkie-talkie technology, more specifically, to a system and method for digitally demodulating FM signals in a digital wireless walkie-talkie system. Background technique [0002] The DMR (Digital Mobile Radio) standard is a digital trunking standard newly released by the European Communications Standards Association. The DMR standard is dominated by digital wireless systems, but it is also clearly required to be compatible with existing analog wireless systems. Therefore, for the current common FM (frequency modulation) analog modulation and demodulation mode, how to realize it on the DMR-based digital platform will be a technical difficulty that must be overcome in the commercialization of the DMR system. [0003] In current digital mobile walkie-talkies, FPGA (Field Programmable Logic Gate Array chip) is usually used to implement each functional module, but there is no solution for realizing analog ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/152H04L27/14H04Q5/24
CPCH04L27/1525
Inventor 张晓波
Owner HYTERA COMM CORP
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