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

A FM signal, digital wireless technology, applied in digital transmission systems, two-way line system stations, transmission systems, etc., to achieve the effects of digital processing, compatibility, and enhancement of anti-interference capabilities

Active Publication Date: 2008-05-21
HYTERA COMM CORP
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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 e

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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 and Perf...

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Abstract

The present invention relates to a system and method for digitally demodulating FM signals in a digital wireless walkie-talkie system. In order to be compatible with the problem of analog FM demodulation in a digital mobile walkie-talkie system, in the present invention, the data sampling module first The input analog FM signal is sampled, and then the carrier removal module performs carrier removal processing on the data to be demodulated, and then the baseband analysis module analyzes the IQ two-way carrier signal to restore the modulated signal, and finally the low The pass filter module performs low pass filter to output the demodulation result signal. The clock module, carrier removal module, baseband analysis module, and low-pass filter module in the system can be realized by one FPGA. The invention realizes the compatibility of the analog FM demodulation in the digital mobile walkie-talkie system, realizes the digital processing of the analog signal, thereby achieving the purpose of enhancing the anti-interference ability of the signal and the like.

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 ...

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Application Information

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IPC IPC(8): H04Q5/24H04L27/14
CPCH04L27/1525
Inventor 张晓波
Owner HYTERA COMM CORP
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