Digital interphone signal demodulation device

A digital walkie-talkie, signal demodulation technology, applied in the field of signal demodulation, to achieve the effect of reducing distortion

Active Publication Date: 2013-02-20
DATANG MICROELECTRONICS TECH CO LTD
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[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, the embodiments in the present application and the features in the embodiments may be arbitrarily combined with each other if there is no conflict.

[0026] The embodiment of the present invention proposes a signal demodulation device for a digital walkie-talkie. By tracking the received radio frequency signal, detecting changes in the received demodulation signal, and dynamically adjusting the control voltage of the voltage-controlled oscillator 4 in real time, the demodulated signal can be adjusted in real time. The signal remains at a steady DC level. The specific implementation is as follows:

[0027] The voltage-controlled oscillator 4 is used to generate a local oscillation signal according to the control level output by...

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Abstract

The invention relates to a digital interphone signal demodulation device, relates to the field of signal demodulation and solves problems that demodulation signals are poor in stability and high in distortion degree due to device ageing and temperature changes. The digital interphone signal demodulation device comprises a voltage-controlled oscillator, a mixer, a frequency discriminator and a voltage output module, and the voltage-controlled oscillator produces local oscillation signals according to control levels output by the voltage output module; the mixer mixes the local oscillation signals with radio-frequency signals received by antennas to obtain intermediate frequency signals; the frequency discriminator performs frequency discrimination and demodulation to the intermediate frequency signals and outputs the demodulation signals; and the voltage output module outputs the control levels according to the demodulation signals, calculates direct current components in the demodulation signals and compares calculating results with reference direct current components, and if deviation is larger than a direct current threshold value, the control levels output to the voltage-controlled oscillator are changed till the deviation is smaller than the direct current threshold value. The digital interphone signal demodulation device is used for improving stability of the demodulation signals and reducing the distortion degree of the demodulation signals.

Description

technical field [0001] The invention relates to the field of signal demodulation, in particular to a digital walkie-talkie signal demodulation device. Background technique [0002] For terrestrial professional wireless intercom systems, 2008 to 2013 is a transition period from analog to digital. At this stage, most of the market will turn to low-cost digital intercom, and DPMR is recognized as the best solution for commercial intercom today. Because DPMR uses 4FSK (Frequency-shift keying, frequency-shift keying) digital modulation and demodulation to replace traditional FM modulation and demodulation, the receiver in some solutions uses secondary down-conversion, the first local oscillator signal and the second local Oscillating signals are all signals generated by the reference crystal, so the stability of the output signal frequency of the reference crystal directly affects the performance of the entire receiver. However, the oscillation frequency of the reference crysta...

Claims

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Application Information

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IPC IPC(8): H04L27/152H04L27/14H04Q5/24
Inventor 杨亮唐汤磷
Owner DATANG MICROELECTRONICS TECH CO LTD
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