Digital DMR interphone using digital frequency synthesizer as local oscillator

Abstract

The invention relates to the technical field of wireless communication, and provides a digital DMR (Digital Media Receiver) interphone using a digital frequency synthesizer as a local oscillator, which is simple in circuit, low in manufacturing cost and convenient for debugging, and utilizes the digital frequency synthesizer as a signal source to emit a local oscillator signal. The digital DMR interphone comprises a MCU (Microprogrammed Control Unit) respectively connected to a transmitting channel module, a receiving channel module and a baseband processor, wherein a digital frequency synthesizer is arranged between the transmitting channel module and the MCU; a crystal voltage-controlled oscillator is connected between the baseband processor and a first digital frequency synthesizer; the MCU is further sequentially connected to an audio frequency amplifier and a loudspeaker; the baseband processor is connected to a microphone externally; the audio frequency amplifier is further connected to the baseband processor; and the baseband processor is further sequentially connected to a second digital frequency synthesizer and the receiving channel through the crystal voltage-controlled oscillator.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to a digital DMR walkie-talkie based on a digital frequency synthesizer as a local oscillator. Background technique [0002] With the development of radio communication technology, people have higher requirements for the quality of wireless communication, but radio spectrum resources are increasingly scarce. The emergence of digital walkie-talkies provides more abundant, open and powerful types of use and user needs. As we all know , The DMR trunking communication system adopts TDMA technology based on 2 time slots. In the receiving part, the amplified signal from the radio frequency is mixed with the first local oscillator signal from the phase-locked loop frequency synthesizer circuit at the first mixer and then The first intermediate frequency signal is generated, and then the information required by people is obtained after filtering, amplification and other proce...

AI Technical Summary

Problems solved by technology

[0002] With the development of radio communication technology, people have higher requirements for the quality of wireless communication, but radio spectrum resources are increasingly scarce. The emergence of digital walkie-talkies provides more abundant, open and powerful types of use and user needs. As we all know , The DMR trunking communication system adopts TDMA technology based on 2 time slots. In the receiving part, the amplified signal from the radio frequency is mixed with the first local oscillator signal from the phase-locked loop frequency synthesizer circuit at the first mixer and then The first intermediate frequency signal is generated, and then the information required by people is obtained after filtering, amplification and other processing and analysis. The traditional circuit method of phase-locked loop and VCO is used. Since the DMR system requires a wide frequency coverage, the circuit method of ordinary VCO Difficult to debug, poor integration functionality, difficult to meet satisfactory requirements in terms of coverage, performance, cost and flexibility, unable to meet the scalability requirements of practical applications

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