General 4FSK modem and digital interphone capable of supporting multiple standards

Abstract

The invention discloses a general 4FSK modem and a digital interphone capable of supporting multiple standards. The general 4FSK modem comprises a 4FSK general modulator and a 4FSK general demodulator, the 4FSK general modulator comprises a first rooted raised cosine filter, a shaping filter, a first switch and a double up-sampling module, and the 4FSK general demodulator comprises a second rooted raised cosine filter, a bit synchronizer, a frame synchronizer, a double down-sampling module, an anti-shaping filter, a second switch and a synchronous code selection module. A plurality of communication standards are integrated, the aim that the digital interphone is low in cost and supports multiple standards is achieved, and the size of the present interphone is not increased.

Description

Technical field [0001] The present invention relates to the field of communications, in particular to a universal 4FSK modem and a digital walkie-talkie supporting multiple standards. Background technique [0002] Communication generally refers to the process of transmitting voice, images, data and other information from one subject to another, usually involving two aspects, a transmitter and a receiver. [0003] Traditional walkie-talkies are based on analog voice communication. In analog voice communication, the analog transmitter processes the audio signal received by the microphone through channel filtering and other baseband processing, and uses the 300 Hz to 3000 Hz frequency component as the output of the baseband module to the RF transmitter module. The radio frequency transmitting module modulates the baseband signal to a certain transmitting frequency (several megahertz to several gigahertz), and then transmits it to space through the antenna after amplification. [0004]...

AI Technical Summary

Problems solved by technology

[0011] Traditional analog walkie-talkies follow the same standard, as long as the frequency is the same, they can realize intercommunication. However, digital walkie-talkies using different standards cannot communicate with each other. For example, digital walkie-talkies using dPMR standard and DMR standard cannot communicate with each other. Digital The non-interoperability of walkie-talkies has brought great troubles to the market and seriously affected the promotion of digital walkie-talkies

Because the RF transceiver circuits of different digital standards are relatively similar, the existing practice is to put two basebands using different standards on one walkie-talkie, and pre-set the working mode. In order to achieve a dual-standard digital walkie-talkie, but this brings volume and cost increase

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