Universal 4fsk modem and multi-standard digital walkie-talkie

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 invention relates to the communication field, in particular to a general 4FSK modem and a multi-standard digital walkie-talkie. Background technique [0002] Communication generally refers to the process of transmitting voice, image, 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 passes the audio signal received by the microphone through channel filtering and other baseband processing, and sends the frequency components of 300 Hz to 3000 Hz as the output of the baseband module to the RF transmitter module. The radio frequency transmission module modulates the baseband signal to a certain transmission frequency (several megahertz to several gigahertz), amplifies it and transmits it to space through the antenna. [0004] The analog receiver passes the...

AI Technical Summary

Problems solved by technology

[0011] Traditional analog walkie-talkies all comply with 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. 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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