The Design And Realize Of Baseband System For Digital No-Center Two-Way Radio

In special communication network,no-center system has more superiority when compared with simple two-way radio system and trunked radio system whose dispatch function is realized by base station,for example,it has low cost,easy to compose a network,and can be dispatched by the software in itself. So no-center system is widely used in many enterprise with small or normal scale.With the development of digtal IC industry,the digital no-center system is known and accepted more and more better,because of its advantage of high quality in communication voice,high efficiency in channel used rate,therefore we can make a conclusion that the analog no-center system will be replaced by the digital no-center system in the future.Because of the society background like this,we started our research and development of digtal no-center two-way radio.This paper is mainly about the baseband part,it includes four parts as below.In protocol,some modification is made in DPMR protocol which was used in digital two-way radio system so the new protocol suitable for our digital no-center system is born out.In call control layer,some new methods of call control process is designed and realized which is compling the standard of high efficiency and stability, so we can use the new designed call control process in peer-to-peer call,group call and SMS transmitting function.About the hardware design of baseband system,the microprocessor module,voice coder and decoder module,modulation and demodulation module,key scan module and power supply module are all be designed and realized,I designed the schematics and PCB board.In the software, the driver program and the application program of modulation and demodulation module,key scan module,voice amplifier module and EEPROM module is finished,the function programme of peer-to-peer call,group call and sms is also designed and complished.