Design Of Common Frenquency Broadcasting System

As expanding of modern cities and widening of communication area, limited frequency resources are getting more and more precious. So how to use frequency more effectively becomes one of the most important factors which are considered in the design of wireless communication system."Common Frequency Broadcasting"is a very new networking method which can widen communication area effectively, and its simple networking can save equipment expending and precious frequency resources. Besides, the common frequency broadcasting system can resolve the problem of low power of uplink signal in practical application, and be applicable in handling of special network such as public security, resources and fire protection.In this paper, based on the detailed explanation of the principle and basic requirements of the common frequency broadcasting system, developed a practical wireless network which works under frequency of 350/360MHz and 450/460MHz .It is made up of one linking station and at most 32 broadcasting stations. Specifically speaking we completed the network construction, design of the communication protocal, the hardware of control board and the software for SCM ATmega16l and PC. We used TK868 transmitter-receiver as channelized transmitter, by which established the audio channel. By adding selection function of field strength to the communication protocal,it improved the system performance greatly. We chose ATmega16l as the central unit of the control board and MSM6882 as MSK moderm. for convenience a multifunction PC software was developed by VC6.0 for real-time monitor.After the main design, we tested this system practically whose results showed that this design is easy to set up, convenient and reliable to use. it can be competent to accomplish timely and efficient scheduler tasks.