The Design Of Digital RF Switch Control System Based On ATmega128

Radio broadcasting is one of the greatest inventions of mankind in the 20th century. Its birth, brings the media into the electronic age from the print era, and opens up a new era in the history of human communication. According to the different signal modulation techniques, radio can be divided into AM radio and FM radio. Because of FM radio has many advantages of its own, since it was come out, it received considerable attention, and developed rapidly, while it is generated later than AM radio. At present, FM radio has become the major form of radio broadcasting in our country, and moves towards the digital direction. Today, the 21th century, although a variety of new media and new communication technologies emerging, radio still maintains its status of mainstream media, and generates great and far-reaching impact on every country's political, economic and cultural life. Therefore, it is significant to ensure the broadcast signals be sent normally.FM exciter is the core component of the FM radio transmission system, its main function is to modulate the input audio signals and other additional signals, then output them to the radio transmitting station. In order to ensure the radio programs can be broadcasted uninterruptedly, radio stations generally use the master and slave exciter backup mode to send the programs. So a switching device is needed to switch the slave exciter to the radio transmitting station when the master exciter is failed. Now, however, most of the switching devices are used in manually switching mode, which is poor real-time and depends on the discovery and detection of human. To improve the real-time of switching, we have designed the digital radio switch. It sends signals to the master and slave exciter through the serial communication interface to inquire their working state. And extract information from the response signals of the master and slave exciter to judge their working state, then according to their current working state to execute the automatic switching.According to the function requirements of digital RF switch, this system proposes hardware and software design based on the general process of the embedded system development. The hardware chip was fixed, and the hardware circuit and PCB were designed based on the principle of improving system cost performance and integration, reducing system power consumption, and improving the system reliability. This system was equipped with the AVR series microprocessor typed ATmega128 of ATMEL corporation as the central processing unit, a dot-matrix LCD display MS 12232 and some LEDs were used to be the display module, stand-alone keys were token as the input device. The whole man-machine interface is simple and friendly. System software was programmed in assembly language, and modular designed. The software was divided into the main program, the detection module (including the USART module and the state judging module) and the man-machine interface module (including the operation key module and the state display module), etc. In this paper, we explained the main algorithm of each module detailedly, and given the algorithm flow chart to each module. At present, the system has passed all performance tests, and to be put into production.