Research On Effect Of High-dynamic Doppler On Multi-tone FM Signal

Nowadays, spacecraft tracking, telemetering and control system has been widely used in military, politics, science and technology and people’s life.Safety telecommand system is particularly important cause it is about the safety of people’s life, buildings and astronaut escape. The safety telecommand system in American is based on multi-tone frequency modulation,also known as the high alphabet system,have been widely studied owing to its great performances of real-timing, reliability and Security confidentiality. Because the aircraft such as rockets and missiles from launching to recovering is a kind of high speed, high dynamic flight scenario, leading to a Doppler frequency offset exist in the signal at the receiving. It will be serious influence on safety telecommand signal correct received. Through efficient estimating of Doppler frequency offest and removing can improve system performance. We have a general study of the safety telecommand system based on multi-tone frequency modulation, the main research results as blow:1. Having a comprehensive analysis on multi-tone coding frequency modulation, its symbol error rate, virtual command probability, missed command probability and error command probability expression is derived. Compared with traditional PCM-PSK-FM system, we discuss the performance of its security, reliability, security and confidentiality. The results show that high alphabet based safety telecommand system have obvious advantages2. We deal with its key techniques as well as principles and build its model, by setting up the transmitter and receiver models. Besides, its symbol error rate in AWGN channel is simulated through the MATLAB.3. We analyzed the reason of Doppler frequency offset and introduce the development history and research status of Doppler frequency offset compensation. We build three models of Doppler shift, two are low-dynamic and the other is high-dynamic. We analysis the high alphabet’s resistance to anti-Doppler shift with these models of Doppler shift, and improve the performance by PLL. Through PLL we can estimate Doppler frequency offset and compensate it.4. The user interface of safety telecommand system based on multi-tone frequency modulation is designed.