Research On Fast Acquisition And Tracking Technique Based On High Dynamic DSSS With Large Dynamic Range Doppler Frequerny Shift

In the tt&c system,because the distance between the satellite and other spacecrafts and the ground tt&c equipments is very long,the signals received by the tt&c equipments are very weak,and the useful signals are submerged in the strong noise.At the same time,there is a relatively high-speed radial motion between the spacecraft and the measuring and controlling station,the carrier frequency of the received signal changes with time,and the spread spectrum signal has doppler frequency shift of tens or even hundreds of kHz.Under the preset carrier center frequency,the initial frequency difference of hundreds of kHz will still cause the carrier synchronization time to be too long.In order to ensure that the measuring and controlling system can receive weak signals in the background of strong noise,under the condition that most of the input signals have doppler frequency shift,the acquisition time is too long to meet the requirements of carrier rapid acquisition if the traditional detection and acquisition method is adopted.In this paper,the development of hypersonic aircraft is firstly summarized.Aiming at the requirements of measurement and control of the aircraft under high-speed flight,the main background and research significance of spread spectrum transponder development are discussed.The relevant research situations at home and abroad are discussed.Basic theories of the spread spectrum system are presented,combining with the development of the software radio technology,to explore a kind of PMF–FFT frequency domain parallel search strategy.Based on the study of capture structure,principle and algorithm,the capture algorithm can simultaneously estimate the pn code phase and carrier wave doppler frequency offset,thus shortening the capture time.In order to track spread spectrum code,a design method of phase-locked loop with lead-lag delay is proposed.According to the idea of software defined radio,a Ka band spread spectrum receiver is designed and implemented.Performance including the acquisition time,the acquisition threshold level,the anti-interference characteristic and the bit error rate of the developed transponder is tested,which verify the feasibility of this study.The design idea can be widely used in spacecraft spread spectrum transponder and relay terminal design,providing effective measuring and controlling technology for a variety of follow-up spacecraft in China.