Research On Integral Demodulation Of Multi-carrier Burst Signals

In the application of MF-TDMA/TDM satellite communication system, which is based on star topology , the integral demodulation of multi-carrier burst signals is required. For the short duration of the burst signals coming from different transmitting stations, the information of demodulation parameters based on one station can't be used by the others. Capture and synchronization are required in a short time.The all-digital receiver has an open-loop structure, which needs no feedback control. The sampling clock and the local reference carrier both oscillate at fixed frequencies, then revising the error of synchronous and recovering the optimal samples are both accomplished by high speed digital signal processor. On all accounts, All-digital receiver which has an open-loop structure can capture and track rapidly, therefore it suits for burst signals.Basing on the consideration above, all-digital receiving techniques of multi-carrier burst signals with QPSK modulation are investigated in this paper. The main work includes:First, digital dynamic channelizer. Digital dynamic channelizer is improved based on the research on the existing digital channelization algorithms which can greatly reduce the complexity and improve the flexible. Digital dynamic channelizer can not only channelize, but also switch dynamically .Second, optimal samples recovery. Timing synchronization investigated under the circumstances of low sampling rate is researched that the optimal samples are recovered through timing error estimation and interpolator. Timing error estimation based on square filtering algorithm and interpolation technique of trigonometric polynomial are mainly analyzed.Third, carrier recovery. The NDA and DA carrier recovery is analyzed, and the loop-lock time is accelerated by modify the phase-detector speciality .