The Research On The Method Of Sample Timing Adjustment On Software Radio Receiver

Sample synchronization is a basic problem whether Software Radio Receiver systems can demodulate the received signal correctly, it also affects the performance of the system. The implementary method of sample synchronization is biggest distinctness between software radio and traditional receiver. The former is completed by narrowband filter and PLL, it can be implemented perfectly by feedback loop if only the variational direction of signal has been known, dosen't require the exact numerical value;the latter use opened loop structure whose sampling clock is independent of the transmitted signal, the optimal sample can't be obtained by resampler directly, it is achieved by interpolation for original samples using interpolating filter, which is controlled by the estimated value of timing error. It is obvious that interpolation is the special disposal in software radio, it replaces PLL for timing adjustment. Thus, it makes all-digital signal demodulation comes true. The designment for better performance is important for all-digital receiver or software radio,it is also the main work in my paper. My work belongs to my proffessor's research, which named "The modulation and demodulation algorithm for baseband in Software Radio"The development of implementary method for interpolating estimation is based on numerical analysis principle. The main idea is that it constructs interpolating function by original samples, and computes unknown samples using this function. The paper reviews some traditional interpolating filters which are based on Lagrange Polynomial(Algebraic Polynomial)firstly, and combined with polyphase decomposition for simpleness, in addition obtaining a new interpolation method. Given the latency estimation parameter ,comparing with some classical interpolators it indicate that this interpolator achieves the best performance among all state-of-the-art methods. It is alsodemonstrated that this approach produces a particular simple implementation structure,reduces computation latency and improves the interpolation performance.Firstly, the paper introduces the principles of the tranditional digital communication receiver , all-digital receiver and software radio receiver;Secondly, it introduces the principle and structure of sample synchronization in order to understand the position and function of interpolator , and it pay more attention to introduce interpolation principle , the designment of interpolator and some classical interpolators in this chapter. Lastly, it researchs a new efficient Interpolator and introduces a new anti-aliasing digital filter technical which is not related to interpolation timing adjustment but has some new ideals in it.