The Research And Implementation Of Carrier Recovery In DVB-S2System

The paper studies the DVB-S2carrier recovery algorithm. DVB-S2is a second-generation digital satellite broadcasting standard promulgated by the European Telecommunications Standards Institute (ETSI) in2005. The chip is the highest technical content in the digital TV system for the quality of the demodulation chip of the reception end directly affects the quality of the reception system. Carrier recovery is a very important part in demodulation module of the digital communication system, for correcting the transmission channel and receiving the frequency deviation, phase deviation and phase noise that caused by reception system.Carrier recovery is divided into frequency synchronization and phase synchronization. Frequency synchronization is used to correct the large frequency offset, while phase synchronization is used to correct the residual frequency offset and phase offset. Due to the special nature of the satellite channel and carrier recovery is dealt with the signal that has the low signal-to-noise ratio and large frequency offset, carrier frequency recovery is divided into coarse frequency synchronization and accuracy one, in order to meet the requirements of the DVB-S2standard. Coarse frequency synchronization takes the frequency offset down to an acceptable range for accuracy frequency synchronization, then the accuracy frequency synchronization further reduce residual frequency offset.Next is the phase synchronization module, which continues correcting the remaining frequency offset and the phase offset and phase noise.This paper first analyzes the DVB-S2standard and the background and research of carrier recovery algorithm and emphasizes the importance of carrier recovery module for the receiver and necessity for the development of satellite communication and broadcasting system. Then it briefly analyzes the DVB-S2system, including the sending end, the receiving end of each component part and function. Because of the satellite transmission distance length and other characteristics, it analyzes the channel transmission signal when the various non-ideality factors happen. The carrier recovery algorithm that this paper studies is based on the physical layer frame structure of the frame header or pilot, so I make detailed study of the physical structural system of the DVB-S2standard. Then I refer to the relevant literature and data and select one of several typical algorithms for analysis through comparing the advantages and disadvantages of various algorithms. Coarse frequency synchronization study the M&M algorithm based on the header and AFC algorithm of automatic frequency controlling that DVB-S2standard recommend, accuracy frequency synchronization studies the L&R algorithm and pilot assisted detection algorithm. Phase synchronization studies the FFML linear interpolation algorithm, as well as the processing method of phase synchronization under higher order modulation.Through research and analysis, I made modifications for the smoothing factor of the M&M algorithm based on header and propose two new implementations for pilot-aided algorithm. At last I encoded several typical algorithms for frequency synchronization using c language coding, simulated the algorithm performance and concluded select research algorithm to meet the performance requirements of the DVB-S2standard, M&M improved algorithm achieves well. L&R correction algorithm and pilot-aided algorithm applicably range.