Research Of Encoder And Decoders In Airborne Real-time Transmission System Of Remote Sensing Data

Errors often occur during the transmission of digital signal over noisy channels ,which may cause image jump,discontinuous image and image mosaic,etc. Channel coding carries on processing to the data streams and enables the system to have error correction ability and antijamming ability. In Airborne Real-time Transmission System of Remote Sensing Data we can enhance data transmission efficiency,reduce BER(Bit Error Rate),improve the performance of the system in a great deal by using channel coding technology.The thesis focused on RS codes and LDPC(Low-Density Parity-Check) codes. RS codes are widely used in the error control for data communication system and in recent years LDPC codes have received a lot of attention due to its high performance.The Low-Density Parity-Check codes are among the most powerful forward error correcting codes, since they enable to get as close as a fraction of 1 dB from the Shannon limit. This astonishing performance combined with their relatively simple decoding algorithm make these codes very attractive for the next digital trans -mission system generations. It is already used in DVB-S2(Digital Video Broadcasting-Satellite 2) system.The thesis first describe the digital communication system,channel models and present encoding and decoding algorithms of RS code. We show how to design RS encoder and decoders based on FPGA . The simulation result indicate that the design is correct and feasible. This design can be used not only in satellite space data transmission system,but also in general communication systems and DVB systems, etc.Then LDPC codes and its encoding/decoding algorithms are described. Finally the thesis focus on the research of the code attributes and applications in DVB-S2 systems. A low-complexity algorithm for the decoding of LDPC codes is developed. Different decoding algorithms such as BP(Belief-Propagation) Algorithm,Min-Sum Algorithm and improved Min-Sum Algorithm are simulated.By simulation we compared the performance of different decoding algorithms and analyzed the influence of quantization to decoding performance.