Implementation Of Digital Television Terrestrial Broadcasting Baseband Recovery System And Research Of LDPC Decoding Algorithm

Digital television broadcasting is a more advanced television broadcasting technique than analog television. Chinese digital television broadcasting-terrestrial standard is a standard with independent IP and independently developed by ourselves. After 6 years of research, testing, modification and practice, our country's basic digital television broadcasting-terrestrial system has been established. The scheme has been carried out in August 2006. The new standard is called Digital Television Terrestrial Broadcasting. Based on Meyr receiver model, the receiver can be separated into inner reviever and outer receiver. Baseband recovery system in this paper is the outer receiver of model. Outer receiver is the same and of the same importance to both carrier systems. This paper focuses on several key techniques of outer receiver. They are system mode detection and auto switch, convolutional interleaver based on SDRAM and LDPC encoder and decoder. This paper also refers some coding algorithm due to the decoding algorithm's existence.This paper proposed a new technique of system mode detection and auto switch. The technique abstracts system information vectors from receving datas, getting the interrelative peak values with known mode information. The mode with most probability is regarded as system mode after counting with different right. It can instantaneously scout the change of the transmitter and indicate the LDPC decoder working in the required mode. It is the general director for information processing of the outer receiver. This part is one innovation of this paper.This Paper also focus researches on another key technique of outer receiver, called Convolutional deinterleaver. Deinterleaver is in the front of the LDPC decoder and its function is to randomize the burst errors. Convolutional deinterleaver improves the error correcting ability of LDPC code indirectly and reduces the receiving threshold. Our design faces to the product. Using SDRAM but not SRAM as high speed memory of convolutional interleaver can decrease system cost to a great extent.