Multiplexer In The Digital Television Research And Realization

Digital TV had gone out of the lab, and began to enter the time of industry. It will replace the analog TV for excellent picture and lower bandwidth of a program and bi-directional transport. Many countries entered into intense rivalry in this field,our country also wanted to keep pace with developed country and had made the strategy of three steps walk, DTV was started to broadcast in 2003, all Olympic games programs will be broadcasted by digital equipment in 2008 and analog television will be ceased in 2015.Either the ATSC standard of America or DVB of Europe or ISDB of Japan or the coming standard of our country, MPEG-2 transport stream (TS) multiplex is an important part in terrestrial broadcast or cable broadcast or satellite broadcast of DTV, then research and design of it will create huge economic benefit.MPEG-2 standard was a video and audio compress criterion which was applied widely all over the world. Advanced country kept ahead our country on it. The standard only defined the decoding model, then the multiplex designing was very free, because it was demonstrated good if the output of it could be decoded by the MPEG-2 decoder. First of all, this paper will analysis the operation of TS and syntax of program special information(PSI) and multiplex of TS, then put forward a kind of solution to multiplex,at last introduce present conditions and fortune of DTV and multiplex. This article has two main contributions.On the one hand, cyclic redundancy check (CRC) was essential if the PSI was modified. The CRC model of MPEG-2 was same as that in digital communication, but the initial condition was different, this article inferred in theory to get the model of CRC code in MPEG-2 and discussed the different point.On the other hand, the scheme of multiplex made the special process about core module: PSI process unit and interweave unit, did not correct the PCR(program clock reference) shaking. Studied the MPEG-2 T-STD (transport stream system target decoder) model and constant delay model, found that the shaking of PCR was so small that no correcting on it could satisfy the MPEG-2 standard. The point of view that PCR in multiplex must be corrected was broken.The main part of multiplex which satisfied the prescription function was designed by FPGA, the multiplex was small weight and volume and high stability, appraised highly in Sichuan No.7 TV fair.