| Traditional radio services are entering a new era of digital audio broadcasting (DAB). The DAB system has many advantages, such as high-quality digital audio, efficient use of the radio frequency spectrum, reliable delivery, portable and mobile receivers. Also it is the multimedia broadcasting that can deliver audio, visual, text, data at the same time.This thesis covers the design of a MUSICAM audio decoder in DAB receiver system. It discusses the general audio encoding theory of the DAB system, and then presents an optimized audio decoding algorithm based on the audio standard of MPEG-1 and MPEG-2 LSF. At last, it introduces the ASIC design, system implementation and verification of the DAB audio decoder.The ASIC structure of the decoder includes several functional modules that are bit-allocation decoding, scale factor decoding, requantizing, synthesis filter bank, controller and CRC verification. In the bit-allocation decoding module, 3 short lookup tables are used instead of 5 long tables in MPEG standard. To reduce the chip area and operation complicacy, fast IDCT is implemented in synthesis filter bank, which also uses a 24 bits multiplier in common with requantizing module. The decoder operates with 24 bits precision, and outputs 16 bits PCM sample for audio play. Function verification has shown that the design of audio decoder is correct and satisfiable. By implementing it in the DAB receiver system, the high quality of audio is received. |
