DSP-based Design Of Network Audio Broadcasting

In this paper we design a network broadcasting system which is based on DSP and network interface chip. The network communication and filtering algorithms were experimentally verified.Firstly, this paper introduces the whole design of hardware and the role of each module. Includes the following modules, DSP module is core of the system, responsible for the distribution of all the module functions and run all real-time algorithms. The role of power module is transformer and supply power for systems. CPLD select each module logically. SRAM module is the expanded storage device. D/A module convert signal. Network interface module communicates with PC.Secondly, we analysis and design the classical filtering algorithm and adaptive filtering algorithm, and made a detail analysis of the rules audio signal and Gaussian white noise and pink noise. Rules audio signal superimpose with Gaussian white noise and pink noise respectively to simulate the actual broadcast signal. We made a comparison for FIR and IIR filters and selected the structural model of the FIR filter. We made an in-depth frequency response characteristic analysis of several window functions belong to the FIR filter, and choose the appropriate window function to filtering according to the requirement of the filter technical specifications in network broadcasting device. About adaptive filtering algorithm, we analyzed with the characteristics of two implementations which is the recurrence LMS and the RLS with forgetting factor. And compare with their tracking effects of fixed values and a filter simulation has been made for the better tracking one RLS algorithm with forgetting factor.Again, the system software is design with the core DSP control module. The main program could reads audio data packet transmission from PC through 8019, made filter in the receive interrupt and sent to the D/A chip to play through the McBSP port; The function of MCU program is reset on each chip and finish their initialization, including the DSP bootloader process; CPLD made chip select and the distribution of logic address; PC interface selected audio files and send audio data packets though the network interface to supply data for players.Finally, though the analysis and simulation verification of several filtering algorithms, we verified experimentally the communication of DSP-based network broadcasting system and PC, the filtering algorithm of classic, the adaptive filter algorithm, and achieved good results.