Based On The Model Of The Dab Transmitter Key Module Design And The Fpga Implementation

Digital Audio Broadcasting (DAB), which has complex baseband signal processing architecture, is a wireless communication system. By use of signal processing technology such as QPSK modulation, frequency interleaving and OFDM in the transmitter, DAB system has better performance regarding the quality of delivered audio program, the ability to inhibit fading and to broadcast multimedia information.Model Based Design (MBD), where modeling is considered as key process of every critical step of development, is a burgeoning method. Compared with traditional development, MBD is considered to be more efficient and reliable.This dissertation concentrates on design and FPGA implementation, using MBD methodology, of key modules of DAB transmitter. Theory of MBD is first discussed and then the idea of combining abstract level and design level modeling for development of FPGA modules is proposed in this dissertation. Two different DAB transmitter architectures that are based on SRS and ML605platform are discussed respectively and key modules of the two transmitters are analyzed. Based on this, following modules have been designed and implemented:(1) Number conversion module:number conversion based on identification is proposed and sub-modules such as exponent processing and mantissa processing are designed to identify the input numbers. Number conversion is realized based on manipulation of identification results. B method which is a formal method is used to model proposed algorithm and consistence of B model is examined.(2) Signal processing module:24times oversampling of the input signal is realized by use of FIR filter combined with CIC filter and image frequency interference is suppressed. None linear distortion is avoided during signal processing.(3) Modulation and multiplexing module:this module consists of several sub-modules such as QPSK modulation, frequency interleaving, differential modulation and OFDM. Algorithms such as double space flow processing are proposed to solve real time processing problem of specified sub-modules. During design and implementation of above listed modules, B method and Block diagram are used for abstract level modeling, subsequently abstract model is mapped into Simulink platform to obtain design model. Finally design model is automatically converted to implementable project by use of code generation software.According to testing results, all three modules meet requirement specification. Number converter could realize required functionality with processing speed as high as50MS/s and absolute conversion error is smaller than2-16, signal to noise ratio of output I and Q signal of signal processing module is33.5dB and36dB respectively, modulation and multiplexing module has more than80000lines hardware language description, and the realtime signal processing of involved sub-modules such as QPSK, frequency interleaving, differential modulation and OFDM is accurate.