Research And Implementation Of Software System In DRM Receiver

DRM is a digital system designed as a new generation of AM broadcast for the frequency bands used blew 30 MHz. OFDM as well as multi-channel-coding and multi-modulation is adopted by DRM. This combine with interleaving and error protection to decrease the effect of frequency selective fading, multi-path time delay and Doppler effect. Then the robustness of the signal transmitted is enhanced. The implementation of software system in DRM receiver is descriped in this thesis.The transmitter and receiver system are introduced firstly. Then three parts are detailed descriped, such as baseband signal acquisition, synchronization algorithm and channel estimation and equalization algorithm. Baseband signal acquisition consists of digital down convertion, down sampling and multi-phase filter design. Synchronization algorithm is composed of symbol time synchronization, frequency synchronization and frame synchronization. The synchronization of DRM is divided into different procedures, i.e. acquisition and tracking. PID control theory is used in synchronization tracking procedure. The sampling clock frequency offset can cause ICI, so the mothod to estimate and eliminate the sample rate error is derived. Three methods of channel estimation are tried to estimate the channel reponse including Wiener Filtering method, linear insertion method and DFT based mothod. Finally, use a mixture of the DFT based and linear method in PC and linear method in DSP. The multi-path channel mathematical model is detailed derived. The data acquisition of MSC, FAC and SDC, the unmultiplex of MSC, the unmapping of QAM and channel decoding are also introduced.