Iterative Receiving Technology Research On Digital-Analog In Band Broadcasting System

Digitization has become the inevitable trend of the development of world radio industry. China digital radio (CDRadio) broadcasting technology scheme is specifically targeted at Chinese FM radio design. China digital radio (CDRadio) system enables the existing FM radio stations to broadcast OFDM digital audio of CD-like quality (including data service) within conventional FM band simultaneously together with analog FM without any base installations or spectrum change.At first, this paper gives the specific system architecture and coding design etc of the CDRadio digital audio broadcasting system.Therefore, the separation of digital-analog mixed signals is of strategic importance to the system. A unique preprocessing structure is applied to convert digital-analog mixed signals into co-channel FM signals, and an innovative extended Combined Measurement Kalman filter (ECMKF) algorithm, namely predicting and estimating the original signals with more than one observation from the preprocessing structure, is put forward to avoid the crisscross separation effectively. Simulation results show that, compared with the Viterbi [2] algorithm,the innovative ECMKF algorithm gains much better performance for considering the noise.In this paper, for kinds of synchronization algorithms of the system are investigated:ML, Schmidt&Cox, Park. By improving existing algorithms and simulation, the applied Park algorithm is a good choice with better performance and lower complexity.Evaluating the impact of OFDM on FM demodulation gives the reference for selecting OFDM to FM power ratio. The details the most popular three FM demodulation algorithm is given, extensive simulation are then conducted to evaluate the OFDM impact on FM demodulation.