Drm Digital Receiver Key Technologies

With the development of communication techniques, digital signal processing brought in enormous affection on media broadcasting. The Digital Radio Mondiale takes the bandwidth of traditional amplitude modulation under 30M Hz and utilize OFDM ,QAM,viterbi encoding ,multilevel modulation, bit interleaving and cell interleaving as main transmission frame work. The music transmission quality can reach the CD level and data file convey ability is also provided. The chip production of DRM receiver worldwide is currently on initialization stage. It's a good chance for us to produce a chip with our own IP.This paper focuses on the research of baseband realization of DRM receiver which comprise of two main blocks. The first one is the ionosphere short-wave channel simulation. The second one is receiver framework and algorithms selection of baseband process.The first part describes in detail the ionosphere short-wave channel modeling technique. The chapter start from the basic simulation model of wireless communication channel, then introduces the characteristic of ionosphere short-wave channel and the WSSUS simulation model. This model got a unsymmetrical Doppler Power Spectrum Gaussian like shape and White Noise Filtering method is introduced to realize this model. The key point of generating single path attenuation include: the Gaussian shape filter generating, the selection of up-sampling filter, multilevel up-sampling structure and the Doppler shift affection. The key point of multipath delay line is to approximately set the delay samples to the integer multiply of sample rate.The second part is derived into two chapters which discuss the synchronization and channel estimation techniques of digital receiver. The synchronization part include the fundamental synchronization theory of OFDM,the DRM baseband receiver structure and the detailed algorithms for synchronization. Pre FFT and post-FFT algorithms are separately discussed. Pre-FFT includes the carrier synchronization based on frequency pilot, the Maximum likelihood method for OFDM symbol synchronization based on cyclic prefix and the robustness mode detection method based on the priority of cyclic prefix correlation peek. The post-FFT includes the frame synchronization based on time pilot and the sample rate and fractional frequency synchronization method based on frequency pilot. These algorithms are analyzed in theory as well as simulation result. Proposed parameters are discussed for practical realization of DRM receiver.Channel estimation is derived form the star shape pilot position of DRM ODFM symbol structure. Basic LS and MMSE estimation are introduced, the following estimation methods are interpolation algorithms and the FFT based method. With the combination of the three parts, proposed channel estimation work flow is presented. It integrates interpolation in time direction of pilots, Gaussian shape window, zero setting at data position and noise elimination in time domain after FFT of pre-estimated channel function. This method could support the basic requirement of DRM channel estimation. In medium level of SNR, the BER could be remarkably improved. Furthermore, the advantage of this method can be adjusted and optimized easily.