An ATSC DTV receiver with improved robustness to multipath and distributed transmission environments

摘要

This paper presents the design and implementation of an 8-VSB DTV receiver for indoor and distributed transmission environments. The receiver is designed to handle severe multipath distortion from indoor and Single Frequency Network (SFN) transmission conditions. The architecture of the receiver is first introduced. The adaptive equalizer structure and design are then discussed in detail. A channel-matched filter is employed as a pre-filter such that the signal energies from different echoes are combined optimally and the signal to noise ratio of the equalizer input is maximized. Feedforward and feedback equalizers are used to handle the pre-echo (pre-cursor) and post-echo (post-cursor), respectively. The feedforward filter is designed to minimize the pre-cursors or convert them into post-cursors, while the feedback equalizer is used to eliminate the post-cursors. Initial tap coefficients are computed to speed up the convergence of these two filters based on the channel estimation. Laboratory tests show that the new prototype DTV receiver has very robust performance in multipath environments. 0 dB echoes can be handled with this receiver due to the enhanced design of the equalizer. It can withstand a -10 dB single echo within a -29.5 to +38.5 microsecond range and a 0 dB echo within a 12 microsecond range.