Equalization of ATSC DTV Systems Based on Space-Time Signal Processing for Mobile Reception

A joint operation of the Capon and the least mean square (LMS) beamformers is proposed to get reliable reception performance for the advanced television system committee´s (ATSC´s) digital television (DTV) system. The proposed beamformer called a Capon and LMS (CLMS) beamformer provides an initial weight set for the operation of the LMS beamformer during the training sequence. The Capon beamformer is operated during the payload data period. By the way, the Capon beamformer could be unstable because of frequent changes of the steering beam direction in mobile conditions. To get a stable operation in mobile conditions with the CLMS beamformer, the signal-to-noise ratio (SNR) is estimated to control the operation by utilizing the Viterbi decoder output. When the SNR level is below the threshold of visibility (TOV), the Capon beamformer is operated to get a fast initialization of the LMS beamformer. When the receiver is moving with a speed of 60 km/h for 700 MHz band, the successful reception probability of the CLMS beamformer based on SNR estimation is 76% compared to 60% for that of the conventional CLMS beamformer