Patent ID: 8406345
Filing Date: 2013-03-26
Classification: H04L,H04N

Abstract:
1. A method for acquiring a channel with a frequency offset less than half symbol rate in a receiver of a Digital Video Broadcasting-Satellite (DVB-S) system, the method comprising the steps of: (A) selecting a target channel; (B) acquiring a carrier frequency and symbol rate of the target channel; (C) tuning a tuner according to the carrier frequency so as to obtain a digital baseband signal corresponding to the target channel; (D) calculating a down-sampling factor (DSF) according to the symbol rate in step (B); (E) performing a down-sampling operation on the digital baseband signal according to the down-sampling factor for further finding a spectrum of the target channel; (F) using a moving average and spectrum inversion technique to detect a position of the spectrum of the target channel and to calculate a first cross point and a second cross point of the spectrum of the target channel, in which step (F) comprises: (G) calculating a coarse carrier frequency offset and a coarse symbol rate according to the cross points; (H) determining whether the coarse carrier frequency offset is greater than a first threshold, and tuning the tuner based on the coarse carrier frequency offset when the coarse carrier frequency offset is greater than the first threshold, so that the spectrum of the target channel is located at a middle of a working bandwidth of the tuner to obtain a tuned digital baseband signal corresponding to the target channel; (I) calculating a fine carrier frequency offset and a symbol rate estimate for the target channel according to the tuned digital baseband signal; and (J) arranging a digital mixer based on the fine carrier frequency offset for determining whether a signal at the fine carrier frequency offset is a channel to be acquired, and arranging the digital mixer based on the fine carrier frequency offset when a signal at the fine carrier frequency offset presents, so as to locate the spectrum of the target channel in a working bandwidth of the digital mixer for acquiring data.