Tuning system for achieving quick acquisition times for a digital satellite receiver

Abstract

The RF signals received from the LNB and the corresponding IF signal produced by the tuner may be offset in frequency due to reasons other than a frequency drift of the oscillator of the LNB, such as satellite transponder frequency adjustments made by the satellite transmission system. A tuner ( ) includes a local oscillator ( ) controlled by a controller. The controller (a) controls the frequency of the local oscillator ( ); (b) stores digital nominal frequency representative words for respective ones of RF signals received; (c) stores digital offset representative words for respective ones of the RF signals; (d) determines a frequency offset of said carrier signal after a RF signal has been tuned; (e) updates all of the digital offset representative words in accordance with the frequency offset of the carrier; (f) derives the tuning representative word for an RF signal selected to be tuned by combining said nominal frequency representative word for the RF signal selected to be tuned with the previously updated offset representative word for the RF signal selected to be tuned; and (g) updates the respective digital offset representative word for an individual RF signal presently being tuned if correct tuning is not achieved with the previously updated offset representative word.