Patent ID: 6804501
Filing Date: 2004-10-12
Classification: H03G,H04B

Abstract:
An automatic gain controller for use with a receiver adapted to receive a broadcast signal having digital information encoded therein, the receiver including a first amplifier having a fixed gain setting and a unity gain setting, a second amplifier cascaded with the first amplifier, the second amplifier having a variable gain, the automatic gain controller comprising:a signal strength determiner adapted to process the digital information to produce a signal strength metric representative of an average signal strength of the broadcast signal; a threshold comparator adapted to process the digital information to produce a threshold satisfaction indication representative of a magnitude of the digital information in comparison to a threshold; an accumulator communicatively coupled to the threshold comparator and adapted to process the threshold satisfaction indication to determine a historical probability that the digital information exceeds the threshold to produce a threshold satisfaction metric; and a gain adjuster communicatively coupled to the signal strength determiner, the accumulator, the first amplifier and the second amplifier, the gain adjuster adapted to selectively switch the first amplifier between the fixed gain setting and the unity gain setting and to vary the gain of the second amplifier based on the signal strength metric and the threshold satisfaction metric, wherein the gain adjuster is adapted to compare a current value of the signal strength metric with a prior value of the signal strength metric to determine whether the first amplifier should be set to the fixed gain setting and is further adapted to set the first amplifier to the fixed gain setting when the current value of the signal strength metric is substantially equal to the prior value of the signal strength metric.