Patent ID: 7489911
Filing Date: 2009-02-10
Classification: H03G,H03J

Abstract:
1. A method for controlling gain of a dual frequency conversion tuner for reception of a desired signal and provided with a band-pass high frequency input filter, a band-pass first intermediate frequency filter having a passband width narrower than the passband width of the input filter, a detector of the intermediate frequency signal level and amplifiers having gain automatically controlled according to an AGC characteristic of the tuner to provide a constant level of a tuner output signal IF_OUT, the method comprising the following steps: identifying a passband of the input filter for the desired signal; determining a level of the desired signal; tuning the tuner to successive frequencies within the passband of the input filter; calculating a level of signals for each tuned frequency on the basis of the detector output for each tuned frequency; selecting the strongest level of close signals; and calculating the AGC characteristic of the tuner on the basis of the level of the desired signal and the strongest level of close signals.