Patent ID: 6823292
Filing Date: 2004-11-23
Classification: H03J

Abstract:
A signal receiving device comprising a tuneable filter and a control means, wherein the tuneable filter comprises an input for applying a signal at a first frequency, an output for delivering the filtered signal and a variable reactance means, and wherein the control means comprises means for generating a control signal for varying the reactance of the variable reactance means, measurement means for measuring a post-filter signal quality, first storage means comprising data relating the degree of off-tune of the filter to a consequent signal quality, and second storage means for storing an indication of a control signal value and an indication of a frequency, wherein the control means is operable to tune the filter to the input signal at the first frequency by determining a first value of the control signal which produces a peak signal quality, to off-tune the filter from the first frequency by selecting a second value of the control signal, to measure the off-tune signal quality, to determine a peak frequency of the off-tune filter by using the peak signal quality, the measured off-tune signal quality and the data relating the degree of off-tune to the consequent signal quality, and to store an indication of the second value of the control signal and an indication of the peak frequency of the off-tune filter.