Patent ID: 8565294

Claim:
An interference classifier for determining whether a received signal contains a noise burst or interference comprising a sinusoidal signal, the interference classifier comprising: a buffer operable to receive and store data comprising samples of a signal; a scale factor calculator operable to calculate a scale factor for the signal samples in dependence upon the levels of the received signal samples; a normaliser operable to calculate normalised signal samples, y, by using the scale factor to normalise the received signal samples; a nonlinear transformer operable to perform a nonlinear transform, T(y), on the normalised signal samples to calculate transformed signal samples; an averaging circuit operable to calculate an average level of the transformed signal samples; and a comparator operable to compare the calculated average level of the transformed signal samples to a predetermined threshold level in order to determine whether the signal contains interference comprising a sinusoidal signal; wherein: the nonlinear transformer is operable to perform a nonlinear transform, T(y), comprising a combination of a first function, T 1 ( y ), and a second function, T 2 ( y ), wherein the first function defines the transform to be applied to normalised signal samples having a value not exceeding a transition value, y t , and the second function defines a transform to be applied to normalised signal samples having a value at or above the transition value y t , and wherein: T 1 ( y ) is a non-decreasing function with increasing normalised signal sample values; T 2 ( y ) is a decreasing function with increasing normalised signal sample values; and the transition value, y t , has a value in the range 1.3≦y t ≦1.7.