Patent ID: 6295444
Filing Date: 2001-09-25
Classification: H03G

Abstract:
A method of determining an unknown modulated tone frequency in a radio frequency receiver comprising the steps of:detecting a radio frequency signal on a predetermined channel;clearing all sample marks from a sample buffer;entering data into a sample buffer having contiguous samples of the demodulated tone signal waveform;averaging the data in the sample buffer to provide an average data sample;iteratively marking all the samples that differ from the average data sample by some predetermined percentage and re-averaging the remaining unmarked samples, providing a new average data sample;determining if the number of unmarked samples remaining is at least some predetermined percentage of the number of data samples taken;operating a predictive detector looking for a standard tone frequency closest to the frequency corresponding to the average of the remaining unmarked samples if the number of unmarked samples remaining is at least some predetermined percentage of the number of data samples taken;indicating that no standard tone frequency is detected if the number of unmarked samples remaining is less than some predetermined percentage of the number of data samples taken or if the standard tone frequency is not detected by the predictive detector; andreturning the standard tone frequency if the standard tone frequency is detected by the predictive detector.