| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an FSK demodulation circuit and an inflection point detection method which extract more should-be-effective inflection points of a frequency detection signal to reduce noise-induced erroneous detection of inflection points. <P>SOLUTION: An inflection point detection circuit in a frequency offset removal section includes a logical product unit which, by sampling the amplitude of a frequency detection signal for every prescribed operating clock, extracts an inflection point according to a change in sampled value and determines whether an inter-peak magnitude of the sampled value of a frequency detection signal before and after the inflection point extracted by an inflection point extraction unit exists within a first prescribed range. The logical product unit then determines whether a difference between a first sampled and a last sampled value of at least one symbol among a symbol where the extracted inflection point belongs and those immediately preceding it exists within a second prescribed range. When the inter-peak magnitude is found to be within the first prescribed range by an amplitude determination unit and the difference is found to be within the second prescribed range by a preamble determination unit, the logical product unit determines that the extracted inflection point is a normal inflection point. <P>COPYRIGHT: (C)2012,JPO&INPIT |
