Patent ID: 7983360
Filing Date: 2011-07-19
Classification: H03G,H04L

Abstract:
1. A Doppler frequency estimating circuit comprising: count means which compares an amplitude of a received signal obtained by demodulating a radiofrequency signal subjected to orthogonal frequency division multiplex modulation with a first threshold value and counts the number of times that the amplitude of the received signal passes through the first threshold value within a predetermined time every said predetermined time; compare means which compares a count value of the count means with a second threshold value and thereby outputs a signal indicative of a result of comparison; delay means which delays the signal indicative of the result of comparison by the predetermined time and outputs the same therefrom; difference calculating means which calculates a difference between the signals outputted from the compare means and the delay means; and smoothing means which removes high frequency components contained in the difference calculated by the difference calculating means and outputs a Doppler detection signal.