DOPPLER FREQUENCY ESTIMATOR, RADIO MACHINE AND DOPPLER FREQUENCY ESTIMATING METHOD

摘要

PROBLEM TO BE SOLVED: To reduce power consumption and the size of a circuit for calculating the moving speed of its own machine. SOLUTION: A phase variation calculating section 201 detects a pilot symbol included in an I signal and a Q signal based on a frame symbol timing signal and calculates the phase variation θi of the pilot symbol. A storage section 202 stores a phase variation signal temporarily and outputs a delayed phase variation signal θi-1 . A phase variation difference calculating section 203 determines the phase variation difference (θi -θi-1 ) between the phase variation θi and the delayed phase variation signal θi-1 . A presence probability calculating section 204 determines the probability that the phase variation difference is present within some range. With reference to a table, a Doppler frequency calculating section 205 calculates a Doppler frequency based on the presence probability and a receiving field strength outputted from a receiving field strength detecting section 103. A moving speed calculating section 106 calculates the moving speed of its own machine accurately based on the Doppler frequency.