US 6,983,134 B1
Method and apparatus for automatic frequency control and demodulator
Takashi Asahara, Tokyo (Japan); and Toshiharu Kojima, Tokyo (Japan)
Assigned to Mitsubishi Denki Kabushiki Kaisha, Tokyo (Japan)
Appl. No. 9/926,556
PCT Filed Mar. 31, 2000, PCT No. PCT/JP00/02123
§ 371(c)(1), (2), (4) Date Nov. 19, 2001,
PCT Pub. No. WO01/76097, PCT Pub. Date Oct. 11, 2001.
Int. Cl. H04B 1/18 (2006.01)
U.S. Cl. 455—182.2 14 Claims
OG exemplary drawing
 
1. An automatic frequency control method for controlling the frequency of a radio receiving signal by compensating a frequency offset of the radio receiving signal, said radio receiving signal periodically including a plurality of adjacent known signals, comprising:
estimating a frequency of a direct wave of the radio receiving signal and a center frequency of a Doppler spread of the radio receiving signal based on distortion amounts of the adjacent known signals included in the radio receiving signal, and
compensating the frequency offset of the radio receiving signal based on both of said frequency of a direct wave and said center frequency of a Doppler spread.