To provide an automatic frequency control apparatus capable of detecting a phase difference between two symbols without using a multiplier, and hence detecting a difference between a carrier frequency of a receiver side and a carrier frequency of a transmitter side without using a multiplier.
A method for controlling the frequency comprises: a step of obtaining IQ coordinates nearest to a second symbol of a plurality of IQ coordinates obtained by rotating the IQ coordinates of a first symbol, and the first symbol by a predetermined phase on an IQ coordinate axis; a step of obtaining the rotating direction of the second symbol to the IQ coordinates nearest to the second symbol; and a step of inferring a phase rotating amount between the first symbol and the second symbol based on the IQ coordinates of the first symbol, the IQ coordinates nearest to the second symbol, a rotating direction of the second symbol to the IQ coordinates nearest to the second symbol, and the predetermined phase.
HIROSE SHINTARO
KATO SEIJI
