Frequency error estimating apparatus and a frequency error estimating method

A frequency error estimating method for estimating a frequency error between a local oscillation frequency and a carrier frequency of a received signal in a receiver, the frequency error estimating method comprising:

• estimating a frequency error based on a plurality of phase changes in the received signal and for suppressing a noise component over the phase changes with a filter;
• and
• changing the characteristics of the filter based on the estimated frequency error, thereby changing an averaging effect of the filter to account for time variation of Doppler frequency.

A frequency error estimating apparatus for estimating a frequency error in received signals on which a Doppler shift affects, the frequency error estimating apparatus comprising:

• a frequency error estimating unit for estimating a plurality of phase changes in the received signals, and comprising a filter for suppressing a noise component over the phase changes to estimate the frequency error;
• and
• a filter characteristic determination unit for determining and changing a characteristic of the filter in accordance with a variation of Doppler frequency, thereby changing an averaging effect of the filter to account for time variation of Doppler frequency.

A receiver for satellite, satellite mobile, or mobile communication in which a carrier frequency of a received signal receives a Doppler shift, and the carrier frequency is detected for employing a synchronous detection system, the receiver comprising:

• a frequency error estimating unit for estimating a frequency error based on a plurality of phase changes in the received signal, and for suppressing a noise component over the phase changes with a filter to estimate the frequency error;
• and
• a filter characteristic determining unit for changing the characteristics of the filter based on the frequency error estimated by the frequency estimating unit, thereby changing an averaging effect of the filter to account for time variation of Doppler frequency.