transform for an input signal to convert the input signal into a serial signal b detecting signal power of the serial signal to control the passthrough a signal greater than a predetermined critical value c selecting each section of a quadrant for each passed signal d estimating a phase error in each section of the quadrant for one orthogonal frequency division multiplexing symbol with respect to the selected section of the quadrant and e frequency oscillating a signal based on the estimated phase error generating the input signal by multiplying an oscillated signal by a band passed signal and then returning to step a application_number US 83812304 A description hereinafter a preferred embodiment according to the present invention will be described with reference to the accompanying drawings in the following description of the present invention a detailed description of known functions and configuration incorporated herein will be omitted when it may obscure the subject matter of the present invention fig4 is a block diagram illustrating a construction of an apparatus for compensating for a residual frequency offset in an ofdm system according to the present invention as shown in fig4 the apparatus for compensating for a residual frequency offset in the ofdm system according to the present invention.