o t is used for the ad converters 17 1 and 17 2 namely this is a doubled frequency of the central frequency of the signal band to the frequency at the end of the signal band and is the same frequency nf o as the band of the entire signal band in the meantime this becomes a frequency f o equivalent to the band width of one sub carrier if it is divided by the number of sub carriers n additionally the frequency becomes an offset that shifts sub carriers by the value of a af o accordingly multiplying the output frequency of the pll 20 by a n generates a frequency offset af o that shifts sub carriers by the value of a as a result i cos 2 u03c0af o t may be obtained and the signal of j represented by a mathematical expression 7 may be obtained by being multiplied by cos 2 u03c0f c t of the synthesizer 21 fig5 a and 5b illustrate a change in the spectrum of the reception signal which is made by executing the above described process in the embodiment in these figures the horizontal and the vertical axes represent a frequency and an snr respectively in fig5 a and.