To correspond to an arbitrary carrier frequency without the need of a high speed digital element by generating plural bands becoming high from a base band at every prescribed frequency, permitting a complex band pass filter to pass through only the band containing the desired carrier frequency and obtaining the analog signal of the desired carrier frequency.
The input signals of Ich and Qch are made to pass through the base band filters 122 and 125. A modulated frequency exp (jωct) and exp (jωct+jπ/2) are multiplied. The sum is enlarged to 120 MHz at every 20MHz in an interpolation IP130 and only the band near fif is selected by a complex coefficient BPF 131. The real part is changed to the analog signal in a D/A converter 133 and LPF 134 removes an image component and takes out the part of fif. A modulated frequency fc is fif-n.f symb and it is lower than f symb. Thus, the speed of a peripheral digital element can be slow and cost can be reduced.
TAWA KATSUHISA
TOYODA SHIGEHARU
