A multichannel receiver for effectively receiving multichannel signals at
the same time without any restrictions in the symbol timing and channel
interval of modulated signals. A quadrature detector of the multichannel
receiver includes first and second multipliers. The first multiplier
multiplies a received signal by a real number axis signal generated from
a quadrature carrier oscillator. The second multiplier multiplies a
received signal by an imaginary number axis signal. The quadrature
detector converts a carrier of a center signal of odd signals into a DC
component of zero frequency, and converts the center signal into a
complex baseband signal, and at the same time converts carrier signals
other than the center carrier signal into a complex IF signal symmetrical
to the DC component of zero frequency. ADCs (Analog-to-Digital
Converters) convert the complex IF signals into complex IF digital
signals. The complex IF digital signals are applied to a first group of
complex mixers and a second group of complex mixers at the same time. The
complex mixers correspond to individual channels, and their local signal
frequencies have a complex conjugate relation to each other. The complex
mixers perform frequency conversion on their reception signals, and thus
generate complex baseband signals.