Digital demodulating apparatus, digital receiver, controlling method of the apparatus, computer program product, and recording medium recording thereon the product

A digital demodulating apparatus includes an intensity changing unit that changes the intensity of a received signal; a channel selecting unit that applies channel selection processing to the signal whose intensity has been changed by the intensity changing unit; a demodulating unit that applies demodulation processing to the signal to which the channel selecting unit has applied channel selection processing; a noise evaluating unit that evaluates an influence of noise components on a desired component in the signal to be input to the demodulating unit; and a gain changing unit that changes, on the basis of a result of the evaluation by the noise evaluating unit, the gain of the change in the intensity of the received signal by the intensity changing unit so that the influence of the noise components is decreased in the signal to be input to the demodulating unit.