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 a tuner that selectively receives one of frequency bands, and a demodulator that demodulates a signal from the tuner. The apparatus further includes a measuring unit that measures on each carrier wave the intensity of noise to be contained in the signal from the tuner due to an interfering wave contained in the signal received by the tuner; a distribution estimating unit that estimates the distribution of interfering waves in at least one of the received frequency band and a frequency band neighboring the received frequency band, based on the distribution of noises in the frequency band measured on each carrier wave; a noise change deriving unit that derives a change in the intensity of noise to be contained in the signal from the tuner, to the power to be supplied to a circuit element; and a power updating unit that updates the value of the power to be supplied to the circuit element within a range in which the intensity of noise to be contained in the signal from the tuner is less than a noise reference value, based on the derived change in the intensity of noise to the power to supply.