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

A digital demodulating apparatus is provided. A tuning unit performs a tuning process on a received signal and the intensity of the received signal it changed by an intensity changing unit including a variable-gain circuit. A demodulator performs a demodulating process on the signal, whose intensity has been changed by the intensity changing unit, and a power changing unit changes the magnitude of power supplied to the circuit components. When the intensity changing unit changes the intensity of the received signal, a gain changing unit changes a gain of the variable-gain circuit by a predetermined amount substantially at the same time as the power changing unit changes the power supplied to the circuit components. The predetermined amount is arranged so that an overall gain of the circuit components remains unchanged before and after the power and gain are changed by the power changing unit and the gain changing unit.