Digital demodulating apparatus, controlling method of the apparatus, and digital receiver

A digital demodulating apparatus includes circuit elements constituting a tuner that performs channel select processing to a received signal that has been interleaved, and a demodulator that performs demodulation processing to the received signal from the tuner; a deinterleaving section that performs deinterleaving to the interleaved received signal from the tuner; and a parameter controlling section that changes the value of an operation parameter that regulates an operation of at least one of the circuit elements. The parameter controlling section determines two of the circuit elements, the quantities of changes in operation parameters of the two circuit elements, and change timings for the operation parameters of the two circuit elements, such that ranges each of which is occupied by errors to be generated in the received signal by changing the quantities of the operation parameters of the two circuit elements at the change timings for the operation parameters, do not overlap each other in the deinterleaved received signal. The parameter controlling section changes the operation parameters of the determined two circuit elements by the determined change quantities at the determined change timings.