Digital receiving device and radio communication system

A digital receiving device comprising:

• a detecting portion adjusted to detect a specific code under a signal receiving state capable of successively receiving a desired signal;
• a storing portion adjusted to set a period for detecting the specific code as a non-communication state period;
• an adaptive filter having an adaptive mode and a non-adaptive mode, the adaptive mode by which a filter coefficient is sequentially updated so as to remove an ambient noise during the non-communication state period, and the non-adaptive mode by which the filter coefficient is stopped from being updated during a period except for the non-communication state period under the signal receiving state;
• and
• a filter controlling portion adjusted to control an operation for switching the adaptive mode and the non-adaptive mode of the adaptive filter.

A radio communication system comprising:

• a transmitter for transmitting a desired signal;
• a signal receiving device capable of receiving the desired signal;
• a detecting portion adjusted to detect a specific code under a signal receiving state capable of successively receiving the desired signal;
• a storing portion adjusted to set a period for detecting the specific code as a non-communication state period;
• an adaptive filter having an adaptive mode and a non-adaptive mode, the adaptive mode by which a filter coefficient is sequentially updated so as to remove an ambient noise during the non-communication state period, and the non-adaptive mode by which the filter coefficient is stopped from being updated during a period except for the non-communication state period under the signal receiving state;
• and
• a filter controlling portion adjusted to control an operation for switching the adaptive mode and the non-adaptive mode of the adaptive filter.