Radio broadcast reciever, automatic tuning device for radio broadcast and method for receiving radio broadcast

An automatic tuning device for searching a broadcast frequency corresponding to a reception signal level of a reception signal by changing a reception signal frequency of the reception signal, the reception signal level being equal to or larger than a predetermined electric field intensity threshold value, wherein the reception signal is outputted from a radio broadcast receiver having a frequency conversion circuit and a detection circuit, wherein the frequency conversion circuit receives a radio broadcast wave and outputs the reception signal having an intermediate frequency, and wherein the detection circuit detects the reception signal of an analog radio broadcast wave and outputs a modulation signal as a detection signal in an audio range, the device comprising:

• a noise amplifier for amplifying a noise component in the detection signal and for outputting a noise detection signal corresponding to a noise amount;
• and
• a controller, wherein
• the controller controls the frequency conversion circuit to output the reception signal, which is converted to have the intermediate frequency from the broadcast frequency,
• the controller selects the broadcast frequency when the reception signal level is equal to or larger than the predetermined electric field intensity threshold value and a noise detection signal level of the noise detection signal is equal to or smaller than a predetermined noise determination threshold value.

A method for receiving radio broadcast comprising:

• receiving a radio broadcast wave, converting the radio broadcast wave to have an intermediate frequency from a broadcast frequency of the radio broadcast wave, and outputting the converted radio broadcast wave as a reception signal having the intermediate frequency;
• detecting the reception signal of an analog radio broadcast wave and outputting a modulation signal as a detection signal in an audio range;
• searching the broadcast frequency corresponding to a reception signal level of the reception signal by changing a reception signal frequency of the reception signal, the reception signal level being equal to or larger than a predetermined electric field intensity threshold value;
• and
• amplifying a noise component in the detection signal and outputting a noise detection signal corresponding to a noise amount, wherein
• the searching includes selecting the broadcast frequency when the reception signal level is equal to or larger than the predetermined electric field intensity threshold value and a noise detection signal level of the noise detection signal is equal to or smaller than a predetermined noise determination threshold value.