Abstract: The radio receiver includes: a mixer configured to convert a received signal to an IF signal using a local oscillation signal; an IF processing section configured to limit the band of the IF signal; a detection section configured to demodulate the band-limited IF signal; a frequency control section configured to output a frequency control signal corresponding to a desired signal; and a local oscillation section configured to generate the local oscillation signal having a frequency corresponding to the desired signal according to the frequency control signal. The frequency control section outputs as the frequency control signal to change the frequency of the local oscillation signal so that the difference from the frequency corresponding to the desired signal is not more than the frequency of the IF signal, and determines one of the set values with which the corresponding image signal strength is lowest as the frequency control signal.

Abstract: The radio receiver includes: a mixer configured to convert a received signal to an IF signal using a local oscillation signal; an IF processing section configured to limit the band of the IF signal; a detection section configured to demodulate the band-limited IF signal; a frequency control section configured to output a frequency control signal corresponding to a desired signal; and a local oscillation section configured to generate the local oscillation signal having a frequency corresponding to the desired signal according to the frequency control signal. The frequency control section outputs as the frequency control signal to change the frequency of the local oscillation signal so that the difference from the frequency corresponding to the desired signal is not more than the frequency of the IF signal, and determines one of the set values with which the corresponding image signal strength is lowest as the frequency control signal.

Abstract: An AM radio receiver comprises an RF amplifier, a first mixer that converts the RF signal to a first intermediate-frequency signal, a first bandpass filter that band-limits the first intermediate-frequency signal, a second mixer that converts the output from the first bandpass filter to a second intermediate-frequency signal, a second bandpass filter that band-limits the second intermediate-frequency signal, an intermediate-frequency amplifier that amplifies the output from the second bandpass filter, an AM detector that demodulates the output from the intermediate-frequency amplifier and provides output of an audio signal, and a noise detector for detecting and eliminating ambient noise. The noise detector comprises a first noise detector that detects noise from the RF signal and eliminates the noise contained in the first intermediate-frequency signal, and a second noise detector that detects noise from the second intermediate-frequency signal and eliminates that noise.

Abstract: To attain the object of providing an AM receiver capable of accurately recognizing an antenna input level, a DC voltage which indicates the status of RFAGC performance is outputted from an analog RF circuit block at the time of the RFAGC performance. Then the DC voltage is subjected to analog-to-digital conversion to obtain a digital value. This digital value is added to a digital value corresponding to an electric field strength detected at a digital IF circuit block and the result of the addition is outputted as a field-strength output. On account of this, its sensitivity to the detection of a broadcasting station is improved at the time of an automatic station selection.

Abstract: An AM radio receiver comprises an RF amplifier, a first mixer that converts the RF signal to a first intermediate-frequency signal, a first bandpass filter that band-limits the first intermediate-frequency signal, a second mixer that converts the output from the first bandpass filter to a second intermediate-frequency signal, a second bandpass filter that band-limits the second intermediate-frequency signal an intermediate-frequency amplifier that amplifies the output from the second bandpass filter, an AM detector that demodulates the output from the intermediate-frequency amplifier and provides output of an audio signal, and a noise detector for detecting and eliminating ambient noise. The noise detector comprises a first noise detector that detects noise from the RF signal and eliminates the noise contained in the first intermediate-frequency signal, and a second noise detector that detects noise from the second intermediate-frequency signal and eliminates that noise.