Sanyo Electric Co., Ltd.

Semiconductor Components Industries, LLC

Yasuji Saito

Masaaki Taira

Yutaka Hirakoso

Masaya Suto

Masanori Kudo

An adaptive filter includes: a filter configured to perform a filtering process for an input signal with a filter coefficient set therein, and output the processed input signal as an output signal; a calculating unit configured to calculate a value indicative of an error between an amplitude of the output signal and a reference amplitude; an output unit configured to output a first constant as a parameter when the amplitude of the output signal is greater than the predetermined amplitude, the parameter used when updating the filter coefficient, and output a second constant as the parameter when the amplitude of the output signal is smaller than the predetermined amplitude; and an updating unit configured to update the filter coefficient with an update amount corresponding to the parameter and the value indicative of the error, such that the error is reduced.

Adaptive filter

A noise suppression apparatus comprising: a complex signal generation unit configured to convert an intermediate frequency signal into a complex signal having a real part and an imaginary part, the intermediate frequency signal being obtained by frequency-converting a reception signal; a noise detection unit configured to detect whether or not variation in level of the complex signal is greater than a predetermined threshold value, to detect generation of noise; and a noise suppressing unit configured to suppress level of the complex signal if the variation in level is greater than the predetermined threshold value.

Noise suppression apparatus

A band-switch control apparatus for an intermediate-frequency filter comprising: an adjacent interference-signal detecting unit for detecting an adjacent interference-signal, having a frequency adjacent to the desired frequency, superimposed on a reception signal having a frequency tuned to a desired frequency; a modulation-degree detecting unit for detecting a modulation degree of the reception signal; a bandwidth selecting unit for selecting a pass bandwidth of the intermediate-frequency filter corresponding to the amplitude of the adjacent interference-signal; and a band-narrowing suppression control unit for selecting a lower limit value of the pass bandwidth of the intermediate-frequency filter corresponding to the demodulation degree, the intermediate-frequency filter for passing, with a variable pass bandwidth, an intermediate-frequency signal obtained by frequency converting the reception signal, and changing the pass bandwidth selected by the bandwidth selecting unit to the lower limit value, if the pass bandwidth selected by the bandwidth selecting unit is smaller than the value.

Band switch control apparatus for intermediate frequency filter

A noise detecting apparatus detecting presence or absence of noise in a received signal, comprising: a first band selecting unit configured to select a first signal of a first frequency band that does not include a frequency band of the received signal and is higher than a center frequency of the received signal; a second band selecting unit configured to select a second signal of a second frequency band that does not include the frequency band of the received signal and is lower than the center frequency of the received signal; a signal selecting unit configured to compare strength of the first signal selected by the first band selecting unit and strength of the second signal selected by the second band selecting unit to select the signal of lower strength; and a comparing unit configured to compare the strength of the signal selected by the signal selecting unit with a predetermined threshold to output a signal depending on a result of the comparison.

Noise detecting apparatus and AM broadcast receiving apparatus

A multipass noise detecting apparatus comprising: a smoothing process unit configured to receive input of a signal corresponding to electric field strength of a received signal and to smooth the signal; a delay process unit configured to delay the signal; an amplifying unit configured to amplify a signal output from the smoothing process unit; a pulse noise determining unit configured to compare a signal output from the delay process unit with a signal output from the amplifying unit to output a pulse noise determining signal indicating a period of presence of pulse noise; and a noise cancel process unit configured to carry out a process for removing pulse noise on the basis of the pulse noise determining signal, the process being applied to the signal output from the delay process unit.

Multipass noise detecting apparatus and FM receiving apparatus

A noise canceler comprising: a first low-pass filter that a demodulated signal is to be input to; an interpolation processing unit that the demodulated signal after passing through the first low-pass filter and a pulse noise detection signal indicating presence of a pulse noise, are to be input to, the interpolation processing unit configured to perform interpolation processing on a demodulated signal present during a period determined by the pulse noise detection signal, out of the input demodulated signal, based on the input demodulated signal; a replacing processing unit that the demodulated signal subjected to the interpolation processing, the pulse noise detection signal, and the demodulated signal before passing through the first low-pass filter, are to be input to, the replacing processing unit configured to output a signal obtained by replacing a demodulated signal present during the period, out of the demodulated signal before passing through the first low-pass filter, with the demodulated signal subjected to the interpolation processing, wherein the demodulated signal is present during the period; and a second low-pass filter that the signal output from the replacing processing unit is to be input to, the second low-pass filter including a cut-off frequency higher than that of the first low-pass filter.

Noise canceler and receiving apparatus using the same

An AM receiving circuit is disclosed which comprises an intermediate frequency amplifying unit that generates an intermediate frequency signal from a broadcast wave signal received by an antenna to amplify and output the intermediate frequency signal; an AGC (Automatic Gain Control) unit that sets gain of the intermediate frequency amplifying unit depending on electric field intensity of the broadcast wave signal; and an AM detecting unit that detects the intermediate frequency signal output from the intermediate frequency amplifying unit, wherein the AM receiving circuit comprises a sound quality compensating unit including: a filter unit that extracts a predetermined frequency band of the audio signal; an amplifying unit that boosts or attenuates the audio signal in the predetermined frequency band extracted from the filter unit; and a controlling unit that controls filter characteristics of the filter unit and sets a boosting function or an attenuating function of the amplifying unit, depending on the electric field intensity of the broadcast wave signal.

AM receiving circuit

A diversity receiving apparatus receives first and second reception signals and is constituted by including one or more phase shifters that generate one or more third signals having phases different from the second reception signal based on the second reception signal, a correlation calculator that obtains a correlation between the first reception signal and each of the second reception signal and the third reception signals, a correlation comparator that selects the reception signal having the highest correlation with the first reception signal from the second reception signal and the third reception signals, a selector that selects and outputs the second reception signal or the third reception signal selected by the correlation comparator; and a combining device that outputs a signal formed by combining the first reception signal and the reception signal output from the selector.

Diversity receiving apparatus, controlling method of the same, and computer-readable medium containing program therefor

A signal processing circuit is disclosed which comprises: an attenuating unit that attenuates a demodulated signal acquired by detecting a received signal; a detecting unit that detects a first signal indicating intensity of the demodulated signal; and an attenuation rate setting unit that sets an attenuation rate of the attenuating unit based on the first signal, wherein the attenuation rate setting unit sets the attenuation rate of the attenuating unit depending on: at least one signal of a second signal indicating a change in an envelope curve acquired based on an intermediate frequency signal of the received signal and a third signal indicating electric field intensity acquired based on the intermediate frequency signal; and the first signal.

Signal processing circuit comprising an attenuating unit, a detecting unit, and an attenuation rate setting unit

An AM radio receiving circuit is disclosed that comprises a front end circuit that converts an input AM modulation signal to an intermediate frequency signal that in turn is output; a pulse noise detecting circuit that detects pulse noise included in the AM modulation signal; a pulse noise removing circuit that removes the pulse noise included in the intermediate frequency signal output from the front end circuit based on the detection result of the pulse noise detecting circuit to output the signal; and a detecting circuit that detects the intermediate frequency signal output from the pulse noise removing circuit after removing the pulse noise to output an audio signal.

AM radio receiving circuit

A signal processing circuit for a tuner has a detector band pass filter for extracting a carrier of an intermediate frequency signal, a frequency counter for counting, based on a clock signal, a frequency of a carrier of the intermediate frequency signal which passes through the detector band pass filter, and an intermediate frequency variation signal outputting section for outputting an intermediate frequency variation signal based on a difference between the counted frequency and a frequency of the clock signal. Based on the intermediate frequency variation signal, a frequency selection characteristic of an intermediate frequency band pass filter, a signal detector, an adjacent interference detector, or an S-meter-band pass filter are controlled. In this manner, even when a carrier frequency of an intermediate frequency signal input from a tuner varies, the frequency selection characteristic of the intermediate frequency band pass filter, signal detector, adjacent interference detector, and S-meter-band pass filter can be suitably controlled.

Signal processing circuit for tuner which applies signal processing based on variation in frequency of intermediate frequency signal

An AM receiver circuit comprises an IF intensity detection section which detects intensity of a carrier wave of an IF signal and outputs an IF signal carrier wave intensity signal in accordance with the detected intensity. The IF intensity detection section extracts the carrier wave frequency component of the IF signal using a BPF, and converts the extracted intensity of the IF signal carrier wave intensity into a direct current signal using an integrator, to thereby obtain the IF signal carrier wave intensity signal. A sound compensation section, which serves to compensate sound quality of an audio signal output from an AM detection section, performs sound quality compensation based on the IF signal carrier wave intensity signal when the received field intensity is low. In this manner, appropriate sound quality compensation can be performed even when the received broadcast wave field intensity is low.

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Gunma, Japan

Yasuji Saito