Sanyo Electric Co., Ltd.

Semiconductor Components Industries, LLC

Sanyo Semiconductor Co., Ltd.

Masaaki Taira

Yasuji Saito

Yutaka Hirakoso

Hirohisa Suzuki

Masaya Suto

Masanori Kudo

A receiving apparatus comprising: a frequency-fluctuation-detection unit to detect a frequency difference between a received and desired signals; a first-undesired-level-detection unit to output as a first-undesired level an amplitude-level-difference between the signals having passed through first-and-second-band-pass filters in the received signals; one or a plurality of second-undesired-level-detection units to output amplitude levels of signals having passed through third-and-fourth-band-pass filters in the received signals as second-and-third-undesired levels, respectively, and output a sum of the second-and-third-undesired levels as a fourth-undesired level; and a determination unit to determine whether an undesired state, where an adjacent-undesired signal is present, occurs according to the fourth-undesired level if an absolute value of the frequency difference is equal to or greater than a predetermined-reference value, and select any one of the first-to-third-undesired levels to be outputted according to at least one of the frequency difference and the fourth-undesired level if determining that the undesired state occurs.

Receiving apparatus

A receiving apparatus comprising: a first mixing unit to output first and second mixed signals each having a first frequency that is a frequency difference between a received signal and a first local oscillator signal, the first and second mixed signals having phases substantially orthogonal to each other; a phase control unit to output second and third local oscillator signals each having a second frequency, the second and third local oscillator signals having a phase difference from each other corresponding to a phase difference between the first and second mixed signals; and a second mixing unit to add a signal obtained by mixing the first mixed signal and the second local oscillator signal, and a signal obtained by mixing the second mixed signal and the third local oscillator signal, to output an intermediate frequency signal having an intermediate frequency that is a difference between the first and second frequencies.

A noise canceller is constituted by a forward linear prediction processor that performs forward linear prediction for a reception signal in a noisy section where the reception signal includes noise, and a backward linear prediction processor that performs backward linear prediction for the reception signal in the noisy section. A signal generator generates a replacement signal, to replace the reception signal in the noisy section, based on the forward linear prediction values obtained by the forward linear prediction and the backward linear prediction values obtained by the backward linear prediction. The signal generator obtains replacement values for a plurality of points within the noisy section by weighting the corresponding forward prediction value and the corresponding backward prediction value with an internal division ratio, the internal division ratio having a linear or nonlinear functional relationship to the time axis of the signal.

Noise canceller using forward and backward linear prediction with a temporally nonlinear linear weighting

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 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

A raw signal is delayed in a delay circuit () and then supplied to one of the input terminals of a selection circuit (). The raw signal is also supplied to another delay circuit () to be delayed. Subsequently, data of this delayed signal is processed by spline interpolation in an interpolation circuit (), and the interpolation values are supplied to the other of the input terminals of the selection circuit (). Further, a timer () is operated according to an output signal from a noise detection circuit () which detects noise in the raw signal. When noise is detected, the selection circuit () switches to select the output from the interpolation circuit (), thereby achieving interpolation of noisy sections.

Noise cancel circuit

If a mode calculating section () judges that an inputted modulated signal is nearly in a no-sound state, the interpolation width determined by an interpolation width calculating section () is increased, whereas if the mode calculating section () judges that the inputted modulated signal contains a lot of high-frequency components, the interpolation width determined by the interpolation width calculating section () is decreased.

Noise canceller

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.

AM receiver circuit performing sound quality compensation of AM detection output signal

A stereo broadcasting receiving device comprises pseudo stereo signal generation means for generating a pseudo left stereo signal and a pseudo right stereo signal from an L&plus;R signal, first multiplication means for multiplying the pseudo left stereo signal by a first coefficient, second multiplication means for multiplying the pseudo right stereo signal by the first coefficient, third multiplication means for multiplying the L&plus;R signal by a second coefficient, fourth multiplication means for multiplying an L&minus;R signal by a third coefficient, coefficient determination means for determining the first coefficient, the second coefficient, and the third coefficient on the basis of the result of judgment in receiving state judgment means, means for generating a left stereo output signal on the basis of an output signal of the first multiplication means, an output signal of the third multiplication means, and an output signal of the fourth multiplication means, and means for generating a right stereo output signal on the basis of an output signal of the second multiplication means, the output signal of the third multiplication means, and the output signal of the fourth multiplication means.

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Akashi, Japan

Masaaki Taira