Electrical audio signal processing systems and devices – Noise or distortion suppression
Patent
1997-02-27
2000-02-29
Le, Huyen
Electrical audio signal processing systems and devices
Noise or distortion suppression
381 57, 381 86, H04R 2500
Patent
active
060319186
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for controlling the volume of a car radio as a function of driving noise.
The noise level inside a motor vehicle is greatly dependent on the speed at which the vehicle is being driven in each instance. Since manual adjustment of the volume of a car radio to this noise level is considered bothersome, various methods for controlling the volume of a car radio as a function of the driving noise have already become known. From German Patent Application No. DE-A-33 38 413, a circuit arrangement for automatic noise-dependent volume control in a motor vehicle is known, where a signal which represents the interference in the car interior is generated using a microphone affixed in the car interior. To compensate the audio signal component in the microphone output signal generated by the loudspeaker signal, the loudspeaker input signal is subtracted from the microphone output signal in a summation circuit, so that a control value in the form of the interference noise level present in the vehicle interior is present at the output of the subtraction element.
From European Patent Application No. EP-A-0 246 772, an arrangement to attenuate body vibrations in motor vehicles is known, where the vibrations are caused, for example, by driving over uneven areas in the road. For this purpose, the body vibrations are detected using an acceleration-sensor, and the measurement signal is evaluated in a computer unit. The chassis shock absorbers of the vehicle are tuned, as a function of the measurement signal, in such a way that body vibrations are reduced.
It is the task of the present invention to improve the derivation of a signal dependent on driving noise, which is used to control the volume of a car radio as a function of driving noise, in such a way that measures to remove wanted signal components from the control signals are not necessary.
This task is accomplished, according to the invention, in that an acceleration sensor can be mechanically connected with the body of the motor vehicle, to generate a signal dependent on driving noise. In this connection, it can be provided, as a simplification, that the acceleration sensor essentially measures vertical accelerations.
The present invention is based on the recognition that driving noises are transferred into the interior (passenger space) of the motor vehicle mainly as structure-borne noise. These noises are, in particular, engine noises and tire noises. Measures to remove the wanted signal component from the signal obtained using the acceleration sensor are not needed for the device according to the present invention.
The device according to the present invention demonstrates the additional advantage, particularly if the acceleration sensor is arranged in the car radio, according to a further development, that no further installations are required within the vehicle itself--such as laying lines and installing a microphone.
Preferably, it is provided, for the device according to the invention, that the acceleration sensor is rigidly connected with the housing of the car radio. An advantageous development of the device according to the present invention consists of the fact that the acceleration sensor demonstrates a signal band width of about 1 kHz. This covers the entire spectral range required for masking structure-borne noise, and commercially available acceleration sensors can be used, such as the acceleration sensor Type ADXL50 from the company Analog Devices.
Although the device according to the present invention is also suitable, for example, for volume control independent of frequency, better results are obtained with frequency-dependent masking, for which it is provided, according to a further development of the device according to the present invention, that an output of the acceleration sensor can be passed to a multi-channel equalizer, via a signal processing circuit with a known, predetermined algorithm, along with the audio signals generated by the car radio, the outputs of which equalizer are
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Blaupunkt-Werke GmbH
Le Huyen
LandOfFree
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