Ford Motor Company Limited

Ford Global Technolgoies, LLC

Visteon Global Technolgoies, Inc.

Henry F Blind

John Elliott Whitecar

Earl R Geddes

Andrew Cyril Krochmal

Nicholas Lawrence Difiore

Myron Ihor Senyk

Bradley Anderson Ballard

James Leo Czekaj

David Alan Dage

Robert E Pierfelice

Liviu M Nicola

Anthony J Campagne

John W Whikehart

Alan Scott Phillips

Audio signals are reproduced with consistent perception of total harmonic distortion even with varying spectral content of a particular audio signal without separately limiting different frequency bands within the audio signal. A distortion threshold representative of an amount of distortion to be allowed to be introduced by a power amplifier is determined in response to a frequency content of the audio signal. A distortion trigger compares a measured average distortion signal and the distortion threshold and reduces the controllable gain of the amplifier if the average distortion signal exceeds the distortion threshold.

Audio amplifier with voltage limiting in response to spectral content

A noise absorbing cover is provided for an automotive loudspeaker to prevent exterior noise from being coupled through a loudspeaker to the interior of the automobile. An air gap is provided around the cover to provide a vent to static pressure for the loudspeaker, thereby avoiding any degradation in low frequency performance. The air gap is oriented to exclude direct sound transmission paths for exteriorly generated noise to the interior.

Exterior noise absorbing cover for automotive loudspeaker

A DSP-based vehicle equalization design system has been described, which allows the audio engineer to quickly and efficiently design an equalizer from an easy-to-use Graphic User Interface (GUI) computer interface. Vehicle equalizations, with high precision and parameter variability can be developed in a short period of time. The system and method of design provide DSP filter coefficients for use as-is in actual DSP-based production vehicle equalization hardware.

DSP-based vehicle equalization design system

An acoustic production system having multiple signal sources and a power amplifier driving an acoustic transducer such as a loudspeaker includes an arbitrator in a power limiter circuit to selectively limit the input level of one of the sources to the power amp in response to an overdrive signal from the amplifier. The input level to the power amplifier is automatically reduced in response to the overdrive signal until a predetermined level of limiting has been attained. Once the predetermined level of limiting is reached, the arbitrator outputs a second overdrive signal to prompt additional limiting of the power amplifier output. Preferably, the arbitrator is included in an interior active noise cancellation module combined with an audio entertainment system for a passenger compartment of a motor vehicle. The audio system also preferably separates the audio reproduction into high frequency and low frequency branches, whereby the arbitrator acts upon the signals output in the frequency ranges of active noise cancellation and the bass output of the audio entertainment system that are most likely to overdrive an amplifier.

Arbitration adjustment for acoustic reproduction systems

A voltage limiting circuit is disclosed for preventing distortion in amplified audio signals. Clipping of the output of a power amplifier is detected and a clipping signal is integrated in a two-step process for limiting a bass frequency gain and limiting a wideband frequency gain which are applied in series. Separate limiting thresholds cause the bass gain to be limited first. Wideband gain is reduced at higher levels of clipping but is more quickly restored when clipping stops. Voltage limiting feedback is provided using inexpensive RC integrator circuits.

Audio amplifier with voltage limiting

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Grosse Pointe Woods, MI, United States of America

Henry F Blind