Visteon Global Technolgoies, Inc.

Ford Motor Company Limited

Texas Instruments Corporation

Visteon Corporation

John Elliott Whitecar

J William Whikehart

Nicholas Lawrence Difiore

Andrew Cyril Krochmal

Gregory Roger Hamel

James Alfred Wargnier

Darby Edward Hadley

Christopher John Hagan

Frank Michael Hirschenberger

Sylvester P Porambo

Trudy D Stetzler

John William Wagner

Robert Kelly Cadena

Richard Bruce Harris

Richard David Zerod

Philip Mark Bator

Henry F Blind

Jack Harold King

John Michael Dicky

Bradley Anderson Ballard

Robert Donald Plowdrey

Sira Parasurama Rao

Robert G DeMoor

Michael Chrysochoos

David P Stewart

Kai Kwang Lau

Yung Da Wang

Vincent Wang

John D Cotner

The approach shown provides for an efficient implementation of time response, level response and frequency response alignment between two audio sources such as DAB and FM that may be time offset from each other by as much as 2 seconds, and produces an aurally undetectable transition between the sources. Computational load is significantly reduced over the approaches known in the prior art.

Undetectable combining of nonaligned concurrent signals

An FM receiver is unaware of the modulation level (frequency deviation) of the signal and has to make an estimate of it, or some reasonable time-average of it, and accordingly set the input filter's bandwidth. We calculate modulation by measuring the autocorrelation of the recovered audio signal instead of its peaks, and then applying a peakhold detector. Since FM noise can be modeled to be somewhat uncorrelated, we can expect to get an accurate estimate of signal power while rejecting noise power substantially if we measure a one-sample delayed autocorrelation estimate. Since the above measurement is alike a power measurement, we compute its square root, gain adjust it to obtain a cleaner peak measurement, and then track these clean peaks using a leaky integrator. This gives an estimate of modulation that subdues the effect of the noise.

Robust FM modulation detector using signal autocorrelation

In a dual-channel HD radio receiver, when the broadband filter channel is compromised, the broadband channel is inactivated and the narrowband channel is activated. By mixing the signals of the two channels during the change, undesirable audio artifacts can be minimized.

Apparatus and method for IF switching in a dual-tuner, dual-IF, HD radio and FM/AM radio receiver

A system and method for predicting and limiting distortion of an amplified signal is described. The system includes a variable total harmonic distortion ('THD') clipping predictor, a comparator in communication with the variable THD clipping predictor and a distortion limiter in communication with the comparator. As for the method, a reference power supply value, a maximum desired total harmonic distortion value and a preamplified signal value is provided. A THD output threshold value is calculated based on the reference power supply value and the maximum desired THD value and is then compared to the preamplified signal value. Depending on if the preamplified signal value is greater than or less than the THD output threshold value, the amplitude of the preamplified signal may be increased or decreased.

Variable distortion limiter using clip detect predictor

A timing signal is regenerated from an encoded digital signal having a data clock frequency Rin a receiver using a predetermined sample rate F, wherein the data clock period 1/Ris not an integer multiple of the predetermined sample period 1/F. The method comprises generating an input pulse signal in response to the encoded digital signal. Each of the input pulse signals is accumulated in a predetermined delay element which stores an accumulated value, wherein the predetermined delay element is in a delay loop including N delay elements each having a respective accumulated value. The accumulated values are circulated within the delay loop by shifting at each of the sample periods according to a predetermined shift sequence, the predetermined shift sequence including a plurality of single shifts and at least one other shift size to provide a number of shifts N+&#x3b4; during a cycle of N sample periods. A synchronization pulse is generated in response to the accumulated values and a predetermined threshold. A counter is operated to output the timing signal in response to the predetermined sample rate F, the counter having a variable counter period according to a predetermined counter sequence. The variable counter period has an average over time corresponding to the data clock period 1/R. The counter is reset in response to the synchronization pulse (if synchronization becomes necessary).

Timing recovery loop with non-integer length

A vehicle radio receiver has a beamsteering control system with two signal paths. One signal path generates an audio signal in response to incoming radio signals. Another signal path generates a test signal in response to the incoming radio signals. The audio signal is adjusted in response to the test signal.

Beamsteering control system for a vehicle radio receiver

A bit timing signal is regenerated from an encoded digital signal in a receiver using a predetermined sample rate F. An input pulse signal is generated in response to predetermined transitions of the encoded digital signal. A clock count signal is generated having a variable clock period according to cyclical counting of the clock count signal up to a count value S at the predetermined sample rate, the count value alternating between an upper value Sand a lower value Sso that the variable clock period has an average length substantially equal to a data bit period of the encoded digital signal. The clock count signal is synchronized with the encoded digital signal by 1) counting the input pulse signals to generate a pulse count, 2) counting sampling periods between successive input pulse signals to generate a sample count, and 3) generating a sync signal if the pulse count is greater than a pulse threshold and the sample count is greater than a sample threshold. The clock count signal and the pulse count are reset in response to the sync signal.

Clock timing recovery using arbitrary sampling frequency

A vehicle communication system uses one or more components to process both narrow band signals and spread spectrum signals. A spread spectrum-like signal is generated from the narrow band signal. The spread spectrum-like signal is processed as a spread spectrum signal.

Narrow band and spread spectrum communication system for a vehicle

A method of controlling an antenna signal combiner in a vehicle having multiple antenna elements, a navigational system and a receiver comprising the steps of receiving signals from at least one transmitter, determining first position coordinates of the vehicle using the navigational system, determining second position coordinates of the at least one transmitter, and combining signals from the multiple antenna elements to steer an antenna beam from the first position coordinates to the second position coordinates.

Antenna beam steering responsive to receiver and broadcast transmitter

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

The presence or absence of a speaker connected to an output terminal of an audio system is determined based on the electro-generator properties of the speaker. The audio system includes an output amplifier coupled to the output terminal. The method includes driving the output amplifier with a predetermined drive signal sufficient to produce a predetermined speaker excursion if a speaker is connected to the output terminal. The output amplifier is then isolated from the output terminal. A signal at the output terminal is sensed after the output amplifier is isolated. The sensed signal is compared with a predetermined reference for determining whether a speaker back-EMF is present. A speaker detection signal is generated indicating absence of a speaker if the back-EMF is not present.

Audio loudspeaker detection using back-EMF sensing

An audio system limits gain in individual audio channels having a shared clip detect signal from a multi-channel power amplifier such that only channels likely to be exceeding the distortion threshold are gain limited. In addition, any arbitrary channels may be grouped together for common gain limiting. The invention monitors the power level of each audio channel, compares the power level to a power threshold that indicates whether a high power condition with the potential to cause excess distortion exists or not, and makes a decision whether to activate each channel's gain limiter based on whether the corresponding clip detect signal is active and the high power condition exists simultaneously for that channel.

Multi-channel audio signal limiter with shared clip detection

The masking-effect of loud audio passages is utilized to reduce the audibility of the fan noise from a cooling fan in an audio system. A power monitor determines an output power of an audio amplifier and generates a power signal proportional to the output power. A switchable cooling fan is positioned to provide a cooling flow of air within the audio system when the cooling fan is turned on. A fan control is coupled to the power monitor and the switchable cooling fan. The fan control compares the power signal with a predetermined threshold and turns on the switchable cooling fan in response to the comparison indicating that reproduction of the amplified audio signals is at an output power level that will substantially mask audible noise created by the switchable cooling fan.

Cooling fan control strategy for automotive audio system

A method of detecting a DC offset in an audio signal provided by an audio processing unit to an audio power amplifier, wherein the audio amplifier provides a clip detect signal back to the audio processing unit, wherein the method comprises the steps of sampling the clip detect signal to determine if the clip detect is active. Detecting a power level of the audio amplifier if the clip detect is active. Next, comparing the power level to a predetermined power threshold. Then, identifying a dc offset if the power level is less than the predetermined power threshold.

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Plymouth, MI, United States of America

John Elliott Whitecar