Cirrus Logic Inc.

Joel C McKee Cooper

Raghunath Krishna Rao

Miroslav V Dokic

The present invention automatically corrects for subwoofer or other speaker crossover settings or other parameters by providing an adjustable factor passed upon not only pulse location, but on pulse width. In FIG., as the low-pass frequency of the subwoofer is decreased, either by the crossover setting or the physical design of the subwoofer, the impulse response is shifted to the right and the width of the impulse increases. By relating the adjustment factor to the width of the impulse, the accuracy of the computed distance is greatly increased. The relation may be found doing a simple polynomial curve fitting to empirical data from several subwoofers at various crossover settings and distances, storing that data, and then measuring pulse location and width of the actual subwoofer during the setup routine, and adjusting the distance (delay) calculations accordingly.

Technique for subwoofer distance measurement

Multiple passes are executed in the setup of an equalizer, and modification of the equalization is performed after each pass of an analysis phase. After an initial pass, the equalization is adjusted, based upon the location of peaks and valleys in the system response. This initial adjustment of equalization may tend to flatten most of the peaks and valleys to produce the desired uniform linear response. Inexact application of equalization corrections may introduce other artifacts into the system response and/or may not sufficiently normalize equalization. A second pass is then performed to measure the system response using the new equalization settings. The new peaks and valleys are measured, and the equalization adjusted to try to flatten response further. A proximity range may be applied to each pass, to reduce the likelihood that adjustment of one equalizer coefficient will create artifacts in the resulting system response.

Multipass parametric or graphic EQ fitting

Overlay buffering scheme for multi-channel data in which one memory buffer content is overlayed over another as memory locations of an input buffer are freed when data is output from the input buffer. By overlaying the buffer content, only one input buffer is used, reducing the needed memory by half.

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Lafayette, CO, United States of America

Joel C McKee Cooper