C64x Autocorrelation - Autocorrelate input vector or frame-based matrix

Library

Embedded Coder/ Embedded Targets/ Processors/ Texas Instruments C6000/ Optimization/ C64x DSP Library

Description

The C64x Autocorrelation block computes the autocorrelation of an input vector or frame-based matrix. For frame-based inputs, the autocorrelation is computed along each of the input's columns. The number of samples in the input channels must be an integer multiple of eight. Input and output signals are real and Q.15.

Autocorrelation blocks support discrete sample times and little-endian code generation only.

Dialog Box

Compute all non-negative lags

When you select this parameter, the autocorrelation is performed using all nonnegative lags, where the number of lags is one less than the length of the input. The lags produced are therefore in the range [0, length(input)-1]. When this parameter is not selected, you specify the lags used in Maximum non-negative lag (less than input length).

Maximum non-negative lag (less than input length)

Specify the maximum lag (maxLag) the block should use in performing the autocorrelation. The lags used are in the range [0, maxLag]. The maximum lag must be odd, and (maxLag+1) must be divisible by 4, such as maxLag equal to 3, 7, or 19. This parameter is enabled when you clear the Compute all non-negative lags parameter.

Algorithm

In simulation, the Autocorrelation block is equivalent to the TMS320C64x DSP Library assembly code function DSP_autocor. During code generation, this block calls the DSP_autocor routine to produce optimized code.

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