1.4.2.48 DSP_TransformWinInit_Black32 Function

Create a Blackman window.

Description

void DSP_TransformWinInit_Black32(int32_t *OutWindow, int N);

Create a N-element Blackman Window, and store the output to OutWindow. Operations are performed at higher resolution floating point, and rounded for the most accuracy possible. Output values are Q31 fractional format. The Blackman Window follows the equation:

Window(n) = 0.42659 - 0.49656 * COS(2Pin/(N-1)) + 0.076849 * COS(4Pin/(N-1)) where n is the window sample number, N is the total number of samples

Preconditions

N must be a positive number. OutWindow must be declared with N elements or larger.

Parameters

OutWindow pointer to output array of elements (int32_t)

N number of samples (int)

Returns

None.

Remarks

This function is performed in C. The function may be optimized for the library. It is dependent on the floating point math library.

The functional window is an intermediate result that needs to be multiplied by an input vector prior to FFT processing. Because of significant processing time the window need only be computed once and the multiply of the (window * input) vector done during recurring loop processing.

C

void  DSP_TransformWinInit_Black32 (int32_t * OutWindow , int  N );