The real component of a Fast Fourier Transform (FFT) calculated using blocking.  There are two forms.

Note: This item is deprecated and will be removed in a future release.

Syntax

Real_part = BlockFftReal(vec1, vec2, block_size, overlap)

Real_part = BlockFftReal(vec1, vec2, window, overlap)

Arguments

Name

Description

vec1

A vector of the real components of time domain data.

vec2 (optional)

A vector of the imaginary components of time domain data. The vector is of type real.

block_size

The number of elements to be used for each FFT (should be a power of 2).  Must be a positive integer and not greater than the length of vec.

window

A vector of window weights to apply to each block. Should be of length of power of 2. This length is used as the block size.

overlap

The number of elements shared between consecutive blocks.  Must be a non-negative integer and less than block_size.

Output

Name

Description

Real_part

A vector of the real component of the FFT.

Example 1

Find the real components of the FFT of a signal stored in vector data, using a block size of 256 and an overlap of 128:

Syntax

output = BlockFftReal(data, 256, 128)

Results

output is a vector of the real components.

Example 2

Repeat the above example with a Hanning window instead.

Syntax

output = BlockFftReal(data, HannWin(256), 128)

Results

output is a vector of the real components.

Comments

The BlockFftReal function uses blocking to calculate the real component of a Fast Fourier Transform (FFT).  The FFT is complex-valued and used to map time-domain data into the frequency domain. vec1 and vec2 is assumed to be evenly sampled.  The resultant vector has a number of elements equal to the least power of two greater than or equal to the block_size.

The BlockFftReal function is different from a normal FFT in that it introduces blocking. The input vector is subdivided into blocks, each having block_size number of elements.  An FFT is then performed on each individual block.  The results of these FFTs are then averaged to give the final result.

See Also:

BlockFftImag

BlockFftMag

BlockFftPhase

Fold

Freq