Zero Pad (DSP Blockset)

Increase the input frame size by appending zeros.

Library

Signal Operations, in General DSP

Description

The Zero Pad block increases the frame size of the input from M_i to M_o by appending an equal number of zeros to each channel. The output frame size, M_o, is specified by the Output frame size parameter. If the Output frame size value is smaller than the input frame size (M_o<M_i), and the Allow truncation of input check box is enabled, the block truncates elements at the end of each input frame as necessary. If the Allow truncation of input check box is disabled, the input is not altered.

The Zero Pad block assumes that the input is an M_i-by-N frame matrix. Each of the N frames in the matrix contains M_i sequential time samples from an independent signal. The illustration below shows a 6-by-4 matrix input:

The Number of channels parameter specifies the number of independent channels (columns, N) in the matrix. A value of 1 indicates that the input is a vector (i.e., a single frame).

The figure below illustrates how zero-padding increases the number of matrix rows from M_i to M_o by appending zeros at the end of each frame.

Note
If you expect to generate code for the Zero Pad block using the Real-Time Workshop, you should ensure that inputs are contiguous in memory. See the Contiguous Copy block for more information.

Dialog Box

Output frame size: The desired output frame length, M_o. A value of -1 effectively disables zero-padding by passing the input through unchanged.
Allow truncation of input: When selected (default), the block truncates the input to Output frame size if it is larger than this size. When not selected, the block passes such an input through unchanged.
Number of channels: For frame based operation, the number of columns (channels) in the input matrix, N.