Sample and Hold (DSP Blockset)

Sample and hold an input signal.

Library

Switches and Counters, in General DSP

Description

The Sample and Hold block acquires a new sample (scalar, vector, or matrix) from the signal input whenever it is triggered by the control signal at the trigger input (

). The block holds the output at the sampled input value until the next triggering event occurs.

The triggering event at the top port is specified by the Trigger type pop-up menu, and can be one of the following:

Rising edge triggers the block to sample the signal input when the control signal rises from zero to a positive value.
Falling edge triggers the block to sample the signal input when the control signal falls from zero to a negative value.
Either edge triggers the block to sample the signal input when the control signal either rises from zero to a positive value or falls from zero to a negative value.

The block's output prior to the first triggering event is specified by the Initial condition parameter. If the input is a vector, the Initial condition can be a vector of the same size, or a scalar value to be repeated across all elements of the output. If the block's input is an M-by-N matrix, the Initial condition can be a scalar to be repeated across all M*N elements of the output matrix, or a vector, ic, of length M*N, to be reshaped to matrix dimensions.

y = reshape(ic,M,N)      % equivalent MATLAB code

Dialog Box

Trigger type: The type of event that triggers the block's to sample the input signal.
Initial condition: The block output prior to the first triggering event.