N-Sample Switch (DSP Blockset)

Switch between two inputs after a specified number of sample periods.

Library

Switches and Counters, in General DSP

Description

The N-Sample Switch block outputs the signal connected to the top input for the first N sample times after the simulation begins or the block is reset. Beginning at sample time N+1, the block outputs the signal connected to the bottom input until the next reset or the end of the simulation. The two inputs must be the same size except when one is a scalar, in which case the block expands the scalar to the size of the other input.

The block resets the count to zero when a trigger signal is received at the optional Trig port at any time during the simulation. Enable the Trig port by selecting the Reset input check box. The triggering event is specified by the Trigger type pop-up menu, and can be one of the following:

Rising edge resets the block when the discrete trigger input rises from a negative value to zero or a positive value, or from zero to a positive value.
Falling edge resets the block when the discrete trigger input falls from a positive value to zero or a negative value, or from zero to a negative value.
Either edge resets the block when either a rising or falling edge (as described above) occurs.

Dialog Box

Switch count: The number of sample periods for which the output is connected to the top input before switching to the bottom input.
Reset input: Enables the Trig input port when selected.
Trigger type: The type of event at the Trig port that resets the block's counter.
Sample time: The sample period, T_s, for the block's counter. The block switches inputs at t=T_s*(N+1).