Signal Processing Blockset™

Triggered Delay Line - Buffer sequence of inputs into frame-based output

Library

dspobslib

Description

Note   The Triggered Delay Line block is still supported but is likely to be obsoleted in a future release. We strongly recommend replacing this block with the Delay Line block.

The Triggered Delay Line block acquires a collection of M_o input samples into a frame, where you specify M_o in the Delay line size parameter. The block buffers a single sample from input 1 whenever it is triggered by the control signal at input 2 ( ). When the next triggering event occurs, the newly acquired input sample is appended to the output frame so that the new output overlaps the previous output by M_o-1 samples. Between triggering events the block ignores input 1 and holds the output at its last value.

You specify the triggering event at input 2 in the Trigger type pop-up menu:

• Rising edge triggers execution of the block when the trigger input rises from a negative value to zero or a positive value, or from zero to a positive value.

• Falling edge triggers execution of the block when the trigger input falls from a positive value to zero or a negative value, or from zero to a negative value.

• Either edge triggers execution of the block when either a rising or falling edge (as described above) occurs.

The Triggered Delay Line block has zero latency, so the new input appears at the output in the same simulation time step. The output frame period is the same as the input sample period, T_fo=T_si.

Sample-Based Operation

In sample-based operation, the Triggered Delay Line block buffers a sequence of sample-based length-N vector inputs (1-D, row, or column) into a sequence of overlapping sample-based M_o-by-N matrix outputs, where you specify M_o in the Delay line size parameter (M_o>1). That is, each input vector becomes a row in the sample-based output matrix. When M_o=1, the input is simply passed through to the output, and retains the same dimension. Sample-based full-dimension matrix inputs are not accepted.

Frame-Based Operation

In frame-based operation, the Triggered Delay Line block rebuffers a sequence of frame-based M_i-by-N matrix inputs into an sequence of overlapping frame-based M_o-by-N matrix outputs, where M_o is the output frame size specified by the Delay line size parameter (that is, the number of consecutive samples from the input frame to rebuffer into the output frame). M_o can be greater or less than the input frame size, M_i. Each of the N input channels is rebuffered independently.

Initial Conditions

The Triggered Delay Line block's buffer is initialized to the value specified by the Initial condition parameter. The block always outputs this buffer at the first simulation step (t=0). When the block's output 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 initial output. When the block's output is a matrix, the Initial condition can be a matrix of the same size or a scalar to be repeated across all elements of the initial output.

Dialog Box

Trigger type

The type of event that triggers the block's execution.

Delay line size

The length of the output frame (number of rows in output matrix), M_o.

Initial condition

The value of the block's initial output, a scalar, vector, or matrix.

Supported Data Types

See Also

Transpose

Triggered Signal From Workspace