User`s guide

Downsample
5-142
•Enforce single rate
When Enforce single rate is selected, the block forces the output sample
rate to match the input sample rate (T
so
=T
si
) by repeating every Kth input
sample K times at the output. The block is therefore single-rate. (The block’s
operation when
Enforce single rate is selected is similar to the operation of
a Sample and Hold block with a repeating trigger event of period KT
si
.)
The setting of the
Frame-based mode popup menu does not affect
sample-based inputs.
Frame-Based Inputs
When the input is frame-based, the block treats each of the N input columns as
a frame containing M
i
sequential time samples from an independent channel.
The block downsamples each channel independently by discarding K-1 rows of
the input matrix following each row that it passes through to the output.
The
Frame-based mode parameter determines how the block adjusts the rate
at the output to accommodate the reduced number of samples. There are two
available options:
•
Maintain input frame size
The block generates the output at the slower (downsampled) rate by using a
proportionally longer frame period at the output port than at the input port.
For downsampling by a factor of K, the output frame period is K times longer
than the input frame period (T
fo
=KT
fi
), but the input and output frame
sizes are equal.
The model below shows a single-channel input with a frame period of
1 second being downsampled by a factor of 4 to a frame period of 4 seconds.
The input and output frame sizes are identical.