DSP Blockset

Example: Rate Conversion by Frame-Rate Adjustment.   A common example of direct rate conversion is shown in the model below, where the signal is directly downsampled to half its original rate by a Downsample block. The values next to input and output ports are the signal dimensions, displayed by selecting Signal dimensions from the model window's Format menu.

The sample period and frame size of the original signal are set to 0.125 second and 8 samples per frame, respectively, by the Sample time and Samples per frame parameters in the Signal From Workspace block. This results in a frame rate of 1 second (0.125*8), as shown by the first Probe block.

The Downsample block is configured to downsample the signal by changing the frame rate rather than the frame size. The dialog box with this setting is shown below.

The second Probe block in the model verifies that the output from the Downsample block has a frame period of 2, twice that of the input (i.e., half the rate). As a result, the sequence sample period is doubled to 0.25 second without any change to the frame size.

Direct Rate Conversion

Example: Rate Conversion by Frame-Size Adjustment