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Using the Probe Block to Inspect Rates
Connect the Simulink Probe block to any line to display the period of the signal on that line. The period is displayed in the block icon itself (together with the line width and data type, if desired), making it easy to verify that the sample rates in the model are what you expect them to be. When the line width and data type displays are suppressed (by clearing the appropriate check boxes in the block dialog box), the Probe block looks like this.
The block displays the label Ts or Tf, followed by a two-element vector. The first (left) element is the period of the signal being measured. The second (right) is the signal's sample time offset, which is usually 0, as explained in Sample Time Offsets.
For sample-based signals, the value shown in the Probe block icon is the sample period of the sequence, Ts. For frame-based signals, the value shown in the Probe block icon is the frame period, Tf. The difference between sample rates and frame rates is explained in Sample Rate and Frame Rate Concepts.
Probe Block Example: Sample-Based. The three Probe blocks in the sample-based model below verify that the signal's sample period is halved with each upsample operation: The output from the Signal From Workspace block has a sample period of 1 second, the output from the first Upsample block has a sample period of 0.5 second, and the output from the second Upsample block has a sample period of 0.25 second.
Probe Block Example: Frame-Based. The three Probe blocks in the frame-based model below again verify that the signal's sample period is halved with each upsample operation: The output from the Signal From Workspace block has a frame period of 16 seconds, the output from the first Upsample block has a frame period of 8 seconds, and the output from the second Upsample block has a sample period of 4 seconds.
Note that the sample rate conversion is implemented through a change in the frame period rather than the frame size. This is because the Frame-based mode parameter in the Upsample blocks is set to Maintain input frame size rather than Maintain input frame rate. See Converting Sample Rates and Frame Rates for more information.
| | Inspecting Sample Rates and Frame Rates | Using Sample Time Color Coding to Inspect Sample Rates | |
