Getting Started

Using a Probe Block to Determine Symbol Period

If you are unsure how to set the Symbol period, you can find the correct value using a Probe block. To do so, follow these steps:

1. Drag the following blocks from the Simulink Library Browser into the cyclic code model window:
• Probe block, from the Simulink Signal Attributes library
• Two copies of the Terminator block, from the Simulink Sinks library
2. Double-click the Probe block to display its mask.
3. Clear the boxes next to Probe complex signal and Probe signal dimensions and check the boxes next to Probe width and Probe sample time. This reduces the number of output ports in the block to two.
4. Connect the blocks as shown in the following figure.
5. Select Update diagram from the Edit menu.

The model should now appear as shown in the following diagram.

The number after W in the Probe block tells you the frame size, which in this case is 7. The first number after Tf tells you the frame period, which is 4. You can determine the symbol period by the following formula.

In this example, the symbol period is 4 / 7.

When the signal is sample-based, the second value in the Probe block is the sample time, rather than the frame period.

Setting the Symbol Period

Building a Frequency-Shift Keying Model