Communications Blockset

Components of the Example

This section discusses the purpose, behavior, and relevant parameters of each block within the example model. Except for two noncomputational blocks discussed at the end, this section covers blocks in the order in which they process data in the simulation.

Creating Random Binary Data

The Bernoulli Random Binary Generator block, in the Comm Sources library, produces the message information for this model. The output of this block is what the other components of the model encode, modulate, transmit, and decode in turn.

Double-click on the Bernoulli Random Binary Generator block in the model window to open the parameter mask dialog box shown below.

Since the Sample time parameter is 1 second, the block generates one binary number each second. Since the Probability of a zero parameter is 0.5, the block generates the bits so that 0 and 1 are equally probable. The Initial seed parameter initializes the random number generator; if you change the Initial seed parameter, then the block generates a different random sequence.

Because the Frame-based outputs check box is checked, the block produces a frame-based scalar signal instead of a sample-based scalar signal. This is done to accommodate the functionality of the Unbuffer and Buffer blocks in a different part of the model, and illustrates one of several possible ways to handle signals appropriately throughout the model as a whole. When you run the simulation or update the diagram, notice that the connector line that leads out of the Bernoulli Random Binary Generator block is a double line instead of a single line. This double line indicates a frame-based signal.

Exploring the Model

Encoding Using a Convolutional Code