Using the DSP Blockset (DSP Blockset)

DSP Blockset

Example: Using Buffer and Unbuffer

The model below demonstrates how to use the Buffer block to create a frame vector that the FFT block can operate on. At the end of the processing flow, the Partial Unbuffer block converts the frame vectors back to scalar samples for output on a Scope.

Construct the model using:

Buffer and Partial Unbuffer blocks from the Buffers library (in General DSP)
FFT and IFFT blocks in the Transforms library (in General DSP)
Abs block from the Simulink Math library
Time Frame Scope and Frequency Frame Scope blocks from the DSP Sinks library
Signal Generator block from the Simulink Sources library
Zero-Order Hold block from the Simulink Discrete library
Time Scope from the DSP Sources library

To try the model:

1.: Set the input signal parameters in the Signal Generator block:

Wave form = square
Amplitude = 2
Frequency = 3.5
Units = rad/sec

2.: Set the Sample time in the Zero-Order Hold block to 0.001.

3.: Set the Buffer block parameters:

Buffer size = 256
Buffer overlap = 192

4.: Set the Partial Unbuffer block parameters:

Buffer size = 256
First output index = 193
Last output index = 256

5.: Set the Frequency Frame Scope block parameters:

Frequency units = rads/sec
Sample time of vector elements = 0.001

6.: Set the Stop time in the Parameters dialog box to inf, and start the simulation by selecting Start from the Simulation menu.

The Time Frame Scope window displays the buffered input, and the Frequency Frame Scope window displays its FFT. Stop the simulation at any time by selecting Stop from the Simulation menu.

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