Polyphase Implementation of FIR Interpolation Block

This example shows the underlying polyphase implementation of the FIR Interpolation block using upsampling and FIR filtering as building blocks. The model compares the output of the FIR Interpolation block with the output of a polyphase interpolation structure. The Time Scope block compares the two outputs.

Open the ex_polyphaseinterp.slx model.

The model has two branches. The first branch contains an FIR Interpolation block. The second branch contains a polyphase interpolation structure. For more details on the derivation of this structure, see the Algorithms section in the FIR Interpolation block page.

Run the model and view the results on the scope. The first signal on the scope is the original sinusoidal signal. The second and third signals on the scope are the outputs of the FIR Interpolation block and the polyphase structure, respectively. The last signal on the scope shows that the error between the two interpolated outputs is very small, almost zero. This negligible error confirms the underlying polyphase implementation of the FIR Interpolation block.