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Multirate Signal Processing

Decimation, interpolation, downsampling, upsampling, antialiasing filter

Resample uniform or nonuniform data to a new fixed rate. Perform decimation and linear or higher-order interpolation without introducing aliasing.


decimate Decimation — decrease sampling rate
downsample Decrease sampling rate by integer factor
fillgaps Fill gaps using autoregressive modeling
interp Interpolation — increase sampling rate by integer factor
interp1 1-D data interpolation (table lookup)
pchip Piecewise Cubic Hermite Interpolating Polynomial (PCHIP)
resample Resample uniform or nonuniform data to new fixed rate
spline Cubic spline data interpolation
upfirdn Upsample, apply FIR filter, and downsample
upsample Increase sampling rate by integer factor


Downsampling — Signal Phases

Use downsampling to obtain the polyphase components of a signal.

Downsampling — Aliasing

Aliasing is the distortion that occurs when copies of a signal's spectrum overlap. Downsampling can introduce aliasing.

Filtering Before Downsampling

Filter before downsampling to mitigate the distortion caused by aliasing.

Upsampling — Imaging Artifacts

Upsample a signal and see how upsampling can result in images.

Filtering After Upsampling — Interpolation

Upsample a signal and apply a lowpass interpolation filter to remove imaging artifacts.

Simulate a Sample-and-Hold System

Simulate the output of a sample-and-hold system by upsampling and filtering a signal.


Decimate, interpolate, or change the sample rate of signals, with or without intermediate filtering.

Changing Signal Sample Rate

Change the sample rates of a sinusoid and a recorded speech sample.

Multirate Filter Bank Implementation

Implement filter banks using the upfirdn function.

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