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.

Apps

Visualize and compare multiple signals and spectra

`decimate`	Decimation — decrease sample rate by integer factor
`downsample`	Decrease sample rate by integer factor
`fillgaps`	Fill gaps using autoregressive modeling
`interp`	Interpolation — increase sample rate by integer factor
`interp1`	1-D data interpolation (table lookup)
`intfilt`	Interpolation FIR filter design
`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 sample rate by integer factor

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