# interp: Interpolate / Increase the sample rate In signal: Signal Processing

 interp R Documentation

## Interpolate / Increase the sample rate

### Description

Upsample a signal by a constant factor by using an FIR filter to interpolate between points.

### Usage

``````interp(x, q, n = 4, Wc = 0.5)
``````

### Arguments

 `x` the signal to be upsampled. `q` the integer factor to increase the sampling rate by. `n` the FIR filter length. `Wc` the FIR filter cutoff frequency.

### Details

It uses an order `2*q*n+1` FIR filter to interpolate between samples.

### Value

The upsampled signal, an array of length `q * length(x)`.

### Author(s)

Original Octave version by Paul Kienzle pkienzle@user.sf.net. Conversion to R by Tom Short.

### References

Octave Forge https://octave.sourceforge.io/

`fir1`, `resample`, `interp1`, `decimate`

### Examples

``````# The graph shows interpolated signal following through the
# sample points of the original signal.
t <- seq(0, 2, by = 0.01)
x <- chirp(t, 2, 0.5, 10, 'quadratic') + sin(2*pi*t*0.4)
y <- interp(x[seq(1, length(x), by = 4)], 4, 4, 1) # interpolate a sub-sample
plot(t, x, type = "l")
idx <- seq(1,length(t),by = 4)
lines(t, y[1:length(t)], col = "blue")
points(t[idx], y[idx], col = "blue", pch = 19)
``````

signal documentation built on June 26, 2024, 9:06 a.m.