Change the sampling rate of a signal
Resample using bandlimited interpolation.
resample(x, p, q = 1, d = 5)
x |
signal to be resampled. |
p, q |
|
d |
distance. |
Note that p and q do
not need to be integers since this routine does not use a polyphase
rate change algorithm, but instead uses bandlimited interpolation,
wherein the continuous time signal is estimated by summing the sinc
functions of the nearest neighbouring points up to distance d.
Note that resample computes all samples up to but not including time n+1.
If you are increasing the sample rate, this means that it will
generate samples beyond the end of the time range of the original
signal. That is why xf must go all the way to 10.95 in the example below.
Nowadays, the signal version in Matlab and Octave contain more modern code for resample that has not been ported to the signal R package (yet).
The resampled signal, an array of length ceiling(length(x) * p / q).
Original Octave version by Paul Kienzle pkienzle@user.sf.net. Conversion to R by Tom Short.
J. O. Smith and P. Gossett (1984). A flexible sampling-rate conversion method. In ICASSP-84, Volume II, pp. 19.4.1-19.4.2. New York: IEEE Press.
Octave Forge http://octave.sf.net
xf <- seq(0, 10.95, by=0.05)
yf <- sin(2*pi*xf/5)
xp <- 0:10
yp <- sin(2*pi*xp/5)
r <- resample(yp, xp[2], xf[2])
title("confirm that the resampled function matches the original")
plot(xf, yf, type = "l", col = "blue")
lines(xf, r[1:length(xf)], col = "red")
points(xp,yp, pch = 19, col = "blue")
legend("bottomleft", c("Original", "Resample", "Data"),
col = c("blue", "red", "blue"),
pch = c(NA, NA, 19),
lty = c(1, 1, NA), bty = "n")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.