sampled2continuous function

Signal reconstruction

Analog signal reconstruction from discrete samples.

sampled2continuous(xn, fs, t)

Arguments

• xn: the sampled input signal, specified as a vector
• fs: sampling frequency in Hz used in collecting x, specified as a positive scalar value. Default: 1
• t: time points at which data is to be reconstructed, specified as a vector relative to x[0] (not real time).

Returns

Reconstructed signal x(t), returned as a vector.

Details

Given a discrete signal x[n] sampled with a frequency of fs Hz, this function reconstruct the original analog signal x(t) at time points t. The function can be used, for instance, to calculate sampling rate effects on aliasing.

Examples

# 'analog' signal: 3 Hz cosine
t <- seq(0, 1, length.out = 100)
xt <- cos(3 * 2 * pi * t)
plot(t, xt, type = "l", xlab = "", ylab = "", ylim = c(-1, 1.2))

# 'sample' it at 4 Hz to simulate aliasing
fs <- 4
n <- ceiling(length(t) / fs)
xn <- xt[seq(ceiling(n / 2), length(t), n)]
s4 <- sampled2continuous(xn, fs, t)
lines(t, s4, col = "red")

# 'sample' it > 6 Hz to avoid aliasing
fs <- 7
n <- ceiling(length(t) / fs)
xn <- xt[seq(ceiling(n / 2), length(t), n)]
s7 <- sampled2continuous(xn, fs, t)
lines(t, s7, col = "green")
legend("topright", legend = c("original", "aliased", "non-aliased"),
  lty = 1, col = c("black", "red", "green"))

Author(s)

Muthiah Annamalai, muthiah.annamalai@uta.edu . Conversion to R by Geert van Boxtel, G.J.M.vanBoxtel@gmail.com .