Usage
notch_filter(
s,
sample_rate,
lb = c(59, 118, 178),
ub = c(61, 122, 182),
domain = 1
)
Arguments
- s
numerical vector if domain=1 (voltage
signals), or complex vector if domain=0
- sample_rate
sample rate
- lb
filter lower bound of the frequencies to remove
- ub
filter upper bound of the frequencies to remove;
shares the same length as lb
- domain
1 if the input signal is in the
time domain, 0 if it is in the frequency domain
Value
filtered signal in time domain (real numerical
vector)
Details
Mainly used to remove electrical line frequencies
at 60, 120, and 180 Hz.
Examples
time <- seq(0, 3, 0.005)
s <- sin(120 * pi * time) + rnorm(length(time))
# Welch periodogram shows a peak at 60Hz
pwelch(s, 200, plot = 1, log = "y")
# notch filter to remove 60Hz
s1 <- notch_filter(s, 200, lb = 59, ub = 61)
pwelch(s1, 200, plot = 2, log = "y", col = "red")
