notch_filter {ravetools}

Apply 'Notch' filter

Description

Apply 'Notch' filter

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

Details

Mainly used to remove electrical line frequencies at 60, 120, and 180 Hz.

Value

filtered signal in time domain (real numerical vector)

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")