Calculate the peak frequency per axis for bursts

Usage

peak_frequency(x, resolution = NA)

Arguments

x: An IMU vector (e.g. acc, mag, gyro).
resolution: A scalar with the units Hertz

Value

returns a list with the same length as x with the peak frequency per axis

Details

To increase the resolution of the result zero padding can be used. This can be controlled using the resolution argument. Note that increasing resolution without increasing the number of samples in a burst has a limited ability to get closer to the true frequency.

Examples

a <- acc(
  list(
    cbind(
      X = sin(1:200 / (5  / (pi * 2))),
      Z = cos(1:200 / (80 / (pi * 2)))
    )
  ), 
  units::set_units(400, "Hz")
)

peak_frequency(a)
#> [[1]]
#> Units: [Hz]
#>  X  Z 
#> 80  6 
#> 

peak_frequency(a, units::set_units(.25, "Hz"))
#> [[1]]
#> Units: [Hz]
#>  X  Z 
#> 80  5 
#> 

# Increasing resolution more
peak_frequency(a, units::set_units(.005, "Hz"))
#> [[1]]
#> Units: [Hz]
#>      X      Z 
#> 79.995  5.115 
#> 

a <- acc(
  list(
    cbind(
      X = sin((1:200) / (5 / (pi * 2))),
      Z = cos(80 + 1:200 / (80 / (pi * 2)))
    )
  ), 
  units::set_units(400, "Hz")
)

peak_frequency(a, units::set_units(.005, "Hz"))
#> [[1]]
#> Units: [Hz]
#>      X      Z 
#> 79.995  4.875 
#>