class Digiproc::BandpassFilter
Creates a Bandpass Filter via the Windowing method.
Attributes
equation[RW]
Public Class Methods
new(size:, window: Digiproc::RectangularWindow, wo: nil, bw: nil, wcl: nil , wch: nil, correct: true )
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Inputs¶ ↑
- size
- Integer
-
number of datapoints window should be
- window
Digiproc::WindowStrategy
-
desired window strategy
- wo
- Float
-
center frequency in radians
- bw
- Float
-
bandwidth in radians
- wcl
- Float
-
lower cutoff frequency in radians
- wch
- Float
-
higher cutoff frequency in radians
- correct
- Boolean
-
perform frequency corrections to make frequency points more accurate. Defaults to true
Must have either `wo` and `bw` or `wcl` and `wch`
Digiproc::BandpassFilter.new(size: 1000, wo: Math::PI / 4, bw: Math::PI / 10)
Calls superclass method
Digiproc::DigitalFilter::new
# File lib/filters/bandpass_filter.rb, line 20 def initialize(size:, window: Digiproc::RectangularWindow, wo: nil, bw: nil, wcl: nil , wch: nil, correct: true ) super(size: size, window: window) if !!wo && !!bw bw += @window.transition_width * 2 * PI if correct wcl = wo - bw / 2.0 wch = wo + bw / 2.0 else raise ArgumentError.new("You must provide either bandwidth and center freq or frequency bands") if wcl.nil? or wch.nil? wcl -= @window.transition_width * PI if correct wch += @window.transition_width * PI if correct bw = wch - wcl wo = (wch + wcl) / 2.0 end @equation = ->(n){ n == 0 ? bw / PI : ((Math.sin(bw * n / 2.0)) / (PI * n)) * (2.0 * Math.cos(n * wo)) } ideal_filter = calculate_ideal @weights = self.window.values.times ideal_filter @fft = Digiproc::FFT.new(time_data: self.weights) @fft.calculate end