Class: Digiproc::DigitalFilter

Inherits:
Object
  • Object
show all
Defined in:
lib/filters/digital_filter.rb

Overview

Parent class to BandpassFilter, HighpassFilter, LowpassFilter, and BandstopFilter

Constant Summary collapse

PI = 
Math::PI

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size:, window:) ⇒ DigitalFilter

Inputs

size
Integer

number of window datapoints

window
Digiproc::WindowStrategy 


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# File 'lib/filters/digital_filter.rb', line 12

def initialize(size: , window: )
    #TODO: allow size to be even
    @size = size.even? ? size + 1 : size
    @window = window.new(size: size)
end

Instance Attribute Details

#fft ⇒ Object

Returns the value of attribute fft.



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# File 'lib/filters/digital_filter.rb', line 6

def fft
  @fft
end

#size ⇒ Object

Returns the value of attribute size.



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# File 'lib/filters/digital_filter.rb', line 6

def size
  @size
end

#weights ⇒ Object

Returns the value of attribute weights.



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# File 'lib/filters/digital_filter.rb', line 6

def weights
  @weights
end

#window ⇒ Object

Returns the value of attribute window.



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# File 'lib/filters/digital_filter.rb', line 6

def window
  @window
end

Instance Method Details

#calculate_ideal ⇒ Object

Ensures size is odd, and uses @equation to make a return Array of ideal filter values. Used by the child class to multiply by the window to the return value of this method for final weights



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# File 'lib/filters/digital_filter.rb', line 21

def calculate_ideal
    #TODO: allow size to be even
    @size += 1 if @size.even?
    n_vals = ((-1 * (@size - 1) / 2)..((@size - 1) / 2)).to_a
    n_vals.map do |n|
        @equation.call(n)
    end
end

#set_fft_size(size) ⇒ Object

Zero pad @weights to achieve a size of the input value. set @fft to a new Digiproc::FFT, and calculate with the new padded data. .set_fft_size(size [Integer])



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# File 'lib/filters/digital_filter.rb', line 35

def set_fft_size(size)
    if size > @weights.length
        zeros = Array.new(size - @weights.length, 0)
        padded = @weights.concat(zeros)
        @fft = Digiproc::FFT.new(data: padded)
        @fft.calculate
    end
end

#to_ds ⇒ Object

return a Digiproc::DigitalSignal whose values are the weights of the filter



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# File 'lib/filters/digital_filter.rb', line 46

def to_ds
    Digiproc::DigitalSignal.new(data: self.weights)
end