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module SPCore
# Produces a flat top window of a given size (number of samples).
# A flat top window is a partially negative-valued window that has a flat top in
# the frequency domain. They are designed to have a broader bandwidth and so have
# a poorer frequency resolution, leading to low amplitude measurement error suitable
# for use in in spectrum analyzers for the measurement of amplitudes of sinusoidal
# frequency components
# For more info, see https://en.wikipedia.org/wiki/Window_function#Flat_top_window.
class FlatTopWindow
attr_reader :data
def initialize size
@data = Array.new(size)
a0, a1, a2, a3, a4 = 1.0, 1.93, 1.29, 0.388, 0.032
size.times do |n|
@data[n] = a0 - a1 * Math::cos((TWO_PI * n)/(size - 1)) + a2 * Math::cos((FOUR_PI * n)/(size - 1)) - a3 * Math::cos((SIX_PI * n)/(size - 1)) + a4 * Math::cos((EIGHT_PI * n)/(size - 1))
end
max = @data.max
# normalize to max of 1.0
@data.each_index do |i|
@data[i] /= max
end
end
end
end
Version data entries
9 entries across 9 versions & 1 rubygems