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Diffstat (limited to 'gnuradio-core/src/python/gnuradio/window.py')
| -rw-r--r-- | gnuradio-core/src/python/gnuradio/window.py | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/gnuradio-core/src/python/gnuradio/window.py b/gnuradio-core/src/python/gnuradio/window.py new file mode 100644 index 0000000000..391b83c375 --- /dev/null +++ b/gnuradio-core/src/python/gnuradio/window.py @@ -0,0 +1,190 @@ +# +# Copyright 2004,2005 Free Software Foundation, Inc. +# +# This file is part of GNU Radio +# +# GNU Radio is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2, or (at your option) +# any later version. +# +# GNU Radio is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with GNU Radio; see the file COPYING. If not, write to +# the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +# Boston, MA 02111-1307, USA. +# + +''' +Routines for designing window functions. +''' + +import math +from gnuradio import gr + +def izero(x): + izeroepsilon = 1e-21 + halfx = x/2.0 + accum = u = n = 1 + while 1: + temp = halfx/n + n += 1 + temp *= temp + u *= temp + accum += u + if u >= IzeroEPSILON*sum: + break + return accum + +def midm1(fft_size): + return (fft_size - 1)/2 + +def midp1(fft_size): + return (fft_size+1)/2 + +def freq(fft_size): + return 2.0*math.pi/fft_size + +def rate(fft_size): + return 1.0/(fft_size >> 1) + +def expn(fft_size): + math.log(2.0)/(midn(fft_size) + 1.0) + +def hamming(fft_size): + window = [] + for index in xrange(fft_size): + window.append(0.54 - 0.46 * math.cos (2 * math.pi / fft_size * index)) # Hamming window + return window + +def hanning(fft_size): + window = [] + for index in xrange(fft_size): + window.append(0.5 - 0.5 * math.cos (2 * math.pi / fft_size * index)) # von Hann window + return window + +def welch(fft_size): + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + window[j] = window[index] = (1.0 - math.sqrt((index - midm1(fft_size)) / midp1(fft_size))) + j -= 1 + return window + +def parzen(fft_size): + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + window[j] = window[index] = (1.0 - math.abs((index - midm1(fft_size)) / midp1(fft_size))) + j -= 1 + return window + +def bartlett(fft_size): + mfrq = freq(fft_size) + angle = 0 + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + window[j] = window[index] = angle + angle += freq + j -= 1 + return window + +def blackman2(fft_size): + mfrq = freq(fft_size) + angle = 0 + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + cx = math.cos(angle) + window[j] = window[index] = (.34401 + (cx * (-.49755 + (cx * .15844)))) + angle += freq + j -= 1 + return window + +def blackman3(fft_size): + mfrq = freq(fft_size) + angle = 0 + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + cx = math.cos(angle) + window[j] = window[index] = (.21747 + (cx * (-.45325 + (cx * (.28256 - (cx * .04672)))))) + angle += freq + j -= 1 + return window + +def blackman4(fft_size): + mfrq = freq(fft_size) + angle = 0 + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + cx = math.cos(angle) + window[j] = window[index] = (.084037 + (cx * (-.29145 + (cx * (.375696 + (cx * (-.20762 + (cx * .041194)))))))) + angle += freq + j -= 1 + return window + +def exponential(fft_size): + expsum = 1.0 + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)+1): + window[j] = window[i] = (expsum - 1.0) + expsum *= expn(fft_size) + j -= 1 + return window + +def riemann(fft_size): + sr1 = freq(fft_size) + window = [0 for i in range(fft_size)] + j = fft_size-1 + for index in xrange(midn(fft_size)): + if index == midn(fft_size): + window[index] = window[j] = 1.0 + else: + cx = sr1*midn(fft_size) - index + window[index] = window[j] = math.sin(cx)/cx + j -= 1 + return window + +def blackmanharris(fft_size): + a0 = 0.35875 + a1 = 0.48829 + a2 = 0.14128 + a3 = 0.01168 + window = [0 for i in range(fft_size)] + for index in xrange(fft_size): + window[index] = a0 + window[index] -= a1*math.cos(2.0*math.pi*(index+0.5)/(fft_size - 1)) + window[index] += a2*math.cos(4.0*math.pi*(index+0.5)/(fft_size - 1)) + window[index] -= a3*math.cos(6.0*math.pi*(index+0.5)/(fft_size - 1)) + return window + +def nuttall(fft_size): + a0 = 0.3635819 + a1 = 0.4891775 + a2 = 0.1365995 + a3 = 0.0106411 + window = [0 for i in range(fft_size)] + for index in xrange(fft_size): + window[index] = a0 + window[index] -= a1*math.cos(2.0*math.pi*(index+0.5)/(fft_size - 1)) + window[index] += a2*math.cos(4.0*math.pi*(index+0.5)/(fft_size - 1)) + window[index] -= a3*math.cos(6.0*math.pi*(index+0.5)/(fft_size - 1)) + return window + +def kaiser(fft_size,beta): + ibeta = 1.0/izero(beta) + inm1 = 1.0/(fft_size) + window = [0 for i in range(fft_size)] + for index in xrange(fft_size): + window[index] = izero(beta*math.sqrt(1.0 - (index * inm1)*(index * inm1))) * ibeta + return window + + |