mirror of
https://github.com/mborgerding/kissfft.git
synced 2025-06-04 01:28:23 -04:00
71 lines
1.6 KiB
Python
Executable File
71 lines
1.6 KiB
Python
Executable File
#!/usr/local/bin/python2.3
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from Numeric import *
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from FFT import *
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def make_random(len):
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import random
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res=[]
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for i in range(int(len)):
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r=random.uniform(-1,1)
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i=random.uniform(-1,1)
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res.append( complex(r,i) )
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return res
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def slowfilter(sig,h):
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translen = len(h)-1
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return convolve(sig,h)[translen:-translen]
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def nextpow2(x):
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return 2 ** math.ceil(math.log(x)/math.log(2))
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def fastfilter(sig,h,nfft=None):
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if nfft is None:
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nfft = int( nextpow2( 2*len(h) ) )
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H = fft( h , nfft )
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scraplen = len(h)-1
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keeplen = nfft-scraplen
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res=[]
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isdone = 0
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lastidx = nfft
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idx0 = 0
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while not isdone:
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idx1 = idx0 + nfft
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if idx1 >= len(sig):
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idx1 = len(sig)
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lastidx = idx1-idx0
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if lastidx <= scraplen:
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break
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isdone = 1
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Fss = fft(sig[idx0:idx1],nfft)
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fm = Fss * H
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m = inverse_fft(fm)
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res.append( m[scraplen:lastidx] )
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idx0 += keeplen
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return concatenate( res )
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def main():
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siglen = 1e5
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hlen = 500
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nfft = 1024*4
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print 'nfft=%d'%nfft
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# make a signal
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sig = make_random( siglen )
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# make an impulse response
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h = make_random( hlen )
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#h=[1]*2+[0]*3
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# perform MAC filtering
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yslow = slowfilter(sig,h)
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#print '<YSLOW>',yslow,'</YSLOW>'
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yfast = fastfilter(sig,h,nfft)
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#print yfast
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print 'len(yslow)=%d'%len(yslow)
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print 'len(yfast)=%d'%len(yfast)
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diff = yslow-yfast
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snr = 10*log10( vdot(yslow,yslow) / vdot(diff,diff) )
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print 'snr=%s' % snr
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if __name__ == "__main__":
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main()
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