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https://github.com/saitohirga/WSJT-X.git
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45 lines
1.3 KiB
FortranFixed
45 lines
1.3 KiB
FortranFixed
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subroutine fil652(c1,n1,c2,n2)
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C FIR lowpass filter designed using ScopeFIR
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C fsample = 2756.25 Hz
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C Ntaps = 31
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C fc = 500 Hz
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C fstop = 689.0625 Hz
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C Ripple = 0.5 dB
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C Stop Atten = 50 dB
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C fout = 1378.125 Hz
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parameter (NTAPS=31)
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parameter (NH=NTAPS/2)
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parameter (NDOWN=2) !Downsample ratio
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complex c1(n1)
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complex c2(*)
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C Filter coefficients:
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real a(-NH:NH)
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data a/
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+ -0.000859869246,-0.008518289484,-0.011250152625,-0.001061705256,
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+ 0.013958392156, 0.010047338728,-0.015003870003,-0.025027880982,
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+ 0.007151700557, 0.043634723913, 0.016788108012,-0.061886192062,
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+ -0.073548459520, 0.075261027466, 0.306638863577, 0.419826269508,
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+ 0.306638863577, 0.075261027466,-0.073548459520,-0.061886192062,
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+ 0.016788108012, 0.043634723913, 0.007151700557,-0.025027880982,
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+ -0.015003870003, 0.010047338728, 0.013958392156,-0.001061705256,
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+ -0.011250152625,-0.008518289484,-0.000859869246/
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n2=(n1-NTAPS+NDOWN)/NDOWN
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k0=NH-NDOWN+1
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C Loop over all output samples
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do i=1,n2
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c2(i)=0.
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k=k0 + NDOWN*i
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do j=-NH,NH
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c2(i)=c2(i) + c1(j+k)*a(j)
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enddo
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enddo
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return
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end
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