mirror of https://github.com/saitohirga/WSJT-X.git
50 lines
1.6 KiB
Fortran
50 lines
1.6 KiB
Fortran
subroutine fil653(c1,n1,c2,n2)
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C FIR lowpass filter designed using ScopeFIR
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C fsample = 1378.125 Hz
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C Ntaps = 45
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C fc = 100 Hz
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C fstop = 172.265625 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 = 172.265625 Hz
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C BW = 200 Hz
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parameter (NTAPS=45)
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parameter (NH=NTAPS/2)
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parameter (NDOWN=4) !Downsample ratio
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complex c1(n1)
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complex c2(n2)
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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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+ -0.000005569862,-0.002503777832,-0.004040335617,-0.005717910288,
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+ -0.006153385485,-0.004446125293,-0.000305215272, 0.005557289511,
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+ 0.011329120672, 0.014496551280, 0.012703875898, 0.004837591829,
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+ -0.008060363689,-0.022474422302,-0.032964876083,-0.033575486327,
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+ -0.019743889907, 0.009895672340, 0.052467109908, 0.101031155027,
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+ 0.146073001698, 0.177927966814, 0.189427119395, 0.177927966814,
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+ 0.146073001698, 0.101031155027, 0.052467109908, 0.009895672340,
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+ -0.019743889907,-0.033575486327,-0.032964876083,-0.022474422302,
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+ -0.008060363689, 0.004837591829, 0.012703875898, 0.014496551280,
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+ 0.011329120672, 0.005557289511,-0.000305215272,-0.004446125293,
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+ -0.006153385485,-0.005717910288,-0.004040335617,-0.002503777832,
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+ -0.000005569862/
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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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