mirror of https://github.com/saitohirga/WSJT-X.git
68 lines
2.1 KiB
Fortran
68 lines
2.1 KiB
Fortran
subroutine fil651(d,n1,c,n2)
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C FIR lowpass mixing filter designed with ScopeFIR. Real in, complex out.
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C fsample = 5512.5 Hz
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C Ntaps = 31
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C fc = 1000 Hz
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C fstop = 1378.125 Hz
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C Ripple = 0.5 dB
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C Stop Atten = 50 dB
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C fmix = 1378.125 Hz
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C fout = 2706.25 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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real d(n1)
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complex c(n2)
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complex ck(-NH:NH)
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data ck/
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+ (-0.000000073578,-0.000859869243),
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+ ( 0.008518289457,-0.000000680308),
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+ ( 0.000000834309, 0.011250152594),
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+ (-0.001061705254, 0.000000072679),
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+ ( 0.000000875897, 0.013958392128),
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+ (-0.010047338711, 0.000000573160),
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+ ( 0.000000770320, 0.015003869984),
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+ (-0.025027880956, 0.000001142192),
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+ ( 0.000000285583, 0.007151700551),
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+ (-0.043634723888, 0.000001493512),
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+ (-0.000000478847,-0.016788108005),
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+ (-0.061886192046, 0.000001412144),
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+ (-0.000001258694,-0.073548459509),
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+ (-0.075261027462, 0.000000858668),
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+ (-0.000001749252,-0.306638863572),
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+ ( 0.419826269508, 0.000000000000),
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+ (-0.000001749252, 0.306638863572),
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+ (-0.075261027462,-0.000000858668),
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+ (-0.000001258694, 0.073548459509),
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+ (-0.061886192046,-0.000001412144),
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+ (-0.000000478847, 0.016788108005),
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+ (-0.043634723888,-0.000001493512),
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+ ( 0.000000285583,-0.007151700551),
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+ (-0.025027880956,-0.000001142192),
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+ ( 0.000000770320,-0.015003869984),
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+ (-0.010047338711,-0.000000573160),
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+ ( 0.000000875897,-0.013958392128),
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+ (-0.001061705254,-0.000000072679),
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+ ( 0.000000834309,-0.011250152594),
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+ ( 0.008518289457, 0.000000680308),
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+ (-0.000000073578, 0.000859869243)/
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n2=(n1-NTAPS+NDOWN)/NDOWN
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k0=NH-NDOWN+1
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do i=1,n2
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c(i)=0.
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k=k0 + NDOWN*i
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do j=-NH,NH
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c(i)=c(i) + d(j+k)*conjg(ck(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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