56 lines
1.4 KiB
Plaintext
56 lines
1.4 KiB
Plaintext
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integer function savec2(c2name,ntrseconds,f0m1500)
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! Array c0() has complex samples at 1500 Hz sample rate.
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! WSPR-2: downsample by 1/4 to produce c2, centered at 1500 Hz
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! WSPR-15: downsample by 1/32 to produce c2, centered at 1612.5 Hz
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parameter (NDMAX=120*1500) !Sample intervals at 1500 Hz rate
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parameter (MAXFFT=256*1024)
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character*(*) c2name
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character*14 outfile
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real*8 f0m1500
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complex c0
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complex c1(0:MAXFFT-1)
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complex c2(0:65535)
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common/c0com/c0(0:NDMAX-1)
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ntrminutes=ntrseconds/60
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npts=114*1500
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nfft1=262144
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if(ntrminutes.eq.15) then
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npts=890*1500
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nfft1=MAXFFT
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endif
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df1=1500.0/nfft1
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fac=1.0/nfft1
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c1(0:npts-1)=fac*c0(0:npts-1)
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c1(npts:nfft1-1)=0.
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call four2a(c1,nfft1,1,1,1) !Complex FFT to frequency domain
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! Select the desired frequency range
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nfft2=65536
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nh2=nfft2/2
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if(ntrminutes.eq.2) then
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c2(0:nh2)=c1(0:nh2)
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c2(nh2+1:nfft2-1)=c1(nfft1-nh2+1:nfft1-1)
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else
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i0=nint(112.5/df1)
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c2(0:nh2)=c1(i0:i0+nh2)
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c2(nh2+1:nfft2-1)=c1(i0-nh2+1:i0-1)
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endif
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call four2a(c2,nfft2,1,-1,1) !Shorter complex FFT, back to time domain
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! Write complex time-domain data to disk.
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i1=index(c2name,'.c2')
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outfile=c2name(i1-11:i1+2)
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open(18,file=c2name,status='unknown',access='stream', iostat=ioerr)
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if (ioerr.eq.0) then
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write(18) outfile,ntrminutes,f0m1500,c2(0:45000-1)
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close(18)
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endif
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savec2 = ioerr
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end function savec2
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