440 lines
12 KiB
Fortran
440 lines
12 KiB
Fortran
program wsprdpskd
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! Decode WSPRDPSK data read from *.c2 or *.wav files.
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! Currently configured to use (204,68) r=1/3 LDPC code, regular column weight 3.
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! 50 data bits + 14 bit CRC + 4 "0" bits. The 4 "0" bits are unused bits that
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! are not transmitted. At the decoder, these bits are treated as "AP" bits.
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! This shortens the code to (200,64) r=0.32, slightly decreasing the code rate.
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! Frame format is:
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! d100 p32 d100 (232) channel symbols
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!
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use crc
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include 'wsprdpsk_params.f90'
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parameter(NMAX=120*12000)
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character arg*8,message*22,cbits*50,infile*80,fname*16,datetime*11
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character*22 decodes(100)
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character*120 data_dir
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character*32 uwbits
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character*68 dmsg
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complex c2(0:120*12000/30-1) !Complex waveform
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complex cframe(0:232*200-1) !Complex waveform
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complex cd(0:240*10-1) !Complex waveform
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complex cs(0:240)
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complex c1(0:9,0:1),c0(0:9,0:1)
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complex ccor(0:1,232)
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complex csum,cterm
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real*8 fMHz
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real rxdata(ND),llr(204) !Soft symbols
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real sbits(232),sbits1(232),sbits3(232)
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real ps(0:8191),psbest(0:8191)
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real candidates(100,2)
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integer iuniqueword0
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integer isync(200) !Unique word
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integer isync2(232)
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integer ipreamble(16) !Preamble vector
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integer ihdr(11)
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integer*2 iwave(NMAX) !Generated full-length waveform
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integer*1,target :: idat(9)
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integer*1 decoded(68),apmask(204),cw(204)
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integer*1 hbits(232),hbits1(232),hbits3(232)
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integer*1 b(14),bbest(14)
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data ipreamble/1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1/
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data iuniqueword0/z'30C9E8AD'/
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write(uwbits,'(b32.32)') iuniqueword0
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read(uwbits,'(32i1)') isync(1:32)
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read(uwbits,'(32i1)') isync(33:64)
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read(uwbits,'(32i1)') isync(65:96)
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read(uwbits,'(32i1)') isync(97:128)
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read(uwbits,'(32i1)') isync(129:160)
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read(uwbits,'(32i1)') isync(161:192)
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read(uwbits,'(8i1)') isync(193:200)
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fs=12000.0/NDOWN !Sample rate
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dt=1.0/fs !Sample interval (s)
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tt=NSPS*dt !Duration of "itone" symbols (s)
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baud=1.0/tt !Keying rate for "itone" symbols (baud)
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txt=NZ*dt !Transmission length (s)
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h=1.00 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
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twopi=8.0*atan(1.0)
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isync2(1:100)=isync(1:100)
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isync2(101:104)=0 ! This is *not* backwards.
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isync2(105:112)=1
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isync2(113:116)=0
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isync2(117:216)=isync(101:200)
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dphi=twopi*baud*(h/2.0)*dt*20 ! dt*20 is samp interval after downsample
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do j=0,1
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if(j.eq.0) then
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dphi0=-3*dphi
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dphi1=+1*dphi
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else
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dphi0=-1*dphi
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dphi1=+3*dphi
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endif
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phi0=0.0
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phi1=0.0
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do i=0,9
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c1(i,j)=cmplx(cos(phi1),sin(phi1))
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c0(i,j)=cmplx(cos(phi0),sin(phi0))
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phi1=mod(phi1+dphi1,twopi)
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phi0=mod(phi0+dphi0,twopi)
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enddo
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enddo
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nargs=iargc()
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if(nargs.lt.1) then
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print*,'Usage: wsprdpskd [-a <data_dir>] [-f fMHz] [-c ncoh] file1 [file2 ...]'
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go to 999
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endif
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iarg=1
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data_dir="."
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call getarg(iarg,arg)
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if(arg(1:2).eq.'-a') then
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call getarg(iarg+1,data_dir)
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iarg=iarg+2
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endif
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call getarg(iarg,arg)
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if(arg(1:2).eq.'-f') then
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call getarg(iarg+1,arg)
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read(arg,*) fMHz
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iarg=iarg+2
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endif
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ncoh=1
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npdi=16
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if(arg(1:2).eq.'-c') then
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call getarg(iarg+1,arg)
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read(arg,*) ncoh
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iarg=iarg+2
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npdi=16/ncoh
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endif
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! write(*,*) 'ncoh: ',ncoh,' npdi: ',npdi
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open(13,file=trim(data_dir)//'/ALL_WSPR.TXT',status='unknown', &
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position='append')
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xs1=0.0
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xs2=0.0
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fr1=0.0
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fr2=0.0
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nav=0
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ngood=0
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do ifile=iarg,nargs
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call getarg(ifile,infile)
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open(10,file=infile,status='old',access='stream')
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j1=index(infile,'.c2')
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j2=index(infile,'.wav')
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if(j1.gt.0) then
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read(10,end=999) fname,ntrmin,fMHz,c2
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read(fname(8:11),*) nutc
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write(datetime,'(i11)') nutc
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else if(j2.gt.0) then
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read(10,end=999) ihdr,iwave
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read(infile(j2-4:j2-1),*) nutc
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datetime=infile(j2-11:j2-1)
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call wsprdpsk_downsample(iwave,c2)
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else
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print*,'Wrong file format?'
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go to 999
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endif
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close(10)
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fa=-10.0
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fb=10.0
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fs=12000.0/30.0
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npts=120*12000.0/30.0
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! call getcandidate2(c2,npts,fs,fa,fb,ncand,candidates) !First approx for freq
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ncand=1
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candidates(1,1)=0.0
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candidates(1,2)=-28
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ndecodes=0
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do icand=1,ncand
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fc0=candidates(icand,1)
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xsnr=candidates(icand,2)
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call dsdpsk(c2,fc0,cd)
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i0=40
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do i=0,231
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cs(i)=cd(i0+10*i)/5e4
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enddo
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! 2-bit differential detection
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do i=1,231
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! do i=1,232
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sbits(i)=-real(cs(i)*conjg(cs(i-1))) !2 symbol dpsk
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! sbits(i)=real(cs(i-1)) !for coherent dpsk
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! sbits(i)=real(cs(i)) !for coherent bpsk
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enddo
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! do i=1,231
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! sbits3(i)=-sbits(i+1)*sbits(i) ! for coherent dpsk
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! enddo
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! detect a differentially encoded block of symbols using the
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! Divsalar and Simon approach, except that we estimate only
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! the central symbol of the block and then step the block forward
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! by one symbol.
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!
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sbits3=sbits
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!goto 100
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nbit=13 ! number of decoded bits to be derived from nbit+1 symbols
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numseq=2**nbit
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il=(nbit+1)/2
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ih=231-nbit/2
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do isym=il,ih
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rmax=-1e32
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b=0
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do iseq=0,numseq-1
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do i=1,nbit
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b(i)=merge(1,0,iand(iseq,2**(nbit-i))>0)
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enddo
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b(1:nbit)=2*b(1:nbit)-1
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i1=isym-(nbit+1)/2
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csum=cs(i1)
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do i=1,nbit
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bb=1
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do m=1,i
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bb=bb*b(m)
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enddo
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csum=csum+bb*cs(i1+i)
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enddo
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! ps(iseq)=abs(csum)**2
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ps(iseq)=abs(csum)
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if(ps(iseq).gt.rmax) then
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bbest=b
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rmax=ps(iseq)
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endif
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enddo
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if(isym.eq.il) then
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do i=1,isym-1
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call getmetric(2**(nbit-i),ps,numseq,xmet)
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sbits3(i)=-xmet
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enddo
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endif
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call getmetric(2**((nbit-1)/2),ps,numseq,xmet)
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sbits3(isym)=-xmet
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if(isym.eq.ih) then
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do i=ih+1,231
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call getmetric(2**(231-i),ps,numseq,xmet)
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sbits3(i)=-xmet
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enddo
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endif
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enddo
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100 continue
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rxdata(1:100)=sbits3(1:100)
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rxdata(101:200)=sbits3(132:231);
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rxav=sum(rxdata(1:200))/200.0
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rx2av=sum(rxdata(1:200)*rxdata(1:200))/200.0
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rxsig=sqrt(rx2av-rxav*rxav)
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rxdata=rxdata/rxsig
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sigma=0.90
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llr(201:204)=-5.0
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llr(1:200)=2*rxdata/(sigma*sigma)
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apmask=0
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apmask(201:204)=1
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max_iterations=40
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ifer=0
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call bpdecode204(llr,apmask,max_iterations,decoded,cw,nharderror,niterations)
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nhardmin=-1
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if(nharderror.lt.0) call osd204(llr,apmask,5,decoded,cw,nhardmin,dmin)
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if(sum(decoded).eq.0) cycle
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if(nhardmin.ge.0 .or. nharderror.ge.0) then
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idat=0
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write(dmsg,'(68i1)') decoded
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read(dmsg(1:50),'(6b8.8,b2.2)') idat(1:7)
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idat(7)=idat(7)*64
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read(dmsg(51:64),'(b14.14)') ndec_crc
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ncalc_crc=iand(crc14(c_loc(idat),9),z'FFFF')
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nbadcrc=1
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if(ncalc_crc .eq. ndec_crc) nbadcrc=0
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else
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cycle
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endif
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if( nbadcrc.eq.0 ) then
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write(cbits,1200) decoded(1:50)
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1200 format(50i1)
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read(cbits,1202) idat
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1202 format(8b8,b4)
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idat(7)=ishft(idat(7),6)
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call wqdecode(idat,message,itype)
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idupe=0
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do i=1,ndecodes
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if(decodes(i).eq.message) idupe=1
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enddo
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if(idupe.eq.1) goto 888
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ndecodes=ndecodes+1
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decodes(ndecodes)=message
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nsnr=nint(xsnr)
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freq=fMHz + 1.d-6*(fc1+fbest)
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nfdot=0
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write(13,1210) datetime,0,nsnr,xdt,freq,message,nfdot
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1210 format(a11,2i4,f6.2,f12.7,2x,a22,i3)
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write(*,1212) datetime(8:11),nsnr,xdt,freq,nfdot,message,'*',idf,nseq,ijitter,nharderror,nhardmin
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1212 format(a4,i4,f5.1,f11.6,i3,2x,a22,a1,i5,i5,i5,i5,i5)
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goto 888
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endif
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888 continue
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enddo !candidate list
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enddo !files
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write(*,1120)
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1120 format("<DecodeFinished>")
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999 end program wsprdpskd
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subroutine getmetric(ib,ps,ns,xmet)
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real ps(0:ns-1)
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xm1=-1e32
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xm0=-1e32
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do i=0,ns-1
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if( iand(i/ib,1) .eq. 1 .and. ps(i) .gt. xm1 ) then
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xm1=ps(i)
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endif
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if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) then
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xm0=ps(i)
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endif
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enddo
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xmet=xm1-xm0
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return
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end subroutine getmetric
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subroutine getmetric3(ib,ps,ns,xmet)
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real ps(0:ns-1)
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xm1=0
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xm0=0
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do i=0,ns-1
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if( iand(i/ib,1) .eq. 1 ) then
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xm1=xm1+ps(i)
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endif
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if( iand(i/ib,1) .eq. 0 ) then
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xm0=xm0+ps(i)
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endif
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enddo
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xmet=xm1-xm0
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return
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end subroutine getmetric3
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subroutine dsdpsk(ci,f0,co)
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parameter(NI=240*200,NH=NI/2,NO=NI/20) ! downsample from 200 samples per symbol to 10
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complex ci(0:NI-1),ct(0:NI-1)
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complex co(0:NO-1)
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pi=4.0*atan(1.0)
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fs=12000.0/30.0
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df=fs/NI
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ct=ci
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call four2a(ct,NI,1,-1,1) !c2c FFT to freq domain
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i0=nint(f0/df)
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ct=cshift(ct,i0)
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co=0.0
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co(0)=ct(0)
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dt=20/fs
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beta=1.0
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tt=10*dt
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baud=1/tt
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bw=(1+beta)*baud/2.0
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bf=(1-beta)*baud/2.0
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iw=bw/df
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if=bf/df
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co=0.0
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co(0)=ct(0)
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do i=1,iw
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filt=((1.0+cos(pi*(i-if)/(iw-if)))/2.0)**0.5
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co(i)=ct(i)*filt
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co(NO-i)=ct(NI-i)*filt
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enddo
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co=co/NO
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call four2a(co,NO,1,1,1) !c2c FFT back to time domain
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return
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end subroutine dsdpsk
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subroutine getcandidate2(c,npts,fs,fa,fb,ncand,candidates)
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parameter(NDAT=200,NFFT1=120*12000/30,NH1=NFFT1/2,NFFT2=120*12000/300,NH2=NFFT2/2)
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complex c(0:npts-1) !Complex waveform
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complex cc(0:NFFT1-1)
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complex csfil(0:NFFT2-1)
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complex cwork(0:NFFT2-1)
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real bigspec(0:NFFT2-1)
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complex c2(0:NFFT1-1) !Short spectra
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real s(-NH1+1:NH1) !Coarse spectrum
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real ss(-NH1+1:NH1) !Smoothed coarse spectrum
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real candidates(100,2)
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integer indx(NFFT2-1)
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logical first
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data first/.true./
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save first,w,df,csfil
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if(first) then
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df=10*fs/NFFT1
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csfil=cmplx(0.0,0.0)
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do i=0,NFFT2-1
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csfil(i)=exp(-((i-NH2)/20.0)**2)
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enddo
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csfil=cshift(csfil,NH2)
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call four2a(csfil,NFFT2,1,-1,1)
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first=.false.
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endif
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cc=cmplx(0.0,0.0)
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cc(0:npts-1)=c;
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call four2a(cc,NFFT1,1,-1,1)
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cc=abs(cc)**2
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call four2a(cc,NFFT1,1,-1,1)
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cwork(0:NH2)=cc(0:NH2)*conjg(csfil(0:NH2))
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cwork(NH2+1:NFFT2-1)=cc(NFFT1-NH2+1:NFFT1-1)*conjg(csfil(NH2+1:NFFT2-1))
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call four2a(cwork,NFFT2,1,+1,1)
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bigspec=cshift(real(cwork),-NH2)
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il=NH2+fa/df
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ih=NH2+fb/df
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nnl=ih-il+1
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call indexx(bigspec(il:il+nnl-1),nnl,indx)
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xn=bigspec(il-1+indx(nint(0.3*nnl)))
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bigspec=bigspec/xn
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ncand=0
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do i=il,ih
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if((bigspec(i).gt.bigspec(i-1)).and. &
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(bigspec(i).gt.bigspec(i+1)).and. &
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(bigspec(i).gt.1.15).and.ncand.lt.100) then
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ncand=ncand+1
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candidates(ncand,1)=df*(i-NH2)
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candidates(ncand,2)=10*log10(bigspec(i))-30.0
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endif
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enddo
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! do i=1,ncand
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! write(*,*) i,candidates(i,1),candidates(i,2)
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! enddo
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return
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end subroutine getcandidate2
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subroutine wsprdpsk_downsample(iwave,c)
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! Input: i*2 data in iwave() at sample rate 12000 Hz
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! Output: Complex data in c(), sampled at 400 Hz
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include 'wsprdpsk_params.f90'
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parameter (NMAX=120*12000,NFFT2=NMAX/30)
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integer*2 iwave(NMAX)
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complex c(0:NMAX/30-1)
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complex c1(0:NFFT2-1)
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complex cx(0:NMAX/2)
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real x(NMAX)
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equivalence (x,cx)
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df=12000.0/NMAX
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x=iwave
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call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain
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i0=nint(1500.0/df)
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c1(0)=cx(i0)
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do i=1,NFFT2/2
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c1(i)=cx(i0+i)
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c1(NFFT2-i)=cx(i0-i)
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enddo
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c1=c1/NFFT2
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call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
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c=c1(0:NMAX/30-1)
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return
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end subroutine wsprdpsk_downsample
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