2019-01-21 20:31:54 -05:00
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program ft4d
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2019-01-25 17:01:34 -05:00
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use crc
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use packjt77
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include 'ft4_params.f90'
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character arg*8,message*37,c77*77,infile*80,fname*16,datetime*11
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character*37 decodes(100)
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character*120 data_dir
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character*90 dmsg
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complex cd2(0:NMAX/16-1) !Complex waveform
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complex cb(0:NMAX/16-1)
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complex cd(0:76*20-1) !Complex waveform
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complex csum,cterm
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complex ctwk(80),ctwk2(80)
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complex csymb(20)
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complex cs(0:3,NN)
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real s4(0:3,NN)
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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real*8 fMHz
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real ps(0:8191),psbest(0:8191)
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real bmeta(152),bmetb(152),bmetc(152)
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real s(NH1,NHSYM)
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real a(5)
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real llr(128),llr2(128),llra(128),llrb(128),llrc(128)
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real s2(0:255)
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real candidate(3,100)
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real savg(NH1),sbase(NH1)
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integer ihdr(11)
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integer icos4(0:3)
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integer*2 iwave(NMAX) !Generated full-length waveform
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integer*1 message77(77),apmask(128),cw(128)
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integer*1 hbits(152),hbits1(152),hbits3(152)
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integer*1 s12(12)
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integer graymap(0:3)
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integer ip(1)
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logical unpk77_success
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logical one(0:511,0:7) ! 256 4-symbol sequences, 8 bits
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data s12/1,1,1,2,2,2,2,2,2,1,1,1/
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data icos4/0,1,3,2/
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data graymap/0,1,3,2/
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save one
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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fs=12000.0/NDOWN !Sample rate
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dt=1/fs !Sample interval after downsample (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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twopi=8.0*atan(1.0)
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h=1.0 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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one=.false.
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do i=0,255
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do j=0,7
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if(iand(i,2**j).ne.0) one(i,j)=.true.
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enddo
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enddo
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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nargs=iargc()
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if(nargs.lt.1) then
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print*,'Usage: ft4d [-a <data_dir>] [-f fMHz] 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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do ifile=iarg,nargs
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call getarg(ifile,infile)
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j2=index(infile,'.wav')
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open(10,file=infile,status='old',access='stream')
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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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close(10)
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candidate=0.0
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ncand=0
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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nfqso=1500
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nfa=500
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nfb=2700
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syncmin=1.0
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maxcand=100
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! call syncft4(iwave,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,ncand,sbase)
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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call getcandidates4(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidate,ncand,sbase)
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ndecodes=0
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do icand=1,ncand
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f0=candidate(1,icand)-1.5*37.5
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xsnr=1.0
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if( f0.le.375.0 .or. f0.ge.(5000.0-375.0) ) cycle
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call ft4_downsample(iwave,f0,cd2) ! downsample from 320 Sa/Symbol to 20 Sa/Symbol
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sum2=sum(cd2*conjg(cd2))/(20.0*76)
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if(sum2.gt.0.0) cd2=cd2/sqrt(sum2)
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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! 750 samples/second here
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ibest=-1
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smax=-99.
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dfbest=-1.
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do idf=-90,+90,5
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df=idf
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a=0.
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a(1)=df
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ctwk=1.
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call twkfreq1(ctwk,80,fs,a,ctwk2)
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do istart=0,315
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call sync4d(cd2,istart,ctwk2,1,sync)
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if(sync.gt.smax) then
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smax=sync
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ibest=istart
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dfbest=df
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endif
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enddo
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enddo
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f0=f0+dfbest
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!f0=1443.75
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call ft4_downsample(iwave,f0,cb) ! downsample from 320s/Symbol to 20s/Symbol
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sum2=sum(abs(cb)**2)/(20.0*76)
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if(sum2.gt.0.0) cb=cb/sqrt(sum2)
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2019-01-22 12:01:28 -05:00
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!ibest=208
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2019-01-25 17:01:34 -05:00
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cd=cb(ibest:ibest+76*20-1)
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do k=1,NN
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i1=(k-1)*20
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csymb=cd(i1:i1+19)
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call four2a(csymb,20,1,-1,1)
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cs(0:3,k)=csymb(1:4)/1e2
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s4(0:3,k)=abs(csymb(1:4))
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enddo
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! sync quality check
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is1=0
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is2=0
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is3=0
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do k=1,4
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ip=maxloc(s4(:,k))
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if(icos4(k-1).eq.(ip(1)-1)) is1=is1+1
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ip=maxloc(s4(:,k+36))
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if(icos4(k-1).eq.(ip(1)-1)) is2=is2+1
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ip=maxloc(s4(:,k+72))
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if(icos4(k-1).eq.(ip(1)-1)) is3=is3+1
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enddo
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! hard sync sum - max is 12
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nsync=is1+is2+is3
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do nseq=1,3
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if(nseq.eq.1) nsym=1
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if(nseq.eq.2) nsym=2
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if(nseq.eq.3) nsym=4
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nt=2**(2*nsym)
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do ks=1,76,nsym
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amax=-1.0
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do i=0,nt-1
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i1=i/64
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i2=iand(i,63)/16
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i3=iand(i,15)/4
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i4=iand(i,3)
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if(nsym.eq.1) then
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s2(i)=abs(cs(graymap(i4),ks))
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elseif(nsym.eq.2) then
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s2(i)=abs(cs(graymap(i3),ks)+cs(graymap(i4),ks+1))
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elseif(nsym.eq.4) then
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s2(i)=abs(cs(graymap(i1),ks ) + &
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cs(graymap(i2),ks+1) + &
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cs(graymap(i3),ks+2) + &
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cs(graymap(i4),ks+3) &
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)
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else
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print*,"Error - nsym must be 1, 2, or 4."
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endif
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enddo
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ipt=1+(ks-1)*2
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if(nsym.eq.1) ibmax=1
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if(nsym.eq.2) ibmax=3
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if(nsym.eq.4) ibmax=7
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do ib=0,ibmax
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bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - &
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maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib))
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if(ipt+ib .gt.152) cycle
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if(nsym.eq.1) then
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bmeta(ipt+ib)=bm
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elseif(nsym.eq.2) then
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bmetb(ipt+ib)=bm
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elseif(nsym.eq.4) then
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bmetc(ipt+ib)=bm
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endif
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enddo
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enddo
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enddo
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call normalizebmet(bmeta,152)
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call normalizebmet(bmetb,152)
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call normalizebmet(bmetc,152)
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hbits=0
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where(bmeta.ge.0) hbits=1
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ns1=count(hbits( 1: 8).eq.(/0,0,0,1,1,0,1,1/))
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ns2=count(hbits( 73: 80).eq.(/0,0,0,1,1,0,1,1/))
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ns3=count(hbits(145:152).eq.(/0,0,0,1,1,0,1,1/))
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nsync_qual=ns1+ns2+ns3
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sigma=0.7
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llra(1:64)=bmeta(9:72)
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llra(65:128)=bmeta(81:144)
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llra=2*llra/sigma**2
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llrb(1:64)=bmetb(9:72)
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llrb(65:128)=bmetb(81:144)
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llrb=2*llrb/sigma**2
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llrc(1:64)=bmetc(9:72)
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llrc(65:128)=bmetc(81:144)
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llrc=2*llrc/sigma**2
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2019-01-22 12:01:28 -05:00
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2019-01-25 17:01:34 -05:00
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do isd=1,3
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if(isd.eq.1) llr=llra
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if(isd.eq.2) llr=llrb
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if(isd.eq.3) llr=llrc
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apmask=0
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max_iterations=40
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do ibias=0,0
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llr2=llr
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if(ibias.eq.1) llr2=llr+0.4
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if(ibias.eq.2) llr2=llr-0.4
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call bpdecode128_90(llr2,apmask,max_iterations,message77,cw,nharderror,niterations)
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if(nharderror.ge.0) exit
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enddo
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if(sum(message77).eq.0) cycle
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if( nharderror.ge.0 ) then
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write(c77,'(77i1)') message77(1:77)
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call unpack77(c77,1,message,unpk77_success)
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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) cycle
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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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write(*,1212) datetime(8:11),nsnr,ibest/750.0,f0,message,'*',nharderror,nsync_qual,isd,niterations
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1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5,i5)
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endif
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enddo ! sequence estimation
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enddo !candidate list
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enddo !files
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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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write(*,1120)
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2019-01-21 20:31:54 -05:00
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1120 format("<DecodeFinished>")
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999 end program ft4d
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subroutine getbitmetric(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 .and. ps(i) .gt. xm1 ) xm1=ps(i)
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if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) xm0=ps(i)
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enddo
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xmet=xm1-xm0
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return
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end subroutine getbitmetric
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2019-01-25 17:01:34 -05:00
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subroutine downsample4(ci,f0,co)
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parameter(NI=144*160,NH=NI/2,NO=NI/16) ! 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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fs=12000.0
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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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b=8.0
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do i=1,NO/2
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arg=(i*df/b)**2
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filt=exp(-arg)
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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 downsample4
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2019-01-21 20:31:54 -05:00
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subroutine ft4_downsample(iwave,f0,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 1200 Hz
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2019-01-25 17:01:34 -05:00
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include 'ft4_params.f90'
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parameter (NFFT2=NMAX/16)
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integer*2 iwave(NMAX)
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complex c(0:NMAX/16-1)
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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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2019-01-21 20:31:54 -05:00
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2019-01-25 17:01:34 -05:00
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BW=6.0*75
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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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ibw=nint(BW/df)
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i0=nint(f0/df)
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c1=0.
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c1(0)=cx(i0)
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do i=1,NFFT2/2
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arg=(i-1)*df/bw
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win=exp(-arg*arg)
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c1(i)=cx(i0+i)*win
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c1(NFFT2-i)=cx(i0-i)*win
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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/16-1)
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return
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2019-01-21 20:31:54 -05:00
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end subroutine ft4_downsample
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