2019-01-21 20:31:54 -05:00
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program ft4d
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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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2019-01-22 12:01:28 -05:00
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complex cd(0:76*20-1) !Complex waveform
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2019-01-21 20:31:54 -05:00
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complex c3(0:19),c2(0:19),c1(0:19),c0(0:19)
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complex ccor(0:3,76)
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2019-01-22 12:01:28 -05:00
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complex csum,cterm,cc0,cc1,cc2,cc3,csync1,csync2
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2019-01-21 20:31:54 -05:00
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complex csync(12)
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real*8 fMHz
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real a(5)
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real rxdata(128),llr(128) !Soft symbols
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real llr2(128)
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real sbits(152),sbits1(152),sbits3(152)
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real ps(0:8191),psbest(0:8191)
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real candidates(100,2)
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real savg(NH1),sbase(NH1)
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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 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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logical unpk77_success
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data s12/0,0,0,1,1,1,1,1,1,0,0,0/
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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=1.000 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
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dphi=twopi/2*baud*h*dt*16 ! dt*16 is samp interval after downsample
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2019-01-22 12:01:28 -05:00
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dphi0=-3*dphi
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dphi1=-dphi
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dphi2=+dphi
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dphi3=+3*dphi
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2019-01-21 20:31:54 -05:00
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phi0=0.0
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phi1=0.0
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phi2=0.0
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phi3=0.0
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2019-01-22 12:01:28 -05:00
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do i=0,19
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2019-01-21 20:31:54 -05:00
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c3(i)=cmplx(cos(phi3),sin(phi3))
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c2(i)=cmplx(cos(phi2),sin(phi2))
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c1(i)=cmplx(cos(phi1),sin(phi1))
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c0(i)=cmplx(cos(phi0),sin(phi0))
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2019-01-22 12:01:28 -05:00
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phi3=mod(phi3+dphi3,twopi)
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phi2=mod(phi2+dphi2,twopi)
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2019-01-21 20:31:54 -05:00
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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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the=twopi*h/2.0
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2019-01-22 12:01:28 -05:00
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cc3=cmplx(cos(3*the),+sin(3*the))
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cc2=cmplx(cos(the),+sin(the))
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cc1=cmplx(cos(the),-sin(the))
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2019-01-21 20:31:54 -05:00
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cc0=cmplx(cos(3*the),-sin(3*the))
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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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candidates=0.0
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ncand=0
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call getcandidates2(iwave,375.0,3000.0,0.2,2200.0,100,savg,candidates,ncand,sbase)
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ndecodes=0
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do icand=1,ncand
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f0=candidates(icand,1)
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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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2019-01-22 12:01:28 -05:00
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call ft4_downsample(iwave,f0,cd2) ! downsample from 320s/Symbol to 20s/Symbol
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s2=sum(cd2*conjg(cd2))/(20.0*76)
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if(s2.gt.0.0) cd2=cd2/sqrt(s2)
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2019-01-21 20:31:54 -05:00
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! 750 samples/second here
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ibest=-1
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sybest=-99.
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dfbest=-1.
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2019-01-21 20:52:13 -05:00
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do if=-30,+30
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2019-01-21 20:31:54 -05:00
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df=if
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a=0.
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a(1)=-df
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call twkfreq1(cd2,NMAX/16,fs,a,cb)
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2019-01-22 12:01:28 -05:00
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do istart=0,380
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2019-01-21 20:31:54 -05:00
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csync1=0.
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cterm=1
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do ib=1,12
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2019-01-22 12:01:28 -05:00
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i1=(ib-1)*20+istart
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2019-01-21 20:31:54 -05:00
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if(s12(ib).eq.0) then
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csync1=csync1+sum(cb(i1:i1+19)*conjg(c0(0:19)))*cterm
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2019-01-22 12:01:28 -05:00
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cterm=cterm*conjg(cc0)
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2019-01-21 20:31:54 -05:00
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else
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csync1=csync1+sum(cb(i1:i1+19)*conjg(c3(0:19)))*cterm
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2019-01-22 12:01:28 -05:00
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cterm=cterm*conjg(cc3)
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2019-01-21 20:31:54 -05:00
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endif
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enddo
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if(abs(csync1).gt.sybest) then
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2019-01-22 12:01:28 -05:00
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ibest=istart
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2019-01-21 20:31:54 -05:00
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sybest=abs(csync1)
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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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a=0.
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!dfbest=1500.0-f0
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a(1)=-dfbest
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2019-01-22 12:01:28 -05:00
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call twkfreq1(cd2,NMAX/16,fs,a,cb)
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2019-01-21 20:31:54 -05:00
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2019-01-22 12:01:28 -05:00
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!ibest=208
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2019-01-21 20:31:54 -05:00
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ib=ibest
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2019-01-22 12:01:28 -05:00
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cd=cb(ib:ib+76*20-1)
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2019-01-21 20:31:54 -05:00
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do nseq=1,1
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if( nseq.eq.1 ) then ! noncoherent single-symbol detection
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sbits1=0.0
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2019-01-22 12:01:28 -05:00
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do isym=1,76
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ib=(isym-1)*20
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ccor(3,isym)=sum(cd(ib:ib+19)*conjg(c3(0:19)))
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ccor(2,isym)=sum(cd(ib:ib+19)*conjg(c2(0:19)))
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ccor(1,isym)=sum(cd(ib:ib+19)*conjg(c1(0:19)))
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ccor(0,isym)=sum(cd(ib:ib+19)*conjg(c0(0:19)))
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sbits1(2*isym-1)= max(abs(ccor(2,isym)),abs(ccor(3,isym)))- &
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max(abs(ccor(0,isym)),abs(ccor(1,isym)))
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sbits1(2*isym) = max(abs(ccor(1,isym)),abs(ccor(2,isym)))- &
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max(abs(ccor(0,isym)),abs(ccor(3,isym)))
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hbits1(2*isym-1:2*isym)=0
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if(sbits1(2*isym-1).gt.0) hbits1(2*isym-1)=1
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if(sbits1(2*isym ).gt.0) hbits1(2*isym )=1
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2019-01-21 20:31:54 -05:00
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enddo
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sbits=sbits1
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hbits=hbits1
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sbits3=sbits1
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hbits3=hbits1
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elseif( nseq.ge.2 ) then
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nbit=2*nseq-1
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numseq=2**(nbit)
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ps=0
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do ibit=nbit/2+1,144-nbit/2
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ps=0.0
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pmax=0.0
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do iseq=0,numseq-1
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csum=0.0
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cterm=1.0
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k=1
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do i=nbit-1,0,-1
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ibb=iand(iseq/(2**i),1)
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csum=csum+ccor(ibb,ibit-(nbit/2+1)+k)*cterm
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if(ibb.eq.0) cterm=cterm*cc0
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if(ibb.eq.1) cterm=cterm*cc1
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k=k+1
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enddo
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ps(iseq)=abs(csum)
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if( ps(iseq) .gt. pmax ) then
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pmax=ps(iseq)
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ibflag=1
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endif
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enddo
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if( ibflag .eq. 1 ) then
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psbest=ps
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ibflag=0
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endif
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call getbitmetric(2**(nbit/2),psbest,numseq,sbits3(ibit))
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hbits3(ibit)=0
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if(sbits3(ibit).gt.0) hbits3(ibit)=1
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enddo
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sbits=sbits3
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hbits=hbits3
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endif
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2019-01-22 12:01:28 -05:00
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nsync_qual=count(hbits(1:24).eq.(/0,0,0,0,0,0,1,0,1,0,1,0,1,0,1,0,1,0,0,0,0,0,0,0/))
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2019-01-21 20:31:54 -05:00
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! if(nsync_qual.lt.10) exit
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2019-01-22 12:01:28 -05:00
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rxdata=sbits(25:152)
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2019-01-21 20:31:54 -05:00
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rxav=sum(rxdata(1:128))/128.0
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rx2av=sum(rxdata(1:128)*rxdata(1:128))/128.0
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rxsig=sqrt(rx2av-rxav*rxav)
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rxdata=rxdata/rxsig
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sigma=0.80
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llr(1:128)=2*rxdata/(sigma*sigma)
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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) 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=f0+dfbest
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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,ibest/750.0,freq,message,'*',nseq,nharderror,nsync_qual
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1212 format(a4,i4,2x,f5.3,f11.1,2x,a22,a1,i5,i5,i5)
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goto 888
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endif
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enddo ! nseq
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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 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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subroutine downsample2(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 downsample2
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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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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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2019-01-22 12:01:28 -05:00
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BW=6.0*75
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2019-01-21 20:31:54 -05:00
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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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end subroutine ft4_downsample
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