311 lines
9.7 KiB
Plaintext
311 lines
9.7 KiB
Plaintext
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subroutine ft8b(dd0,newdat,nfqso,ndepth,lapon,napwid,lsubtract,iaptype,icand, &
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sync0,f1,xdt,apsym,nharderrors,dmin,nbadcrc,iap,ipass,iera,message,xsnr)
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use timer_module, only: timer
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include 'ft8_params.f90'
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parameter(NRECENT=10,NP2=2812)
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character message*22,msgsent*22
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character*12 recent_calls(NRECENT)
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real a(5)
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real s1(0:7,ND),s2(0:7,NN)
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real ps(0:7)
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real rxdata(3*ND),rxdatap(3*ND)
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real llr(3*ND),llra(3*ND),llr0(3*ND),llrap(3*ND) !Soft symbols
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real dd0(15*12000)
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integer*1 decoded(KK),apmask(3*ND),cw(3*ND)
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integer*1 msgbits(KK)
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integer apsym(KK),rr73(11),cq(28)
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integer itone(NN)
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integer icos7(0:6),ip(1)
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complex cd0(3200)
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complex ctwk(32)
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complex csymb(32)
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logical newdat,lsubtract,lapon
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data icos7/2,5,6,0,4,1,3/
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data rr73/-1,1,1,1,1,1,1,-1,1,1,-1/
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data cq/1,1,1,1,1,-1,1,-1,-1,-1,-1,-1,1,-1,-1,-1,-1,-1,1,1,-1,-1,-1,1,1,-1,-1,1/
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max_iterations=30
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nharderrors=-1
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fs2=12000.0/NDOWN
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dt2=1.0/fs2
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twopi=8.0*atan(1.0)
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delfbest=0.
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ibest=0
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call timer('ft8_down',0)
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call ft8_downsample(dd0,newdat,f1,cd0) !Mix f1 to baseband and downsample
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call timer('ft8_down',1)
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i0=nint((xdt+0.5)*fs2) !Initial guess for start of signal
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smax=0.0
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do idt=i0-8,i0+8 !Search over +/- one quarter symbol
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call sync8d(cd0,idt,ctwk,0,sync)
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if(sync.gt.smax) then
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smax=sync
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ibest=idt
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endif
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enddo
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xdt2=ibest*dt2 !Improved estimate for DT
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! Now peak up in frequency
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i0=nint(xdt2*fs2)
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smax=0.0
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do ifr=-5,5 !Search over +/- 2.5 Hz
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delf=ifr*0.5
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dphi=twopi*delf*dt2
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phi=0.0
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do i=1,32
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ctwk(i)=cmplx(cos(phi),sin(phi))
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phi=mod(phi+dphi,twopi)
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enddo
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call sync8d(cd0,i0,ctwk,1,sync)
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if( sync .gt. smax ) then
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smax=sync
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delfbest=delf
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endif
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enddo
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a=0.0
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a(1)=-delfbest
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call twkfreq1(cd0,NP2,fs2,a,cd0)
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xdt=xdt2
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f1=f1+delfbest !Improved estimate of DF
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call sync8d(cd0,i0,ctwk,2,sync)
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j=0
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do k=1,NN
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i1=ibest+(k-1)*32
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csymb=cmplx(0.0,0.0)
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if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31)
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call four2a(csymb,32,1,-1,1)
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s2(0:7,k)=abs(csymb(1:8))
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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=1,7
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ip=maxloc(s2(:,k))
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if(icos7(k-1).eq.(ip(1)-1)) is1=is1+1
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ip=maxloc(s2(:,k+36))
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if(icos7(k-1).eq.(ip(1)-1)) is2=is2+1
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ip=maxloc(s2(:,k+72))
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if(icos7(k-1).eq.(ip(1)-1)) is3=is3+1
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enddo
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! hard sync sum - max is 21
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nsync=is1+is2+is3
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if(nsync .le. 6) then ! bail out
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nbadcrc=1
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return
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endif
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j=0
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do k=1,NN
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if(k.le.7) cycle
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if(k.ge.37 .and. k.le.43) cycle
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if(k.gt.72) cycle
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j=j+1
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s1(0:7,j)=s2(0:7,k)
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enddo
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do j=1,ND
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ps=s1(0:7,j)
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where (ps.gt.0.0) ps=log(ps)
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r1=max(ps(1),ps(3),ps(5),ps(7))-max(ps(0),ps(2),ps(4),ps(6))
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r2=max(ps(2),ps(3),ps(6),ps(7))-max(ps(0),ps(1),ps(4),ps(5))
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r4=max(ps(4),ps(5),ps(6),ps(7))-max(ps(0),ps(1),ps(2),ps(3))
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i4=3*j-2
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i2=3*j-1
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i1=3*j
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rxdata(i4)=r4
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rxdata(i2)=r2
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rxdata(i1)=r1
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rxdatap(i4)=r4
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rxdatap(i2)=r2
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rxdatap(i1)=r1
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! When bits 88:115 are set as ap bits, bit 115 lives in symbol 39 along
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! with no-ap bits 116 and 117. Take care of metrics for bits 116 and 117.
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! if(j.eq.39) then ! take care of bits that live in symbol 39
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! if(apsym(28).lt.0) then
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! rxdatap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
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! rxdatap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
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! else
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! rxdatap(i2)=max(ps(6),ps(7))-max(ps(4),ps(5))
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! rxdatap(i1)=max(ps(5),ps(7))-max(ps(4),ps(6))
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! endif
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! endif
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! When bits 116:143 are set as ap bits, bit 115 lives in symbol 39 along
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! with ap bits 116 and 117. Take care of metric for bit 115.
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if(j.eq.39) then ! take care of bit 115
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iii=2*(apsym(29)+1)/2 + (apsym(30)+1)/2 ! known values of bits 116 & 117
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if(iii.eq.0) rxdatap(i4)=ps(4)-ps(0)
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if(iii.eq.1) rxdatap(i4)=ps(5)-ps(1)
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if(iii.eq.2) rxdatap(i4)=ps(6)-ps(2)
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if(iii.eq.3) rxdatap(i4)=ps(7)-ps(3)
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endif
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! bit 144 lives in symbol 48 and will be 1 if it is set as an ap bit.
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! take care of metrics for bits 142 and 143
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if(j.eq.48) then ! bit 144 is always 1
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rxdatap(i4)=max(ps(5),ps(7))-max(ps(1),ps(3))
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rxdatap(i2)=max(ps(3),ps(7))-max(ps(1),ps(5))
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endif
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! bit 154 lives in symbol 52 and will be 0 if it is set as an ap bit
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! take care of metrics for bits 155 and 156
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if(j.eq.52) then ! bit 154 will be 0 if it is set as an ap bit.
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rxdatap(i2)=max(ps(2),ps(3))-max(ps(0),ps(1))
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rxdatap(i1)=max(ps(1),ps(3))-max(ps(0),ps(2))
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endif
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enddo
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rxav=sum(rxdata)/(3.0*ND)
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rx2av=sum(rxdata*rxdata)/(3.0*ND)
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var=rx2av-rxav*rxav
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if( var .gt. 0.0 ) then
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rxsig=sqrt(var)
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else
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rxsig=sqrt(rx2av)
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endif
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rxdata=rxdata/rxsig
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! Let's just assume that rxsig is OK for rxdatap too...
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rxdatap=rxdatap/rxsig
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ss=0.84
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llr0=2.0*rxdata/(ss*ss)
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llra=2.0*rxdatap/(ss*ss) ! llr's for use with ap
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apmag=4.0
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! If DxCall exists, only do "MyCall DxCall ???" for candidates within nfqso +/- napwid
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nap=0
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if(lapon.and.(iaptype.eq.1 .or. (iaptype.eq.2.and.abs(nfqso-f1).le.napwid))) nap=2
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if(lapon.and.iaptype.eq.2.and.abs(nfqso-f1).gt.napwid) nap=1
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do iap=0,nap
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nera=1
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if(iap.eq.0) nera=3
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do iera=1,nera
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llr=llr0
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nblank=0
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if(nera.eq.3 .and. iera.eq.1) nblank=0
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if(nera.eq.3 .and. iera.eq.2) nblank=24
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if(nera.eq.3 .and. iera.eq.3) nblank=48
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if(nblank.gt.0) llr(1:nblank)=0.
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if(iap.eq.0) then
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apmask=0
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! apmask(160:162)=1
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llrap=llr
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! llrap(160:162)=apmag*apsym(73:75)/ss
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endif
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if(iaptype.eq.1) then
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if(iap.eq.1) then ! look for plain CQ
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apmask=0
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apmask(88:115)=1 ! plain CQ
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apmask(144)=1 ! not free text
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! apmask(160:162)=1 ! 3 extra bits
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llrap=llr
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llrap(88:115)=apmag*cq/ss
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llrap(116:117)=llra(116:117)
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llrap(142:143)=llra(142:143)
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llrap(144)=-apmag/ss
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! llrap(160:162)=apmag*apsym(73:75)/ss
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endif
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if(iap.eq.2) then ! look for mycall
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apmask=0
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apmask(88:115)=1 ! mycall
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apmask(144)=1 ! not free text
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! apmask(160:162)=1 ! 3 extra bits
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llrap=llr
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llrap(88:115)=apmag*apsym(1:28)/ss
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llrap(116:117)=llra(116:117)
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llrap(142:143)=llra(142:143)
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llrap(144)=-apmag/ss
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! llrap(160:162)=apmag*apsym(73:75)/ss
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endif
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endif
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if(iaptype.eq.2) then
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if(iap.eq.1) then ! look for dxcall
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apmask=0
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! apmask(88:115)=1 ! mycall
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apmask(116:143)=1 ! hiscall
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apmask(144)=1 ! not free text
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! apmask(160:162)=1 ! 3 extra bits
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llrap=llr
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! llrap(88:143)=apmag*apsym(1:56)/ss
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llrap(115)=llra(115)
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llrap(116:143)=apmag*apsym(29:56)/ss
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llrap(144)=-apmag/ss
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! llrap(160:162)=apmag*apsym(73:75)/ss
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endif
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if(iap.eq.2) then ! look mycall, dxcall
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apmask=0
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apmask(88:115)=1 ! mycall
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apmask(116:143)=1 ! hiscall
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apmask(144)=1 ! not free text
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! apmask(144:154)=1 ! RRR or 73
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! apmask(160:162)=1 ! 3 extra bits
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llrap=llr
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llrap(88:143)=apmag*apsym(1:56)/ss
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llrap(144)=-apmag/ss
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! llrap(144:154)=apmag*rr73/ss
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! llrap(155:156)=llra(155:156)
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! llrap(160:162)=apmag*apsym(73:75)/ss
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endif
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endif
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cw=0
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call timer('bpd174 ',0)
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call bpdecode174(llrap,apmask,max_iterations,decoded,cw,nharderrors, &
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niterations)
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call timer('bpd174 ',1)
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dmin=0.0
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if(ndepth.eq.3 .and. nharderrors.lt.0) then
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norder=1
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if(abs(nfqso-f1).le.napwid) then
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if(iap.eq.0) then
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norder=2
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else
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norder=3
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endif
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endif
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call timer('osd174 ',0)
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call osd174(llrap,apmask,norder,decoded,cw,nharderrors,dmin)
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call timer('osd174 ',1)
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endif
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nbadcrc=1
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message=' '
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xsnr=-99.0
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if(count(cw.eq.0).eq.174) cycle !Reject the all-zero codeword
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if(any(decoded(75:75).ne.0)) cycle !Reject if any of the 3 extra bits are nonzero
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if(nharderrors.ge.0 .and. nharderrors+dmin.lt.60.0 .and. &
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.not.(sync.lt.2.0 .and. nharderrors.gt.35) .and. &
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.not.(iap.gt.0 .and. nharderrors.gt.39) .and. &
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.not.(iera.ge.2 .and. nharderrors.gt.30) &
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) then
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call chkcrc12a(decoded,nbadcrc)
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else
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nharderrors=-1
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cycle
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endif
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if(nbadcrc.eq.0) then
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call extractmessage174(decoded,message,ncrcflag,recent_calls,nrecent)
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call genft8(message,msgsent,msgbits,itone)
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if(lsubtract) call subtractft8(dd0,itone,f1,xdt2)
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xsig=0.0
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xnoi=0.0
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do i=1,79
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xsig=xsig+s2(itone(i),i)**2
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ios=mod(itone(i)+4,7)
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xnoi=xnoi+s2(ios,i)**2
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enddo
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xsnr=0.001
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if(xnoi.gt.0 .and. xnoi.lt.xsig) xsnr=xsig/xnoi-1.0
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xsnr=10.0*log10(xsnr)-27.0
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if(xsnr .lt. -24.0) xsnr=-24.0
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return
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endif
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enddo
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enddo
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return
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end subroutine ft8b
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