subroutine ft8b(dd0,nfqso,f1,xdt,nharderrors,dmin,nbadcrc,message,xsnr) use timer_module, only: timer include 'ft8_params.f90' parameter(NRECENT=10,NP2=2812) character*12 recent_calls(NRECENT) character message*22,msgsent*22 real a(5) real s1(0:7,ND),s2(0:7,NN) real ps(0:7) real rxdata(3*ND),llr(3*ND) !Soft symbols real dd0(15*12000) integer*1 decoded(KK),apmask(3*ND),cw(3*ND) integer itone(NN) integer icos7(0:6) complex cd0(NP2) complex csync(0:6,32) complex ctwk(32) complex csymb(32) logical first data icos7/2,5,6,0,4,1,3/ data first/.true./ save first,twopi,fs2,dt2,taus,baud,csync if( first ) then twopi=8.0*atan(1.0) fs2=12000.0/64.0 dt2=1/fs2 taus=32*dt2 baud=1/taus do i=0,6 phi=0.0 dphi=twopi*icos7(i)*baud*dt2 do j=1,32 csync(i,j)=cmplx(cos(phi),sin(phi)) phi=mod(phi+dphi,twopi) enddo enddo first=.false. endif max_iterations=40 norder=2 ! if(abs(nfqso-f1).lt.10.0) norder=3 tstep=0.5*NSPS/12000.0 df=12000.0/NFFT1 call ft8_downsample(dd0,f1,cd0) i0=xdt*fs2 smax=0.0 do idt=i0-16,i0+16 sync=0 do i=0,6 i1=idt+i*32 i2=i1+36*32 i3=i1+72*32 term1=0.0 ! this needs to be fixed... term2=0.0 term3=0.0 if( i1.ge.1 .and. i1+31.le.NP2 ) & term1=abs(sum(cd0(i1:i1+31)*conjg(csync(i,1:32)))) if( i2.ge.1 .and. i2+31.le.NP2 ) & term2=abs(sum(cd0(i2:i2+31)*conjg(csync(i,1:32)))) if( i3.ge.1 .and. i3+31.le.NP2 ) & term3=abs(sum(cd0(i3:i3+31)*conjg(csync(i,1:32)))) sync=sync+term1+term2+term3 enddo if( sync .gt. smax ) then smax=sync ibest=idt delfbest=delf ifbest=if endif enddo xdt2=ibest*dt2 ! peak up the frequency i0=xdt2*fs2 smax=0.0 do ifr=-5,5 delf=ifr*0.5 dphi=twopi*delf*dt2 phi=0.0 do i=1,32 ctwk(i)=cmplx(cos(phi),sin(phi)) phi=mod(phi+dphi,twopi) enddo sync=0.0 do i=0,6 i1=i0+i*32 i2=i1+36*32 i3=i1+72*32 term1=0.0 ! this needs to be fixed... term2=0.0 term3=0.0 if( i1.ge.1 .and. i1+31.le.NP2 ) & term1=abs(sum(cd0(i1:i1+31)*conjg(ctwk*csync(i,1:32)))) if( i2.ge.1 .and. i2+31.le.NP2 ) & term2=abs(sum(cd0(i2:i2+31)*conjg(ctwk*csync(i,1:32)))) if( i3.ge.1 .and. i3+31.le.NP2 ) & term3=abs(sum(cd0(i3:i3+31)*conjg(ctwk*csync(i,1:32)))) sync=sync+term1+term2+term3 enddo if( sync .gt. smax ) then smax=sync delfbest=delf endif enddo a=0.0 a(1)=-delfbest call twkfreq1(cd0,NP2,fs2,a,cd0) xdt=xdt2 f1=f1+delfbest j=0 do k=1,NN i1=ibest+(k-1)*32 csymb=cmplx(0.0,0.0) if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31) call four2a(csymb,32,1,-1,1) s2(0:7,k)=abs(csymb(1:8)) enddo j=0 do k=1,NN if(k.le.7) cycle if(k.ge.37 .and. k.le.43) cycle if(k.gt.72) cycle j=j+1 s1(0:7,j)=s2(0:7,k) enddo do j=1,ND ps=s1(0:7,j) where (ps.gt.0.0) ps=log(ps) r1=max(ps(1),ps(3),ps(5),ps(7))-max(ps(0),ps(2),ps(4),ps(6)) r2=max(ps(2),ps(3),ps(6),ps(7))-max(ps(0),ps(1),ps(4),ps(5)) r4=max(ps(4),ps(5),ps(6),ps(7))-max(ps(0),ps(1),ps(2),ps(3)) rxdata(3*j-2)=r4 rxdata(3*j-1)=r2 rxdata(3*j)=r1 enddo rxav=sum(rxdata)/(3.0*ND) rx2av=sum(rxdata*rxdata)/(3.0*ND) var=rx2av-rxav*rxav if( var .gt. 0.0 ) then rxsig=sqrt(var) else rxsig=sqrt(rx2av) endif rxdata=rxdata/rxsig ss=0.84 llr=2.0*rxdata/(ss*ss) apmask=0 cw=0 call timer('bpd174 ',0) call bpdecode174(llr,apmask,max_iterations,decoded,cw,nharderrors) call timer('bpd174 ',1) dmin=0.0 if(nharderrors.lt.0) then call timer('osd174 ',0) call osd174(llr,norder,decoded,cw,nharderrors,dmin) call timer('osd174 ',1) endif nbadcrc=1 message=' ' xsnr=-99.0 if(count(cw.eq.0).eq.174) go to 900 !Reject the all-zero codeword if( nharderrors.ge.0 .and. dmin.le.30.0 .and. nharderrors .lt. 30) then call chkcrc12a(decoded,nbadcrc) else nharderrors=-1 go to 900 endif if(nbadcrc.eq.0) then call extractmessage174(decoded,message,ncrcflag,recent_calls,nrecent) call genft8(message,msgsent,itone) xsig=0.0 xnoi=0.0 do i=1,79 xsig=xsig+s2(itone(i),i)**2 ios=mod(itone(i)+4,7) xnoi=xnoi+s2(ios,i)**2 enddo xsnr=xsig/xnoi-1.0 if( xsnr .lt. 0.0 ) xsnr=0.005 xsnr=10.0*log10(xsnr)-26.3 if( xsnr .lt. -24.0 ) xsnr=-24.0 endif 900 continue return end subroutine ft8b subroutine ft8_downsample(dd,f0,c1) ! Downconvert to complex data sampled at 187.5 Hz, 32 samples/symbol parameter (NMAX=15*12000,NFFT2=2812) complex c1(0:NFFT2-1) complex cx(0:NMAX/2-1) real dd(NMAX),x(NMAX) equivalence (x,cx) df=12000.0/NMAX x=dd call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain baud=12000.0/(32.0*64.0) i0=nint(f0/df) ft=f0+8.0*baud it=min(nint(ft/df),NMAX/2-1) fb=f0-1.0*baud ib=max(1,nint(fb/df)) k=0 c1=cmplx(0.0,0.0) do i=ib,it c1(k)=cx(i) k=k+1 enddo c1=cshift(c1,i0-ib) call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain c1=c1/(NMAX*NFFT2) return end subroutine ft8_downsample