subroutine symspec(id,kbuf,kk,kkdone,nutc,newdat) ! Compute spectra at four polarizations, using half-symbol steps. parameter (NSMAX=60*96000) integer*2 id(4,NSMAX,2) complex z real*8 ts,hsym include 'spcom.f90' include 'gcom2.f90' complex cx(NFFT),cy(NFFT) ! pad to 32k with zeros data kbuf0/-999/,n/0/ save kkk=kk if(kbuf.eq.2) kkk=kk-5760000 fac=0.0002 hsym=2048.d0*96000.d0/11025.d0 !Samples per half symbol npts=hsym !Integral samples per half symbol ntot=322 !Half symbols per transmission ! ntot=279 !Half symbols in 51.8 sec if(kbuf.ne.kbuf0 .or. ndiskdat.eq.1) then kkdone=0 kbuf0=kbuf ts=1.d0 - hsym n=0 do ip=1,4 do i=1,NFFT szavg(ip,i)=0. enddo enddo endif do nn=1,ntot i0=ts+hsym !Starting sample pointer if((i0+npts-1).gt.kkk) go to 998 !See if we have enough points i1=ts+2*hsym !Next starting sample pointer ts=ts+hsym !OK, update the exact sample pointer do i=1,npts !Copy data to FFT arrays xr=fac*id(1,i0+i,kbuf) xi=fac*id(2,i0+i,kbuf) cx(i)=cmplx(xr,xi) yr=fac*id(3,i0+i,kbuf) yi=fac*id(4,i0+i,kbuf) cy(i)=cmplx(yr,yi) enddo do i=npts+1,NFFT !Pad to 32k with zeros cx(i)=0. cy(i)=0. enddo call four2a(cx,NFFT,1,1,1) !Do the FFTs call four2a(cy,NFFT,1,1,1) n=n+1 do i=1,NFFT !Save and accumulate power spectra sx=real(cx(i))**2 + aimag(cx(i))**2 ssz(1,n,i)=sx ! Pol = 0 szavg(1,i)=szavg(1,i) + sx z=cx(i) + cy(i) s45=0.5*(real(z)**2 + aimag(z)**2) ssz(2,n,i)=s45 ! Pol = 45 szavg(2,i)=szavg(2,i) + s45 sy=real(cy(i))**2 + aimag(cy(i))**2 ssz(3,n,i)=sy ! Pol = 90 szavg(3,i)=szavg(3,i) + sy z=cx(i) - cy(i) s135=0.5*(real(z)**2 + aimag(z)**2) ssz(4,n,i)=s135 ! Pol = 135 szavg(4,i)=szavg(4,i) + s135 z=cx(i)*conjg(cy(i)) ! Leif's formula: ! ss5(n,i)=0.5*(sx+sy) + (real(z)**2 + aimag(z)**2 - ! + sx*sy)/(sx+sy) ! Leif's suggestion: ! ss5(n,i)=max(sx,s45,sy,s135) ! Linearly polarized component, from the Stokes parameters: q=sx - sy u=2.0*real(z) ! v=2.0*aimag(z) ssz5(n,i)=0.707*sqrt(q*q + u*u) enddo ! if(n.eq.ntot) then if(n.ge.279) then call move(ssz5,ss5,322*NFFT) write(utcdata,1002) nutc 1002 format(i4.4) utcdata=utcdata(1:2)//':'//utcdata(3:4) newspec=1 call move(ssz,ss,4*322*NFFT) call move(szavg,savg,4*NFFT) newdat=1 ndecoding=1 go to 999 endif kkdone=i1-1 nhsym=n call sleep_msec(0) enddo 998 kkdone=i1-1 999 continue return end subroutine symspec