subroutine qra_loops(c00,npts2,nsps,mode,mode64,nsubmode,nFadingModel,   &
     ndepth,nc1,nc2,ng2,naptype,jpk0,xdt,f0,width,snr2,irc,dat4)

  use packjt
  use timer_module, only: timer
  parameter (LN=1152*63)
  character*37 decoded
  complex c00(0:720000)            !Analytic representation of dd(), 6000 Hz
  complex c0(0:720000)             !Ditto, with freq shift
  real a(3)                        !twkfreq params f,f1,f2
  real s3(LN)                      !Symbol spectra
  real s3avg(LN)                   !Averaged symbol spectra
  integer dat4(12),dat4x(12)       !Decoded message (as 12 integers)
  integer nap(0:11)                !AP return codes
  data nap/0,2,3,2,3,4,2,3,6,4,6,6/,nsave/0/
  save nsave,s3avg

  irc=-99
  s3lim=20.
  ibwmax=11
  if(mode64.le.4) ibwmax=9
  ibwmin=ibwmax
  idtmax=3
  call qra_params(ndepth,maxaptype,idfmax,idtmax,ibwmin,ibwmax)
  LL=64*(mode64+2)
  NN=63
  napmin=99
  ncall=0
  maxdist=5
  if(ndepth.eq.2) maxdist=10
  if(ndepth.eq.3) maxdist=30

  do iavg=0,1
     if(iavg.eq.1) then
        idfmax=1
        idtmax=1
     endif
     do idf=1,idfmax
        ndf=idf/2
        if(mod(idf,2).eq.0) ndf=-ndf
        a=0.
        a(1)=-(f0+0.4*ndf)
        call twkfreq(c00,c0,npts2,6000.0,a)
        do idt=1,idtmax
           ndt=idt/2
           if(iavg.eq.0) then
              if(mod(idt,2).eq.0) ndt=-ndt
              jpk=jpk0 + 240*ndt                  !240/6000 = 0.04 s = tsym/32
              if(jpk.lt.0) jpk=0
              call timer('spec64  ',0)
              call spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
              call timer('spec64  ',1)
              call pctile(s3,LL*NN,40,base)
              s3=s3/base
              where(s3(1:LL*NN)>s3lim) s3(1:LL*NN)=s3lim
!              if(iavg.eq.0 .and. idf.eq.1 .and. idt.eq.1) s3a(1:LL*NN)=s3(1:LL*NN)
           else
              s3(1:LL*NN)=s3avg(1:LL*NN)
           endif
           do ibw=ibwmax,ibwmin,-2
              ndist=ndf**2 + ndt**2 + ((ibwmax-ibw)/2)**2
              if(ndist.gt.maxdist) cycle
              b90=1.728**ibw
              if(b90.gt.230.0) cycle
              if(b90.lt.0.15*width) exit
              ncall=ncall+1
              call timer('qra64_de',0)
              call qra64_dec(s3,nc1,nc2,ng2,naptype,0,nSubmode,b90,      &
                   nFadingModel,dat4,snr2,irc)
              call timer('qra64_de',1)
              if(irc.eq.0) go to 200
              if(irc.gt.0) call badmsg(irc,dat4,nc1,nc2,ng2)
              iirc=max(0,min(irc,11))
              if(irc.gt.0 .and. nap(iirc).lt.napmin) then
                 dat4x=dat4
                 b90x=b90
                 snr2x=snr2
                 napmin=nap(iirc)
                 irckeep=irc
                 xdtkeep=jpk/6000.0 - 1.0
                 f0keep=-a(1)
                 idfkeep=idf
                 idtkeep=idt
                 ibwkeep=ibw
                 ndistx=ndist
                 go to 100   !###
              endif
           enddo  ! ibw (b90 loop)
           !###        if(iand(ndepth,3).lt.3 .and. irc.ge.0) go to 100
        enddo  ! idt (DT loop)
     enddo  ! idf (f0 loop)
!     if(iavg.eq.0 .and. abs(jpk0-4320).le.1300) then
     if(iavg.eq.0) then
        a=0.
        a(1)=-f0
        call twkfreq(c00,c0,npts2,6000.0,a)
!        jpk=4320
        jpk=4080
        call spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
        call pctile(s3,LL*NN,40,base)
        s3=s3/base
        where(s3(1:LL*NN)>s3lim) s3(1:LL*NN)=s3lim
        s3avg(1:LL*NN)=s3avg(1:LL*NN)+s3(1:LL*NN)
        nsave=nsave+1
     endif
     if(iavg.eq.0 .and. nsave.lt.2) exit
  enddo  ! iavg 
  
100 if(napmin.ne.99) then
     dat4=dat4x
     b90=b90x
     snr2=snr2x
     irc=irckeep
     xdt=xdtkeep
     f0=f0keep
     idt=idtkeep
     idf=idfkeep
     ibw=ibwkeep
     ndist=ndistx
  endif

200 if(mode.eq.65 .and. nsps.eq.7680/2) xdt=xdt+0.4 !### Empirical -- WHY ??? ###

  if(irc.ge.0) then
     navg=nsave
     if(iavg.eq.0) navg=0
     !### For tests only:
     open(53,file='fort.53',status='unknown',position='append')
     call unpackmsg(dat4,decoded)               !Unpack the user message
     write(53,3053) idf,idt,ibw,b90,xdt,f0,snr2,ndist,irc,navg,decoded(1:22)
3053 format(3i5,f7.1,f7.2,2f7.1,3i4,2x,a22)
     close(53)
     !###  
     nsave=0
     s3avg=0.
     irc=irc + 100*navg
  endif
  return
end subroutine qra_loops