WSJT-X/lib/qra65_decode.f90

module qra65_decode

   type :: qra65_decoder
      procedure(qra65_decode_callback), pointer :: callback
   contains
      procedure :: decode
   end type qra65_decoder

   abstract interface
      subroutine qra65_decode_callback (this,nutc,sync,nsnr,dt,freq,    &
         decoded,nap,qual,ntrperiod,fmid,w50)
         import qra65_decoder
         implicit none
         class(qra65_decoder), intent(inout) :: this
         integer, intent(in) :: nutc
         real, intent(in) :: sync
         integer, intent(in) :: nsnr
         real, intent(in) :: dt
         real, intent(in) :: freq
         character(len=37), intent(in) :: decoded
         integer, intent(in) :: nap
         real, intent(in) :: qual
         integer, intent(in) :: ntrperiod
         real, intent(in) :: fmid
         real, intent(in) :: w50
      end subroutine qra65_decode_callback
   end interface

contains

  subroutine decode(this,callback,iwave,nutc,ntrperiod,nsubmode,nfqso,   &
       ntol,ndepth,mycall,hiscall,hisgrid)

    use timer_module, only: timer
    use packjt
    use, intrinsic :: iso_c_binding
    parameter (NMAX=300*12000)             !### Needs to be 300*12000 ###
    class(qra65_decoder), intent(inout) :: this
    procedure(qra65_decode_callback) :: callback
    character(len=12) :: mycall, hiscall
    character(len=6) :: hisgrid
    character*37 decoded
    integer*2 iwave(NMAX)                 !Raw data
    real dd(NMAX)                         !Raw data
    integer dat4(12)
    logical lapdx,ltext
    complex, allocatable :: c00(:)        !Analytic signal, 6000 S/s
    complex, allocatable :: c0(:)         !Analytic signal, 6000 S/s
    real, allocatable, save :: s3(:,:)    !Symbol spectra
    real, allocatable, save :: s3a(:,:)   !Symbol spectra for avg messages
    data nc1z/-1/,nc2z/-1/,ng2z/-1/,maxaptypez/-1/,nsubmodez/-1/
    save nc1z,nc2z,ng2z,maxaptypez,nsave,nsubmodez

    mode65=2**nsubmode
    nfft1=ntrperiod*12000
    nfft2=ntrperiod*6000
    allocate (c00(0:nfft1-1))
    allocate (c0(0:nfft1-1))

    if(nsubmode.ne.nsubmodez) then
       if(allocated(s3)) deallocate(s3)
       if(allocated(s3a)) deallocate(s3a)
       allocate(s3(-64:64*mode65+63,63))
       allocate(s3a(-64:64*mode65+63,63))
    endif
    
    if(ntrperiod.eq.15) then
       nsps=1800
    else if(ntrperiod.eq.30) then
       nsps=3600
    else if(ntrperiod.eq.60) then
       nsps=7680
    else if(ntrperiod.eq.120) then
       nsps=16000
    else if(ntrperiod.eq.300) then
       nsps=41472
    else
      stop 'Invalid TR period'
   endif
   npts=ntrperiod*12000
   baud=12000.0/nsps
   df1=12000.0/nfft1
   this%callback => callback    
   if(nutc.eq.-999) print*,lapdx,nfa,nfb,nfqso  !Silence warning

! Prime the QRA decoder for possible use of AP
   call packcall(mycall(1:6),nc1,ltext)
   call packcall(hiscall(1:6),nc2,ltext)
   call packgrid(hisgrid(1:4),ng2,ltext)
   b90=20.0                 !8 to 25 is OK; not very critical
   nFadingModel=1

! AP control could be done differently, but this works well:
   maxaptype=0
   if(ndepth.eq.2) maxaptype=3
   if(ndepth.eq.3) maxaptype=5

   if(nc1.ne.nc1z .or. nc2.ne.nc2z .or. ng2.ne.ng2z .or.            &
        maxaptype.ne.maxaptypez) then
      do naptype=0,maxaptype
         if(naptype.eq.2 .and. maxaptype.eq.4) cycle
         call qra64_dec(s3,nc1,nc2,ng2,naptype,1,nSubmode,b90,      &
              nFadingModel,dat4,snr2,irc)
      enddo
      nc1z=nc1
      nc2z=nc2
      ng2z=ng2
      maxaptypez=maxaptype
      s3a=0.
      nsave=0
   endif
   naptype=maxaptype

   call timer('sync_q65',0)
   call sync_qra65(iwave,ntrperiod*12000,mode65,nsps,nfqso,ntol,xdt,f0,snr1)
   call timer('sync_q65',1)

   jpk0=(xdt+1.0)*6000   !###
   if(jpk0.lt.0) jpk0=0

   fac=1.0/32767.0
   dd=fac*iwave
!   npts=648000
   minsync=-2
   nmode=65

   call ana64(dd,npts,c00)

   call timer('qraloops',0)
   call qra_loops(c00,npts/2,nmode,mode65,nsubmode,nFadingModel,minsync,     &
        ndepth,nc1,nc2,ng2,naptype,jpk0,xdt,f0,width,snr2,s3,irc,dat4)
   if(nmode.eq.65) xdt=xdt+0.4        !### Empirical  WHY ??? ###
   call timer('qraloops',1)

    decoded='                                     '
    if(irc.ge.0) then
       nsave=0
       s3a=0.
       call unpackmsg(dat4,decoded)               !Unpack the user message
       call fmtmsg(decoded,iz)
       if(index(decoded,"000AAA ").ge.1) then
! Suppress a certain type of garbage decode.
          decoded='                      '
          irc=-1
       endif
       nsnr=nint(snr2)
       call this%callback(nutc,sync,nsnr,xdt,f0,decoded,              &
            irc,qual,ntrperiod,fmid,w50)
    else
       snr2=0.
       nsnr=-25 
!### TEMPORARY? ###       
       call this%callback(nutc,sync,nsnr,xdt,f0,decoded,              &
            irc,qual,ntrperiod,fmid,w50)
!###
    endif

!    write(61,3061) nutc,irc,xdt,f0,snr1,snr2,trim(decoded)
!3061 format(i6.6,i4,4f10.2,2x,a)

    return
  end subroutine decode

end module qra65_decode