WSJT-X/lib/qra66_decode.f90
2020-08-04 10:49:14 -04:00

174 lines
4.9 KiB
Fortran

module qra66_decode
type :: qra66_decoder
procedure(qra66_decode_callback), pointer :: callback
contains
procedure :: decode
end type qra66_decoder
abstract interface
subroutine qra66_decode_callback (this,nutc,sync,nsnr,dt,freq, &
decoded,nap,qual,ntrperiod,fmid,w50)
import qra66_decoder
implicit none
class(qra66_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 qra66_decode_callback
end interface
contains
subroutine decode(this,callback,iwave,nutc,nfa,nfb,nfqso,ndepth,lapdx, &
mycall,hiscall,hisgrid)
use timer_module, only: timer
use packjt
use, intrinsic :: iso_c_binding
parameter (NFFT1=15*12000,NFFT2=15*6000)
class(qra66_decoder), intent(inout) :: this
procedure(qra66_decode_callback) :: callback
character(len=12) :: mycall, hiscall
character(len=6) :: hisgrid
character*37 decoded
integer*2 iwave(NFFT1) !Raw data
integer ipk(1)
integer dat4(12)
logical lapdx,ltext
complex c00(0:NFFT1-1) !Spectrum, then analytic signal
complex c0(0:NFFT1-1) !Snalytic signal
real s(900)
real s3(-64:127,63)
real a(5)
data nc1z/-1/,nc2z/-1/,ng2z/-1/,maxaptypez/-1/
save nc1z,nc2z,ng2z,maxaptypez
this%callback => callback
nsps=1920
baud=12000.0/nsps
df1=12000.0/NFFT1
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)
nSubmode=0
b90=20.0 !8 to 25 is OK; not very critical
nFadingModel=1
! These probably need work:
maxaptype=0
if(ndepth.eq.2) maxaptype=3
if(ndepth.eq.3) maxaptype=5
! Prime the decoder for possible AP decoding
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
endif
naptype=maxaptype
! Compute the full-length spectrum
fac=2.0/NFFT1
c0=fac*iwave
call four2a(c0,NFFT1,1,-1,1) !Forward c2c FFT
nadd=101
nh=nadd/2
df2=nh*df1
iz=3000.0/df2
do i=1,iz !Compute smoothed spectrum
s(i)=0.
j0=nh*i
do j=j0-nh,j0+nh
s(i)=s(i) + real(c0(j))**2 + aimag(c0(j))**2
enddo
enddo
call smo121(s,iz)
ia=1450/df2
ib=1550/df2
s(:ia)=0.
s(ib:)=0.
ipk=maxloc(s)
f0=df2*ipk(1) - 0.5*baud !Candidate sync frequency
c0(NFFT2/2+1:NFFT2)=0. !Zero the top half
c0(0)=0.5*c0(0)
call four2a(c0,nfft2,1,1,1) !Inverse c2c FFT
ntol=100
call sync66a(iwave,15*12000,nsps,nfqso,ntol,xdt,f0,snr1)
jpk=(xdt+0.5)*6000 - 384 !### Empirical ###
if(jpk.lt.0) jpk=0
c00=c0
a=0.
a(1)=-(f0 + 2.0*baud) !For sync66a
call twkfreq(c00,c0,15*6000,6000.0,a)
xdt=jpk/6000.0 - 0.5
call spec66(c0(jpk:jpk+85*NSPS/2-1),s3)
do j=1,63
call pctile(s3(:,j),192,40,base)
s3(:,j)=s3(:,j)/base
enddo
! Apply AGC
s3max=20.0
do j=1,63
xx=maxval(s3(-64:127,j))
if(xx.gt.s3max) s3(-64:127,j)=s3(-64:127,j)*s3max/xx
enddo
call qra64_dec(s3,nc1,nc2,ng2,naptype,0,nSubmode,b90, &
nFadingModel,dat4,snr2,irc)
snr2=snr2 + 6.0
if(irc.gt.0) call badmsg(irc,dat4,nc1,nc2,ng2)
decoded=' '
if(irc.ge.0) then
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=nint(db(sync))
!### 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 qra66_decode