WSJT-X/lib/qra65_decode.f90

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module qra65_decode
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type :: qra65_decoder
procedure(qra65_decode_callback), pointer :: callback
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contains
procedure :: decode
end type qra65_decoder
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abstract interface
subroutine qra65_decode_callback (this,nutc,sync,nsnr,dt,freq, &
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decoded,nap,qual,ntrperiod,fmid,w50)
import qra65_decoder
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implicit none
class(qra65_decoder), intent(inout) :: this
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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
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end interface
contains
subroutine decode(this,callback,iwave,nutc,ntrperiod,nsubmode,nfqso, &
ntol,ndepth,mycall,hiscall,hisgrid)
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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
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character(len=12) :: mycall, hiscall
character(len=6) :: hisgrid
character*37 decoded
integer*2 iwave(NMAX) !Raw data
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integer dat4(12)
logical lapdx,ltext
complex, allocatable :: c0(:) !Analytic signal, 6000 S/s
real, allocatable, save :: s3(:,:) !Symbol spectra
real, allocatable, save :: s3a(:,:) !Symbol spectra for avg messages
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real a(5)
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 (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
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baud=12000.0/nsps
df1=12000.0/nfft1
! do i=1,12000*ntrperiod
! write(61,3061) i/12000.0,iwave(i)/32767.0
!3061 format(2f12.6)
! enddo
this%callback => callback
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if(nutc.eq.-999) print*,lapdx,nfa,nfb,nfqso !Silence warning
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! 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)
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b90=20.0 !8 to 25 is OK; not very critical
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nFadingModel=1
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! AP control could be done differently, but this works well:
maxaptype=0
if(ndepth.eq.2) maxaptype=3
if(ndepth.eq.3) maxaptype=5
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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
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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)
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! Downsample to give complex data at 6000 S/s
call timer('down_q65',0)
fac=2.0/nfft1
c0=fac*iwave(1:nfft1)
call four2a(c0,nfft1,1,-1,1) !Forward c2c FFT
c0(nfft2/2+1:nfft2)=0. !Zero the top half
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c0(0)=0.5*c0(0)
call four2a(c0,nfft2,1,1,1) !Inverse c2c FFT
a=0.
a(1)=-(f0 + mode65*baud) !Data tones start mode65 bins higher
call twkfreq(c0,c0,ntrperiod*6000,6000.0,a)
call timer('down_q65',1)
jpk=(xdt+0.5)*6000 - 384 !### Empirical ###
if(ntrperiod.ge.60) jpk=(xdt+1.0)*6000 - 384 !### TBD ??? ###
if(jpk.lt.0) jpk=0
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xdt=jpk/6000.0 - 0.5
LL=64*(mode65+2)
NN=63
call timer('spec_q65',0)
call spec_qra65(c0(jpk:),nsps/2,s3,LL,NN) !Compute synced symbol spectra
call timer('spec_q65',1)
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do j=1,63 !Normalize to symbol baseline
call pctile(s3(:,j),LL,40,base)
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s3(:,j)=s3(:,j)/base
enddo
LL2=64*(mode65+1)-1
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s3max=20.0
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do j=1,63 !Apply AGC to suppress pings
xx=maxval(s3(-64:LL2,j))
if(xx.gt.s3max) s3(-64:LL2,j)=s3(-64:LL2,j)*s3max/xx
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enddo
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! Call Nico's QRA64 decoder
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call timer('qra64_de',0)
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call qra64_dec(s3,nc1,nc2,ng2,naptype,0,nSubmode,b90, &
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nFadingModel,dat4,snr2,irc)
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call timer('qra64_de',1)
if(irc.lt.0) then
! No luck so far. Try for an average decode.
call timer('qra64_av',0)
s3a=s3a+s3
nsave=nsave+1
if(nsave.ge.2) then
call qra64_dec(s3a,nc1,nc2,ng2,naptype,0,nSubmode,b90, &
nFadingModel,dat4,snr2,irc)
if(irc.ge.0) irc=100*nsave + irc
endif
call timer('qra64_av',1)
endif
snr2=snr2 + db(6912.0/nsps)
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if(irc.gt.0) call badmsg(irc,dat4,nc1,nc2,ng2)
decoded=' '
if(irc.ge.0) then
nsave=0
s3a=0.
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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)
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else
snr2=0.
nsnr=-25
!### TEMPORARY? ###
call this%callback(nutc,sync,nsnr,xdt,f0,decoded, &
irc,qual,ntrperiod,fmid,w50)
!###
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endif
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! write(61,3061) nutc,irc,xdt,f0,snr1,snr2,trim(decoded)
!3061 format(i6.6,i4,4f10.2,2x,a)
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return
end subroutine decode
end module qra65_decode