WSJT-X/lib/qra/q65/q65_loops.f90

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subroutine q65_loops(c00,npts2,nsps2,nsubmode,ndepth,jpk0, &
xdt0,f0,iaptype,xdt1,f1,snr2,dat4,idec)
use packjt77
use timer_module, only: timer
use q65
parameter (NN=63)
parameter (LN=2176*63) !LN=LL*NN; LL=64*(mode_q65+2), NN=63
complex c00(0:npts2-1) !Analytic representation of dd(), 6000 Hz
complex ,allocatable :: c0(:) !Ditto, with freq shift
character decoded*37
real a(3) !twkfreq params f,f1,f2
real,allocatable :: s3(:) !Symbol spectra
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integer dat4(13) !Decoded message (as 13 six-bit integers)
integer nap(0:11) !AP return codes
data nap/0,2,3,2,3,4,2,3,6,4,6,6/
LL=64*(mode_q65+2)
allocate(s3(LL*NN))
allocate(c0(0:npts2-1))
idec=-1
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ircbest=9999
irc=-99
s3lim=20.
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baud=6000.0/nsps2
idfmax=3
idtmax=3
ibw0=(ibwa+ibwb)/2
maxdist=5
if(iand(ndepth,3).ge.2) then
idfmax=5
idtmax=5
maxdist=10
endif
if(iand(ndepth,3).eq.3) maxdist=15
napmin=99
xdt1=xdt0
f1=f0
idfbest=0
idtbest=0
ndistbest=0
do idf=1,idfmax
ndf=idf/2
if(mod(idf,2).eq.0) ndf=-ndf
a=0.
a(1)=-(f0+0.5*baud*ndf)
call twkfreq(c00,c0,npts2,6000.0,a)
do idt=1,idtmax
ndt=idt/2
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if(mod(idt,2).eq.0) ndt=-ndt
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jpk=jpk0 + nsps2*ndt/16 !tsym/16
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if(jpk.lt.0) jpk=0
call timer('spec64 ',0)
call spec64(c0,nsps2,mode_q65,jpk,s3,LL,NN)
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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
call q65_bzap(s3,LL) !Zap birdies
do ibw=ibwa,ibwb
ndist=ndf**2 + ndt**2 + (ibw-ibw0)**2
if(ndist.gt.maxdist) cycle
b90=1.72**ibw
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if(b90.gt.345.0) cycle
b90ts = b90/baud
call timer('dec2 ',0)
call q65_dec2(s3,nsubmode,b90ts,esnodb,irc,dat4,decoded)
call timer('dec2 ',1)
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! irc > 0 ==> number of iterations required to decode
! -1 = invalid params
! -2 = decode failed
! -3 = CRC mismatch
if(irc.ge.0) then
idfbest=idf
idtbest=idt
ndistbest=ndist
nrc=irc
go to 100
endif
enddo ! ibw (b90 loop)
enddo ! idt (DT loop)
enddo ! idf (f0 loop)
100 if(irc.ge.0) then
idec=iaptype
snr2=esnodb - db(2500.0/baud)
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xdt1=xdt0 + nsps2*ndt/(16.0*6000.0)
f1=f0 + 0.5*baud*ndf
endif
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return
end subroutine q65_loops