WSJT-X/lib/q65_decode.f90

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Fortran
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module q65_decode
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type :: q65_decoder
procedure(q65_decode_callback), pointer :: callback
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contains
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procedure :: decode
end type q65_decoder
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abstract interface
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subroutine q65_decode_callback (this,nutc,snr1,nsnr,dt,freq, &
decoded,idec,nused,ntrperiod)
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import q65_decoder
implicit none
class(q65_decoder), intent(inout) :: this
integer, intent(in) :: nutc
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real, intent(in) :: snr1
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integer, intent(in) :: nsnr
real, intent(in) :: dt
real, intent(in) :: freq
character(len=37), intent(in) :: decoded
integer, intent(in) :: idec
integer, intent(in) :: nused
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integer, intent(in) :: ntrperiod
end subroutine q65_decode_callback
end interface
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contains
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subroutine decode(this,callback,iwave,nutc,ntrperiod,nsubmode,nfqso, &
ntol,ndepth,nfa0,nfb0,lclearave,emedelay,mycall,hiscall,hisgrid, &
nQSOprogress,ncontest,lapcqonly,navg0)
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! Top-level routine that organizes the decoding of Q65 signals
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! Input: iwave Raw data, i*2
! nutc UTC for time-tagging the decode
! ntrperiod T/R sequence length (s)
! nsubmode Tone-spacing indicator, 0-4 for A-E
! nfqso Target signal frequency (Hz)
! ntol Search range around nfqso (Hz)
! ndepth Optional decoding level
! lclearave Flag to clear the message-averaging arrays
! emedelay Sync search extended to cover EME delays
! nQSOprogress Auto-sequencing state for the present QSO
! ncontest Supported contest type
! lapcqonly Flag to use AP only for CQ calls
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! Output: sent to the callback routine for display to user
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use timer_module, only: timer
use packjt77
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use, intrinsic :: iso_c_binding
use q65 !Shared variables
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parameter (NMAX=300*12000) !Max TRperiod is 300 s
class(q65_decoder), intent(inout) :: this
procedure(q65_decode_callback) :: callback
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character(len=12) :: mycall, hiscall !Used for AP decoding
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character(len=6) :: hisgrid
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character*37 decoded !Decoded message
character*77 c77
character*78 c78
character*6 cutc
integer*2 iwave(NMAX) !Raw data
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real, allocatable :: dd(:) !Raw data
integer dat4(13) !Decoded message as 12 6-bit integers
integer dgen(13)
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logical lclearave,lapcqonly,unpk77_success
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complex, allocatable :: c00(:) !Analytic signal, 6000 Sa/s
complex, allocatable :: c0(:) !Analytic signal, 6000 Sa/s
! Start by setting some parameters and allocating storage for large arrays
nfa=nfa0
nfb=nfb0
idec=-1
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mode_q65=2**nsubmode
npts=ntrperiod*12000
nfft1=ntrperiod*12000
nfft2=ntrperiod*6000
! Determine the T/R sequence: iseq=0 (even), or iseq=1 (odd)
n=nutc
if(ntrperiod.ge.60) n=100*n
write(cutc,'(i6.6)') n
read(cutc,'(3i2)') ih,im,is
nsec=3600*ih + 60*im + is
iseq=mod(nsec/ntrperiod,2)
if(lclearave) call q65_clravg
allocate(dd(npts))
allocate (c00(0:nfft1-1))
allocate (c0(0:nfft1-1))
if(ntrperiod.eq.15) then
nsps=1800
else if(ntrperiod.eq.30) then
nsps=3600
else if(ntrperiod.eq.60) then
nsps=7200
else if(ntrperiod.eq.120) then
nsps=16000
else if(ntrperiod.eq.300) then
nsps=41472
else
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stop 'Invalid TR period'
endif
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baud=12000.0/nsps
this%callback => callback
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nFadingModel=1
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ibwa=max(1,int(1.8*log(baud*mode_q65)) + 2)
ibwb=min(10,ibwa+4)
if(iand(ndepth,3).eq.3) then
ibwa=max(1,ibwa-1)
ibwb=min(10,ibwb+1)
endif
! Generate codewords for full-AP list decoding
call q65_set_list(mycall,hiscall,hisgrid,codewords,ncw)
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dgen=0
call q65_enc(dgen,codewords) !Initialize the Q65 codec
nused=1
iavg=0
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call timer('q65_dec0',0)
! Call top-level routine in q65 module: establish sync and try for a q3 decode.
call q65_dec0(iavg,nutc,iwave,ntrperiod,nfqso,ntol,ndepth,lclearave, &
emedelay,xdt,f0,snr1,width,dat4,snr2,idec)
! idec=-1 !### TEMPORARY ###
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call timer('q65_dec0',1)
if(idec.ge.0) then
dtdec=xdt !We have a list-decode result
f0dec=f0
go to 100
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endif
if(snr1.lt.2.8) then
dtdec=0. !No reliable sync, abandon decoding attempt
f0dec=0.
go to 100
endif
! Prepare for a single-period decode woth iaptype = 0, 1, or 2 (also 4?)
jpk0=(xdt+1.0)*6000 !Index of nominal start of signal
if(ntrperiod.le.30) jpk0=(xdt+0.5)*6000 !For shortest sequences
if(jpk0.lt.0) jpk0=0
fac=1.0/32767.0
dd=fac*iwave(1:npts)
call ana64(dd,npts,c00) !Convert to complex c00() at 6000 Sa/s
call ft8apset(mycall,hiscall,ncontest,apsym0,aph10) ! Generate ap symbols
where(apsym0.eq.-1) apsym0=0
npasses=2
if(nQSOprogress.eq.5) npasses=3
if(lapcqonly) npasses=1
iaptype=0
do ipass=0,npasses !Loop over AP passes
apmask=0 !Try first with no AP information
apsymbols=0
if(ipass.ge.1) then
! Subsequent passes use AP information appropiate for nQSOprogress
call q65_ap(nQSOprogress,ipass,ncontest,lapcqonly,iaptype, &
apsym0,apmask1,apsymbols1)
write(c78,1050) apmask1
1050 format(78i1)
read(c78,1060) apmask
1060 format(13b6.6)
write(c78,1050) apsymbols1
read(c78,1060) apsymbols
endif
call timer('q65loops',0)
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call q65_loops(c00,npts/2,nsps/2,nsubmode,ndepth,jpk0, &
xdt,f0,iaptype,xdt1,f1,snr2,dat4,idec)
! idec=-1 !### TEMPORARY ###
call timer('q65loops',1)
if(idec.ge.0) then
dtdec=xdt1
f0dec=f1
go to 100 !Successful decode, we're done
endif
enddo ! ipass
if(iand(ndepth,16).eq.0 .or. navg(iseq).lt.2) go to 100
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! There was no single-transmission decode. Try for an average 'q3n' decode.
call timer('list_avg',0)
! Call top-level routine in q65 module: establish sync and try for a q3
! decode, this time using the cumulative 's1a' symbol spectra.
iavg=1
call q65_dec0(iavg,nutc,iwave,ntrperiod,nfqso,ntol,ndepth,lclearave, &
emedelay,xdt,f0,snr1,width,dat4,snr2,idec)
call timer('list_avg',1)
if(idec.ge.0) then
dtdec=xdt !We have a list-decode result from averaged data
f0dec=f0
nused=navg(iseq)
go to 100
endif
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! There was no 'q3n' decode. Try for a 'q[012]n' decode.
! Call top-level routine in q65 module: establish sync and try for a q[012]n
! decode, this time using the cumulative 's1a' symbol spectra.
call timer('q65_avg ',0)
iavg=2
call q65_dec0(iavg,nutc,iwave,ntrperiod,nfqso,ntol,ndepth,lclearave, &
emedelay,xdt,f0,snr1,width,dat4,snr2,idec)
call timer('q65_avg ',1)
if(idec.ge.0) then
dtdec=xdt !We have a q[012]n result
f0dec=f0
nused=navg(iseq)
endif
100 decoded=' '
if(idec.ge.0) then
! idec Meaning
! ------------------------------------------------------
! -1: No decode
! 0: Decode without AP information
! 1: Decode with AP for "CQ ? ?"
! 2: Decode with AP for "MyCall ? ?"
! 3: Decode with AP for "MyCall DxCall ?"
! Unpack decoded message for display to user
write(c77,1000) dat4(1:12),dat4(13)/2
1000 format(12b6.6,b5.5)
call unpack77(c77,0,decoded,unpk77_success) !Unpack to get msgsent
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nsnr=nint(snr2)
call this%callback(nutc,snr1,nsnr,dtdec,f0dec,decoded, &
idec,nused,ntrperiod)
if(iand(ndepth,128).ne.0) call q65_clravg !AutoClrAvg after decode
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else
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! Report snr1, even if no decode.
nsnr=db(snr1) - 35.0
if(nsnr.lt.-35) nsnr=-35
idec=-1
call this%callback(nutc,snr1,nsnr,xdt,f0,decoded, &
idec,0,ntrperiod)
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endif
navg0=1000*navg(0) + navg(1)
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return
end subroutine decode
end module q65_decode