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https://github.com/saitohirga/WSJT-X.git
synced 2024-11-18 18:12:12 -05:00
854 lines
28 KiB
Fortran
854 lines
28 KiB
Fortran
module fst4_decode
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type :: fst4_decoder
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procedure(fst4_decode_callback), pointer :: callback
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contains
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procedure :: decode
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end type fst4_decoder
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abstract interface
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subroutine fst4_decode_callback (this,nutc,sync,nsnr,dt,freq, &
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decoded,nap,qual,ntrperiod,lwspr,fmid,w50)
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import fst4_decoder
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implicit none
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class(fst4_decoder), intent(inout) :: this
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integer, intent(in) :: nutc
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real, intent(in) :: sync
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integer, intent(in) :: nsnr
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real, intent(in) :: dt
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real, intent(in) :: freq
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character(len=37), intent(in) :: decoded
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integer, intent(in) :: nap
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real, intent(in) :: qual
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integer, intent(in) :: ntrperiod
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logical, intent(in) :: lwspr
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real, intent(in) :: fmid
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real, intent(in) :: w50
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end subroutine fst4_decode_callback
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end interface
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contains
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subroutine decode(this,callback,iwave,nutc,nQSOProgress,nfa,nfb,nfqso, &
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ndepth,ntrperiod,nexp_decode,ntol,emedelay,lapcqonly,mycall, &
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hiscall,iwspr)
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use timer_module, only: timer
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use packjt77
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use, intrinsic :: iso_c_binding
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include 'fst4/fst4_params.f90'
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parameter (MAXCAND=100)
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class(fst4_decoder), intent(inout) :: this
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procedure(fst4_decode_callback) :: callback
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character*37 decodes(100)
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character*37 msg,msgsent
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character*77 c77
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character*12 mycall,hiscall
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character*12 mycall0,hiscall0
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complex, allocatable :: c2(:)
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complex, allocatable :: cframe(:)
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complex, allocatable :: c_bigfft(:) !Complex waveform
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real llr(240),llrs(240,4)
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real candidates(200,5)
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real bitmetrics(320,4)
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real s4(0:3,NN)
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real minsync
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logical lapcqonly
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integer itone(NN)
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integer hmod
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integer*1 apmask(240),cw(240)
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integer*1 message101(101),message74(74),message77(77)
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integer*1 rvec(77)
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integer apbits(240)
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integer nappasses(0:5) ! # of decoding passes for QSO states 0-5
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integer naptypes(0:5,4) ! (nQSOProgress,decoding pass)
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integer mcq(29),mrrr(19),m73(19),mrr73(19)
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logical badsync,unpk77_success,single_decode
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logical first,nohiscall,lwspr,ex
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integer*2 iwave(30*60*12000)
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data mcq/0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0/
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data mrrr/0,1,1,1,1,1,1,0,1,0,0,1,0,0,1,0,0,0,1/
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data m73/0,1,1,1,1,1,1,0,1,0,0,1,0,1,0,0,0,0,1/
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data mrr73/0,1,1,1,1,1,1,0,0,1,1,1,0,1,0,1,0,0,1/
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data rvec/0,1,0,0,1,0,1,0,0,1,0,1,1,1,1,0,1,0,0,0,1,0,0,1,1,0,1,1,0, &
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1,0,0,1,0,1,1,0,0,0,0,1,0,0,0,1,0,1,0,0,1,1,1,1,0,0,1,0,1, &
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0,1,0,1,0,1,1,0,1,1,1,1,1,0,0,0,1,0,1/
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data first/.true./,hmod/1/
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save first,apbits,nappasses,naptypes,mycall0,hiscall0
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this%callback => callback
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dxcall13=hiscall ! initialize for use in packjt77
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mycall13=mycall
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if(iwspr.ne.0.and.iwspr.ne.1) return
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if(first) then
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mcq=2*mod(mcq+rvec(1:29),2)-1
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mrrr=2*mod(mrrr+rvec(59:77),2)-1
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m73=2*mod(m73+rvec(59:77),2)-1
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mrr73=2*mod(mrr73+rvec(59:77),2)-1
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nappasses(0)=2
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nappasses(1)=2
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nappasses(2)=2
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nappasses(3)=2
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nappasses(4)=2
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nappasses(5)=3
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! iaptype
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!------------------------
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! 1 CQ ??? ??? (29 ap bits)
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! 2 MyCall ??? ??? (29 ap bits)
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! 3 MyCall DxCall ??? (58 ap bits)
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! 4 MyCall DxCall RRR (77 ap bits)
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! 5 MyCall DxCall 73 (77 ap bits)
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! 6 MyCall DxCall RR73 (77 ap bits)
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!********
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naptypes(0,1:4)=(/1,2,0,0/) ! Tx6 selected (CQ)
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naptypes(1,1:4)=(/2,3,0,0/) ! Tx1
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naptypes(2,1:4)=(/2,3,0,0/) ! Tx2
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naptypes(3,1:4)=(/3,6,0,0/) ! Tx3
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naptypes(4,1:4)=(/3,6,0,0/) ! Tx4
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naptypes(5,1:4)=(/3,1,2,0/) ! Tx5
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mycall0=''
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hiscall0=''
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first=.false.
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endif
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l1=index(mycall,char(0))
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if(l1.ne.0) mycall(l1:)=" "
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l1=index(hiscall,char(0))
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if(l1.ne.0) hiscall(l1:)=" "
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if(mycall.ne.mycall0 .or. hiscall.ne.hiscall0) then
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apbits=0
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apbits(1)=99
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apbits(30)=99
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if(len(trim(mycall)) .lt. 3) go to 10
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nohiscall=.false.
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hiscall0=hiscall
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if(len(trim(hiscall0)).lt.3) then
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hiscall0=mycall ! use mycall for dummy hiscall - mycall won't be hashed.
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nohiscall=.true.
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endif
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msg=trim(mycall)//' '//trim(hiscall0)//' RR73'
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i3=-1
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n3=-1
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call pack77(msg,i3,n3,c77)
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call unpack77(c77,1,msgsent,unpk77_success)
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if(i3.ne.1 .or. (msg.ne.msgsent) .or. .not.unpk77_success) go to 10
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read(c77,'(77i1)') message77
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message77=mod(message77+rvec,2)
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apbits(1:77)=2*message77-1
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if(nohiscall) apbits(30)=99
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10 continue
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mycall0=mycall
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hiscall0=hiscall
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endif
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!************************************
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if(nfqso+nqsoprogress.eq.-999) return
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Keff=91
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nmax=15*12000
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if(ntrperiod.eq.15) then
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nsps=720
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nmax=15*12000
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ndown=18 !nss=40,80,160,400
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nfft1=int(nmax/ndown)*ndown
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else if(ntrperiod.eq.30) then
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nsps=1680
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nmax=30*12000
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ndown=42 !nss=40,80,168,336
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nfft1=359856 !nfft2=8568=2^3*3^2*7*17
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else if(ntrperiod.eq.60) then
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nsps=3888
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nmax=60*12000
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ndown=108
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nfft1=7500*96 ! nfft2=7500=2^2*3*5^4
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else if(ntrperiod.eq.120) then
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nsps=8200
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nmax=120*12000
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ndown=205 !nss=40,82,164,328
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nfft1=7200*200 ! nfft2=7200=2^5*3^2*5^2
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else if(ntrperiod.eq.300) then
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nsps=21504
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nmax=300*12000
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ndown=512 !nss=42,84,168,336
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nfft1=7020*512 ! nfft2=7020=2^2*3^3*5*13
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else if(ntrperiod.eq.900) then
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nsps=66560
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nmax=900*12000
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ndown=1664 !nss=40,80,160,320
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nfft1=6480*1664 ! nfft2=6480=2^4*3^4*5
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else if(ntrperiod.eq.1800) then
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nsps=134400
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nmax=1800*12000
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ndown=3360 !nss=40,80,160,320
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nfft1=6426*3360 ! nfft2=6426=2*3^3*7*17
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end if
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nss=nsps/ndown
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fs=12000.0 !Sample rate
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fs2=fs/ndown
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nspsec=nint(fs2)
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dt=1.0/fs !Sample interval (s)
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dt2=1.0/fs2
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tt=nsps*dt !Duration of "itone" symbols (s)
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baud=1.0/tt
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sigbw=4.0*baud
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nfft2=nfft1/ndown !make sure that nfft1 is exactly nfft2*ndown
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nfft1=nfft2*ndown
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nh1=nfft1/2
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allocate( c_bigfft(0:nfft1/2) )
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allocate( c2(0:nfft2-1) )
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allocate( cframe(0:160*nss-1) )
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jittermax=2
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if(ndepth.eq.3) then
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nblock=4
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jittermax=2
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elseif(ndepth.eq.2) then
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nblock=3
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jittermax=0
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elseif(ndepth.eq.1) then
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nblock=1
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jittermax=0
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endif
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ndropmax=1
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npct=nexp_decode/256
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call blanker(iwave,nfft1,ndropmax,npct,c_bigfft)
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! The big fft is done once and is used for calculating the smoothed spectrum
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! and also for downconverting/downsampling each candidate.
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call four2a(c_bigfft,nfft1,1,-1,0) !r2c
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nhicoh=1
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nsyncoh=8
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fa=nfa
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fb=nfb
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single_decode=iand(nexp_decode,32).ne.0
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if(single_decode) then
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fa=max(100,nint(nfqso+1.5*baud-ntol))
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fb=min(4800,nint(nfqso+1.5*baud+ntol))
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endif
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minsync=1.20
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if(ntrperiod.eq.15) minsync=1.15
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! Get first approximation of candidate frequencies
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call get_candidates_fst4(c_bigfft,nfft1,nsps,hmod,fs,fa,fb,nfa,nfb, &
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minsync,ncand,candidates)
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ndecodes=0
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decodes=' '
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isbest=0
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fc2=0.
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do icand=1,ncand
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fc0=candidates(icand,1)
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detmet=candidates(icand,2)
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! Downconvert and downsample a slice of the spectrum centered on the
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! rough estimate of the candidates frequency.
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! Output array c2 is complex baseband sampled at 12000/ndown Sa/sec.
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! The size of the downsampled c2 array is nfft2=nfft1/ndown
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call timer('dwnsmpl ',0)
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call fst4_downsample(c_bigfft,nfft1,ndown,fc0,sigbw,c2)
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call timer('dwnsmpl ',1)
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call timer('sync240 ',0)
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call fst4_sync_search(c2,nfft2,hmod,fs2,nss,ntrperiod,nsyncoh,emedelay,sbest,fcbest,isbest)
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call timer('sync240 ',1)
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fc_synced = fc0 + fcbest
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dt_synced = (isbest-fs2)*dt2 !nominal dt is 1 second so frame starts at sample fs2
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candidates(icand,3)=fc_synced
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candidates(icand,4)=isbest
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enddo
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! remove duplicate candidates
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do icand=1,ncand
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fc=candidates(icand,3)
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isbest=nint(candidates(icand,4))
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do ic2=1,ncand
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fc2=candidates(ic2,3)
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isbest2=nint(candidates(ic2,4))
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if(ic2.ne.icand .and. fc2.gt.0.0) then
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if(abs(fc2-fc).lt.0.10*baud) then ! same frequency
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if(abs(isbest2-isbest).le.2) then
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candidates(ic2,3)=-1
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endif
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endif
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endif
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enddo
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enddo
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ic=0
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do icand=1,ncand
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if(candidates(icand,3).gt.0) then
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ic=ic+1
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candidates(ic,:)=candidates(icand,:)
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endif
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enddo
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ncand=ic
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xsnr=0.
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!write(*,*) 'ncand ',ncand
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do icand=1,ncand
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sync=candidates(icand,2)
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fc_synced=candidates(icand,3)
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isbest=nint(candidates(icand,4))
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xdt=(isbest-nspsec)/fs2
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if(ntrperiod.eq.15) xdt=(isbest-real(nspsec)/2.0)/fs2
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call timer('dwnsmpl ',0)
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call fst4_downsample(c_bigfft,nfft1,ndown,fc_synced,sigbw,c2)
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call timer('dwnsmpl ',1)
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do ijitter=0,jittermax
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if(ijitter.eq.0) ioffset=0
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if(ijitter.eq.1) ioffset=1
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if(ijitter.eq.2) ioffset=-1
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is0=isbest+ioffset
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if(is0.lt.0) cycle
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cframe=c2(is0:is0+160*nss-1)
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bitmetrics=0
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call timer('bitmetrc',0)
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call get_fst4_bitmetrics(cframe,nss,nblock,nhicoh,bitmetrics, &
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s4,nsync_qual,badsync)
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call timer('bitmetrc',1)
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if(badsync) cycle
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do il=1,4
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llrs( 1: 60,il)=bitmetrics( 17: 76, il)
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llrs( 61:120,il)=bitmetrics( 93:152, il)
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llrs(121:180,il)=bitmetrics(169:228, il)
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llrs(181:240,il)=bitmetrics(245:304, il)
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enddo
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apmag=maxval(abs(llrs(:,1)))*1.1
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ntmax=nblock+nappasses(nQSOProgress)
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if(lapcqonly) ntmax=nblock+1
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if(ndepth.eq.1) ntmax=nblock
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apmask=0
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if(iwspr.eq.1) then ! 50-bit msgs, no ap decoding
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nblock=4
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ntmax=nblock
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endif
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do itry=1,ntmax
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if(itry.eq.1) llr=llrs(:,1)
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if(itry.eq.2.and.itry.le.nblock) llr=llrs(:,2)
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if(itry.eq.3.and.itry.le.nblock) llr=llrs(:,3)
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if(itry.eq.4.and.itry.le.nblock) llr=llrs(:,4)
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if(itry.le.nblock) then
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apmask=0
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iaptype=0
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endif
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if(itry.gt.nblock) then ! do ap passes
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llr=llrs(:,nblock) ! Use largest blocksize as the basis for AP passes
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iaptype=naptypes(nQSOProgress,itry-nblock)
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if(lapcqonly) iaptype=1
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if(iaptype.ge.2 .and. apbits(1).gt.1) cycle ! No, or nonstandard, mycall
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if(iaptype.ge.3 .and. apbits(30).gt.1) cycle ! No, or nonstandard, dxcall
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if(iaptype.eq.1) then ! CQ
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apmask=0
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apmask(1:29)=1
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llr(1:29)=apmag*mcq(1:29)
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endif
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if(iaptype.eq.2) then ! MyCall ??? ???
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apmask=0
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apmask(1:29)=1
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llr(1:29)=apmag*apbits(1:29)
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endif
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if(iaptype.eq.3) then ! MyCall DxCall ???
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apmask=0
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apmask(1:58)=1
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llr(1:58)=apmag*apbits(1:58)
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endif
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if(iaptype.eq.4 .or. iaptype.eq.5 .or. iaptype .eq.6) then
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apmask=0
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apmask(1:77)=1
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llr(1:58)=apmag*apbits(1:58)
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if(iaptype.eq.4) llr(59:77)=apmag*mrrr(1:19)
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if(iaptype.eq.5) llr(59:77)=apmag*m73(1:19)
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if(iaptype.eq.6) llr(59:77)=apmag*mrr73(1:19)
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endif
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endif
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dmin=0.0
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nharderrors=-1
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unpk77_success=.false.
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if(iwspr.eq.0) then
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maxosd=2
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Keff=91
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norder=3
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call timer('d240_101',0)
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call decode240_101(llr,Keff,maxosd,norder,apmask,message101, &
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cw,ntype,nharderrors,dmin)
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call timer('d240_101',1)
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elseif(iwspr.eq.1) then
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maxosd=2
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call timer('d240_74 ',0)
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Keff=64
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norder=4
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call decode240_74(llr,Keff,maxosd,norder,apmask,message74,cw, &
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ntype,nharderrors,dmin)
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call timer('d240_74 ',1)
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endif
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if(nharderrors .ge.0) then
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if(count(cw.eq.1).eq.0) then
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nharderrors=-nharderrors
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cycle
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endif
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if(iwspr.eq.0) then
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write(c77,'(77i1)') mod(message101(1:77)+rvec,2)
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call unpack77(c77,1,msg,unpk77_success)
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else
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write(c77,'(50i1)') message74(1:50)
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c77(51:77)='000000000000000000000110000'
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call unpack77(c77,1,msg,unpk77_success)
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endif
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if(unpk77_success) then
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idupe=0
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do i=1,ndecodes
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if(decodes(i).eq.msg) idupe=1
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enddo
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if(idupe.eq.1) goto 2002
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ndecodes=ndecodes+1
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decodes(ndecodes)=msg
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if(iwspr.eq.0) then
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|
call get_fst4_tones_from_bits(message101,itone,0)
|
|
else
|
|
call get_fst4_tones_from_bits(message74,itone,1)
|
|
endif
|
|
inquire(file='plotspec',exist=ex)
|
|
fmid=-999.0
|
|
call timer('dopsprd ',0)
|
|
if(ex) then
|
|
call dopspread(itone,iwave,nsps,nmax,ndown,hmod, &
|
|
isbest,fc_synced,fmid,w50)
|
|
endif
|
|
call timer('dopsprd ',1)
|
|
xsig=0
|
|
do i=1,NN
|
|
xsig=xsig+s4(itone(i),i)
|
|
enddo
|
|
base=candidates(icand,5)
|
|
arg=600.0*(xsig/base)-1.0
|
|
if(arg.gt.0.0) then
|
|
xsnr=10*log10(arg)-35.5-12.5*log10(nsps/8200.0)
|
|
if(ntrperiod.eq. 15) xsnr=xsnr+2
|
|
if(ntrperiod.eq. 30) xsnr=xsnr+1
|
|
if(ntrperiod.eq. 900) xsnr=xsnr+1
|
|
if(ntrperiod.eq.1800) xsnr=xsnr+2
|
|
else
|
|
xsnr=-99.9
|
|
endif
|
|
else
|
|
cycle
|
|
endif
|
|
nsnr=nint(xsnr)
|
|
qual=0.
|
|
fsig=fc_synced - 1.5*baud
|
|
if(ex) then
|
|
write(21,3021) nutc,icand,itry,nsyncoh,iaptype, &
|
|
ijitter,ntype,nsync_qual,nharderrors,dmin, &
|
|
sync,xsnr,xdt,fsig,w50,trim(msg)
|
|
3021 format(i6.6,6i3,2i4,f6.1,f7.2,f6.1,f6.2,f7.1,f7.3,1x,a)
|
|
flush(21)
|
|
endif
|
|
call this%callback(nutc,smax1,nsnr,xdt,fsig,msg, &
|
|
iaptype,qual,ntrperiod,lwspr,fmid,w50)
|
|
goto 2002
|
|
endif
|
|
enddo ! metrics
|
|
enddo ! istart jitter
|
|
2002 enddo !candidate list
|
|
|
|
return
|
|
end subroutine decode
|
|
|
|
subroutine sync_fst4(cd0,i0,f0,hmod,ncoh,np,nss,ntr,fs,sync)
|
|
|
|
! Compute sync power for a complex, downsampled FST4 signal.
|
|
|
|
use timer_module, only: timer
|
|
include 'fst4/fst4_params.f90'
|
|
complex cd0(0:np-1)
|
|
complex csync1,csync2,csynct1,csynct2
|
|
complex ctwk(3200)
|
|
complex z1,z2,z3,z4,z5
|
|
integer hmod,isyncword1(0:7),isyncword2(0:7)
|
|
real f0save
|
|
common/sync240com/csync1(3200),csync2(3200),csynct1(3200),csynct2(3200)
|
|
data isyncword1/0,1,3,2,1,0,2,3/
|
|
data isyncword2/2,3,1,0,3,2,0,1/
|
|
data f0save/-99.9/,nss0/-1/,ntr0/-1/
|
|
save twopi,dt,fac,f0save,nss0,ntr0
|
|
|
|
p(z1)=(real(z1*fac)**2 + aimag(z1*fac)**2)**0.5 !Compute power
|
|
|
|
nz=8*nss
|
|
call timer('sync240a',0)
|
|
if(nss.ne.nss0 .or. ntr.ne.ntr0) then
|
|
twopi=8.0*atan(1.0)
|
|
dt=1/fs
|
|
k=1
|
|
phi1=0.0
|
|
phi2=0.0
|
|
do i=0,7
|
|
dphi1=twopi*hmod*(isyncword1(i)-1.5)/real(nss)
|
|
dphi2=twopi*hmod*(isyncword2(i)-1.5)/real(nss)
|
|
do j=1,nss
|
|
csync1(k)=cmplx(cos(phi1),sin(phi1))
|
|
csync2(k)=cmplx(cos(phi2),sin(phi2))
|
|
phi1=mod(phi1+dphi1,twopi)
|
|
phi2=mod(phi2+dphi2,twopi)
|
|
k=k+1
|
|
enddo
|
|
enddo
|
|
fac=1.0/(8.0*nss)
|
|
nss0=nss
|
|
ntr0=ntr
|
|
f0save=-1.e30
|
|
endif
|
|
|
|
if(f0.ne.f0save) then
|
|
dphi=twopi*f0*dt
|
|
phi=0.0
|
|
do i=1,nz
|
|
ctwk(i)=cmplx(cos(phi),sin(phi))
|
|
phi=mod(phi+dphi,twopi)
|
|
enddo
|
|
csynct1(1:nz)=ctwk(1:nz)*csync1(1:nz)
|
|
csynct2(1:nz)=ctwk(1:nz)*csync2(1:nz)
|
|
f0save=f0
|
|
nss0=nss
|
|
endif
|
|
call timer('sync240a',1)
|
|
|
|
i1=i0 !Costas arrays
|
|
i2=i0+38*nss
|
|
i3=i0+76*nss
|
|
i4=i0+114*nss
|
|
i5=i0+152*nss
|
|
|
|
s1=0.0
|
|
s2=0.0
|
|
s3=0.0
|
|
s4=0.0
|
|
s5=0.0
|
|
|
|
if(ncoh.gt.0) then
|
|
nsec=8/ncoh
|
|
do i=1,nsec
|
|
is=(i-1)*ncoh*nss
|
|
z1=0
|
|
if(i1+is.ge.1) then
|
|
z1=sum(cd0(i1+is:i1+is+ncoh*nss-1)*conjg(csynct1(is+1:is+ncoh*nss)))
|
|
endif
|
|
z2=sum(cd0(i2+is:i2+is+ncoh*nss-1)*conjg(csynct2(is+1:is+ncoh*nss)))
|
|
z3=sum(cd0(i3+is:i3+is+ncoh*nss-1)*conjg(csynct1(is+1:is+ncoh*nss)))
|
|
z4=sum(cd0(i4+is:i4+is+ncoh*nss-1)*conjg(csynct2(is+1:is+ncoh*nss)))
|
|
z5=0
|
|
if(i5+is+ncoh*nss-1.le.np) then
|
|
z5=sum(cd0(i5+is:i5+is+ncoh*nss-1)*conjg(csynct1(is+1:is+ncoh*nss)))
|
|
endif
|
|
s1=s1+abs(z1)/nz
|
|
s2=s2+abs(z2)/nz
|
|
s3=s3+abs(z3)/nz
|
|
s4=s4+abs(z4)/nz
|
|
s5=s5+abs(z5)/nz
|
|
enddo
|
|
else
|
|
nsub=-ncoh
|
|
nps=nss/nsub
|
|
do i=1,8
|
|
do isub=1,nsub
|
|
is=(i-1)*nss+(isub-1)*nps
|
|
z1=0.0
|
|
if(i1+is.ge.1) then
|
|
z1=sum(cd0(i1+is:i1+is+nps-1)*conjg(csynct1(is+1:is+nps)))
|
|
endif
|
|
z2=sum(cd0(i2+is:i2+is+nps-1)*conjg(csynct2(is+1:is+nps)))
|
|
z3=sum(cd0(i3+is:i3+is+nps-1)*conjg(csynct1(is+1:is+nps)))
|
|
z4=sum(cd0(i4+is:i4+is+nps-1)*conjg(csynct2(is+1:is+nps)))
|
|
z5=0.0
|
|
if(i5+is+ncoh*nss-1.le.np) then
|
|
z5=sum(cd0(i5+is:i5+is+nps-1)*conjg(csynct1(is+1:is+nps)))
|
|
endif
|
|
s1=s1+abs(z1)/(8*nss)
|
|
s2=s2+abs(z2)/(8*nss)
|
|
s3=s3+abs(z3)/(8*nss)
|
|
s4=s4+abs(z4)/(8*nss)
|
|
s5=s5+abs(z5)/(8*nss)
|
|
enddo
|
|
enddo
|
|
endif
|
|
sync = s1+s2+s3+s4+s5
|
|
return
|
|
end subroutine sync_fst4
|
|
|
|
subroutine fst4_downsample(c_bigfft,nfft1,ndown,f0,sigbw,c1)
|
|
|
|
! Output: Complex data in c(), sampled at 12000/ndown Hz
|
|
|
|
complex c_bigfft(0:nfft1/2)
|
|
complex c1(0:nfft1/ndown-1)
|
|
|
|
df=12000.0/nfft1
|
|
i0=nint(f0/df)
|
|
ih=nint( ( f0 + 1.3*sigbw/2.0 )/df)
|
|
nbw=ih-i0+1
|
|
c1=0.
|
|
c1(0)=c_bigfft(i0)
|
|
nfft2=nfft1/ndown
|
|
do i=1,nbw
|
|
if(i0+i.le.nfft1/2) c1(i)=c_bigfft(i0+i)
|
|
if(i0-i.ge.0) c1(nfft2-i)=c_bigfft(i0-i)
|
|
enddo
|
|
c1=c1/nfft2
|
|
call four2a(c1,nfft2,1,1,1) !c2c FFT back to time domain
|
|
return
|
|
|
|
end subroutine fst4_downsample
|
|
|
|
subroutine get_candidates_fst4(c_bigfft,nfft1,nsps,hmod,fs,fa,fb,nfa,nfb, &
|
|
minsync,ncand,candidates)
|
|
|
|
complex c_bigfft(0:nfft1/2) !Full length FFT of raw data
|
|
integer hmod !Modulation index (submode)
|
|
integer im(1) !For maxloc
|
|
real candidates(200,5) !Candidate list
|
|
real, allocatable :: s(:) !Low resolution power spectrum
|
|
real, allocatable :: s2(:) !CCF of s() with 4 tones
|
|
real, allocatable :: sbase(:) !noise baseline estimate
|
|
real xdb(-3:3) !Model 4-tone CCF peaks
|
|
real minsync
|
|
data xdb/0.25,0.50,0.75,1.0,0.75,0.50,0.25/
|
|
|
|
nh1=nfft1/2
|
|
df1=fs/nfft1
|
|
baud=fs/nsps !Keying rate
|
|
df2=baud/2.0
|
|
nd=df2/df1 !s() sums this many bins of big FFT
|
|
ndh=nd/2
|
|
ia=nint(max(100.0,fa)/df2) !Low frequency search limit
|
|
ib=nint(min(4800.0,fb)/df2) !High frequency limit
|
|
ina=nint(max(100.0,real(nfa))/df2) !Low freq limit for noise baseline fit
|
|
inb=nint(min(4800.0,real(nfb))/df2) !High freq limit for noise fit
|
|
if(ia.lt.ina) ia=ina
|
|
if(ib.gt.inb) ib=inb
|
|
nnw=nint(48000.*nsps*2./fs)
|
|
allocate (s(nnw))
|
|
s=0. !Compute low-resolution power spectrum
|
|
do i=ina,inb ! noise analysis window includes signal analysis window
|
|
j0=nint(i*df2/df1)
|
|
do j=j0-ndh,j0+ndh
|
|
s(i)=s(i) + real(c_bigfft(j))**2 + aimag(c_bigfft(j))**2
|
|
enddo
|
|
enddo
|
|
|
|
ina=max(ina,1+3*hmod) !Don't run off the ends
|
|
inb=min(inb,nnw-3*hmod)
|
|
allocate (s2(nnw))
|
|
allocate (sbase(nnw))
|
|
s2=0.
|
|
do i=ina,inb !Compute CCF of s() and 4 tones
|
|
s2(i)=s(i-hmod*3) + s(i-hmod) +s(i+hmod) +s(i+hmod*3)
|
|
enddo
|
|
npct=30
|
|
call fst4_baseline(s2,nnw,ina+hmod*3,inb-hmod*3,npct,sbase)
|
|
if(any(sbase(ina:inb).le.0.0)) return
|
|
s2(ina:inb)=s2(ina:inb)/sbase(ina:inb) !Normalize wrt noise level
|
|
|
|
ncand=0
|
|
candidates=0
|
|
if(ia.lt.3) ia=3
|
|
if(ib.gt.nnw-2) ib=nnw-2
|
|
|
|
! Find candidates, using the CLEAN algorithm to remove a model of each one
|
|
! from s2() after it has been found.
|
|
pval=99.99
|
|
do while(ncand.lt.200)
|
|
im=maxloc(s2(ia:ib))
|
|
iploc=ia+im(1)-1 !Index of CCF peak
|
|
pval=s2(iploc) !Peak value
|
|
if(pval.lt.minsync) exit
|
|
do i=-3,+3 !Remove 0.9 of a model CCF at
|
|
k=iploc+2*hmod*i !this frequency from s2()
|
|
if(k.ge.ia .and. k.le.ib) then
|
|
s2(k)=max(0.,s2(k)-0.9*pval*xdb(i))
|
|
endif
|
|
enddo
|
|
ncand=ncand+1
|
|
candidates(ncand,1)=df2*iploc !Candidate frequency
|
|
candidates(ncand,2)=pval !Rough estimate of SNR
|
|
candidates(ncand,5)=sbase(iploc)
|
|
enddo
|
|
return
|
|
end subroutine get_candidates_fst4
|
|
|
|
subroutine fst4_sync_search(c2,nfft2,hmod,fs2,nss,ntrperiod,nsyncoh,emedelay,sbest,fcbest,isbest)
|
|
complex c2(0:nfft2-1)
|
|
integer hmod
|
|
nspsec=int(fs2)
|
|
baud=fs2/real(nss)
|
|
fc1=0.0
|
|
if(emedelay.lt.0.1) then ! search offsets from 0 s to 2 s
|
|
is0=1.5*nspsec
|
|
ishw=1.5*nspsec
|
|
else ! search plus or minus 1.5 s centered on emedelay
|
|
is0=nint((emedelay+1.0)*nspsec)
|
|
ishw=1.5*nspsec
|
|
endif
|
|
|
|
sbest=-1.e30
|
|
do if=-12,12
|
|
fc=fc1 + 0.1*baud*if
|
|
do istart=max(1,is0-ishw),is0+ishw,4*hmod
|
|
call sync_fst4(c2,istart,fc,hmod,nsyncoh,nfft2,nss, &
|
|
ntrperiod,fs2,sync)
|
|
if(sync.gt.sbest) then
|
|
fcbest=fc
|
|
isbest=istart
|
|
sbest=sync
|
|
endif
|
|
enddo
|
|
enddo
|
|
|
|
fc1=fcbest
|
|
is0=isbest
|
|
ishw=4*hmod
|
|
isst=1*hmod
|
|
|
|
sbest=0.0
|
|
do if=-7,7
|
|
fc=fc1 + 0.02*baud*if
|
|
do istart=max(1,is0-ishw),is0+ishw,isst
|
|
call sync_fst4(c2,istart,fc,hmod,nsyncoh,nfft2,nss, &
|
|
ntrperiod,fs2,sync)
|
|
if(sync.gt.sbest) then
|
|
fcbest=fc
|
|
isbest=istart
|
|
sbest=sync
|
|
endif
|
|
enddo
|
|
enddo
|
|
end subroutine fst4_sync_search
|
|
|
|
subroutine dopspread(itone,iwave,nsps,nmax,ndown,hmod,i0,fc,fmid,w50)
|
|
|
|
! On "plotspec" special request, compute Doppler spread for a decoded signal
|
|
|
|
include 'fst4/fst4_params.f90'
|
|
complex, allocatable :: cwave(:) !Reconstructed complex signal
|
|
complex, allocatable :: g(:) !Channel gain, g(t) in QEX paper
|
|
real,allocatable :: ss(:) !Computed power spectrum of g(t)
|
|
integer itone(160) !Tones for this message
|
|
integer*2 iwave(nmax) !Raw Rx data
|
|
integer hmod !Modulation index
|
|
data ncall/0/
|
|
save ncall
|
|
|
|
ncall=ncall+1
|
|
nfft=2*nmax
|
|
nwave=max(nmax,(NN+2)*nsps)
|
|
allocate(cwave(0:nwave-1))
|
|
allocate(g(0:nfft-1))
|
|
wave=0
|
|
fsample=12000.0
|
|
call gen_fst4wave(itone,NN,nsps,nwave,fsample,hmod,fc,1,cwave,wave)
|
|
cwave=cshift(cwave,-i0*ndown)
|
|
fac=1.0/32768
|
|
g(0:nmax-1)=fac*float(iwave)*conjg(cwave(:nmax-1))
|
|
g(nmax:)=0.
|
|
call four2a(g,nfft,1,-1,1) !Forward c2c FFT
|
|
|
|
df=12000.0/nfft
|
|
ia=1.0/df
|
|
smax=0.
|
|
do i=-ia,ia !Find smax in +/- 1 Hz around 0.
|
|
j=i
|
|
if(j.lt.0) j=i+nfft
|
|
s=real(g(j))**2 + aimag(g(j))**2
|
|
smax=max(s,smax)
|
|
enddo
|
|
|
|
ia=10.1/df
|
|
allocate(ss(-ia:ia)) !Allocate space for +/- 10 Hz
|
|
sum1=0.
|
|
sum2=0.
|
|
nns=0
|
|
do i=-ia,ia
|
|
j=i
|
|
if(j.lt.0) j=i+nfft
|
|
ss(i)=(real(g(j))**2 + aimag(g(j))**2)/smax
|
|
f=i*df
|
|
if(f.ge.-4.0 .and. f.le.-2.0) then
|
|
sum1=sum1 + ss(i) !Power between -2 and -4 Hz
|
|
nns=nns+1
|
|
else if(f.ge.2.0 .and. f.le.4.0) then
|
|
sum2=sum2 + ss(i) !Power between +2 and +4 Hz
|
|
endif
|
|
enddo
|
|
avg=min(sum1/nns,sum2/nns) !Compute avg from smaller sum
|
|
|
|
sum1=0.
|
|
do i=-ia,ia
|
|
f=i*df
|
|
if(abs(f).le.1.0) sum1=sum1 + ss(i)-avg !Power in abs(f) < 1 Hz
|
|
enddo
|
|
|
|
ia=nint(1.0/df) + 1
|
|
sum2=0.0
|
|
xi1=-999
|
|
xi2=-999
|
|
xi3=-999
|
|
sum2z=0.
|
|
do i=-ia,ia !Find freq range that has 50% of signal power
|
|
sum2=sum2 + ss(i)-avg
|
|
if(sum2.ge.0.25*sum1 .and. xi1.eq.-999.0) then
|
|
xi1=i - 1 + (sum2-0.25*sum1)/(sum2-sum2z)
|
|
endif
|
|
if(sum2.ge.0.50*sum1 .and. xi2.eq.-999.0) then
|
|
xi2=i - 1 + (sum2-0.50*sum1)/(sum2-sum2z)
|
|
endif
|
|
if(sum2.ge.0.75*sum1) then
|
|
xi3=i - 1 + (sum2-0.75*sum1)/(sum2-sum2z)
|
|
exit
|
|
endif
|
|
sum2z=sum2
|
|
enddo
|
|
xdiff=sqrt(1.0+(xi3-xi1)**2) !Keep small values from fluctuating too widely
|
|
w50=xdiff*df !Compute Doppler spread
|
|
fmid=xi2*df !Frequency midpoint of signal powere
|
|
|
|
do i=-ia,ia !Save the spectrum for plotting
|
|
y=ncall-1
|
|
j=i+nint(xi2)
|
|
if(abs(j*df).lt.10.0) y=0.99*ss(i+nint(xi2)) + ncall-1
|
|
write(52,1010) i*df,y
|
|
1010 format(f12.6,f12.6)
|
|
enddo
|
|
|
|
return
|
|
end subroutine dopspread
|
|
|
|
end module fst4_decode
|