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377 lines
10 KiB
Fortran
377 lines
10 KiB
Fortran
module ft8_a7
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parameter(MAXDEC=100)
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! For the following three arrays
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! First index i=decode number in this sequence
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! Second index j=0 or 1 for even or odd sequence
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! Third index k=0 or 1 for previous or current tally for this j
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real dt0(MAXDEC,0:1,0:1) !dt0(i,j,k)
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real f0(MAXDEC,0:1,0:1) !f0(i,j,k)
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character*37 msg0(MAXDEC,0:1,0:1) !msg0(i,j,k)
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integer itone_a7(79)
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integer jseq !even=0, odd=1
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integer ndec(0:1,0:1) !ndec(j,k)
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data ndec/4*0/,jseq/0/
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contains
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subroutine ft8_a7_save(nutc,dt,f,msg)
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use packjt77
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character*37 msg,msg1
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character*13 w(19)
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character*4 g4
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integer nw(19)
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logical isgrid4
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! Statement function:
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isgrid4(g4)=(len_trim(g4).eq.4 .and. &
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ichar(g4(1:1)).ge.ichar('A') .and. ichar(g4(1:1)).le.ichar('R') .and. &
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ichar(g4(2:2)).ge.ichar('A') .and. ichar(g4(2:2)).le.ichar('R') .and. &
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ichar(g4(3:3)).ge.ichar('0') .and. ichar(g4(3:3)).le.ichar('9') .and. &
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ichar(g4(4:4)).ge.ichar('0') .and. ichar(g4(4:4)).le.ichar('9'))
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j=mod(nutc/5,2) !j is 0 or 1 for odd/even sequence
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jseq=j
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! Add this decode to current table for this sequence
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ndec(j,1)=ndec(j,1)+1 !Number of decodes in this sequence
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i=ndec(j,1) !i is index of a new table entry
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if(i.ge.MAXDEC-1) return !Prevent table overflow
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dt0(i,j,1)=dt !Save dt in table
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f0(i,j,1)=f !Save f in table
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call split77(msg,nwords,nw,w) !Parse msg into words
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if(nwords.lt.1) go to 999
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msg0(i,j,1)=trim(w(1))//' '//trim(w(2)) !Save "call_1 call_2"
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if(w(1)(1:3).eq.'CQ ' .and. nw(2).le.2) then
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msg0(i,j,1)='CQ '//trim(w(2))//' '//trim(w(3)) !Save "CQ DX Call_2"
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endif
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msg1=msg0(i,j,1) !Message without grid
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nn=len(trim(msg1)) !Message length without grid
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! Include grid as part of message
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if(isgrid4(w(nwords))) msg0(i,j,1)=trim(msg0(i,j,1))//' '//trim(w(nwords))
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! If a transmission at this frequency with message fragment "call_1 call_2"
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! was decoded in the previous sequence, flag it as "DO NOT USE" because
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! we have already decoded and subtracted that station's next transmission.
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call split77(msg0(i,j,1),nwords,nw,w) !Parse msg into words
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do i=1,ndec(j,0)
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if(f0(i,j,0).le.-98.0) cycle
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i2=index(msg0(i,j,0),' '//trim(w(2)))
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if(abs(f-f0(i,j,0)).le.3.0 .and. i2.ge.3) then
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f0(i,j,0)=-98.0 !Flag as "do not use" for a potential a7 decode
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endif
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enddo
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999 return
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end subroutine ft8_a7_save
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subroutine ft8_a7d(dd0,newdat,call_1,call_2,grid4,xdt,f1,nharderrors,dmin, &
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msg37,xsnr)
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! Examine the raw data in dd0() for possible "a7" decodes.
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use crc
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use timer_module, only: timer
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use packjt77
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include 'ft8_params.f90'
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parameter(NP2=2812)
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character*37 msg37,msg,msgsent,msgbest
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character*12 call_1,call_2
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character*4 grid4
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real a(5)
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real s8(0:7,NN)
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real s2(0:511)
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real dmm(206)
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real bmeta(174),bmetb(174),bmetc(174),bmetd(174)
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real llra(174),llrb(174),llrc(174),llrd(174) !Soft symbols
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real dd0(15*12000)
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real ss(9)
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real rcw(174)
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integer*1 cw(174)
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integer*1 msgbits(77)
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integer*1 nxor(174),hdec(174)
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integer itone(NN)
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integer icos7(0:6),ip(1)
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logical one(0:511,0:8)
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integer graymap(0:7)
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integer iloc(1)
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complex cd0(0:3199)
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complex ctwk(32)
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complex csymb(32)
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complex cs(0:7,NN)
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logical std_1,std_2
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logical first,newdat
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data icos7/3,1,4,0,6,5,2/ !Sync array
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data first/.true./
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data graymap/0,1,3,2,5,6,4,7/
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save one
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if(first) then
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one=.false.
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do i=0,511
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do j=0,8
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if(iand(i,2**j).ne.0) one(i,j)=.true.
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enddo
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enddo
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first=.false.
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endif
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call stdcall(call_1,std_1)
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if(call_1(1:3).eq.'CQ ') std_1=.true.
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call stdcall(call_2,std_2)
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fs2=12000.0/NDOWN
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dt2=1.0/fs2
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twopi=8.0*atan(1.0)
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delfbest=0.
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ibest=0
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call timer('ft8_down',0)
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call ft8_downsample(dd0,newdat,f1,cd0) !Mix f1 to baseband and downsample
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call timer('ft8_down',1)
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i0=nint((xdt+0.5)*fs2) !Initial guess for start of signal
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smax=0.0
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do idt=i0-10,i0+10 !Search over +/- one quarter symbol
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call sync8d(cd0,idt,ctwk,0,sync) !NB: ctwk not used here
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if(sync.gt.smax) then
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smax=sync
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ibest=idt
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endif
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enddo
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! Peak up in frequency
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smax=0.0
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do ifr=-5,5 !Search over +/- 2.5 Hz
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delf=ifr*0.5
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dphi=twopi*delf*dt2
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phi=0.0
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do i=1,32
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ctwk(i)=cmplx(cos(phi),sin(phi))
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phi=mod(phi+dphi,twopi)
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enddo
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call sync8d(cd0,ibest,ctwk,1,sync)
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if( sync .gt. smax ) then
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smax=sync
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delfbest=delf
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endif
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enddo
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a=0.0
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a(1)=-delfbest
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call twkfreq1(cd0,NP2,fs2,a,cd0)
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f1=f1+delfbest !Improved estimate of DF
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call timer('ft8_down',0)
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call ft8_downsample(dd0,.false.,f1,cd0) !Mix f1 to baseband and downsample
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call timer('ft8_down',1)
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smax=0.0
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do idt=-4,4 !Search over +/- one quarter symbol
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call sync8d(cd0,ibest+idt,ctwk,0,sync)
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ss(idt+5)=sync
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enddo
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smax=maxval(ss)
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iloc=maxloc(ss)
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ibest=iloc(1)-5+ibest
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xdt=(ibest-1)*dt2 - 0.5
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sync=smax
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do k=1,NN
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i1=ibest+(k-1)*32
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csymb=cmplx(0.0,0.0)
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if( i1.ge.0 .and. i1+31 .le. NP2-1 ) csymb=cd0(i1:i1+31)
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call four2a(csymb,32,1,-1,1)
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cs(0:7,k)=csymb(1:8)/1e3
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s8(0:7,k)=abs(csymb(1:8))
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enddo
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! sync quality check
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is1=0
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is2=0
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is3=0
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do k=1,7
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ip=maxloc(s8(:,k))
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if(icos7(k-1).eq.(ip(1)-1)) is1=is1+1
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ip=maxloc(s8(:,k+36))
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if(icos7(k-1).eq.(ip(1)-1)) is2=is2+1
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ip=maxloc(s8(:,k+72))
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if(icos7(k-1).eq.(ip(1)-1)) is3=is3+1
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enddo
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! hard sync sum - max is 21
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nsync=is1+is2+is3
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! if(nsync .le. 6) return ! bail out
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do nsym=1,3
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nt=2**(3*nsym)
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do ihalf=1,2
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do k=1,29,nsym
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if(ihalf.eq.1) ks=k+7
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if(ihalf.eq.2) ks=k+43
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amax=-1.0
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do i=0,nt-1
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i1=i/64
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i2=iand(i,63)/8
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i3=iand(i,7)
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if(nsym.eq.1) then
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s2(i)=abs(cs(graymap(i3),ks))
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elseif(nsym.eq.2) then
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s2(i)=abs(cs(graymap(i2),ks)+cs(graymap(i3),ks+1))
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elseif(nsym.eq.3) then
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s2(i)=abs(cs(graymap(i1),ks)+cs(graymap(i2),ks+1)+cs(graymap(i3),ks+2))
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else
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print*,"Error - nsym must be 1, 2, or 3."
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endif
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enddo
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i32=1+(k-1)*3+(ihalf-1)*87
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if(nsym.eq.1) ibmax=2
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if(nsym.eq.2) ibmax=5
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if(nsym.eq.3) ibmax=8
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do ib=0,ibmax
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bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - &
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maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib))
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if(i32+ib .gt.174) cycle
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if(nsym.eq.1) then
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bmeta(i32+ib)=bm
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den=max(maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)), &
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maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib)))
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if(den.gt.0.0) then
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cm=bm/den
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else ! erase it
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cm=0.0
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endif
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bmetd(i32+ib)=cm
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elseif(nsym.eq.2) then
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bmetb(i32+ib)=bm
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elseif(nsym.eq.3) then
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bmetc(i32+ib)=bm
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endif
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enddo
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enddo
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enddo
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enddo
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call normalizebmet(bmeta,174)
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call normalizebmet(bmetb,174)
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call normalizebmet(bmetc,174)
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call normalizebmet(bmetd,174)
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scalefac=2.83
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llra=scalefac*bmeta
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llrb=scalefac*bmetb
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llrc=scalefac*bmetc
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llrd=scalefac*bmetd
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! apmag=maxval(abs(llra))*1.01
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MAXMSG=206
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pbest=0.
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dmin=1.e30
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nharderrors=-1
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do imsg=1,MAXMSG
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msg=trim(call_1)//' '//trim(call_2)
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i=imsg
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if(call_1(1:3).eq.'CQ ' .and. i.ne.5) msg='QQ0XYZ '//trim(call_2)
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if(.not.std_1) then
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if(i.eq.1 .or. i.ge.6) msg='<'//trim(call_1)//'> '//trim(call_2)
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if(i.ge.2 .and. i.le.4) msg=trim(call_1)//' <'//trim(call_2)//'>'
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else if(.not.std_2) then
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if(i.le.4 .or. i.eq.6) msg='<'//trim(call_1)//'> '//trim(call_2)
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if(i.ge.7) msg=trim(call_1)//' <'//trim(call_2)//'>'
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endif
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j0=len(trim(msg))+2
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if(i.eq.2) msg(j0:j0+2)='RRR'
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if(i.eq.3) msg(j0:j0+3)='RR73'
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if(i.eq.4) msg(j0:j0+1)='73'
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if(i.eq.5) then
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if(std_2) then
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msg='CQ '//trim(call_2)
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if(call_1(3:3).eq.'_') msg=trim(call_1)//' '//trim(call_2)
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if(grid4.ne.'RR73') msg=trim(msg)//' '//grid4
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endif
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if(.not.std_2) msg='CQ '//trim(call_2)
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endif
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if(i.eq.6 .and. std_2) msg(j0:j0+3)=grid4
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if(i.ge.7) then
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isnr = -50 + (i-7)/2
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if(iand(i,1).eq.1) then
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write(msg(j0:j0+2),'(i3.2)') isnr
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if(msg(j0:j0).eq.' ') msg(j0:j0)='+'
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else
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write(msg(j0:j0+3),'("R",i3.2)') isnr
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if(msg(j0+1:j0+1).eq.' ') msg(j0+1:j0+1)='+'
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endif
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endif
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i3=-1
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n3=-1
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call genft8(msg,i3,n3,msgsent,msgbits,itone) !Source-encode this message
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call encode174_91(msgbits,cw) !Get codeword for this message
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rcw=2*cw-1
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pa=sum(llra*rcw)
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pb=sum(llrb*rcw)
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pc=sum(llrc*rcw)
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pd=sum(llrd*rcw)
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hdec=0
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where(llra.ge.0.0) hdec=1
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nxor=ieor(hdec,cw)
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da=sum(nxor*abs(llra))
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hdec=0
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where(llrb.ge.0.0) hdec=1
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nxor=ieor(hdec,cw)
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dbb=sum(nxor*abs(llrb))
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hdec=0
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where(llrc.ge.0.0) hdec=1
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nxor=ieor(hdec,cw)
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dc=sum(nxor*abs(llrc))
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hdec=0
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where(llrd.ge.0.0) hdec=1
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nxor=ieor(hdec,cw)
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dd=sum(nxor*abs(llrd))
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dm=min(da,dbb,dc,dd)
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dmm(imsg)=dm
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if(dm.lt.dmin) then
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dmin=dm
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msgbest=msgsent
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if(dm.eq.da) then
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nharderrors=count((2*cw-1)*llra.lt.0.0)
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pbest=pa
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else if(dm.eq.dbb) then
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nharderrors=count((2*cw-1)*llrb.lt.0.0)
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pbest=pb
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else if(dm.eq.dc) then
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nharderrors=count((2*cw-1)*llrc.lt.0.0)
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pbest=pc
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else if(dm.eq.dd) then
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nharderrors=count((2*cw-1)*llrd.lt.0.0)
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pbest=pd
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endif
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endif
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enddo ! imsg
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iloc=minloc(dmm)
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dmm(iloc(1))=1.e30
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iloc=minloc(dmm)
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dmin2=dmm(iloc(1))
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xsnr=-24.
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if(pbest.gt.0.0) xsnr=db(pbest/50.0) - 24.0
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! write(41,3041) nharderrors,dmin,dmin2,dmin2/dmin,xsnr,trim(msgbest)
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!3041 format(i3,2f7.1,f7.2,f7.1,1x,a)
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if(dmin.gt.100.0 .or. dmin2/dmin.lt.1.3) nharderrors=-1
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msg37=msgbest
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return
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end subroutine ft8_a7d
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end module ft8_a7
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