subroutine mskrtd(id2,nutc0,tsec,ntol,nrxfreq,ndepth,mycall,hiscall, & bshmsg,btrain,pcoeffs,bswl,datadir,line) ! Real-time decoder for MSK144. ! Analysis block size = NZ = 7168 samples, t_block = 0.597333 s ! Called from hspec() at half-block increments, about 0.3 s use packjt77 parameter (NZ=7168) !Block size parameter (NSPM=864) !Number of samples per message frame parameter (NFFT1=8192) !FFT size for making analytic signal parameter (NPATTERNS=4) !Number of frame averaging patterns to try parameter (NSHMEM=50) !Number of recent SWL messages to remember character*4 decsym !"&" for mskspd or "^" for long averages character*37 msgreceived !Decoded message character*37 msglast,msglastswl !Used for dupechecking character*80 line !Formatted line with UTC dB T Freq Msg character*12 mycall,hiscall character*37 recent_shmsgs(NSHMEM) character*512 datadir complex cdat(NFFT1) !Analytic signal complex c(NSPM) !Coherently averaged complex data complex ct(NSPM) integer*2 id2(NZ) !Raw 16-bit data integer iavmask(8) integer iavpatterns(8,NPATTERNS) integer npkloc(10) integer nhasharray(MAXRECENT,MAXRECENT) integer nsnrlast,nsnrlastswl real d(NFFT1) real pow(8) real softbits(144) real xmc(NPATTERNS) real*8 pcoeffs(5) logical*1 bshmsg,btrain,bswl logical*1 first logical*1 bshdecode logical*1 seenb4 logical*1 bflag logical*1 bvar logical*1 doosd data first/.true./ data iavpatterns/ & 1,1,1,1,0,0,0,0, & 0,0,1,1,1,1,0,0, & 1,1,1,1,1,0,0,0, & 1,1,1,1,1,1,1,0/ data xmc/2.0,4.5,2.5,3.5/ !Used to set time at center of averaging mask save first,tsec0,nutc00,pnoise,cdat,msglast,msglastswl, & nsnrlast,nsnrlastswl,nhasharray,recent_shmsgs ! nsnrlast,nsnrlastswl,nhasharray,recent_shmsgs,mycall13 if(first) then tsec0=tsec nutc00=nutc0 pnoise=-1.0 do i=1,MAXRECENT recent_calls(i)(1:13)=' ' enddo do i=1,nshmem recent_shmsgs(i)(1:37)=' ' enddo msglast=' ' msglastswl=' ' nsnrlast=-99 nsnrlastswl=-99 mycall13=mycall//' ' dxcall13=hiscall//' ' first=.false. endif fc=nrxfreq ! Reset if mycall or dxcall changes if(mycall13(1:12).ne.mycall .or. dxcall13(1:12).ne.hiscall) first=.true. ! Dupe checking setup if(nutc00.ne.nutc0 .or. tsec.lt.tsec0) then ! reset dupe checker msglast=' ' msglastswl=' ' nsnrlast=-99 nsnrlastswl=-99 nutc00=nutc0 endif tframe=float(NSPM)/12000.0 line=char(0) msgreceived=' ' max_iterations=10 niterations=0 d(1:NZ)=id2 rms=sqrt(sum(d(1:NZ)*d(1:NZ))/NZ) if(rms.lt.1.0) go to 999 fac=1.0/rms d(1:NZ)=fac*d(1:NZ) d(NZ+1:NFFT1)=0. bvar=.true. if( btrain ) bvar=.false. ! if training, turn off rx eq call analytic(d,NZ,NFFT1,cdat,pcoeffs,bvar) ! Calculate average power for each frame and for the entire block. ! If decode is successful, largest power will be taken as signal+noise. ! If no decode, entire-block average will be used to update noise estimate. pmax=-99 do i=1,8 ib=(i-1)*NSPM+1 ie=ib+NSPM-1 pow(i)=real(dot_product(cdat(ib:ie),cdat(ib:ie)))*rms**2 pmax=max(pmax,pow(i)) enddo pavg=sum(pow)/8.0 ! Short ping decoder uses squared-signal spectrum to determine where to ! center a 3-frame analysis window and attempts to decode each of the ! 3 frames along with 2- and 3-frame averages. np=8*NSPM call msk144spd(cdat,np,ntol,ndecodesuccess,msgreceived,fc,fest,tdec,navg,ct, & softbits) bshdecode=.false. if(ndecodesuccess.eq.0 .and. (bshmsg.or.bswl)) then call msk40spd(cdat,np,ntol,mycall,hiscall,bswl,nhasharray, & ndecodesuccess,msgreceived,fc,fest,tdec,navg) if(ndecodesuccess .ge.1) bshdecode=.true. endif if( ndecodesuccess .ge. 1 ) then tdec=tsec+tdec ipk=0 is=0 goto 900 endif ! If short ping decoder doesn't find a decode, ! Fast - short ping decoder only. ! Normal - try 4-frame averages ! Deep - try 4-, 5- and 7-frame averages. npat=NPATTERNS if( ndepth .eq. 1 ) npat=0 if( ndepth .eq. 2 ) npat=2 doosd=.false. if( ntol .le. 50 ) doosd = .true. do iavg=1,npat iavmask=iavpatterns(1:8,iavg) navg=sum(iavmask) deltaf=10.0/real(navg) ! search increment for frequency sync npeaks=2 call msk144sync(cdat(1:8*NSPM),8,ntol,deltaf,iavmask,npeaks,fc, & fest,npkloc,nsyncsuccess,xmax,c) if( nsyncsuccess .eq. 0 ) cycle do ipk=1,npeaks do is=1,3 ic0=npkloc(ipk) if(is.eq.2) ic0=max(1,ic0-1) if(is.eq.3) ic0=min(NSPM,ic0+1) ct=cshift(c,ic0-1) call msk144decodeframe(ct,softbits,msgreceived,ndecodesuccess,doosd) if(ndecodesuccess .gt. 0) then tdec=tsec+xmc(iavg)*tframe goto 900 endif enddo !Slicer dither enddo !Peak loop enddo msgreceived=' ' ! no decode - update noise level used for calculating displayed snr. if( pnoise .lt. 0 ) then ! initialize noise level pnoise=pavg elseif( pavg .gt. pnoise ) then ! noise level is slow to rise pnoise=0.9*pnoise+0.1*pavg elseif( pavg .lt. pnoise ) then ! and quick to fall pnoise=pavg endif go to 999 900 continue ! Successful decode - estimate snr if( pnoise .gt. 0.0 ) then snr0=10.0*log10(pmax/pnoise-1.0) else snr0=0.0 endif nsnr=nint(snr0) if(.not. bshdecode) then call msk144signalquality(ct,snr0,fest,tdec,softbits,msgreceived,hiscall, & btrain,datadir,ncorrected,eyeopening,pcoeffs) endif decsym=' & ' if( btrain ) decsym=' ^ ' if( bshdecode ) then ncorrected=0 eyeopening=0.0 endif if( nsnr .lt. -8 ) nsnr=-8 if( nsnr .gt. 24 ) nsnr=24 ! Dupe check. bflag=ndecodesuccess.eq.1 .and. & (msgreceived.ne.msglast .or. nsnr.gt.nsnrlast .or. tsec.lt.tsec0) if(bflag) then msglast=msgreceived nsnrlast=nsnr if(.not. bshdecode) then call update_msk40_hasharray(nhasharray) endif write(line,1021) nutc0,nsnr,tdec,nint(fest),decsym,msgreceived,char(0) 1021 format(i6.6,i4,f5.1,i5,a4,a37,a1) elseif(bswl .and. ndecodesuccess.ge.2) then seenb4=.false. do i=1,nshmem if( msgreceived .eq. recent_shmsgs(i) ) then seenb4=.true. endif enddo call update_recent_shmsgs(msgreceived,recent_shmsgs,nshmem) bflag=seenb4 .and. & (msgreceived.ne.msglastswl .or. nsnr.gt.nsnrlastswl .or. tsec.lt.tsec0) & .and. nsnr.gt.-6 if(bflag) then msglastswl=msgreceived nsnrlastswl=nsnr write(line,1021) nutc0,nsnr,tdec,nint(fest),decsym,msgreceived,char(0) endif endif 999 tsec0=tsec return end subroutine mskrtd subroutine update_recent_shmsgs(message,msgs,nsize) character*37 msgs(nsize) character*37 message logical*1 seen seen=.false. do i=1,nsize if( msgs(i) .eq. message ) seen=.true. enddo if( .not. seen ) then do i=nsize,2,-1 msgs(i)=msgs(i-1) enddo msgs(1)=message endif return end subroutine update_recent_shmsgs