program wsprcpmd ! Decode WSPRCPM data read from *.c2 or *.wav files. ! WSPRCPM is a WSPR-like mode based on full-response CPM. ! ! Currently configured to use (204,68) r=1/3 LDPC code, regular column weight 3. ! 50 data bits + 14 bit CRC + 4 "0" bits. The 4 "0" bits are unused bits that ! are not transmitted. At the decoder, these bits are treated as "AP" bits. ! This shortens the code to (200,64) r=0.32, slightly decreasing the code rate. ! ! Frame format is: ! d100 p32 d100 (232) channel symbols ! use crc include 'wsprcpm_params.f90' parameter(NMAX=120*12000) character arg*8,message*22,cbits*50,infile*80,fname*16,datetime*11 character ch1*1,ch4*4,cseq*31 character*22 decodes(100) character*120 data_dir character*32 uwbits character*68 dmsg complex c2(0:120*12000/32-1) !Complex waveform complex cframe(0:216*200-1) !Complex waveform complex cd(0:216*10-1) !Complex waveform complex c1(0:9,0:1),c0(0:9,0:1) complex ccor(0:1,216) complex cp(0:1,0:1) complex csum,cterm real*8 fMHz real rxdata(ND),llr(204) !Soft symbols real sbits(216),sbits1(216),sbits3(216) real ps(0:8191),psbest(0:8191) real candidates(100,2) integer iuniqueword0 integer isync(200) !Unique word integer isync2(216) ! integer ipreamble(16) !Preamble vector integer isyncword(16) integer ihdr(11) integer*2 iwave(NMAX) !Generated full-length waveform integer*1,target :: idat(9) integer*1 decoded(68),apmask(204),cw(204) integer*1 hbits(216),hbits1(216),hbits3(216) ! data ipreamble/1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1/ data isyncword/0,1,3,2,1,0,2,3,2,3,1,0,3,2,0,1/ data cseq /'9D9F C48B 797A DD60 58CB 2EBC 6'/ data iuniqueword0/z'30C9E8AD'/ k=0 do i=1,31 ch1=cseq(i:i) if(ch1.eq.' ') cycle read(ch1,'(z1)') n write(ch4,'(b4.4)') n do j=1,4 k=k+1 isync(k)=0 if(ch4(j:j).eq.'1') isync(k)=1 enddo enddo isync(101:200)=isync(1:100) fs=12000.0/NDOWN !Sample rate dt=1.0/fs !Sample interval (s) tt=NSPS*dt !Duration of "itone" symbols (s) baud=1.0/tt !Keying rate for "itone" symbols (baud) txt=NZ*dt !Transmission length (s) h=0.50 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading) twopi=8.0*atan(1.0) pi=4.0*atan(1.0) nargs=iargc() if(nargs.lt.1) then print*,'Usage: wsprcpmd [-a ] [-f fMHz] [-c ncoh] [-h h] file1 [file2 ...]' go to 999 endif iarg=1 data_dir="." call getarg(iarg,arg) if(arg(1:2).eq.'-a') then call getarg(iarg+1,data_dir) iarg=iarg+2 endif call getarg(iarg,arg) if(arg(1:2).eq.'-f') then call getarg(iarg+1,arg) read(arg,*) fMHz iarg=iarg+2 endif ncoh=1 if(arg(1:2).eq.'-h') then call getarg(iarg+1,arg) read(arg,*) h iarg=iarg+2 endif isync2(1:100)=isync(1:100) isync2(101:116)=(/0,1,1,0,1,0,0,1,0,1,1,0,1,0,0,1/) isync2(117:216)=isync(101:200) ! data MSB ! data sync tone ! 0 0 0 ! 0 1 1 ! 1 0 2 ! 1 1 3 dphi=twopi*baud*(h/2.0)*dt*20 ! dt*10 is samp interval after downsample do j=0,1 if(j.eq.0) then dphi0=-3*dphi dphi1=+1*dphi else dphi0=-1*dphi dphi1=+3*dphi endif phi0=0.0 phi1=0.0 do i=0,9 c1(i,j)=cmplx(cos(phi1),sin(phi1)) c0(i,j)=cmplx(cos(phi0),sin(phi0)) phi1=mod(phi1+dphi1,twopi) phi0=mod(phi0+dphi0,twopi) enddo cp(1,j)=cmplx(cos(phi1),sin(phi1)) cp(0,j)=cmplx(cos(phi0),sin(phi0)) enddo open(13,file=trim(data_dir)//'/ALL_WSPR.TXT',status='unknown', & position='append') xs1=0.0 xs2=0.0 fr1=0.0 fr2=0.0 nav=0 ngood=0 do ifile=iarg,nargs call getarg(ifile,infile) open(10,file=infile,status='old',access='stream') j1=index(infile,'.c2') j2=index(infile,'.wav') if(j1.gt.0) then read(10,end=999) fname,ntrmin,fMHz,c2 read(fname(8:11),*) nutc write(datetime,'(i11)') nutc else if(j2.gt.0) then read(10,end=999) ihdr,iwave read(infile(j2-4:j2-1),*) nutc datetime=infile(j2-11:j2-1) call wsprcpm_downsample(iwave,c2) else print*,'Wrong file format?' go to 999 endif close(10) fa=-100.0 fb=100.0 fs=12000.0/32.0 npts=120*12000.0/32.0 nsync=16 call getcandidate2(c2,npts,fs,fa,fb,ncand,candidates) !First approx for freq ndecodes=0 do icand=1,ncand fc0=candidates(icand,1) xsnr=candidates(icand,2) xmax=-1e32 do i=-7,7 ft=fc0+i*0.2 call noncoherent_frame_sync(c2,h,ft,isync2,is,xf1) if(xf1.gt.xmax) then xmax=xf1 fc1=ft is0=is endif enddo fcest=fc1 imode=0 ! refine freq call coherent_sync(c2,h,isyncword,nsync,NSPS,is0,fcest,imode,xp0) imode=1 ! refine istart istart=is0 call coherent_sync(c2,h,isyncword,nsync,NSPS,istart,fcest,imode,xp1) write(*,'(i5,i5,i5,6(f11.5,2x))') ifile-2,is0,istart,fc0,fc1,fcest,xf1,xp0,xp1 !genie sync !istart=375 !fcest=0.0 do ijitter=0,4 io=-10*(ijitter/2+1) if(mod(ijitter,2).eq.0) io=10*(ijitter/2) ib=max(0,istart+io) cframe=c2(ib:ib+216*200-1) call downsample2(cframe,fcest,h,cd) s2=sum(cd*conjg(cd))/(10*216) cd=cd/sqrt(s2) do nseq=1,5 if( nseq.eq.1 ) then ! noncoherent single-symbol detection sbits1=0.0 do ibit=1,216 j=isync2(ibit) ib=(ibit-1)*10 ccor(1,ibit)=sum(cd(ib:ib+9)*conjg(c1(0:9,j))) ccor(0,ibit)=sum(cd(ib:ib+9)*conjg(c0(0:9,j))) sbits1(ibit)=abs(ccor(1,ibit))-abs(ccor(0,ibit)) hbits1(ibit)=0 if(sbits1(ibit).gt.0) hbits1(ibit)=1 enddo sbits=sbits1 hbits=hbits1 sbits3=sbits1 hbits3=hbits1 elseif( nseq.ge.2 ) then ps=0 if( nseq.eq. 2 ) nbit=3 if( nseq.eq. 3 ) nbit=5 if( nseq.eq. 4 ) nbit=7 if( nseq.eq. 5 ) nbit=9 if( nseq.eq. 6 ) nbit=11 if( nseq.eq. 7 ) nbit=13 numseq=2**(nbit) do ibit=nbit/2+1,216-nbit/2 ps=0.0 pmax=0.0 do iseq=0,numseq-1 csum=0.0 cterm=1.0 k=1 do i=nbit-1,0,-1 j=isync2(ibit-(nbit/2+1)+k) ibb=iand(iseq/(2**i),1) csum=csum+ccor(ibb,ibit-(nbit/2+1)+k)*cterm cterm=cterm*conjg(cp(ibb,j)) k=k+1 enddo ps(iseq)=abs(csum) if( ps(iseq) .gt. pmax ) then pmax=ps(iseq) ibflag=1 endif enddo if( ibflag .eq. 1 ) then psbest=ps ibflag=0 endif call getmetric2(2**(nbit/2),psbest,numseq,sbits3(ibit)) hbits3(ibit)=0 if(sbits3(ibit).gt.0) hbits3(ibit)=1 enddo sbits=sbits3 hbits=hbits3 endif rxdata(1:100)=sbits(1:100) rxdata(101:200)=sbits(117:216); rxav=sum(rxdata(1:200))/200.0 rx2av=sum(rxdata(1:200)*rxdata(1:200))/200.0 rxsig=sqrt(rx2av-rxav*rxav) rxdata=rxdata/rxsig sigma=0.90 llr(201:204)=-5.0 llr(1:200)=2*rxdata/(sigma*sigma) apmask=0 apmask(201:204)=1 max_iterations=40 ifer=0 call bpdecode204(llr,apmask,max_iterations,decoded,cw,nharderror,niterations) nhardmin=-1 if(nharderror.lt.0) call osd204(llr,apmask,4,decoded,cw,nhardmin,dmin) if(sum(decoded).eq.0) cycle if(nhardmin.ge.0 .or. nharderror.ge.0) then idat=0 write(dmsg,'(68i1)') decoded read(dmsg(1:50),'(6b8.8,b2.2)') idat(1:7) idat(7)=idat(7)*64 read(dmsg(51:64),'(b14.14)') ndec_crc ncalc_crc=iand(crc14(c_loc(idat),9),z'FFFF') nbadcrc=1 if(ncalc_crc .eq. ndec_crc) nbadcrc=0 else cycle endif if( nbadcrc.eq.0 ) then write(cbits,1200) decoded(1:50) 1200 format(50i1) read(cbits,1202) idat 1202 format(8b8,b4) idat(7)=ishft(idat(7),6) call wqdecode(idat,message,itype) idupe=0 do i=1,ndecodes if(decodes(i).eq.message) idupe=1 enddo if(idupe.eq.1) goto 888 ndecodes=ndecodes+1 decodes(ndecodes)=message nsnr=nint(xsnr) freq=fMHz + 1.d-6*(fc1+fbest) nfdot=0 write(13,1210) datetime,0,nsnr,xdt,freq,message,nfdot 1210 format(a11,2i4,f6.2,f12.7,2x,a22,i3) write(*,1212) datetime(8:11),nsnr,xdt,freq,nfdot,message,'*',nseq,ijitter,nharderror,nhardmin 1212 format(a4,i4,f5.1,f11.6,i3,2x,a22,a1,i5,i5,i5,i5) goto 888 endif enddo ! nseq enddo !jitter 888 continue enddo !candidate list enddo !files write(*,1120) 1120 format("") 999 end program wsprcpmd subroutine coherent_sync(c2,h,isyncword,nsync,nsps,istart,fc,imode,xmax) ! imode=0: refine fc using given istart ! imode=1: refine istart using given fc complex c2(0:120*12000/32-1) complex csync(0:16*200-1) complex ctmp1(0:4*16*200-1) complex ctwkp(0:16*200-1) complex ccohp(0:15) integer isyncword(nsync) logical first/.true./ save dt,first,twopi,csync if(first) then baud=12000.0/6400.0 dt=32.0/12000.0 twopi=8.0*atan(1.0) k=0 phi=0.0 dphi=twopi*baud*0.5*h*dt do i=1,16 dp=dphi*2*(isyncword(i)-1.5) do j=1,200 csync(k)=cmplx(cos(phi),sin(phi)) phi=mod(phi+dp,twopi) k=k+1 enddo enddo first=.false. endif dphi=twopi*fc*dt ctwkp=cmplx(0.0,0.0) phi=0 do i=0,nsync*nsps-1 ctwkp(i)=csync(i)*cmplx(cos(phi),sin(phi)) phi=mod(phi+dphi,twopi) enddo ipstart=istart+100*200 ctmp1=0.0 xmax=0.0 if(imode.eq.1) then !refine DT with given fc do iii=-50,50,5 ctmp1(0:16*200-1)=c2(ipstart+iii:ipstart+iii+16*200-1)*conjg(ctwkp) xnorm=sqrt(sum(abs(ctmp1(0:16*200-1))**2))*sqrt(16.0*200.0) xc=abs(sum(ctmp1))/xnorm if(xc.gt.xmax) then iiibest=iii xmax=xc endif enddo istart=istart+iiibest return endif ! else refine fc with given DT ctmp1(0:16*200-1)=c2(ipstart:ipstart+16*200-1)*conjg(ctwkp) xnorm=sqrt(sum(abs(ctmp1(0:16*200-1))**2))*sqrt(16.0*200.0) ctmp1=ctmp1/xnorm call four2a(ctmp1,4*16*200,1,-1,1) !c2c FFT to freq domain xmax=0.0 ctmp1=cshift(ctmp1,-200) dfp=1/(4*6400.0/12000.0*16) ! do i=150,250 do i=190,210 xa=abs(ctmp1(i)) !write(51,*) (i-200)*dfp,xa if(xa.gt.xmax) then ishift=i xmax=xa endif enddo delta=(ishift-200)*dfp xm1=abs(ctmp1(ishift-1)) x0=abs(ctmp1(ishift)) xp1=abs(ctmp1(ishift+1)) xint=(log(xm1)-log(xp1))/(log(xm1)+log(xp1)-2*log(x0)) delta2=delta+xint*dfp/2.0 fc=fc+delta2 return end subroutine coherent_sync subroutine noncoherent_frame_sync(c2,h,fc,isync2,istart,ssmax) complex c2(0:120*12000/32-1) complex ct0(0:199),ct1(0:199),ct2(0:199),ct3(0:199) integer isync2(216) twopi=8.0*atan(1.0) dt=32.0/12000.0 baud=12000.0/6400.0 imax=370 ! defines dt search range (375 samples/s) ssmax=-1e32 izero=375 do it = -imax,imax,5 ! noncoherent wspr-type dt estimation dp0=twopi*(fc-1.5*h*baud)*dt dp1=twopi*(fc-0.5*h*baud)*dt dp2=twopi*(fc+0.5*h*baud)*dt dp3=twopi*(fc+1.5*h*baud)*dt th0=0.0 th1=0.0 th2=0.0 th3=0.0 do i=0,199 ct0(i)=cmplx(cos(th0),sin(th0)) ct1(i)=cmplx(cos(th1),sin(th1)) ct2(i)=cmplx(cos(th2),sin(th2)) ct3(i)=cmplx(cos(th3),sin(th3)) th0=mod(th0+dp0,twopi) th1=mod(th1+dp1,twopi) th2=mod(th2+dp2,twopi) th3=mod(th3+dp3,twopi) enddo xs=0.0 xn=0.0 do is=1,216 i0=izero+it+(is-1)*200 p0=abs(sum(c2(i0:i0+199)*conjg(ct0))) p1=abs(sum(c2(i0:i0+199)*conjg(ct1))) p2=abs(sum(c2(i0:i0+199)*conjg(ct2))) p3=abs(sum(c2(i0:i0+199)*conjg(ct3))) p0=p0**2 p1=p1**2 p2=p2**2 p3=p3**2 if(isync2(is).eq.0) then ! xs=xs+(p0+p2)/2.0 xs=xs+max(p0,p2) xn=xn+(p1+p3)/2.0 elseif(isync2(is).eq.1) then ! xs=xs+(p1+p3)/2.0 xs=xs+max(p1,p3) xn=xn+(p0+p2)/2.0 endif enddo sy=xs/xn !write(41,*) it,sy if(sy.gt.ssmax) then ioffset=it ssmax=sy endif enddo istart=izero+ioffset return end subroutine noncoherent_frame_sync subroutine getmetric2(ib,ps,ns,xmet) real ps(0:ns-1) xm1=0 xm0=0 do i=0,ns-1 if( iand(i/ib,1) .eq. 1 .and. ps(i) .gt. xm1 ) xm1=ps(i) if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) xm0=ps(i) enddo xmet=xm1-xm0 return end subroutine getmetric2 subroutine downsample2(ci,f0,h,co) parameter(NI=216*200,NH=NI/2,NO=NI/20) ! downsample from 200 samples per symbol to 10 complex ci(0:NI-1),ct(0:NI-1) complex co(0:NO-1) fs=12000.0/32.0 df=fs/NI ct=ci call four2a(ct,NI,1,-1,1) !c2c FFT to freq domain i0=nint(f0/df) ct=cshift(ct,i0) co=0.0 co(0)=ct(0) b=max(1.0,h)*8.0 do i=1,NO/2 arg=(i*df/b)**2 filt=exp(-arg) co(i)=ct(i)*filt co(NO-i)=ct(NI-i)*filt enddo co=co/NO call four2a(co,NO,1,1,1) !c2c FFT back to time domain return end subroutine downsample2 subroutine getcandidate2(c,npts,fs,fa,fb,ncand,candidates) parameter(NDAT=200,NFFT1=120*12000/32,NH1=NFFT1/2,NFFT2=120*12000/320,NH2=NFFT2/2) complex c(0:npts-1) !Complex waveform complex cc(0:NFFT1-1) complex csfil(0:NFFT2-1) complex cwork(0:NFFT2-1) real bigspec(0:NFFT2-1) complex c2(0:NFFT1-1) !Short spectra real s(-NH1+1:NH1) !Coarse spectrum real ss(-NH1+1:NH1) !Smoothed coarse spectrum real candidates(100,2) integer indx(NFFT2-1) logical first data first/.true./ save first,w,df,csfil if(first) then df=10*fs/NFFT1 csfil=cmplx(0.0,0.0) do i=0,NFFT2-1 csfil(i)=exp(-((i-NH2)/32.0)**2) ! revisit this enddo csfil=cshift(csfil,NH2) call four2a(csfil,NFFT2,1,-1,1) first=.false. endif cc=cmplx(0.0,0.0) cc(0:npts-1)=c; call four2a(cc,NFFT1,1,-1,1) cc=abs(cc)**2 call four2a(cc,NFFT1,1,-1,1) cwork(0:NH2)=cc(0:NH2)*conjg(csfil(0:NH2)) cwork(NH2+1:NFFT2-1)=cc(NFFT1-NH2+1:NFFT1-1)*conjg(csfil(NH2+1:NFFT2-1)) call four2a(cwork,NFFT2,1,+1,1) bigspec=cshift(real(cwork),-NH2) il=NH2+fa/df ih=NH2+fb/df nnl=ih-il+1 call indexx(bigspec(il:il+nnl-1),nnl,indx) xn=bigspec(il-1+indx(nint(0.3*nnl))) bigspec=bigspec/xn ncand=0 do i=il,ih if((bigspec(i).gt.bigspec(i-1)).and. & (bigspec(i).gt.bigspec(i+1)).and. & (bigspec(i).gt.1.12).and.ncand.lt.100) then ncand=ncand+1 candidates(ncand,1)=df*(i-NH2) candidates(ncand,2)=10*log10(bigspec(i)-1)-26.0 endif enddo return end subroutine getcandidate2 subroutine wsprcpm_downsample(iwave,c) ! Input: i*2 data in iwave() at sample rate 12000 Hz ! Output: Complex data in c(), sampled at 400 Hz include 'wsprcpm_params.f90' parameter (NMAX=120*12000,NFFT2=NMAX/32) integer*2 iwave(NMAX) complex c(0:NMAX/32-1) complex c1(0:NFFT2-1) complex cx(0:NMAX/2) real x(NMAX) equivalence (x,cx) df=12000.0/NMAX x=iwave call four2a(x,NMAX,1,-1,0) !r2c FFT to freq domain i0=nint(1500.0/df) c1(0)=cx(i0) do i=1,NFFT2/2 c1(i)=cx(i0+i) c1(NFFT2-i)=cx(i0-i) enddo c1=c1/NFFT2 call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain c=c1(0:NMAX/32-1) return end subroutine wsprcpm_downsample