program wsprdpskd ! Decode WSPRDPSK data read from *.c2 or *.wav files. ! 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 'wsprdpsk_params.f90' parameter(NMAX=120*12000) character arg*8,message*22,cbits*50,infile*80,fname*16,datetime*11 character*22 decodes(100) character*120 data_dir character*32 uwbits character*68 dmsg complex c2(0:120*12000/30-1) !Complex waveform complex cframe(0:232*200-1) !Complex waveform complex cd(0:240*10-1) !Complex waveform complex cs(0:240) complex c1(0:9,0:1),c0(0:9,0:1) complex ccor(0:1,232) complex csum,cterm real*8 fMHz real rxdata(ND),llr(204) !Soft symbols real sbits(232),sbits1(232),sbits3(232) real ps(0:8191),psbest(0:8191) real candidates(100,2) integer iuniqueword0 integer isync(200) !Unique word integer isync2(232) integer ipreamble(16) !Preamble vector 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(232),hbits1(232),hbits3(232) integer*1 b(14),bbest(14) data ipreamble/1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1/ data iuniqueword0/z'30C9E8AD'/ write(uwbits,'(b32.32)') iuniqueword0 read(uwbits,'(32i1)') isync(1:32) read(uwbits,'(32i1)') isync(33:64) read(uwbits,'(32i1)') isync(65:96) read(uwbits,'(32i1)') isync(97:128) read(uwbits,'(32i1)') isync(129:160) read(uwbits,'(32i1)') isync(161:192) read(uwbits,'(8i1)') isync(193:200) 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=1.00 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading) twopi=8.0*atan(1.0) isync2(1:100)=isync(1:100) isync2(101:104)=0 ! This is *not* backwards. isync2(105:112)=1 isync2(113:116)=0 isync2(117:216)=isync(101:200) dphi=twopi*baud*(h/2.0)*dt*20 ! dt*20 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 enddo nargs=iargc() if(nargs.lt.1) then print*,'Usage: wsprdpskd [-a ] [-f fMHz] [-c ncoh] 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 npdi=16 if(arg(1:2).eq.'-c') then call getarg(iarg+1,arg) read(arg,*) ncoh iarg=iarg+2 npdi=16/ncoh endif ! write(*,*) 'ncoh: ',ncoh,' npdi: ',npdi 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 wsprdpsk_downsample(iwave,c2) else print*,'Wrong file format?' go to 999 endif close(10) fa=-10.0 fb=10.0 fs=12000.0/30.0 npts=120*12000.0/30.0 ! call getcandidate2(c2,npts,fs,fa,fb,ncand,candidates) !First approx for freq ncand=1 candidates(1,1)=0.0 candidates(1,2)=-28 ndecodes=0 do icand=1,ncand fc0=candidates(icand,1) xsnr=candidates(icand,2) call dsdpsk(c2,fc0,cd) i0=40 do i=0,231 cs(i)=cd(i0+10*i)/5e4 enddo ! 2-bit differential detection do i=1,231 ! do i=1,232 sbits(i)=-real(cs(i)*conjg(cs(i-1))) !2 symbol dpsk ! sbits(i)=real(cs(i-1)) !for coherent dpsk ! sbits(i)=real(cs(i)) !for coherent bpsk enddo ! do i=1,231 ! sbits3(i)=-sbits(i+1)*sbits(i) ! for coherent dpsk ! enddo ! detect a differentially encoded block of symbols using the ! Divsalar and Simon approach, except that we estimate only ! the central symbol of the block and then step the block forward ! by one symbol. ! sbits3=sbits !goto 100 nbit=13 ! number of decoded bits to be derived from nbit+1 symbols numseq=2**nbit il=(nbit+1)/2 ih=231-nbit/2 do isym=il,ih rmax=-1e32 b=0 do iseq=0,numseq-1 do i=1,nbit b(i)=merge(1,0,iand(iseq,2**(nbit-i))>0) enddo b(1:nbit)=2*b(1:nbit)-1 i1=isym-(nbit+1)/2 csum=cs(i1) do i=1,nbit bb=1 do m=1,i bb=bb*b(m) enddo csum=csum+bb*cs(i1+i) enddo ! ps(iseq)=abs(csum)**2 ps(iseq)=abs(csum) if(ps(iseq).gt.rmax) then bbest=b rmax=ps(iseq) endif enddo if(isym.eq.il) then do i=1,isym-1 call getmetric(2**(nbit-i),ps,numseq,xmet) sbits3(i)=-xmet enddo endif call getmetric(2**((nbit-1)/2),ps,numseq,xmet) sbits3(isym)=-xmet if(isym.eq.ih) then do i=ih+1,231 call getmetric(2**(231-i),ps,numseq,xmet) sbits3(i)=-xmet enddo endif enddo 100 continue rxdata(1:100)=sbits3(1:100) rxdata(101:200)=sbits3(132:231); 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,5,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,'*',idf,nseq,ijitter,nharderror,nhardmin 1212 format(a4,i4,f5.1,f11.6,i3,2x,a22,a1,i5,i5,i5,i5,i5) goto 888 endif 888 continue enddo !candidate list enddo !files write(*,1120) 1120 format("") 999 end program wsprdpskd subroutine getmetric(ib,ps,ns,xmet) real ps(0:ns-1) xm1=-1e32 xm0=-1e32 do i=0,ns-1 if( iand(i/ib,1) .eq. 1 .and. ps(i) .gt. xm1 ) then xm1=ps(i) endif if( iand(i/ib,1) .eq. 0 .and. ps(i) .gt. xm0 ) then xm0=ps(i) endif enddo xmet=xm1-xm0 return end subroutine getmetric subroutine getmetric3(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 ) then xm1=xm1+ps(i) endif if( iand(i/ib,1) .eq. 0 ) then xm0=xm0+ps(i) endif enddo xmet=xm1-xm0 return end subroutine getmetric3 subroutine dsdpsk(ci,f0,co) parameter(NI=240*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) pi=4.0*atan(1.0) fs=12000.0/30.0 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) dt=20/fs beta=1.0 tt=10*dt baud=1/tt bw=(1+beta)*baud/2.0 bf=(1-beta)*baud/2.0 iw=bw/df if=bf/df co=0.0 co(0)=ct(0) do i=1,iw filt=((1.0+cos(pi*(i-if)/(iw-if)))/2.0)**0.5 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 dsdpsk subroutine getcandidate2(c,npts,fs,fa,fb,ncand,candidates) parameter(NDAT=200,NFFT1=120*12000/30,NH1=NFFT1/2,NFFT2=120*12000/300,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)/20.0)**2) 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.1.15).and.ncand.lt.100) then ncand=ncand+1 candidates(ncand,1)=df*(i-NH2) candidates(ncand,2)=10*log10(bigspec(i))-30.0 endif enddo ! do i=1,ncand ! write(*,*) i,candidates(i,1),candidates(i,2) ! enddo return end subroutine getcandidate2 subroutine wsprdpsk_downsample(iwave,c) ! Input: i*2 data in iwave() at sample rate 12000 Hz ! Output: Complex data in c(), sampled at 400 Hz include 'wsprdpsk_params.f90' parameter (NMAX=120*12000,NFFT2=NMAX/30) integer*2 iwave(NMAX) complex c(0:NMAX/30-1) 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/30-1) return end subroutine wsprdpsk_downsample