program wspr5d ! Decode WSPR-LF data read from *.c5 or *.wav files. ! WSPR-LF is a potential WSPR-like mode intended for use at LF and MF. ! It uses an LDPC (300,60) code, OQPSK modulation, and 5 minute T/R sequences. ! Reception and Demodulation algorithm: ! 1. Compute coarse spectrum; find fc1 = approx carrier freq ! 2. Mix from fc1 to 0; LPF at +/- 0.75*R ! 3. Square, FFT; find peaks near -R/2 and +R/2 to get fc2 ! 4. Mix from fc2 to 0 ! 5. Fit cb13 (central part of csync) to c -> lag, phase ! 6. Fit complex ploynomial for channel equalization ! 7. Get soft bits from equalized data ! Still to do: find and decode more than one signal in the specified passband. include 'wsprlf_params.f90' parameter (NMAX=300*12000) character arg*8,message*22,cbits*50,infile*80,fname*16,datetime*11 character*120 data_dir complex csync(0:NZ-1) !Sync symbols only, from cbb complex c(0:NZ-1) !Complex waveform complex c1(0:NZ-1) !Complex waveform complex zz(NS+ND) !Complex symbol values (intermediate) complex z real*8 fMHz real rxdata(ND),llr(ND) !Soft symbols real pp(2*NSPS) !Shaped pulse for OQPSK real a(5) !For twkfreq1 real aa(20),bb(20) !Fitted polyco's real fpks(20) integer id(NS+ND) !NRZ values (+/-1) for Sync and Data integer ierror(NS+ND) integer isync(48) !Long sync vector integer ib13(13) !Barker 13 code integer ihdr(11) integer*8 n8 integer*2 iwave(NMAX) !Generated full-length waveform integer*1 idat(7) integer*1 decoded(KK),apmask(ND),cw(ND) data ib13/1,1,1,1,1,-1,-1,1,1,-1,1,-1,1/ nargs=iargc() if(nargs.lt.2) then print*,'Usage: wspr5d [-a ] [-f fMHz] 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 open(13,file=trim(data_dir)//'/ALL_WSPR.TXT',status='unknown', & position='append') maxn=8 !Default value twopi=8.0*atan(1.0) fs=NSPS*12000.0/NSPS0 !Sample rate dt=1.0/fs !Sample interval (s) tt=NSPS*dt !Duration of "itone" symbols (s) ts=2*NSPS*dt !Duration of OQPSK symbols (s) baud=1.0/tt !Keying rate for "itone" symbols (baud) txt=NZ*dt !Transmission length (s) do i=1,N2 !Half-sine pulse shape pp(i)=sin(0.5*(i-1)*twopi/(2*NSPS)) enddo n8=z'cbf089223a51' do i=1,48 isync(i)=-1 if(iand(n8,1).eq.1) isync(i)=1 n8=n8/2 enddo ! Define array id() for sync symbols id=0 do j=1,48 !First group of 48 id(2*j-1)=2*isync(j) enddo do j=1,13 !Barker 13 code id(j+96)=2*ib13(j) enddo do j=1,48 !Second group of 48 id(2*j+109)=2*isync(j) enddo csync=0. do j=1,205 if(abs(id(j)).eq.2) then ia=nint((j-0.5)*N2) ib=ia+N2-1 csync(ia:ib)=pp*id(j)/abs(id(j)) endif enddo do ifile=iarg,nargs call getarg(ifile,infile) open(10,file=infile,status='old',access='stream') j1=index(infile,'.c5') j2=index(infile,'.wav') if(j1.gt.0) then read(10,end=999) fname,ntrmin,fMHz,c 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 wspr5_downsample(iwave,c) else print*,'Wrong file format?' go to 999 endif close(10) fa=100.0 fb=150.0 call getfc1w(c,fs,fa,fb,fc1,xsnr) !First approx for freq npeaks=20 call getfc2w(c,csync,npeaks,fs,fc1,fpks) !Refined freq a(1)=-fc1 a(2:5)=0. call twkfreq1(c,NZ,fs,a,c) !Mix c down by fc1+fc2 ! Find time offset xdt amax=0. jpk=0 iaa=0 ibb=NZ-1 jmax=1260 do j=-jmax,jmax,NSPS/8 ia=j ib=NZ-1+j if(ia.lt.0) then ia=0 iaa=-j else iaa=0 endif if(ib.gt.NZ-1) then ib=NZ-1 ibb=NZ-1-j endif z=sum(c(ia:ib)*conjg(csync(iaa:ibb))) write(51,*) j/fs,real(z),imag(z) if(abs(z).gt.amax) then amax=abs(z) jpk=j endif enddo xdt=jpk/fs xdt=1.0 jpk=fs*xdt do i=0,NZ-1 j=i+jpk if(j.ge.0 .and. j.lt.NZ) c1(i)=c(j) enddo nterms=maxn do itry=1,npeaks nhard0=0 nhardsync0=0 ifer=1 a(1)=-fpks(itry) a(2:5)=0. call twkfreq1(c1,NZ,fs,a,c) !Mix c1 into c call cpolyfitw(c,pp,id,maxn,aa,bb,zz,nhs) call msksoftsymw(zz,aa,bb,id,nterms,ierror,rxdata,nhard0,nhardsync0) if(nhardsync0.gt.35) cycle rxav=sum(rxdata)/ND rx2av=sum(rxdata*rxdata)/ND rxsig=sqrt(rx2av-rxav*rxav) rxdata=rxdata/rxsig ss=0.84 llr=2.0*rxdata/(ss*ss) apmask=0 max_iterations=40 ifer=0 call bpdecode300(llr,apmask,max_iterations,decoded,niterations,cw) if(niterations.lt.0) call osd300(llr,4,decoded,niterations,cw) nbadcrc=0 if(niterations.ge.0) call chkcrc10(decoded,nbadcrc) if(niterations.lt.0 .or. nbadcrc.ne.0) ifer=1 if(ifer.eq.0) exit enddo !Freq dither loop message=' ' if(ifer.eq.0) then write(cbits,1100) decoded(1:50) 1100 format(50i1) read(cbits,1102) idat 1102 format(6b8,b2) idat(7)=ishft(idat(7),6) call wqdecode(idat,message,itype) nsnr=nint(xsnr) ! freq=fMHz + 1.d-6*(fc1+fc2) freq=fMHz + 1.d-6*(fc1+fpks(itry)) nfdot=0 write(13,1110) datetime,0,nsnr,xdt,freq,message,nfdot 1110 format(a11,2i4,f6.2,f12.7,2x,a22,i3) write(*,1112) datetime(8:11),nsnr,xdt,freq,nfdot,message,itry 1112 format(a4,i4,f5.1,f11.6,i3,2x,a22,i4) endif enddo ! ifile loop write(*,1120) 1120 format("") 999 end program wspr5d