WSJT-X/lib/fsk4hf/wsprcpmd.f90

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Fortran
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program wsprcpmd
! Decode WSPRCPM data read from *.c2 or *.wav files.
! WSPRCPM is a WSPR-like mode based on full-response CPM.
!
! Modulation Capabilities include:
! support for multi-h cpm with two modulation indexes: [h1,h2].
! h1,h2 (modulation index) are variable; h1=h2=0.5 is MSK, h1=h2=1.0 is standard
! fsk intended for noncoherent demodulation.
! demodulator uses noncoherent sequence detection with variable window size.
! symbol demodulation is done symbol-by-symbol - each symbol is
! estimated using a data frame comprising N symbol intervals, where N can
! be 1, 3, 5, 7, 9, 11. The central symbol is estimated and then the window
! is stepped forward by one symbol.
! soft symbols are decoded by log-domain belief propagation followed by ordered-
! statistics decoding.
!
! 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:
! s32 d200 p32 (264) 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*120 data_dir
character*32 uwbits
character*68 dmsg
complex csync(0:32*100-1) !Sync symbols only, from cbb
complex cpreamble(0:32*100-1) !Sync symbols only, from cbb
complex cp2(0:32*100-1)
complex ctwks(0:32*100-1)
complex ctwkp(0:32*100-1)
complex c2(0:120*12000/53-1) !Complex waveform
complex ctmp(0:4*32*100-1)
complex cframe(0:264*100-1) !Complex waveform
complex cd(0:264*100-1) !Complex waveform
complex c1(0:9,1:2),c0(0:9,1:2)
complex ccor(0:1,264)
complex csum,cp(0:1,1:2),cterm
complex ccohs(0:31)
complex ccohp(0:31)
real*8 fMHz
real rxdata(ND),llr(204) !Soft symbols
real sbits(264),sbits1(264),sbits3(264)
real ps(0:8191),psbest(0:8191)
integer iuniqueword0
integer isync(32) !Unique word
integer ipreamble(32) !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(264),hbits1(264),hbits3(264)
data ipreamble/1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1/
data iuniqueword0/z'30C9E8AD'/
write(uwbits,'(b32.32)') iuniqueword0
read(uwbits,'(32i1)') isync
ipreamble=2*ipreamble-1
isync=2*isync-1
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)
h1=0.80 !h=0.8 seems to be optimum for AWGN sensitivity (not for fading)
h2=0.80
twopi=8.0*atan(1.0)
dphi11=twopi*baud*(h1/2.0)*dt
dphi01=-twopi*baud*(h1/2.0)*dt
dphi12=twopi*baud*(h2/2.0)*dt
dphi02=-twopi*baud*(h2/2.0)*dt
k=0
phi=0.0
do i=1,32
if( mod(i,2) .eq. 0 ) then
dphi1=dphi11
dphi0=dphi01
else
dphi1=dphi12
dphi0=dphi02
endif
dphi=dphi0
if( isync(i) .eq. 1 ) dphi=dphi1
do j=1,100
phi=mod(phi+dphi,twopi)
csync(k)=cmplx(cos(phi),sin(phi))
k=k+1
enddo
enddo
k=0
phi=0.0
do i=1,32
if( mod(i,2) .eq. 0 ) then
dphi1=dphi11
dphi0=dphi01
else
dphi1=dphi12
dphi0=dphi02
endif
dphi=dphi0
if( ipreamble(i) .eq. 1 ) dphi=dphi1
do j=1,100
phi=mod(phi+dphi,twopi)
cpreamble(k)=cmplx(cos(phi),sin(phi))
k=k+1
enddo
enddo
dphi1=twopi*baud*(h1/2.0)*dt*10 ! dt*10 is samp interval after downsample
dphi2=twopi*baud*(h2/2.0)*dt*10 ! dt*10 is samp interval after downsample
cp(1,1)=cmplx(cos(dphi1*10),sin(dphi1*10))
cp(0,1)=conjg(cp(1,1))
cp(1,2)=cmplx(cos(dphi2*10),sin(dphi2*10))
cp(0,2)=conjg(cp(1,2))
do j=1,2
if( j.eq.1 ) then
dphi=dphi1
else
dphi=dphi2
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+dphi,twopi)
phi0=mod(phi0-dphi,twopi)
enddo
enddo
nargs=iargc()
if(nargs.lt.1) then
print*,'Usage: wsprcpmd [-a <data_dir>] [-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=32
if(arg(1:2).eq.'-c') then
call getarg(iarg+1,arg)
read(arg,*) ncoh
iarg=iarg+2
npdi=32/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 wsprcpm_downsample(iwave,c2)
else
print*,'Wrong file format?'
go to 999
endif
close(10)
fa=-100.0
fb=100.0
fs=12000.0/53.0
npts=120*12000/53
nsync=32
call getcandidate2(c2,npts,fs,fa,fb,fc1,xsnr) !First approx for freq
fcest=fc1
do iii=1,2
izero=226
dphi=twopi*fcest*dt
ctwks=cmplx(0.0,0.0)
ctwkp=cmplx(0.0,0.0)
phi=0
do i=0,nsync*NSPS-1
phi=mod(phi+dphi,twopi)
ctwks(i)=csync(i)*cmplx(cos(phi),sin(phi))
ctwkp(i)=cpreamble(i)*cmplx(cos(phi),sin(phi))
enddo
imax=100
xcmax=-1e32
do it = -imax,imax
its=izero+it
ccohs=0.0
do k=0,npdi-1
is=k*ncoh*nsps
ccohs(k)=sum(c2(its+is:its+is+ncoh*nsps-1)*conjg(ctwks(is:is+ncoh*nsps-1)))
ccohs(k)=ccohs(k)/(ncoh*nsps)
enddo
! term1=sum(abs(ccohs(0:npdi-1))**2)
itp=izero+it+232*100
ccohp=0.0
do k=0,npdi-1
is=k*ncoh*nsps
ccohp(k)=sum(c2(itp+is:itp+is+ncoh*nsps-1)*conjg(ctwkp(is:is+ncoh*nsps-1)))
ccohp(k)=ccohp(k)/(ncoh*nsps)
enddo
csum=0.0
terms=0.0
do n=1,npdi-1
do k=n,npdi-1
csum=csum+ccohs(k)*conjg(ccohs(k-n))
enddo
terms=terms+abs(csum)
enddo
csum=0.0
termp=0.0
do n=1,npdi-1
do k=n,npdi-1
csum=csum+ccohp(k)*conjg(ccohp(k-n))
enddo
termp=termp+abs(csum)
enddo
!write(23,*) it,terms,termp
xmetric=sqrt(terms*termp)
if( xmetric .gt. xcmax ) then
xcmax=xmetric
ibestt=it
endif
enddo
istart=izero+ibestt
if(iii .eq. 2) goto 887
ctmp=0.0
ctmp(0:32*100-1)=c2(istart+232*100:istart+264*100-1)*conjg(ctwkp)
call four2a(ctmp,4*32*100,1,-1,1) !c2c FFT to freq domain
xmax=0.0
ctmp=cshift(ctmp,-200)
do i=150,250
xa=abs(ctmp(i))
if(xa.gt.xmax) then
ishift=i
xmax=xa
endif
enddo
dfp=1/(4*5300.0/12000.0*32)
delta=(ishift-200)*dfp
! need to add bounds protection
xm1=abs(ctmp(ishift-1))
x0=abs(ctmp(ishift))
xp1=abs(ctmp(ishift+1))
xint=(log(xm1)-log(xp1))/(log(xm1)+log(xp1)-2*log(x0))
delta2=delta+xint*dfp/2.0
fcest=fcest+delta2
enddo
887 write(*,'(i4,i5,5(2x,f9.5))') ifile,istart,xcmax,fc1,fcest
xdt=(istart-226)/100.0
if(abs(xdt).le.0.1) ngood=ngood+1
xs1=xs1+xdt
xs2=xs2+xdt**2
fr1=fr1+fc1
fr2=fr2+fc1**2
nav=nav+1
!**************
! fcest=0.0
! istart=226
do ijitter=0,2
io=ijitter
if(ijitter.eq.2) io=-1
cframe=c2(istart+io:istart+io+264*100-1)
call downsample2(cframe,fcest,cd)
dts=10*dt
s2=sum(cd*conjg(cd))/(10*264)
cd=cd/sqrt(s2)
do nseq=1,7
if( nseq.eq.1 ) then ! noncoherent single-symbol detection
sbits1=0.0
do ibit=1,264
if( mod(ibit,2).eq.0 ) j=1
if( mod(ibit,2).eq.1 ) j=2
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+1,264-nbit/2
ps=0.0
pmax=0.0
do iseq=0,numseq-1
csum=0.0
cterm=cmplx(1.0,0.0)
k=1
do i=nbit-1,0,-1
ibb=iand(iseq/(2**i),1)
csum=csum+ccor(ibb,ibit-(nbit/2+1)+k)*cterm
if( mod(ibit-(nbit/2+1)+k,2) .eq. 0 ) j=1
if( mod(ibit-(nbit/2+1)+k,2) .eq. 1 ) j=2
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(1:200)=sbits(33:232)
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)
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
enddo ! nseq
enddo !jitter
888 continue
enddo !files
avshift=xs1/nav
varshift=xs2/nav
stdshift=sqrt(varshift-avshift**2)
avfr=fr1/nav
varfr=fr2/nav
stdfr=sqrt(varfr-avfr**2)
write(*,*) 'ngood: ',ngood
write(*,'(a7,f7.3,f7.3)') 'shift: ',avshift,stdshift
write(*,*) 'freq: ',avfr,stdfr
write(*,1120)
1120 format("<DecodeFinished>")
999 end program wsprcpmd
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,co)
parameter(NI=264*100,NH=NI/2,NO=NI/10) ! downsample from 100 samples per symbol to 10
complex ci(0:NI-1),ct(0:NI-1)
complex co(0:NO-1)
fs=12000.0/53.0
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=3.4*0.875/0.715
! b=2.6*0.5625/0.715
b=12.0
do i=1,NO/2
arg=(i*df/b)**2
filt=exp(-arg)
! filt=0.0
! if( i*df .le. b ) filt=1.0
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,fc1,xsnr)
parameter(NDAT=100,NFFT1=8*NDAT,NH1=NFFT1/2)
complex c(0:npts-1) !Complex waveform
complex c2(0:NFFT1-1) !Short spectra
real s(-NH1+1:NH1) !Coarse spectrum
real ss(-NH1+1:NH1) !Smoothed coarse spectrum
real w(0:NFFT1-1)
real pi
logical first
data first/.true./
save first,w
if(first) then
pi=4.0*atan(1.0)
do i=0,NFFT1-1
w(i)=sin(pi*i/(NDAT-1))**2
enddo
first=.false.
endif
nspec=int((npts-NFFT1)/NDAT)+1
df1=fs/NFFT1
s=0.
do k=1,nspec
ia=(k-1)*NDAT
ib=ia+NFFT1-1
c2(0:NFFT1-1)=c(ia:ib)*w
call four2a(c2,NFFT1,1,-1,1)
do i=0,NFFT1-1
j=i
if(j.gt.NH1) j=j-NFFT1
s(j)=s(j) + real(c2(i))**2 + aimag(c2(i))**2
enddo
enddo
do i=-NH1+1+4,NH1-4
ss(i)=sum(s(i-4:i+4))/9.0
enddo
! do i=-NH1+1+8,NH1-8
! ss(i)=sum(ss(i-4:i+4))/9.0
! enddo
do i=-20,20
write(52,*) i*df1,ss(i)
enddo
smax=0.
ipk=0
fc1=0.
ia=nint(fa/df1)
ib=nint(fb/df1)
do i=ia,ib
f=i*df1
if(ss(i).gt.smax) then
smax=ss(i)
ipk=i
fc1=f
endif
enddo
xint=(log(ss(ipk-1))-log(ss(ipk+1)))/(log(ss(ipk-1))+log(ss(ipk+1))-2*log(ss(ipk)))
fc1=fc1+xint*df1/2.0
! The following is for testing SNR calibration:
sp3n=sum(s(ipk-5:ipk+5))
base=(sum(s)-sp3n)/(NFFT1-11.0)
psig=sp3n-11*base
pnoise=(2500.0/df1)*base
xsnr=db(psig/pnoise)
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/53)
integer*2 iwave(NMAX)
complex c(0:NZ-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:NZ-1)
return
end subroutine wsprcpm_downsample