mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-12-24 11:40:31 -05:00
new combined detector/demodulator/decoder routine for msk144
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6768 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
f585500505
commit
d45dc65a87
373
lib/detectmsk144.f90
Normal file
373
lib/detectmsk144.f90
Normal file
@ -0,0 +1,373 @@
|
||||
subroutine detectmsk144(cbig,n,pchk_file,lines,nmessages,nutc)
|
||||
!nutc and t0 are for debug output
|
||||
use iso_c_binding, only: c_loc,c_size_t
|
||||
use packjt
|
||||
use hashing
|
||||
use timer_module, only: timer
|
||||
|
||||
parameter (NSPM=864, NPTS=3*NSPM)
|
||||
character*22 msgreceived,allmessages(20)
|
||||
character*80 lines(100)
|
||||
character*512 pchk_file,gen_file
|
||||
complex cbig(n)
|
||||
complex cdat(NPTS) !Analytic signal
|
||||
complex cdat2(NPTS)
|
||||
complex c(NSPM)
|
||||
complex ctmp(6000)
|
||||
complex cb(42) !Complex waveform for sync word
|
||||
complex cfac,cca,ccb
|
||||
complex cc(NPTS)
|
||||
complex cc1(NPTS)
|
||||
complex cc2(NPTS)
|
||||
complex bb(6)
|
||||
integer s8(8),hardbits(144)
|
||||
integer*1, target:: i1Dec8BitBytes(10)
|
||||
integer, dimension(1) :: iloc
|
||||
integer*4 i4Dec6BitWords(12)
|
||||
integer*1 decoded(80)
|
||||
integer*1 i1hashdec
|
||||
integer indices(700)
|
||||
integer ipeaks(10)
|
||||
logical ismask(6000)
|
||||
real cbi(42),cbq(42)
|
||||
real detmet(700)
|
||||
real detfer(700)
|
||||
real tonespec(6000)
|
||||
real rcw(12)
|
||||
real dd(NPTS)
|
||||
real ferrs(20)
|
||||
real pp(12) !Half-sine pulse shape
|
||||
real snrs(20)
|
||||
real times(20)
|
||||
real*8 dt, df, fs, pi, twopi
|
||||
real softbits(144)
|
||||
real*8 unscrambledsoftbits(128)
|
||||
real lratio(128)
|
||||
real ttt(NPTS)
|
||||
logical first
|
||||
data first/.true./
|
||||
|
||||
data s8/0,1,1,1,0,0,1,0/
|
||||
save df,first,cb,fs,nfft,pi,twopi,dt,s8,rcw,pp
|
||||
|
||||
if(first) then
|
||||
allmessages=' '
|
||||
lines=' '
|
||||
i=index(pchk_file,".pchk")
|
||||
gen_file=pchk_file(1:i-1)//".gen"
|
||||
call init_ldpc(trim(pchk_file)//char(0),trim(gen_file)//char(0))
|
||||
! define half-sine pulse and raised-cosine edge window
|
||||
pi=4d0*datan(1d0)
|
||||
twopi=8d0*datan(1d0)
|
||||
fs=12000.0
|
||||
dt=1.0/fs
|
||||
nfft=6000 !using a zero-padded fft to get 2 Hz bins
|
||||
df=fs/nfft
|
||||
|
||||
do i=1,12
|
||||
angle=(i-1)*pi/12.0
|
||||
pp(i)=sin(angle)
|
||||
rcw(i)=(1-cos(angle))/2
|
||||
enddo
|
||||
|
||||
! define the sync word waveform
|
||||
s8=2*s8-1
|
||||
cbq(1:6)=pp(7:12)*s8(1)
|
||||
cbq(7:18)=pp*s8(3)
|
||||
cbq(19:30)=pp*s8(5)
|
||||
cbq(31:42)=pp*s8(7)
|
||||
cbi(1:12)=pp*s8(2)
|
||||
cbi(13:24)=pp*s8(4)
|
||||
cbi(25:36)=pp*s8(6)
|
||||
cbi(37:42)=pp(1:6)*s8(8)
|
||||
cb=cmplx(cbi,cbq)
|
||||
|
||||
ttt=(/ (i, i=1,NPTS) /)
|
||||
ttt=(ttt-NPTS/2)/(NPTS/2)
|
||||
first=.false.
|
||||
endif
|
||||
|
||||
nstep=694 ! fill the detmet, detsnr, detferr arrays
|
||||
do istp=1,nstep
|
||||
ns=1+256*(istp-1)
|
||||
ne=ns+NPTS-1
|
||||
tt=(ns+ne)/2.0/12000.0
|
||||
cdat=cbig(ns:ne)
|
||||
|
||||
! Coarse carrier frequency sync - seek tones at 2000 Hz and 4000 Hz in
|
||||
! squared signal spectrum.
|
||||
! search range for coarse frequency error is +/- 100 Hz
|
||||
|
||||
ctmp=cmplx(0.0,0.0)
|
||||
ctmp(1:NPTS)=cdat**2
|
||||
ctmp(1:12)=ctmp(1:12)*rcw
|
||||
ctmp(NPTS-11:NPTS)=ctmp(NPTS-11:NPTS)*rcw(12:1:-1)
|
||||
call four2a(ctmp,nfft,1,-1,1)
|
||||
tonespec=abs(ctmp)**2
|
||||
|
||||
ismask=.false.
|
||||
ismask(1901:2101)=.true. ! high tone search window
|
||||
iloc=maxloc(tonespec,ismask)
|
||||
ihpk=iloc(1)
|
||||
ah=tonespec(ihpk)
|
||||
ismask=.false.
|
||||
ismask(901:1101)=.true. ! window for low tone
|
||||
iloc=maxloc(tonespec,ismask)
|
||||
ilpk=iloc(1)
|
||||
al=tonespec(ilpk)
|
||||
fdiff=(ihpk-ilpk)*df
|
||||
ferrh=(ihpk-2001)*df/2.0
|
||||
ferrl=(ilpk-1001)*df/2.0
|
||||
if( abs(fdiff-2000) .le. 16.0 ) then
|
||||
if( ah .ge. al ) then
|
||||
ferr=ferrh
|
||||
else
|
||||
ferr=ferrl
|
||||
endif
|
||||
else
|
||||
ferr=-999.99
|
||||
endif
|
||||
detmet(istp)=ah+al
|
||||
detfer(istp)=ferr
|
||||
enddo ! end of detection-metric, snr, and frequency error estimation loop
|
||||
|
||||
call indexx(detmet,nstep,indices) !find median of detection metric vector
|
||||
xmed=detmet(indices(nstep/2))
|
||||
detmet=detmet/xmed ! noise floor of detection metric is 1.0
|
||||
|
||||
ndet=0
|
||||
do ip=1,20 ! use something like the "clean" algorithm to find candidates
|
||||
iloc=maxloc(detmet)
|
||||
il=iloc(1)
|
||||
if( (detmet(il) .lt. 2.0) .or. (abs(detfer(il)) .gt. 100.0) ) cycle
|
||||
ndet=ndet+1
|
||||
times(ndet)=((il-1)*256+NPTS/2)*dt
|
||||
ferrs(ndet)=detfer(il)
|
||||
snrs(ndet)=10.0*log10(detmet(il))/2-5.0 !/2 because detmet is a 4th order moment
|
||||
detmet(il-3:il+3)=0.0
|
||||
enddo
|
||||
|
||||
nmessages=0
|
||||
do ip=1,ndet
|
||||
imid=times(ip)*fs
|
||||
t0=times(ip)
|
||||
cdat=cbig(imid-NPTS/2+1:imid+NPTS/2)
|
||||
ferr=ferrs(ip)
|
||||
nsnr=snrs(ip)
|
||||
|
||||
! remove coarse freq error - should now be within a few Hz
|
||||
call tweak1(cdat,NPTS,-(1500+ferr),cdat)
|
||||
|
||||
! attempt frame synchronization
|
||||
! correlate with sync word waveforms
|
||||
cc=0
|
||||
cc1=0
|
||||
cc2=0
|
||||
do i=1,NPTS-(56*6+41)
|
||||
cc1(i)=sum(cdat(i:i+41)*conjg(cb))
|
||||
cc2(i)=sum(cdat(i+56*6:i+56*6+41)*conjg(cb))
|
||||
enddo
|
||||
cc=cc1+cc2
|
||||
dd=abs(cc1)*abs(cc2)
|
||||
|
||||
! Find 5 largest peaks
|
||||
do ipk=1,5
|
||||
iloc=maxloc(abs(cc))
|
||||
ic1=iloc(1)
|
||||
iloc=maxloc(dd)
|
||||
ic2=iloc(1)
|
||||
ipeaks(ipk)=ic2
|
||||
dd(max(1,ic2-7):min(NPTS-56*6-41,ic2+7))=0.0
|
||||
enddo
|
||||
|
||||
do ipk=1,5
|
||||
|
||||
! we want ic to be the index of the first sample of the frame
|
||||
ic0=ipeaks(ipk)
|
||||
|
||||
! fine adjustment of sync index
|
||||
! bb lag used to place the sampling index at the center of the eye
|
||||
do i=1,6
|
||||
if( ic0+11+NSPM .le. NPTS ) then
|
||||
bb(i) = sum( ( cdat(ic0+i-1+6:ic0+i-1+6+NSPM:6) * conjg( cdat(ic0+i-1:ic0+i-1+NSPM:6) ) )*2 )
|
||||
else
|
||||
bb(i) = sum( ( cdat(ic0+i-1+6:NPTS:6) * conjg( cdat(ic0+i-1:NPTS-6:6) ) )*2 )
|
||||
endif
|
||||
enddo
|
||||
iloc=maxloc(abs(bb))
|
||||
ibb=iloc(1)
|
||||
bba=abs(bb(ibb))
|
||||
if( ibb .le. 3 ) ibb=ibb-1
|
||||
if( ibb .gt. 3 ) ibb=ibb-7
|
||||
do id=1,3 ! slicer dither
|
||||
if( id .eq. 1 ) is=0
|
||||
if( id .eq. 2 ) is=-1
|
||||
if( id .eq. 3 ) is=1
|
||||
|
||||
! Adjust frame index to place peak of bb at desired lag
|
||||
ic=ic0+ibb+is
|
||||
if( ic .lt. 1 ) ic=ic+864
|
||||
|
||||
! Estimate fine frequency error.
|
||||
! Should a larger separation be used when frames are averaged?
|
||||
cca=sum(cdat(ic:ic+41)*conjg(cb))
|
||||
if( ic+56*6+41 .le. NPTS ) then
|
||||
ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
|
||||
cfac=ccb*conjg(cca)
|
||||
ferr2=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
|
||||
else
|
||||
ccb=sum(cdat(ic-88*6:ic-88*6+41)*conjg(cb))
|
||||
cfac=cca*conjg(ccb)
|
||||
ferr2=atan2(imag(cfac),real(cfac))/(twopi*88*6*dt)
|
||||
endif
|
||||
|
||||
! Final estimate of the carrier frequency - returned to the calling program
|
||||
fest=1500+ferr+ferr2
|
||||
|
||||
! Remove fine frequency error
|
||||
call tweak1(cdat,NPTS,-ferr2,cdat2)
|
||||
|
||||
! place the beginning of frame at index NSPM+1
|
||||
cdat2=cshift(cdat2,ic-(NSPM+1))
|
||||
|
||||
do iav=1,7 ! try each of 7 averaging patterns, hope that one works
|
||||
|
||||
if( iav .eq. 1 ) then
|
||||
c(1:NSPM)=cdat2(NSPM+1:2*NSPM) !avg 1 frame to the right of ic
|
||||
elseif( iav .eq. 2 ) then
|
||||
c=cdat2(NSPM-431:NSPM+432) !1 frame centered on ic
|
||||
c=cshift(c,-432)
|
||||
elseif( iav .eq. 3 ) then !1 frame to the left of ic
|
||||
c=cdat2(1:NSPM)
|
||||
elseif( iav .eq. 4 ) then
|
||||
c=cdat2(NSPM+432:NSPM+432+863) !1 frame beginning 36ms to the right of ic
|
||||
c=cshift(c,432)
|
||||
elseif( iav .eq. 5 ) then
|
||||
c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
|
||||
elseif( iav .eq. 6 ) then
|
||||
c=cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:NPTS)
|
||||
elseif( iav .eq. 7 ) then
|
||||
c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:NPTS)
|
||||
endif
|
||||
|
||||
! Estimate final frequency error and carrier phase.
|
||||
cca=sum(c(1:1+41)*conjg(cb))
|
||||
ccb=sum(c(1+56*6:1+56*6+41)*conjg(cb))
|
||||
cfac=ccb*conjg(cca)
|
||||
ffin=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
|
||||
phase0=atan2(imag(cca+ccb),real(cca+ccb))
|
||||
|
||||
! Remove phase error - want constellation such that sample points lie on re,im axes
|
||||
cfac=cmplx(cos(phase0),sin(phase0))
|
||||
c=c*conjg(cfac)
|
||||
|
||||
! sample to get softsamples
|
||||
! do i=1,72
|
||||
! softbits(2*i-1)=imag(c(1+(i-1)*12))
|
||||
! softbits(2*i)=real(c(7+(i-1)*12))
|
||||
! enddo
|
||||
|
||||
! matched filter - might be possible to improve this
|
||||
softbits(1)=sum(imag(c(1:6))*pp(7:12))+sum(imag(c(864-5:864))*pp(1:6))
|
||||
softbits(2)=sum(real(c(1:12))*pp)
|
||||
do i=2,72
|
||||
softbits(2*i-1)=sum(imag(c(1+(i-1)*12-6:1+(i-1)*12+5))*pp)
|
||||
softbits(2*i)=sum(real(c(7+(i-1)*12-6:7+(i-1)*12+5))*pp)
|
||||
enddo
|
||||
|
||||
hardbits=0
|
||||
do i=1,144
|
||||
if( softbits(i) .ge. 0.0 ) then
|
||||
hardbits(i)=1
|
||||
endif
|
||||
enddo
|
||||
nbadsync1=(8-sum( (2*hardbits(1:8)-1)*s8 ) )/2
|
||||
nbadsync2=(8-sum( (2*hardbits(1+56:8+56)-1)*s8 ) )/2
|
||||
nbadsync=nbadsync1+nbadsync2
|
||||
if( nbadsync .gt. 4 ) cycle
|
||||
|
||||
! normalize the softsymbols before submitting to decoder
|
||||
sav=sum(softbits)/144
|
||||
s2av=sum(softbits*softbits)/144
|
||||
ssig=sqrt(s2av-sav*sav)
|
||||
softbits=softbits/ssig
|
||||
|
||||
sigma=0.65
|
||||
lratio(1:48)=softbits(9:9+47)
|
||||
lratio(49:128)=softbits(65:65+80-1)
|
||||
lratio=exp(2.0*lratio/(sigma*sigma))
|
||||
|
||||
unscrambledsoftbits(1:127:2)=lratio(1:64)
|
||||
unscrambledsoftbits(2:128:2)=lratio(65:128)
|
||||
|
||||
max_iterations=20
|
||||
max_dither=50
|
||||
call ldpc_decode(unscrambledsoftbits, decoded, &
|
||||
max_iterations, niterations, max_dither, ndither)
|
||||
|
||||
if( niterations .ge. 0.0 ) then
|
||||
goto 778
|
||||
endif
|
||||
|
||||
enddo ! frame averaging loop
|
||||
enddo ! sample-time dither loop
|
||||
enddo ! peak loop - could be made more efficient
|
||||
|
||||
msgreceived=' '
|
||||
phase0=-98
|
||||
i1hashdec=0
|
||||
goto 999
|
||||
|
||||
778 continue
|
||||
! The decoder found a codeword - compare decoded hash with calculated
|
||||
! Collapse 80 decoded bits to 10 bytes. Bytes 1-9 are the message, byte 10 is the hash
|
||||
do ibyte=1,10
|
||||
itmp=0
|
||||
do ibit=1,8
|
||||
itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*8+ibit))
|
||||
enddo
|
||||
i1Dec8BitBytes(ibyte)=itmp
|
||||
enddo
|
||||
|
||||
! Calculate the hash using the first 9 bytes.
|
||||
ihashdec=nhash(c_loc(i1Dec8BitBytes),int(9,c_size_t),146)
|
||||
ihashdec=2*iand(ihashdec,255)
|
||||
|
||||
! Compare calculated hash with received byte 10 - if they agree, keep the message.
|
||||
i1hashdec=ihashdec
|
||||
|
||||
if( i1hashdec .eq. i1Dec8BitBytes(10) ) then
|
||||
! Good hash --- unpack 72-bit message
|
||||
do ibyte=1,12
|
||||
itmp=0
|
||||
do ibit=1,6
|
||||
itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit))
|
||||
enddo
|
||||
i4Dec6BitWords(ibyte)=itmp
|
||||
enddo
|
||||
call unpackmsg(i4Dec6BitWords,msgreceived)
|
||||
else
|
||||
msgreceived=' '
|
||||
phase0=-99
|
||||
endif
|
||||
if( msgreceived .ne. ' ' ) then
|
||||
ndupe=0
|
||||
do im=1,nmessages
|
||||
if( allmessages(im) .eq. msgreceived ) ndupe=1
|
||||
enddo
|
||||
if( ndupe .eq. 0 ) then
|
||||
nmessages=nmessages+1
|
||||
allmessages(nmessages)=msgreceived
|
||||
write(lines(nmessages),1020) nutc,nsnr,t0,nint(fest),msgreceived,char(0)
|
||||
1020 format(i6.6,i4,f5.1,i5,' & ',a22,a1)
|
||||
endif
|
||||
endif
|
||||
|
||||
999 continue
|
||||
! write(78,1001) nutc,t0,iav,ipk,is,fest,ffin,nbadsync1,nbadsync2, &
|
||||
! phase0,niterations,ndither,i1hashdec,i1Dec8BitBytes(10),msgreceived
|
||||
!1001 format(i6,f8.2,i4,i4,i4,f8.2,f8.2,i4,i4,f8.2,i4,i4,i4,i4,2x,a22)
|
||||
|
||||
enddo
|
||||
return
|
||||
end subroutine detectmsk144
|
||||
Loading…
Reference in New Issue
Block a user