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First functioning QRA65 encode and decode.

This commit is contained in:
Joe Taylor 2020-09-25 10:55:21 -04:00
parent 8e69f84bdd
commit 2057600f43
5 changed files with 75 additions and 64 deletions
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21
lib/genqra64.f90
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@ -1,6 +1,6 @@
subroutine genqra64(msg0,ichk,msgsent,itone,itype)
! Encodes a QRA64 message to yield itone(1:84)
! Encodes a QRA64 message to yield itone(1:84) or a QRA65 msg, itone(1:85)
use packjt
character*22 msg0
@ -8,15 +8,15 @@ subroutine genqra64(msg0,ichk,msgsent,itone,itype)
character*22 msgsent !Message as it will be received
integer itone(85) !QRA64 uses only 84
character*3 cok !' ' or 'OOO'
logical old_qra_sync
integer dgen(13)
integer sent(63)
integer b11(11) !Barker 11 code
integer isync(22)
integer icos7(0:6)
data icos7/2,5,6,0,4,1,3/ !Defines a 7x7 Costas array
data b11/1,1,1,0,0,0,1,0,0,1,0/ !Barker 11 definition
data isync/1,9,12,13,15,22,23,26,27,33,35,38,46,50,55,60,62,66,69,74,76,85/
save
print*,'ichk:',ichk
if(msg0(1:1).eq.'@') then
read(msg0(2:5),*,end=1,err=1) nfreq
go to 2
@ -44,18 +44,17 @@ subroutine genqra64(msg0,ichk,msgsent,itone,itype)
if(ichk.eq.1) go to 999 !Return if checking only
call qra64_enc(dgen,sent) !Encode using QRA64
if(ichk.eq.66) then
! Experimental QRA66 (FST66?) mode
j=0
if(ichk.eq.65) then
! Experimental QRA65 mode
j=1
k=0
do i=1,85
if(mod(i,4).eq.1) then
if(i.eq.isync(j)) then
j=j+1 !Index for next sync symbol
if(j.eq.12) j=1
itone(i)=b11(j) !Insert a sync symbol
itone(i)=0 !Insert a sync symbol
else
k=k+1
itone(i)=sent(k) + 2
itone(i)=sent(k) + 1
endif
enddo
else

2
lib/qra/qra66/qra66sim.f90
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@ -65,7 +65,7 @@ program qra66sim
mode66=2**(ichar(csubmode) - ichar('A'))
print*,csubmode,mode66
ichk=66 !Flag sent to genqra64
ichk=65 !Flag sent to genqra64
call genqra64(msg,ichk,msgsent,itone,itype)
write(*,1001) itone
1001 format('Channel symbols:'/(20i3))

11
lib/qra66_decode.f90
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@ -115,6 +115,10 @@ contains
endif
naptype=maxaptype
call timer('sync66 ',0)
call sync66(iwave,ntrperiod*12000,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
call timer('sync66 ',1)
! Downsample to give complex data at 6000 S/s
fac=2.0/nfft1
c0=fac*iwave(1:nfft1)
@ -122,21 +126,18 @@ contains
c0(nfft2/2+1:nfft2)=0. !Zero the top half
c0(0)=0.5*c0(0)
call four2a(c0,nfft2,1,1,1) !Inverse c2c FFT
call timer('sync66 ',0)
call sync66(iwave,ntrperiod*12000,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
call timer('sync66 ',1)
jpk=(xdt+0.5)*6000 - 384 !### Empirical ###
if(ntrperiod.ge.60) jpk=(xdt+1.0)*6000 - 384 !### TBD ###
if(jpk.lt.0) jpk=0
a=0.
a(1)=-(f0 + 2.0*mode66*baud) !Data tones start 2*mode66 bins higher
a(1)=-(f0 + mode66*baud) !Data tones start mode66 bins higher
call twkfreq(c0,c0,ntrperiod*6000,6000.0,a)
xdt=jpk/6000.0 - 0.5
LL=64*(mode66+2)
NN=63
call spec66(c0(jpk:),nsps/2,s3,LL,NN) !Compute the synchronized symbol spectra
call spec66(c0(jpk:),nsps/2,s3,LL,NN) !Compute synchronized symbol spectra
do j=1,63 !Normalize to symbol baseline
call pctile(s3(:,j),LL,40,base)

15
lib/spec66.f90
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@ -6,12 +6,19 @@ subroutine spec66(c0,nsps,s3,LL,NN)
complex cs(0:nsps-1) !Complex symbol spectrum
real s3(LL,NN) !Synchronized symbol spectra
real xbase0(LL),xbase(LL) !Work arrays
integer isync(22) !Indices of sync symbols
data isync/1,9,12,13,15,22,23,26,27,33,35,38,46,50,55,60,62,66,69,74,76,85/
fac=1.0/nsps
ja=-nsps
do j=1,NN
ja=ja+nsps
if(mod(ja/nsps,4).eq.0) ja=ja+nsps
j=0
n=1
do k=1,84
if(k.eq.isync(n)) then
n=n+1
cycle
endif
j=j+1
ja=(k-1)*nsps
jb=ja+nsps-1
cs=fac*c0(ja:jb)
call four2a(cs,nsps,1,-1,1) !c2c FFT to frequency

90
lib/sync66.f90
View File

@ -1,36 +1,32 @@
subroutine sync66(iwave,nmax,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
parameter (NSTEP=4) !Quarter-symbol steps
integer*2 iwave(0:nmax-1) !Raw data
integer b11(11) !Barker 11 code
integer ijpk(2) !Indices i and j at peak of sync_sig
real, allocatable :: s1(:,:) !Symbol spectra
real, allocatable :: x(:) !Work array; demoduated 2FSK sync signal
real sync(4*85) !sync vector
real sync_sig(-64:64,-15:15)
parameter (NSTEP=4) !Quarter-symbol steps
integer*2 iwave(0:nmax-1) !Raw data
integer isync(22) !Indices of sync symbols
integer ijpk(2) !Indices i and j at peak of ccf
real, allocatable :: s1(:,:) !Symbol spectra, quarter-symbol steps
real sync(85) !sync vector
real ccf(-64:64,-15:15)
complex, allocatable :: c0(:) !Complex spectrum of symbol
data b11/1,1,1,0,0,0,1,0,0,1,0/ !Barker 11 code
data isync/1,9,12,13,15,22,23,26,27,33,35,38,46,50,55,60,62,66,69,74,76,85/
data sync(1)/99.0/
save sync
nfft=2*nsps
df=12000.0/nfft
istep=nsps/NSTEP
iz=5000.0/df !Uppermost frequency bin, at 5000 Hz
iz=5000.0/df !Uppermost frequency bin, at 5000 Hz
txt=85.0*nsps/12000.0
jz=(txt+1.0)*12000.0/istep !Number of quarter-symbol steps
jz=(txt+1.0)*12000.0/istep !Number of quarter-symbol steps
if(nsps.ge.7680) jz=(txt+2.0)*12000.0/istep !For TR 60 s and higher
allocate(s1(iz,jz))
allocate(x(jz))
allocate(c0(0:nsps))
allocate(c0(0:nfft-1))
if(sync(1).eq.99.0) then
sync=0.
sync=-22.0/63.0 !Sync OFF
do k=1,22
kk=k
if(kk.gt.11) kk=k-11
i=4*NSTEP*(k-1) + 1
sync(i)=2.0*b11(kk) - 1.0
sync(isync(k))=1.0 !Sync ON
enddo
endif
@ -45,7 +41,7 @@ subroutine sync66(iwave,nmax,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
k=k+1
c0(k)=fac*cmplx(xx,yy)
enddo
c0(k+1:nfft/2)=0.
c0(k+1:)=0.
call four2a(c0,nfft,1,-1,0) !r2c FFT
do i=1,iz
s1(i,j)=real(c0(i))**2 + aimag(c0(i))**2
@ -58,14 +54,18 @@ subroutine sync66(iwave,nmax,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
s1max=20.0
! Apply AGC
do j=1,jz
x(j)=maxval(s1(i0-64:i0+192,j))
if(x(j).gt.s1max) s1(i0-64:i0+192,j)=s1(i0-64:i0+192,j)*s1max/x(j)
enddo
! do j=1,jz
! smax=maxval(s1(i0-64:i0+192,j))
! if(smax.gt.s1max) s1(i0-64:i0+192,j)=s1(i0-64:i0+192,j)*s1max/smax
! enddo
sync_sig=0.
! do i=1,iz
! write(60,3060) i,i*df,sum(s1(i,1:jz))
!3060 format(i6,f10.3,e12.3)
! enddo
ccf=0.
ia=min(64,nint(ntol/df))
dt4=nsps/(NSTEP*12000.0) !duration of 1/4 symbol
jadd=11
if(nsps.ge.3600) jadd=7
@ -74,31 +74,35 @@ subroutine sync66(iwave,nmax,mode66,nsps,nfqso,ntol,xdt,f0,snr1)
if(nsps.ge.41472) jadd=1
do i=-ia,ia
x=s1(i0+2*mode66+i,:)-s1(i0+i,:) !Do the 2FSK demodulation
do lag=-15,15
do k=1,22
n=4*NSTEP*(k-1) + 1
do k=1,85
n=NSTEP*(k-1) + 1
j=n+lag+jadd
if(j.ge.1 .and. j.le.jz) sync_sig(i,lag)=sync_sig(i,lag) + sync(n)*x(j)
if(j.ge.1 .and. j.le.jz) then
ccf(i,lag)=ccf(i,lag) + sync(k)*s1(i0+i,j)
endif
enddo
enddo
enddo
ijpk=maxloc(sync_sig)
ii=ijpk(1)-65
jj=ijpk(2)-16
! do i=-64,64
! write(61,3061) i,ccf(i,jpk)
!3061 format(i5,e12.3)
! enddo
! do j=-15,15
! write(62,3061) j,ccf(ipk,j)
! enddo
! Use peakup() here?
f0=nfqso + ii*df
jdt=jj
! j0=0.5/dt4
! if(nsps.ge.7680) j0=1.0/dt4
tsym=nsps/12000.0
xdt=jdt*tsym/4.0
snr1=maxval(sync_sig)/22.0
ijpk=maxloc(ccf)
ipk=ijpk(1)-65
jpk=ijpk(2)-16
dt4=nsps/(NSTEP*12000.0) !1/4 of symbol duration
if(nsps.ge.7680) j0=1.0/dt4
f0=nfqso + ipk*df
xdt=jpk*dt4
snr1=maxval(ccf)/22.0
! write(*,3100) ipk,jpk,xdt,f0,snr1
!3100 format(2i5,f7.2,2f10.2)
return
end subroutine sync66