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New JTMS3 definition (again). Now using 7-bit characters, as in

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the JTMS of WSJT9.  Modulation changed to BPSK, speed increased 
from 1378.125 to 2000 baud.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/jtms3@2505 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2012-07-12 19:10:39 +00:00
parent f7355e8f77
commit 04c4b99a53
7 changed files with 260 additions and 190 deletions
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79
jtms3.txt
View File

@ -3,63 +3,48 @@
1. Transmitting
Type 1 messages are 72 user-information bits, source encoded as in
JT65. Convolutional FEC (K=32, r=1/2) increases the number of bits to
(72+31)*2 = 206; nine bits are sent twice, extending the array to 215
bits. These are interleaved by bit-reversal of index values. Then 43
sync bits are inserted, spread evenly so as to fall at positions 1, 7,
13, ... 253. Frame size is 258 bits: 215 information-carrying bits
and 43 sync bits. Frame duration is 129 ms.
Messages are sent character-by character, 6 bits plus even parity.
Message length can be one of {5 7 9 11 13 17 19 23 29}; if necessary
the message is padded with blanks to the next available length. No
other FEC is used.
Type 2 messages convey 4 user information bits (report, R+report, RRR,
73) encoded with a (15,4,8) block code, plus an 11-bit CRC derived
from MyCall + HisCall, encoded with the (16,11) extended Hamming code.
This makes for 31 information-carrying bits. They are interspersed
with 31 sync bits, making a frame of 62 bits and frame time 31 ms.
Modulation is BPSK at 2000 baud. The baseband waveform is built by
inserting a tapered sinc function for each bit, then multiplying by a
sine wave at frequency f0 = 10000.0/7 = 1428.57 Hz. Agt sample rate
48000 Hz there are 24 samples per PSK symbol and 7*24=168 samples per
character. The carrier phase increment over one character is
f0*(168/48000) = 5 cycles.
2. Modulation is BPSK at 2000 baud, 24 samples per symbol at 48000 Hz
asmple rate. The baseband waveform is built by inserting a tapered
sinc function for each bit, then multiplying by a 1500 Hz sine wave.
2. Receiving
3. Receiving
a. Pings are detected (or mouse-picked data is selected) as in
WSJT9.
a. Compute real-to-complex windowed FFTs, N=8192 (t=170 ms),
stepped by 4k (say). Zap birdies, remove frequency components
outside the range 300 - 2700 Hz, and convert to analytic
time-domain signal.
b. Compute real-to-complex FFT. Zap birdies, remove frequency
components outside the range 300 - 2700 Hz, and convert to analytic
time-domain signal. (analytic)
b. Square the complex signal, cx2=cx*cx, and compute N=8k FFT of
cx2 (resolution = 5.9 Hz). Look for carrier at 3000 + 2*DF Hz
+/- 2*Tol.
c. Square the complex signal, cx2=cx*cx, and compute FFT. Look for
carrier at frequency 3000 + 2*DF +/- 2*Tol. (msdf)
c. If carrier is found, measure frequency f and phase phi. Multiply
d. If carrier is found, measure frequency f and phase phi. Multiply
cx by exp(-twopi*i*f*t - phi) to recover the real baseband signal
x() to within a sign ambiguity.
x() to within a sign ambiguity. (tweak1)
d. Apply matched filter for the Tx pulse shape to x(). This is
essentially a rectangular BPF, -1000 to +1000 Hz ?
e. Apply matched filter for the Tx pulse shape to x(). This is
essentially a rectangular BPF, -1000 to +1000 Hz ? (Or convolve
with the generated PSK pulse shape, the tapered sinc() function.)
e. Establish PSK symbol sync (offset i0, 0 to nsps-1 samples) by finding
maximum of Sum(sum*sum) over groups of nsps consecutive samples.
f. Establish symbol and character sync by cross-correlating with
conjg(cwb), where cwb is the baseband PSK waveform for the
<space> character.
f. Read off the soft symbols, sym(1:512), and compute CCF with 3
versions of the 43-bit sync vector (rotated by 0, 14, 29 out of
its 43 positions) and three of the 31-bit sync vector (rotated by
0, 10, 20 of 31).
g. Find message length by computing ACF (of what? cdat? soft
symbol values?)
g. If the best CCF abs(peak) exceeds a specified threshold, the
signal is detected and synchronized. Sign of peak resolves the
sign ambiguity.
h. Decode the message by cross-correlating character-length segments
of cdat against complex waveforms for each possible character.
h. For Type 1 messages: Gather the proper set of 215
information-carrying soft symbols. Form averages using the 9
extra symbols, reducing the number to 206; and remove
interleaving to re-order the symbols. Then run the fano232
decoder. If decoding fails, add soft symbols into an
accumulation array and (if nsum is 2 or more) try decoding the
average.
i. If msglen is established and long enough, try folding the data and
determining best-fit characters as above.
i. For Type 2 messages: Gather the proper set of 31 soft symbols.
Decode Nrpt using exhaustive search (find peak lag of ccf). For
the CRC, also do an exhaustive search -- and make sure that the
expected value is best (or in the top few, anyway).

251
libm65/genjtms3.f90
View File

@ -1,93 +1,158 @@
subroutine genjtms3(msg,msgsent,iwave,nwave)
character*22 msg,msgsent
integer*1 chansym(258)
integer*2 iwave(30*48000)
integer dgen(13)
integer*1 data0(13)
integer*1 datsym(215)
real*8 pi,twopi,f0,dt,phi,dphi
real*4 p(-3095:3096)
real*4 s(6192)
real*4 carrier(6192)
logical first
integer*1 isync(43)
integer indx0(9) !Indices of duplicated symbols
data indx0 /16,38,60,82,104,126,148,170,192/
data first/.true./
data isync/0,1,0,0,1,0,1,0,0,1,1,1,0,1,1,1,1,1,0,0, &
0,1,0,1,1,1,0,0,0,0,0,1,0,0,0,1,1,0,1,0, &
1,1,0/ !Hadamard-43 sync code
save
sinc(x)=sin(pi*x)/(pi*x)
if(first) then
pi=4.d0*atan(1.d0)
twopi=2.d0*pi
k=0
x=0.
dx=1.0/24.0
do i=1,3096 !Generate the BPSK pulse shape
k=k+1
if(k.gt.3096) k=k-6192
x=x+dx
p(k)=sinc(x) * (sinc(x/2.0))**2
if(k.ne.3096) p(-k)=p(k)
enddo
p(0)=1.0
f0=193.d0*48000.d0/(258.d0*24.d0)
dt=1.d0/48000.d0
dphi=twopi*f0*dt
phi=0.d0
nmax=0.
do i=1,6192 !Generate the carrier
phi=phi+dphi
if(phi.gt.twopi)phi=phi-twopi
xphi=phi
carrier(i)=sin(xphi)
enddo
endif
call packmsg(msg,dgen) !Pack message into 12 six-bit symbols
call entail(dgen,data0) !Move from 6-bit to 8-bit symbols, add tail
ndat=(72+31)*2
call encode232(data0,ndat,datsym) !Convolutional encoding
do i=1,9 !Duplicate 9 symbols at end of datsym
datsym(206+i)=datsym(indx0(i))
enddo
call scr258(isync,datsym,1,chansym) !Insert sync and data into chansym(258)
if(msg(1:1).eq.'@') chansym=0
s=0.
do j=1,258
k1=-3096-24*j
if(chansym(j).eq.1) s=s + cshift(p,k1)
if(chansym(j).eq.0) s=s - cshift(p,k1)
enddo
nmax=0
do i=1,6192
n=30000.0*carrier(i)*s(i)
nmax=max(nmax,abs(n))
if(n.gt.32767) n=32767
if(n.lt.-32767) n=-32767
iwave(i)=n
enddo
nblk=30*48000/6192
do n=2,nblk
ib=n*6192
ia=ib-6191
iwave(ia:ib)=iwave(1:6192)
enddo
nwave=ib
msgsent=msg
return
end subroutine genjtms3
subroutine genjtms3(msg28,iwave,nwave)
!subroutine genjtms3(msg28,iwave,cwave,isrch,nwave)
! Generate a JTMS3 wavefile.
parameter (NMAX=30*48000) !Max length of wave file
integer*2 iwave(NMAX) !Generated wave file
complex cwave(NMAX) !Alternative for searchms
character*28 msg28 !User message
character*29 msg
character cc*64
integer sentsym(203) !Transmitted symbols (0/1)
real sentsam(4872) !Transmitted waveform
real*8 dt,phi,f0,dphi,pi,twopi,samfac
real p(0:420)
real carrier(4872)
real dat(4872),bb(4872),wave(4872)
complex cdat(0:2436)
logical first
integer np(9)
data np/5,7,9,11,13,17,19,23,29/ !Permissible message lengths
! 1 2 3 4 5 6
! 0123456789012345678901234567890123456789012345678901234567890123
data cc/'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ./?- _ @'/
data samfac/1.d0/,first/.true./
equivalence (dat,cdat)
save
sinc(x)=sin(pi*x)/(pi*x)
if(first) then
pi=4.d0*atan(1.d0)
twopi=2.d0*pi
x=0.
dx=1.0/24.0
width=3.0
do i=1,420 !Generate the BPSK pulse shape
x=x+dx
fac=0.0
if(x/width.lt.0.5*pi) then
fac=(cos(x/width))**2
ipz=i
endif
p(i)=fac*sinc(x)
enddo
p(0)=1.0
f0=10000.d0/7.d0
dt=1.d0/48000.d0
dphi=twopi*f0*dt
phi=0.d0
do i=1,4872 !Generate the carrier
phi=phi+dphi
if(phi.gt.twopi)phi=phi-twopi
xphi=phi
carrier(i)=sin(xphi)
enddo
first=.false.
endif
msg=msg28//' ' !Extend to 29 characters
do i=28,1,-1 !Find user's message length
if(msg(i:i).ne.' ') go to 1
enddo
1 iz=i+1 !Add one for space at EOM
msglen=iz
if(isrch.ne.0) go to 3
do i=1,9
if(np(i).ge.iz) go to 2
enddo
i=8
2 msglen=np(i)
! Convert message to a bit sequence, 7 bits per character (6 + even parity)
3 sentsym=0
k=0
do j=1,msglen
if(msg(j:j).eq.' ') then
i=58
go to 5
else
do i=1,64
if(msg(j:j).eq.cc(i:i)) go to 5
enddo
endif
5 m=0
do n=5,0,-1 !Each character gets 6 bits
k=k+1
sentsym(k)=iand(1,ishft(i-1,-n))
m=m+sentsym(k)
enddo
k=k+1
sentsym(k)=iand(m,1) !Insert bit for even parity
enddo
nsym=7*msglen !# symbols in message
nsam=24*nsym !# samples in message
bb(1:nsam)=0.
do j=1,nsym
fac=1.0
if(sentsym(j).eq.0) fac=-1.0
k0=24*j - 23
do i=0,ipz
k=k0+i
if(k.gt.nsam) k=k-nsam
bb(k)=bb(k) + fac*p(i)
if(i.gt.0) then
k=k0-i
if(k.lt.1) k=k+nsam
bb(k)=bb(k) + fac*p(i)
endif
enddo
enddo
sq=0.
wmax=0.
do i=1,nsam
wave(i)=carrier(i)*bb(i)
sq=sq + wave(i)**2
wmax=max(wmax,abs(wave(i)))
! write(15,3002) i*dt,bb(i),wave(i)
!3002 format(f12.6,2f12.3)
enddo
rms=sqrt(sq/nsam)
! print*,rms,wmax,wmax/rms
fac=32767.0/wmax
iwave(1:nsam)=fac*wave(1:nsam)
nwave=nsam
! nblk=30*48000/nsam
! do n=2,nblk
! i0=(n-1)*nsam
! iwave(i0+1:i0+nsam)=iwave(1:nsam)
! enddo
! nwave=i0+nsam
! Compute the spectrum
! nfft=nsam
! df=48000.0/nfft
! ib=4000.0/df
! fac=10.0/nfft
! dat(1:nfft)=fac*bb(1:nfft)
! call four2a(dat,nfft,1,-1,0)
! do i=0,ib
! sq=real(cdat(i))**2 + aimag(cdat(i))**2
! write(14,3010) i*df,sq,10.0*log10(sq)
!3010 format(3f12.3)
! enddo
! if(isrch.eq.0) iwave(k+1:)=0
! nwave=k
return
end subroutine genjtms3

2
libm65/scr258.f90
View File

@ -43,7 +43,7 @@ subroutine scr258(isync,idat,ndir,ichan)
else
do i=1,258
j=indx(i)
! if(j.lt.0) isync(-j)=ichan(i)
if(j.lt.0) isync(-j)=ichan(i)
if(j.gt.0) idat(j)=ichan(i)
enddo
endif

100
libm65/specjtms.f90
View File

@ -3,16 +3,26 @@ subroutine specjtms(k)
! Starting code for a JTMS3 decoder.
parameter (NSMAX=30*48000)
parameter (NFFT=8192,NH=NFFT/2)
parameter (NFFT=16384,NH=NFFT/2)
character*22 decoded
character*72 c72
integer*2 id
real x(NFFT),w(NFFT)
real p(24)
real chansym(258),softsym(341)
real rsent(258),softsym(683),sym2(258)
integer nsum(24)
complex cx(NFFT),cx2(NFFT),cx0(NFFT)
complex covx(NH)
real s1a(NH),s2a(580)
real s1a(NH),s2a(NH)
integer mettab(0:255,0:1) !Metric table
integer data4a(9) !Decoded data (8-bit byte values)
integer data4(12) !Decoded data (6-bit byte values)
integer*1 data1(13)
integer*1 isync(43)
integer*1 chansym1(258),datsym2(215)
logical first,window
integer*1 i1
equivalence (i1,i4)
common/mscom/id(1440000),s1(215,703),s2(215,703)
data first/.true./
save
@ -28,23 +38,37 @@ subroutine specjtms(k)
jb=nint(3400.0)/df
iz=3000.0/df
covx=0.
read(10,3001) chansym
kstep=4096
read(10,3001) rsent
3001 format(50f1.0)
chansym=2.0*chansym - 1.0
do i=1,258,6
rsent(i)=0.
enddo
rsent=2.0*rsent - 1.0
open(11,file='bpskmetrics.dat',status='old')
bias=0.5
scale=20.0
do i=0,255
read(11,*) xjunk,x0,x1
mettab(i,0)=nint(scale*(x0-bias))
mettab(i,1)=nint(scale*(x1-bias))
enddo
close(11)
window=.false.
first=.false.
endif
ib=k
ia=k-4095
i0=ib-8191
ia=k-kstep+1
i0=k-nfft+1
sq=0.
do i=ia,ib
sq=sq + (0.001*id(i))**2
enddo
write(13,1010) t,sq,db(sq)
1010 format(3f12.3)
if(k.lt.8192) return
if(k.lt.nfft) return
x(1:nfft)=0.001*id(i0:ib)
@ -79,30 +103,19 @@ subroutine specjtms(k)
f0=0.5*(f-3000.0)
phi0=0.5*atan2(aimag(cx2(j)),real(cx2(j)))
endif
write(15,1020) (j-1)*df,sq
write(15,1020) f,sq
1020 format(f10.3,f12.3)
enddo
slimit=2.0
! slimit=87.5
slimit=2.5
! if(spk0.gt.slimit) then
if(abs(spk0-87.3).lt.0.1) then
if(abs(spk0-43.5).lt.0.1) then
write(*,1030) t,f0,phi0,spk0
1030 format('t:',f6.2,' f0:',f7.1,' phi0:',f6.2,' spk0:',f8.1)
do i=1,iz
write(16,1040) i*df,s1a(i),db(s1a(i))
1040 format(3f12.3)
enddo
do j=ja,jb
f=(j-1)*df
f0a=0.5*(f-3000.0)
write(17,1050) f0a,s2a(j)
1050 format(2f12.3)
enddo
phi=phi0
phi=3.9
dphi=2.0*pi*(f0+1500.0 -1.1)/48000.0
phi=3.9 !### test ###
dphi=twopi*(f0+1500.0 -1.1)/48000.0
p=0.
nsum=0
do i=1,nfft
@ -110,8 +123,8 @@ subroutine specjtms(k)
if(phi.gt.twopi) phi=phi-twopi
cx0(i)=cx(i)*cmplx(cos(phi),-sin(phi))
pha=atan2(aimag(cx0(i)),real(cx0(i)))
write(18,1060) i,cx0(i),pha
1060 format(i6,5f12.3)
! write(18,1060) i,cx0(i),pha
!1060 format(i6,5f12.3)
j=mod(i-1,24) + 1
! p(j)=p(j)+abs(cx0(i))
p(j)=p(j) + real(cx0(i))**2 + aimag(cx0(i))**2
@ -124,18 +137,20 @@ subroutine specjtms(k)
1070 format(i6,f12.3)
enddo
do i=16,nfft,24
do i=19,nfft,24
amp=abs(cx0(i))
pha=atan2(aimag(cx0(i)),real(cx0(i)))
j=(i+23)/24
write(21,1060) j,cx0(i),pha,pha+twopi,amp
1060 format(i6,5f12.3)
softsym(j)=real(cx0(i))
enddo
! do iter=1,5
chansym=cshift(chansym,-86)
do lag=0,83
sum=dot_product(chansym,softsym(lag+1:lag+258))
rsent=cshift(rsent,86)
lagmax=nfft/24 - 258
do lag=0,lagmax
sum=dot_product(rsent,softsym(lag+1:lag+258))
if(abs(sum).gt.smax) then
smax=abs(sum)
lagpk=lag
@ -143,18 +158,27 @@ subroutine specjtms(k)
write(22,1080) lag,sum
1080 format(i3,f12.3)
enddo
! chansym=cshift(chansym,43)
! rsent=cshift(rsent,43)
! enddo
do i=1,258
prod=-chansym(i)*softsym(lagpk+i)
write(23,1090) i,prod,chansym(i),softsym(lagpk+i)
1090 format(i5,3f10.3)
j=mod(i-1+2580,258) + 1
prod=rsent(j)*softsym(lagpk+i)
nchsym=nint(0.5*(rsent(j)+1.0))
write(23,1090) i,prod,rsent(j),softsym(lagpk+i),j,nchsym,lagpk+i
1090 format(i5,3f10.3,3i5)
enddo
do i=1,258,6
write(24,1100) (i+5)/6,int(chansym(i)),softsym(lagpk+i)
1100 format(2i5,f8.1)
sym2=softsym(lagpk+1:lagpk+258)
sym2=cshift(sym2,-86)
do i=1,258
i4=128 + nint(6.0*sym2(i))
if(i4.lt.0) i4=0
if(i4.gt.255) i4=255
chansym1(i)=i1
write(24,2001) i,sym2(i),i4,chansym1(i)
2001 format(i6,f8.3,2i6)
enddo
endif

13
mainwindow.cpp
View File

@ -408,7 +408,7 @@ void MainWindow::dataSink(int k)
mscom_.ndiskdat=0;
}
specjtms_(&k,&px);
// specjtms_(&k,&px);
QString t;
t.sprintf(" Rx noise: %5.1f ",px);
lab2->setText(t);
@ -1116,7 +1116,7 @@ void MainWindow::guiUpdate()
static bool btxok0=false;
static int nc0=1;
static int nc1=1;
static char msgsent[23];
static char msgsent[29];
static int nsendingsh=0;
int khsym=0;
double trperiod=30.0;
@ -1147,7 +1147,6 @@ void MainWindow::guiUpdate()
if(!soundOutThread.isRunning()) {
soundOutThread.start(QThread::HighPriority);
}
qDebug() << "PTT raised, soundOut started";
}
if(!bTxTime || m_txMute) {
btxok=false;
@ -1156,7 +1155,7 @@ void MainWindow::guiUpdate()
// Calculate Tx waveform when needed
if((iptt==1 && iptt0==0) || m_restart) {
char message[23];
char message[29];
QByteArray ba;
if(m_ntx == 1) ba=ui->tx1->text().toLocal8Bit();
if(m_ntx == 2) ba=ui->tx2->text().toLocal8Bit();
@ -1166,9 +1165,9 @@ void MainWindow::guiUpdate()
if(m_ntx == 6) ba=ui->tx6->text().toLocal8Bit();
ba2msg(ba,message);
int len1=22;
genjtms3_(message,msgsent,iwave,&nwave,len1,len1);
msgsent[22]=0;
ba2msg(ba,msgsent);
int len1=28;
genjtms3_(message,iwave,&nwave,len1);
if(m_restart) {
QFile f("jtms3_tx.log");

3
mainwindow.h
View File

@ -237,8 +237,7 @@ extern "C" {
//----------------------------------------------------- C and Fortran routines
void specjtms_(int* k, float* px);
void genjtms3_(char* message, char* msgsent, short iwave[],
int* nwave, int len1, int len2);
void genjtms3_(char* message, short iwave[], int* nwave, int len1);
void gen65_(char* msg, int* mode65, double* samfac, int* nsendingsh,
char* msgsent, short iwave[], int* nwave, int len1, int len2);

2
soundout.cpp
View File

@ -83,7 +83,6 @@ void SoundOutThread::run()
}
const PaStreamInfo* p=Pa_GetStreamInfo(outStream);
outputLatency = p->outputLatency;
qDebug() << "SoundOut started, latency =" << outputLatency;
bool qe = quitExecution;
//---------------------------------------------- Soundcard output loop
@ -97,7 +96,6 @@ void SoundOutThread::run()
}
Pa_StopStream(outStream);
Pa_CloseStream(outStream);
qDebug() << "SoundOut terminated";
}
void SoundOutThread::setOutputDevice(int n) //setOutputDevice()