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Program jt9sim is now basically functional.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2603 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
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Joe Taylor 2012-09-28 18:07:07 +00:00
parent 32171f3696
commit fba5846b49
8 changed files with 209 additions and 156 deletions
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82
jt9.txt
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@ -1,65 +1,63 @@
JT9 is a mode designed for amateur QSOs and beacon-like transmissions
at MF and LF. The mode uses the same 72-bit user messages as JT65,
augmented by a 12-bit cyclic redundancy check (CRC). Error-control
coding uses a convolutional code with constraint length K=16, rate
r=1/2, and a zero tail, leading to an encoded message length of
(72+12+15)*2 = 198 bits. Modulation is 9-FSK -- 8 tones for data, and
one for a synchronization vector. With 15 symbol intervals used for
synchronization, a transmission requires a total of 198/3 + 15 = 81
channel symbols. Tone spacing df of the 9-FSK modulation is equal to
the keying rate; symbol duration tsym = 1/df, and the total occupied
bandwidth is 9*df. Transmission length is slightly less than the T/R
sequence time, to allow for message decoding at time Tdec, a time
Tfree seconds before the next transmission starts.
at MF and LF. The mode uses the same 72-bit user messages as JT65.
Convolutional error-control coding (ECC) uses constraint length K=32,
rate r=1/2, and a zero tail, which leads to an encoded message length
of (72+31)*2 = 206 bits. Modulation is 9-FSK: 8 tones for data, one
for synchronization. Sixteen symbol intervals are used for
synchronization, so a transmission requires a total of 207/3 + 16 = 85
channel symbols. Symbol durations tsym are set to approximately
(TRperiod-10)/85, where TRperiod is the T/R sequence length in
seconds. The exact symbol lengths are chosen so as to make nsps, the
number of samples at 12000 samples per second, a number rich in
factors less than 7. This choice makes for efficient FFTs. Tone
spacing of the 9-FSK modulation is df=1/tsym, the same as the keying
rate. The total occupied bandwidth is 9*df.
Parameters of the five JT9 sub-modes are summarized in the following
table, along with S/N thresholds measured by simulation on an AWGN
(additive white Gaussian noise) channel. Parameter nsps1 is the number
of samples per symbol at sample rate 12000 Hz; nsps is the same
quantity at 750 Hz.
(additive white Gaussian noise) channel.
------------------------------------------------------------------------
Mode nsps1 nsps df tsym BW S/N* Tdec Tfree Factors
-------------------------------------------------------------------------
Mode nsps nsps2 df tsym BW S/N* Tdec Tfree Factors
12000 750 (Hz) (s) (Hz) (dB) (s) (s) of nsps
------------------------------------------------------------------------
JT9-1 7168 448 1.674 0.60 15.1 -26.9 51.9 8.1 2^10 7
JT9-2 16000 1000 0.750 1.33 6.8 -30.2 111.5 8.5 2^7 5^3
JT9-5 42336 2646 0.283 3.53 2.5 -34.4 289.4 10.6 2^5 3^3 7^2
JT9-10 86400 5400 0.139 7.20 1.3 -37.5 586.7 13.3 2^7 3^3 5^2
JT9-30 262144 16384 0.046 21.85 0.4 -42.3 1773.4 26.6 2^18
------------------------------------------------------------------------
-------------------------------------------------------------------------
JT9-1 6912 432 1.736 0.58 15.6 -26.9 52.5 7.5 2^8 3^3
JT9-2 15360 960 0.781 1.28 7.0 -30.2 112.3 7.7 2^10 3 5
JT9-5 40960 2560 0.293 3.41 2.6 -34.4 293.6 6.4 2^13 5
JT9-10 82944 5184 0.145 6.91 1.3 -37.5 591.0 9.0 2^10 3^4
JT9-30 250880 15750 0.048 20.91 0.4 -42.3 1788.5 11.5 2^5 3^2 5^3 7
-------------------------------------------------------------------------
* Noise power measured in a 2500 Hz bandwidth.
Transmitting
------------
1. Source encode the structured message to 72 bits
2. Add 12-bit CRC
3. Convolutionally encode (K=16, r=1/2) to (72+12+15)*2 = 198 bits
4. Interleave to scramble the bit order
5. Assemble 3-bit groups to make 198/3 = 66 symbols
6. Apply Gray code to the symbol values
7. Insert 15 sync symbols ==> 66+15=81 channel symbols with values 0-8
2. Convolutionally encode (K=32, r=1/2) to (72+31)*2 = 206 bits
3. Interleave to scramble the bit order
4. Assemble 3-bit groups to make (206+1)/3 = 69 symbols
5. Gray-code the symbol values
6. Insert 16 sync symbols ==> 69+15=81 channel symbols, values 0-8
Receiving
---------
1. Apply noise blanking with the timf2 method
2. Filter to 500 Hz bandwidth, downsample (1/16) to 750 Hz complex
using FIR filter with 61 taps. Data in array c0(1800*750) (1.35M)
(FIR filter with 61 taps). Complex data to array c0 (max 1.35M)
3. Compute symbol-length spectra at half-symbol steps. Use for
waterfalls s(16384) and save in ss(180,16384), savg(16384)
4. At time Tdec, look for sync vectors in ss() to get estimates of DF, DT
5. Do full-length FFTs of length NFFT1=96*nsps
6. For each candidate JT9 signal, do inverse FFT of length 1536. This
gives 16 complex samples per symbol, sync tone should be close to f=0.
waterfalls s(15750) and detecting sync vectors; save in ss(184,15750)
and savg(15750)
4. At time Tdec, look for sync vectors in ss(); get estimates of DF, DT
5. Do full-length FFTs, NFFT1=96*nsps2
6. For each candidate signal, do inverse FFT of length 1536. This
will provide 16 complex samples per symbol, and sync tone should be
close to f=0.
7. Use afc65b method to get improved values of DF, DT.
8. Tweak freq and time offset to 0.
9. Compute 8-bin spectra of 66 data symbols: s2(8,66). Re-order the
9. Compute 8-bin spectra of 69 data symbols: s2(8,69). Re-order the
bins by removing Gray code.
10. Compute soft symbols for 198 bits
10. Compute soft symbols for 206 bits
11. Re-order the bits by removing interleaving.
12. Pack bits into bytes, send to Viterbi decoder ==> 72-bit message,
12-bit CRC, and metric.
13. Declare erasure if CRC check fails
14. If CRC is good, remove source encoding and display user message.
12. Pack bits into bytes, send to Fano decoder
13. If Fano succeeds, remove source encoding and display user message.

94
libm65/genjt9.f90
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@ -1,77 +1,86 @@
subroutine genjt9(message,minutes,lwave,msgsent,d7,iwave,nwave)
subroutine genjt9(message,minutes,lwave,msgsent,d8,iwave,nwave)
! Encodes a "JT9-minutes" message and returns array d7(81) of tone
! Encodes a "JT9-minutes" message and returns array d7(85) of tone
! values in the range 0-8. If lwave is true, also returns a generated
! waveform in iwave(nwave), at 12000 samples per second.
parameter (NMAX=1800*12000) !Max length of wave file
character*22 message !Message to be generated
character*22 msgsent !Message as it will be received
character*3 cok
real*8 dt,phi,f,f0,dfgen,dphi,twopi
integer*2 iwave(NMAX) !Generated wave file
integer d0(14) !72-bit message + 12-bit CRC, as 6-bit bytes
integer*1 d1(84) !72+12 = 84 single bits
integer d2(11) !72+12 bits, as 8-bit words
integer*1 d3(11) !72+12 bits, as 8-bit bytes
integer*1 d4(198) !Encoded information-carrying bits
integer*1 d5(198) !Bits from d4, after interleaving
integer*1 d6(66) !Symbols from d5, values 0-7
integer*1 d7(66) !Gray-coded symbols, values 0-7
integer*1 d8(81) !Channel symbols including sync, values 0-8
integer*4 d0(12) !72-bit message as 6-bit words
integer*1 d1(72) !72 single bits
integer*4 d2(9) !72 bits as 8-bit words
integer*1 d3(9) !72 bits as 8-bit bytes
integer*1 d4(206) !Encoded information-carrying bits
integer*1 d5(206) !Bits from d4, after interleaving
integer*4 d6(69) !Symbols from d5, values 0-7
integer*4 d7(69) !Gray-coded symbols, values 0-7
integer*4 d8(85) !Channel symbols including sync, values 0-8
logical lwave
integer isync(15)
data isync/1,6,11,16,21,26,31,39,45,51,57,63,69,75,81/
integer isync(85)
data isync/ &
1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0,0,0,0, &
1,0,0,0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,0, &
0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0, &
0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0, &
1,0,0,0,1/
data twopi/6.283185307179586476d0/
save
call chkmsg(message,cok,nspecial,flip)
call packmsg(message,d0) !Pack message into 12 6-bit bytes
d0(11)=0 !### Temporary CRC=0 ###
d0(12)=0
call unpackbits(d0,14,6,d1) !Unpack into 84 bits
nbits=84
call packbits(d1,nbits,8,d2) !Pack into 11 8-bit words
nbytes=(nbits+7)/8
do i=1,nbytes
call unpackbits(d0,12,6,d1) !Unpack into 72 bits
nbits=72
nbytes=9
call packbits(d1,nbits,8,d2) !Pack into 9 8-bit words
do i=1,9
if(d2(i).lt.128) d3(i)=d2(i)
if(d2(i).ge.128) d3(i)=d2(i)-256
enddo
call enc216(d3,nbits,d4,nsym2,16,2) !Convolutional code, K=16, r=1/2
! NB: Should give nsym2 = (72+12+15)*2 = 198
! call interleavejt9(d4,1,d5)
d5=d4 !### TEMP ###
call encode232(d3,nbytes,d4) !Convolutional code, K=32, r=1/2
nsym2=206
call interleave9(d4,1,d5)
call packbits(d5,nsym2,3,d6)
! call graycode(d6,nsym2,1,d7)
call graycode(d6,69,1,d7)
! Now insert sync symbols and add 1 to the tone numbers.
! Insert sync symbols (ntone=0) and add 1 to the data-tone numbers.
j=0
do i=1,85
if(isync(i).eq.1) then
d8(i)=0
else
j=j+1
d8(i)=d7(j)+1
endif
enddo
nwave=0
if(lwave) then
nsps1=0
if(minutes.eq.1) nsps1=7168
if(minutes.eq.2) nsps1=16000
if(minutes.eq.5) nsps1=42336
if(minutes.eq.10) nsps1=86400
if(minutes.eq.30) nsps1=262144
if(nsps1.eq.0) stop 'Bad value for minutes in genjt9.'
nsps=0
if(minutes.eq.1) nsps=6912
if(minutes.eq.2) nsps=15360
if(minutes.eq.5) nsps=40960
if(minutes.eq.10) nsps=82944
if(minutes.eq.30) nsps=250880
if(nsps.eq.0) stop 'Bad value for minutes in genjt9.'
! Set up necessary constants
dt=1.d0/12000.d0
f0=1500.d0
dfgen=12000.d0/nsps1
dfgen=12000.d0/nsps
phi=0.d0
i=0
k=0
do j=1,81
do j=1,85
f=f0 +d7(j)*dfgen
dphi=twopi*dt*f
do i=1,nsps1
do i=1,nsps
phi=phi+dphi
if(phi.gt.twopi) phi=phi-twopi
xphi=phi
@ -79,9 +88,10 @@ subroutine genjt9(message,minutes,lwave,msgsent,d7,iwave,nwave)
iwave(k)=32767.0*sin(xphi)
enddo
enddo
nwave=81*nsps1
nwave=85*nsps
endif
call unpackmsg(dgen,msgsent)
call unpackmsg(d0,msgsent)
return
end subroutine genjt9

10
libm65/graycode.f
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@ -1,10 +0,0 @@
subroutine graycode(dat,n,idir)
integer dat(n)
do i=1,n
dat(i)=igray(dat(i),idir)
enddo
return
end

9
libm65/graycode.f90 Normal file
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@ -0,0 +1,9 @@
subroutine graycode(ia,n,idir,ib)
integer ia(n),ib(n)
do i=1,n
ib(i)=igray(ia(i),idir)
enddo
return
end subroutine graycode

4
libm65/igray.c
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@ -1,8 +1,4 @@
#ifdef CVF
extern int __stdcall IGRAY(int *n0, int *idir)
#else
int igray_(int *n0, int *idir)
#endif
{
int n;
unsigned long sh;

39
libm65/interleave9.f90 Normal file
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@ -0,0 +1,39 @@
subroutine interleave9(ia,ndir,ib)
integer*1 ia(0:205),ib(0:205)
integer j0(0:205)
logical first
data first/.true./
save first,j0
if(first) then
k=-1
do i=0,255
m=i
n=iand(m,1)
n=2*n + iand(m/2,1)
n=2*n + iand(m/4,1)
n=2*n + iand(m/8,1)
n=2*n + iand(m/16,1)
n=2*n + iand(m/32,1)
n=2*n + iand(m/64,1)
n=2*n + iand(m/128,1)
if(n.le.205) then
k=k+1
j0(k)=n
endif
enddo
! first=.false.
endif
if(ndir.gt.0) then
do i=0,205
ib(j0(i))=ia(i)
enddo
else
do i=0,205
ib(i)=ia(j0(i))
enddo
endif
return
end subroutine interleave9

75
libm65/jt9sim.f90
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@ -1,19 +1,18 @@
program jt9sim
! Generate simulated data for testing of MAP65
! Generate simulated data for testing of WSJT-X
parameter (NMAX=1800*12000)
real*4 d4(NMAX) !Floating-point data
integer ihdr(11)
integer*2 id2(NMAX) !i*2 data
integer*2 iwave(NMAX) !Generated waveform (no noise)
real*8 f0,f,dt,twopi,phi,dphi,baud
integer*2 iwave !Generated waveform (no noise)
real*8 f0,f,dt,twopi,phi,dphi,baud,fspan
character msg0*22,message*22,msgsent*22,arg*8,fname*11
logical lwave
integer*1 d7(81)
integer*4 d8(85)
common/acom/dat(NMAX),iwave(NMAX)
nargs=iargc()
if(nargs.ne.9) then
if(nargs.ne.6) then
print*,'Usage: jt9sim "message" fspan nsigs minutes SNR nfiles'
print*,'Example: "CQ K1ABC FN42" 200 20 2 -28 1'
print*,' '
@ -41,16 +40,16 @@ program jt9sim
fsample=12000.d0 !Sample rate (Hz)
dt=1.d0/fsample !Sample interval (s)
twopi=8.d0*atan(1.d0)
rad=360.0/twopi
npts=12000*(60*minutes-6)
lwave=.false.
nsps1=0
if(minutes.eq.1) nsps1=7168
if(minutes.eq.2) nsps1=16000
if(minutes.eq.5) nsps1=42336
if(minutes.eq.10) nsps1=86400
if(minutes.eq.30) nsps1=262144
if(nsps1.eq.0) stop 'Bad value for minutes.'
nsps=0
if(minutes.eq.1) nsps=6912
if(minutes.eq.2) nsps=15360
if(minutes.eq.5) nsps=40960
if(minutes.eq.10) nsps=82944
if(minutes.eq.30) nsps=250880
if(nsps.eq.0) stop 'Bad value for minutes.'
ihdr=0 !Temporary ###
open(12,file='msgs.txt',status='old')
@ -66,10 +65,14 @@ program jt9sim
1002 format('000000_',2i2.2)
open(10,file=fname//'.wav',access='stream',status='unknown')
call noisegen(d4,npts) !Generate Gaussian noise
if(snrdb.lt.90) then
call noisegen(dat,npts) !Generate Gaussian noise
else
dat(1:npts)=0.
endif
if(msg0.ne.' ') then
call genjt9(message,minutes,lwave,msgsent,d7,iwave,nwave)
call genjt9(message,minutes,lwave,msgsent,d8,iwave,nwave)
endif
rewind 12
@ -78,40 +81,48 @@ program jt9sim
if(msg0.eq.' ') then
read(12,1004) message
1004 format(a22)
call genjt9(message,minutes,lwave,msgsent,d7,iwave,nwave)
call genjt9(message,minutes,lwave,msgsent,d8,iwave,nwave)
endif
f=1500.d0
if(nsigs.gt.1) f=1500.0 - 0.5* fspan + fspan*(isig-1.0)/(nsigs-1.0)
f=f0
if(nsigs.gt.1) f=f0 - 0.5d0*fspan + fspan*(isig-1.d0)/(nsigs-1.d0)
snrdbx=snrdb
if(snrdb.ge.-1.0) snrdbx=-15.0 - 15.0*(isig-1.0)/nsigs
sig=sqrt(2.2*2500.0/96000.0) * 10.0**(0.05*snrdbx)
write(*,1020) ifile,isig,0.001*f,snrdbx,msgsent
1020 format(i3,i4,f8.3,f7.1,2x,a22)
! if(snrdb.ge.-1.0) snrdbx=-15.0 - 15.0*(isig-1.0)/nsigs
sig=sqrt(2500.0/12000.0) * 10.0**(0.05*snrdbx)
write(*,1020) ifile,isig,f,snrdbx,msgsent
1020 format(i3,i4,f10.3,f7.1,2x,a22)
phi=0.
baud=12000.0/nsps1
baud=12000.0/nsps
k=12000 !Start at t = 1 s
do isym=1,81
freq=f + d7(isym)*baud
dphi=twopi*freq*dt + 0.5*twopi
do i=1,nsps1
do isym=1,85
freq=f + d8(isym)*baud
dphi=twopi*freq*dt
do i=1,nsps
phi=phi + dphi
if(phi.lt.-twopi) phi=phi+twopi
if(phi.gt.twopi) phi=phi-twopi
xphi=phi
k=k+1
d4(k)=d4(k) + sin(phi)
dat(k)=dat(k) + sig*sin(xphi)
enddo
enddo
enddo
do i=1,npts
id2(i)=nint(rms*d4(i))
iwave(i)=nint(rms*dat(i))
! iwave(i)=nint(100.0*dat(i))
enddo
write(10) ihdr,id2(1:npts)
write(10) ihdr,iwave(1:npts)
close(10)
do i=1,30000
write(71,3001) i,iwave(12000+i)
3001 format(2i8)
enddo
enddo
999 end program jt9sim

2
mainwindow.cpp
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@ -1,4 +1,4 @@
//---------------------------------------------------------------- MainWindow
//--------------------------------------------------------------- MainWindow
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "devsetup.h"