mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-19 10:32:02 -05:00
8c9ed820c8
2. "/A" added to list of optional callsign suffixes. 3. Improved algorithm for measuring error in soundcard sample rates. 4. Optional 5-sec shift of input data, to catch some clock errors. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/trunk@274 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
129 lines
3.6 KiB
Fortran
129 lines
3.6 KiB
Fortran
subroutine longx(dat,npts0,ps,DFTolerance,noffset,
|
|
+ msg,msglen,bauderr)
|
|
|
|
C Look for 441-baud modulation, synchronize to it, and decode message.
|
|
C Longest allowed data analysis is 1 second.
|
|
|
|
parameter (NMAX=11025)
|
|
parameter (NDMAX=NMAX/25)
|
|
real dat(npts0)
|
|
real ps(128),psmo(20)
|
|
integer DFTolerance
|
|
real y1(NMAX)
|
|
real y2(NMAX)
|
|
real y3(NMAX)
|
|
real y4(NMAX)
|
|
real wgt(-2:2)
|
|
integer dit(NDMAX)
|
|
integer n4(0:2)
|
|
character msg*40
|
|
character c*48
|
|
common/acom/a1,a2,a3,a4
|
|
data c/' 123456789.,?/# $ABCD FGHIJKLMNOPQRSTUVWXY 0EZ '/
|
|
data wgt/1.0,4.0,6.0,4.0,1.0/
|
|
|
|
NSPD=25 !Change if FSK110 is implemented
|
|
LTone=2
|
|
NBaud=11025/NSPD
|
|
npts=min(NMAX,npts0)
|
|
df=11025.0/256.0
|
|
smax=0.
|
|
|
|
C Find the frequency offset of this ping.
|
|
C NB: this might be improved by including a bandpass correction to ps.
|
|
|
|
ia=nint((LTone*NBaud-DFTolerance)/df)
|
|
ib=nint((LTone*NBaud+DFTolerance)/df)
|
|
|
|
do i=ia,ib !Search for correct DF
|
|
sum=0.
|
|
do j=1,4 !Sum over the 4 tones
|
|
m=nint((i*df+(j-1)*NBaud)/df)
|
|
do k=-2,2 !Weighted averages over 5 bins
|
|
sum=sum+wgt(k)*ps(m+k)
|
|
enddo
|
|
enddo
|
|
k=i-ia+1
|
|
psmo(k)=sum
|
|
kpk=0
|
|
if(sum.gt.smax) then
|
|
smax=sum
|
|
noffset=nint(i*df-LTone*NBaud)
|
|
kpk=k
|
|
endif
|
|
enddo
|
|
|
|
|
|
if(kpk.gt.1 .and. kpk.lt.20) then
|
|
call peakup(psmo(kpk-1),psmo(kpk),psmo(kpk+1),dx)
|
|
noffset=nint(noffset+dx*df)
|
|
endif
|
|
|
|
C Do square-law detection in each of four filters.
|
|
f1=LTone*NBaud+noffset
|
|
f2=(LTone+1)*NBaud+noffset
|
|
f3=(LTone+2)*NBaud+noffset
|
|
f4=(LTone+3)*NBaud+noffset
|
|
call detect(dat,npts,f1,y1)
|
|
call detect(dat,npts,f2,y2)
|
|
call detect(dat,npts,f3,y3)
|
|
call detect(dat,npts,f4,y4)
|
|
|
|
C Bandpass correction:
|
|
npts=npts-(NSPD-1)
|
|
do i=1,npts
|
|
y1(i)=y1(i)*a1
|
|
y2(i)=y2(i)*a2
|
|
y3(i)=y3(i)*a3
|
|
y4(i)=y4(i)*a4
|
|
enddo
|
|
|
|
call sync(y1,y2,y3,y4,npts,jpk,baud,bauderr)
|
|
|
|
C Decimate y arrays by NSPD
|
|
ndits=npts/NSPD - 1
|
|
do i=1,ndits
|
|
y1(i)=y1(jpk+(i-1)*NSPD)
|
|
y2(i)=y2(jpk+(i-1)*NSPD)
|
|
y3(i)=y3(jpk+(i-1)*NSPD)
|
|
y4(i)=y4(jpk+(i-1)*NSPD)
|
|
enddo
|
|
|
|
C Now find the mod3 phase that has no tone 3's
|
|
n4(0)=0
|
|
n4(1)=0
|
|
n4(2)=0
|
|
do i=1,ndits
|
|
ymax=max(y1(i),y2(i),y3(i),y4(i))
|
|
if(y1(i).eq.ymax) dit(i)=0
|
|
if(y2(i).eq.ymax) dit(i)=1
|
|
if(y3(i).eq.ymax) dit(i)=2
|
|
if(y4(i).eq.ymax) then
|
|
dit(i)=3
|
|
k=mod(i,3)
|
|
n4(k)=n4(k)+1
|
|
endif
|
|
enddo
|
|
|
|
n4min=min(n4(0),n4(1),n4(2))
|
|
if(n4min.eq.n4(0)) jsync=3
|
|
if(n4min.eq.n4(1)) jsync=1
|
|
if(n4min.eq.n4(2)) jsync=2
|
|
C Might want to notify if n4min>0 or if one of the others is equal
|
|
C to n4min. In both cases, could then decode 2 or 3 times, using
|
|
C other starting phases.
|
|
|
|
C Finally, decode the message.
|
|
msg=' '
|
|
msglen=ndits/3
|
|
msglen=min(msglen,40)
|
|
do i=1,msglen
|
|
j=(i-1)*3+jsync
|
|
nc=16*dit(j) + 4*dit(j+1) +dit(j+2)
|
|
msg(i:i)=' '
|
|
if(nc.le.47) msg(i:i)=c(nc+1:nc+1)
|
|
enddo
|
|
|
|
return
|
|
end
|