WSJT-X/map65/libm65/s3avg.f90

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subroutine s3avg(nsave,mode65,nutc,nhz,xdt,npol,ntol,s3,nsum,nkv,decoded)
! Save the current synchronized spectra, s3(64,63), for possible
! decoding of average.
real s3(64,63) !Synchronized spectra for 63 symbols
real s3a(64,63,64) !Saved spectra
real s3b(64,63) !Average spectra
integer iutc(64),ihz(64),ipol(64)
real dt(64)
character*22 decoded
logical ltext,first
data first/.true./
save
if(first) then
iutc=-1
ihz=0
ipol=0
first=.false.
ihzdiff=min(100,ntol)
dtdiff=0.2
endif
do i=1,64
if(nutc.eq.iutc(i) .and. abs(nhz-ihz(i)).lt.ihzdiff) then
nsave=mod(nsave-1+64,64)+1
go to 10
endif
enddo
iutc(nsave)=nutc !Save UTC
ihz(nsave)=nhz !Save freq in Hz
ipol(nsave)=npol !Save pol
dt(nsave)=xdt !Save DT
s3a(1:64,1:63,nsave)=s3 !Save the spectra
10 s3b=0.
do i=1,64 !Accumulate avg spectra
if(iutc(i).lt.0) cycle
if(mod(iutc(i),2).ne.mod(nutc,2)) cycle !Use only same sequence
if(abs(nhz-ihz(i)).gt.ihzdiff) cycle !Freq must match
if(abs(xdt-dt(i)).gt.dtdiff) cycle !DT must match
s3b=s3b + s3a(1:64,1:63,i)
nsum=nsum+1
enddo
decoded=' '
if(nsum.ge.2) then !Try decoding the sverage
nadd=mode65*nsum
call extract(s3b,nadd,ncount,nhist,decoded,ltext) !Extract the message
nkv=nsum
if(ncount.lt.0) then
nkv=0
decoded=' '
endif
endif
return
end subroutine s3avg