Code cleanup and documentation.

q65w/libq65/decode0.f90

@@ -43,7 +43,7 @@ subroutine decode0(dd,ss,savg)
 
   call timer('q65wa   ',0)
   call q65wa(dd,ss,savg,newdat,nutc,fcenter,ntol,nfa,nfb,           &
-       mousedf,mousefqso,nagain,ndecdone,nfshift,max_drift,         &
+       mousedf,mousefqso,nagain,nfshift,max_drift,                  &
        nfcal,mycall,hiscall,hisgrid,nfsample,nmode,ndepth,          &
        datetime,ndop00)
   call timer('q65wa   ',1)

q65w/libq65/filbig.f90

@@ -102,7 +102,7 @@ subroutine filbig(dd,nmax,f0,newdat,nfsample,c4a,n4)
   enddo
   do i=nh+1,nfft2
      j=i0+i-1-nfft2
-     if(j.lt.1) j=j+nfft1                  !nfft1 was nfft2
+     if(j.lt.1) j=j+nfft1
      c4a(i)=rfilt(i)*ca(j)
   enddo
 

q65w/libq65/getcand2.f90

@@ -1,6 +1,6 @@
 subroutine getcand2(ss,savg0,nts_q65,cand,ncand)
 
-!  use wideband_sync
+! Get candidates for Q65 decodes, based on presence of sync tone.
   
   type candidate
      real :: snr          !Relative S/N of sync detection
@@ -8,18 +8,18 @@ subroutine getcand2(ss,savg0,nts_q65,cand,ncand)
      real :: xdt          !DT of matching sync pattern, -1.0 to +4.0 s
   end type candidate
 
-  parameter (NFFT=32768)
+  parameter (NFFT=32768)                !FFTs done in symspec()
   parameter (MAX_CANDIDATES=50)
-  real ss(322,NFFT)
-  real savg0(NFFT),savg(NFFT)
-  integer ipk1(1)
-  logical sync_ok
   type(candidate) :: cand(MAX_CANDIDATES)
+  real ss(322,NFFT)                     !Symbol spectra
+  real savg0(NFFT),savg(NFFT)           !Average spectra over whole Rx sequence
+  integer ipk1(1)                       !Peak index of local portion of spectrum
+  logical sync_ok                       !True if sync pattern is present
   data nseg/16/,npct/40/
 
-  savg=savg0
+  savg=savg0                            !Save the original spectrum
   nlen=NFFT/nseg
-  do iseg=1,nseg
+  do iseg=1,nseg                        !Normalize spectrum with nearby baseline
      ja=(iseg-1)*nlen + 1
      jb=ja + nlen - 1
      call pctile(savg(ja),nlen,npct,base)
@@ -28,22 +28,24 @@ subroutine getcand2(ss,savg0,nts_q65,cand,ncand)
   enddo
 
   df=96000.0/NFFT
-  bw=65*nts_q65*1.666666667
+  bw=65*nts_q65*1.666666667             !Bandwidth of Q65 signal
-  nbw=bw/df + 1
+  nbw=bw/df + 1                         !Bandwidth in bins
-  nb0=2*nts_q65
+  nb0=2*nts_q65                         !Range of peak search, in bins
-  smin=1.4
+  smin=1.4                              !First threshold
-  nguard=5
+  nguard=5                              !Guard range in bins
 
   j=0
-  do i=1,NFFT-nbw-nguard
+  do i=1,NFFT-nbw-nguard          !Look for local peaks in average spectrum
      if(savg(i).lt.smin) cycle
      spk=maxval(savg(i:i+nb0))
      ipk1=maxloc(savg(i:i+nb0))
-     i0=ipk1(1) + i - 1
+     i0=ipk1(1) + i - 1                         !Index of local peak in savg()
-     fpk=0.001*i0*df
+     fpk=0.001*i0*df                            !Frequency of peak (kHz)
 ! Check to see if sync tone is present.
      call q65_sync(ss,i0,nts_q65,sync_ok,snr_sync,xdt)
      if(.not.sync_ok) cycle
+
+! Sync tone is present, we have a candidate for decoding
      j=j+1
      cand(j)%f=fpk
      cand(j)%xdt=xdt
@@ -51,9 +53,9 @@ subroutine getcand2(ss,savg0,nts_q65,cand,ncand)
      ia=min(i,i0-nguard)
      ib=i0+nbw+nguard
      savg(ia:ib)=0.
-     if(j.ge.30) exit
+     if(j.ge.MAX_CANDIDATES) exit
   enddo
-  ncand=j
+  ncand=j                              !Total number of candidates found
 
   return
 end subroutine getcand2

q65w/libq65/q65_sync.f90

@@ -1,9 +1,11 @@
 subroutine q65_sync(ss,i0,nts_q65,sync_ok,snr,xdt)
 
+! Test for presence of Q65 sync tone
+
   parameter (NFFT=32768)
   parameter (LAGMAX=33)
-  real ss(322,NFFT)
+  real ss(322,NFFT)                !Symbol spectra
-  real ccf(0:LAGMAX)
+  real ccf(0:LAGMAX)               !The WSJT "blue curve", peak at DT
   logical sync_ok
   logical first
   integer isync(22),ipk(1)
@@ -24,12 +26,12 @@ subroutine q65_sync(ss,i0,nts_q65,sync_ok,snr,xdt)
 
   m=nts_q65/2
   ccf=0.
-  do lag=0,LAGMAX
+  do lag=0,LAGMAX                     !Search over range of DT
      do j=1,22                        !Test for Q65 sync
         k=isync(j) + lag
-!        ccf=ccf + ss(k,i0) + ss(k+1,i0) + ss(k+2,i0)
         ccf(lag)=ccf(lag) + sum(ss(k,i0-m:i0+m)) + sum(ss(k+1,i0-m:i0+m)) &
              + sum(ss(k+2,i0-m:i0+m))
+! Q: Should we use weighted sums, perhaps a Lorentzian peak?
      enddo
   enddo
   ccfmax=maxval(ccf)
@@ -40,7 +42,7 @@ subroutine q65_sync(ss,i0,nts_q65,sync_ok,snr,xdt)
   xsum=0.
   sq=0.
   nsum=0
-  do i=0,lagmax
+  do i=0,lagmax                       !Compute ave and rms of "blue curve"
      if(abs(i-lagbest).gt.2) then
         xsum=xsum+ccf(i)
         sq=sq+ccf(i)**2
@@ -50,7 +52,7 @@ subroutine q65_sync(ss,i0,nts_q65,sync_ok,snr,xdt)
   ave=xsum/nsum
   rms=sqrt(sq/nsum - ave*ave)
   snr=(ccfmax-ave)/rms
-  sync_ok=snr.ge.5.0
+  sync_ok=snr.ge.5.0                  !Require snr > 5.0 for sync detection
 
   return
 end subroutine q65_sync

q65w/libq65/q65b.f90

@@ -2,13 +2,12 @@ subroutine q65b(nutc,nqd,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,          &
      mycall0,hiscall0,hisgrid,mode_q65,f0,fqso,nkhz_center, newdat,nagain,  &
      max_drift,ndepth,datetime,ndop00,idec)
 
-! This routine provides an interface between MAP65 and the Q65 decoder
+! This routine provides an interface between Q65W and the Q65 decoder
-! in WSJT-X.  All arguments are input data obtained from the MAP65 GUI.
+! in WSJT-X.  All arguments are input data obtained from the Q65W GUI.
 ! Raw Rx data are available as the 96 kHz complex spectrum ca(MAXFFT1)
-! in common/cacb.  Decoded messages are sent back to the GUI on stdout.
+! in common/cacb.  Decoded messages are sent back to the GUI.
 
   use q65_decode
-!  use wideband_sync
   use timer_module, only: timer
 
   parameter (MAXFFT1=5376000)              !56*96000
@@ -16,7 +15,7 @@ subroutine q65b(nutc,nqd,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,          &
   parameter (NMAX=60*12000)
   parameter (RAD=57.2957795)
   integer*2 iwave(60*12000)
-  complex ca(MAXFFT1)                      !FFTs of raw x,y data
+  complex ca(MAXFFT1)                      !FFT of raw I/Q data from Linrad
   complex cx(0:MAXFFT2-1),cz(0:MAXFFT2)
   real*8 fcenter,freq0,freq1
   character*12 mycall0,hiscall0
@@ -64,10 +63,8 @@ subroutine q65b(nutc,nqd,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,          &
 !    (Hz)              (Hz)                 (Hz)
 !----------------------------------------------------
 !   96000  5376000  0.017857143  336000   6000.000
-!   95238  5120000  0.018601172  322560   5999.994
 
   cz(0:MAXFFT2-1)=cx
-
   cz(MAXFFT2)=0.
 ! Roll off below 500 Hz and above 2500 Hz.
   ja=nint(500.0/df)

q65w/libq65/q65wa.f90

@@ -1,11 +1,9 @@
 subroutine q65wa(dd,ss,savg,newdat,nutc,fcenter,ntol,nfa,nfb,         &
-     mousedf,mousefqso,nagain,ndecdone,nfshift,max_drift,             &
+     mousedf,mousefqso,nagain,nfshift,max_drift,nfcal,mycall,         &
-     nfcal,mycall,hiscall,hisgrid,nfsample,nmode,ndepth,        &
+     hiscall,hisgrid,nfsample,nmode,ndepth,datetime,ndop00)
-     datetime,ndop00)
 
-!  Processes timf2 data from Linrad to find and decode JT65 and Q65 signals.
+!  Processes timf2 data received from Linrad to find and decode Q65 signals.
 
-!  use wideband_sync
   use timer_module, only: timer
 
   type candidate
@@ -14,27 +12,24 @@ subroutine q65wa(dd,ss,savg,newdat,nutc,fcenter,ntol,nfa,nfb,         &
      real :: xdt          !DT of matching sync pattern, -1.0 to +4.0 s
   end type candidate
 
-  parameter (NFFT=32768)
+  parameter (NFFT=32768)             !Size of FFTs done in symspec()
   parameter (MAX_CANDIDATES=50)
-
   parameter (MAXMSG=1000)            !Size of decoded message list
   parameter (NSMAX=60*96000)
   complex cx(NSMAX/64)               !Data at 1378.125 samples/s
-  real dd(2,NSMAX)
+  real dd(2,NSMAX)                   !I/Q data from Linrad
-  real*4 ss(322,NFFT),savg(NFFT)
+  real ss(322,NFFT)                  !Symbol spectra
-  real*8 fcenter
+  real savg(NFFT)                    !Average spectrum
+  real*8 fcenter                             !Center RF frequency, MHz
   character mycall*12,hiscall*12,hisgrid*6
-  logical bq65
-  logical candec(MAX_CANDIDATES)
   type(candidate) :: cand(MAX_CANDIDATES)
   character*60 result
   character*20 datetime
   common/decodes/ndecodes,ncand,nQDecoderDone,nWDecoderBusy,              &
        nWTransmitting,result(50)
-  common/testcom/ifreq
   save
 
-  if(nagain.eq.1) ndepth=3
+  if(nagain.eq.1) ndepth=3            !Use full depth for click-to-decode
   nkhz_center=nint(1000.0*(fcenter-int(fcenter)))
   mfa=nfa-nkhz_center+48
   mfb=nfb-nkhz_center+48
@@ -42,40 +37,32 @@ subroutine q65wa(dd,ss,savg,newdat,nutc,fcenter,ntol,nfa,nfb,         &
   nts_q65=2**(mode_q65-1)             !Q65 tone separation factor
 
   call timer('get_cand',0)
-  call getcand2(ss,savg,nts_q65,cand,ncand)
+  call getcand2(ss,savg,nts_q65,cand,ncand) !Get a list of decoding candidates
   call timer('get_cand',1)
 
-  candec=.false.
   nwrite_q65=0
-  bq65=mode_q65.gt.0
   df=96000.0/NFFT                     !df = 96000/NFFT = 2.930 Hz
   if(nfsample.eq.95238) df=95238.1/NFFT
   ftol=0.010                          !Frequency tolerance (kHz)
-  foffset=0.001*(1270 + nfcal)              !Offset from sync tone, plus CAL
+  foffset=0.001*(1270 + nfcal)        !Offset from sync tone, plus CAL
   fqso=mousefqso + foffset - 0.5*(nfa+nfb) + nfshift !fqso at baseband (khz)
-  iloop=0
   nqd=0
 
   call timer('filbig  ',0)
-  call filbig(dd,NSMAX,f0,newdat,nfsample,cx,n5)
+  call filbig(dd,NSMAX,f0,newdat,nfsample,cx,n5) !Do the full-length FFT
   call timer('filbig  ',1)
 
-! Do the wideband Q65 decode
+  do icand=1,ncand                        !Attempt to decode each candidate
-  do icand=1,ncand
      f0=cand(icand)%f
-     if(candec(icand)) cycle             !Skip if already decoded
      freq=cand(icand)%f+nkhz_center-48.0-1.27046
      ikhz=nint(freq)
      idec=-1
-
      call timer('q65b    ',0)
      call q65b(nutc,nqd,fcenter,nfcal,nfsample,ikhz,mousedf,ntol,       &
           mycall,hiscall,hisgrid,mode_q65,f0,fqso,nkhz_center,newdat,   &
           nagain,max_drift,ndepth,datetime,ndop00,idec)
      call timer('q65b    ',1)
-     if(idec.ge.0) candec(icand)=.true.
   enddo  ! icand
-  ndecdone=2
 
   return
 end subroutine q65wa