Tweak decoder for better decodes under poor conditions
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Jordan Sherer
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6201de8c12
@ -1,126 +0,0 @@
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Quick Start for DXpedition Mode
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-------------------------------
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These notes are intended for operators already familiar with WSJT-X
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and FT8 mode. QSOs between the Dxpedition ("Fox") and other stations
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("Hounds") are completed with as little as one transmission per Hound,
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as in the following examples:
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----------------------------------------------------------------------------
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Fox (300-600 Hz) Hounds
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----------------------------------------------------------------------------
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1. CQ KH1DX AJ10
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2. KH1DX K1ABC FN42, KH1DX W9XYZ EN37, ...
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3. K1ABC KH1DX -13
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4. KH1DX K1ABC R-11
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5. K1ABC RR73; W9XYZ <KH1DX> -17
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6. KH1DX W9XYZ R-16
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7. W9XYZ RR73; G4AAA <KH1DX> -09
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8. ...
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----------------------------------------------------------------------------
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Everybody sets dial frequency to an agreed number and uses CAT control
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with Split Operation (either *Rig* or *Fake It*). Fox transmits up to
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5 signals simultaneously, at audio frequencies 300, 360, ... 540
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Hz. Hounds make initial calls (e.g., line 2 above) anywhere in the
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range 1000 - 4000 Hz. They send "R+rpt" 350 Hz above the frequency
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where Fox called them.
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INSTRUCTIONS FOR FOX
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--------------------
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1. Start WSJT-X in FT8 mode. Select *Fox* on the *Settings ->
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Advanced tab*. On the main window, check *Tx even/1st*, *Auto Seq*,
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and *Hold Tx Freq*; uncheck *Call 1st*. Set *Tx 300 Hz* and select
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Tab 3.
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2. In Fox mode the left window (called "Band Activity" in normal FT8
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mode) is labeled "Stations calling DXpedition <MyCall>". It will be
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filled with a sorted list of calling Hounds. You can sort by Call,
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Grid, S/N, Distance, or Random order by using the comboBox at top
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right of Tab 3. You can limit the displayed Hound callsigns to those
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no stronger than *Max dB*. Fox might use this feature to discourage
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Hounds from engaging in a QRO arms race.
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3. *N Slots* sets the number of simultaneous Fox signals to be used.
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Fox carries out as many as *N Slots* QSOs simultaneously.
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4. *Repeats* sets the maximum number of repeat transmissions of the
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same message. A QSO is aborted when this number would be exceeded.
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5. The *CQ* comboBox on Tab 3 offers a selection of directed CQ
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messages. *Reset* clears the QSO queue.
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6. The Fox operator's main task is to select Hounds to be called and
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worked. The text box on Tab 3 holds the "QSO queue": a list of Hound
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calls to be worked. Hit Enter to select the top callsign from the
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sorted list of callers (left window), or double-click on any
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particular call. Either actiion moves that Hound into the "QSO
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queue".
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7. The right window displays decodes of signals below 1000 Hz.
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Normally these should include only Hound messages containing "R+rpt"
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and Fox's own transmissions.
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8. To get things started, toggle *Enable Tx* to red. If a Hound call
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is available in the QSO queue, that station will be called. If the
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QSO queue is empty, Fox calls CQ.
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9. If you're using Nslots = 2 or higher, your signal no longer has
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a constant envelope. To avoid producing intermod sidebands you need
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to ensure linearity in your Tx system. One way to get things about right
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is to use the WSJT-X *Tune* button to generate a pure tone. Reduce the
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Tx audio level until your power output decreases by 10% or so. Use this
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level for your Fox transmissions.
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NOTE: If you are generating Nslots signals, the average power in each one
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will be 1/Nslots^2 of its normal value for single-signal transmissions.
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Nslots Relative dB
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-------------------
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1 0
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2 -6
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3 -9.5
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4 -12
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5 -14
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The following features are not yet implemented for Fox:
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1. Enforce all required settings
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2. Tx message timeout
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3. Manual abort of selected QSO
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4. All Tx and Rx messages to all.txt
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5. Additional sort criteria for Hound calls
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6. Selectable timeout for keeping Hounds in the sorted list
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7. Display number of active callers
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8. Display QSO rate
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INSTRUCTIONS FOR HOUND
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----------------------
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1. Start WSJT-X in FT8 mode. Select *Hound* On the *Settings ->
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Advanced* tab. On the main window check *Auto Seq* and uncheck *Tx
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even/1st*, *Call 1st*, and *Hold Tx Freq*. Set *Tx nnnn Hz* to some
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frequency between 1000 and 4000 Hz, and select *Tab 1*. Enter Fox's
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callsign and locator in DX Call and DX Grid, select Tx1, and start
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*Monitor*.
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2. When you have copied Fox, hit *Enable Tx* to call him. You may
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keep calling until he answers. You may wish to move your TxFreq
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around, hoping to find a clear calling frequency.
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3. When you are called by Fox with a signal report, your next
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transmission will automatically be sent as Tx3 ("R+rpt"). When Fox
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receives that message he responds with "RR73", and your QSO is
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complete!
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The following features are not yet implemented for Hound:
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1. Force all required settings
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2. React properly to directed CQs from Fox
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3. Disable Tx2, 4, 5, 6
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4. For Tx1, enforce TxFreq >= 1000 Hz
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@ -5,13 +5,21 @@ subroutine ft8_downsample(dd,newdat,f0,c1)
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parameter (NMAX=15*12000,NSPS=1920)
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parameter (NFFT1=192000,NFFT2=3200) !192000/60 = 3200
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logical newdat
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logical newdat,first
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complex c1(0:NFFT2-1)
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complex cx(0:NFFT1/2)
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real dd(NMAX),x(NFFT1)
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real dd(NMAX),x(NFFT1),taper(0:100)
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equivalence (x,cx)
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save cx
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data first/.true./
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save cx,first,taper
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if(first) then
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pi=4.0*atan(1.0)
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do i=0,100
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taper(i)=0.5*(1.0+cos(i*pi/100))
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enddo
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first=.false.
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endif
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if(newdat) then
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! Data in dd have changed, recompute the long FFT
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x(1:NMAX)=dd
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@ -23,9 +31,9 @@ subroutine ft8_downsample(dd,newdat,f0,c1)
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df=12000.0/NFFT1
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baud=12000.0/NSPS
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i0=nint(f0/df)
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ft=f0+8.0*baud
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ft=f0+8.5*baud
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it=min(nint(ft/df),NFFT1/2)
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fb=f0-1.0*baud
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fb=f0-1.5*baud
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ib=max(1,nint(fb/df))
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k=0
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c1=0.
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@ -33,6 +41,8 @@ subroutine ft8_downsample(dd,newdat,f0,c1)
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c1(k)=cx(i)
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k=k+1
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enddo
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c1(0:100)=c1(0:100)*taper(100:0:-1)
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c1(k-1-100:k-1)=c1(k-1-100:k-1)*taper
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c1=cshift(c1,i0-ib)
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call four2a(c1,NFFT2,1,1,1) !c2c FFT back to time domain
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fac=1.0/sqrt(float(NFFT1)*NFFT2)
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@ -28,7 +28,7 @@ subroutine ft8b(dd0,newdat,nQSOProgress,nfqso,nftx,ndepth,lapon,lapcqonly, &
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integer nappasses(0:5) !Number of decoding passes to use for each QSO state
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integer naptypes(0:5,4) ! (nQSOProgress, decoding pass) maximum of 4 passes for now
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integer*1, target:: i1hiscall(12)
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complex cd0(3200)
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complex cd0(0:3199)
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complex ctwk(32)
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complex csymb(32)
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logical first,newdat,lsubtract,lapon,lapcqonly,nagain
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@ -126,7 +126,8 @@ subroutine ft8b(dd0,newdat,nQSOProgress,nfqso,nftx,ndepth,lapon,lapcqonly, &
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do k=1,NN
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i1=ibest+(k-1)*32
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csymb=cmplx(0.0,0.0)
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if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31)
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!if( i1.ge.1 .and. i1+31 .le. NP2 ) csymb=cd0(i1:i1+31)
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if( i1.ge.0 .and. i1+31 .le. NP2-1 ) csymb=cd0(i1:i1+31)
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call four2a(csymb,32,1,-1,1)
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s2(0:7,k)=abs(csymb(1:8))/1e3
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enddo
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@ -181,7 +182,7 @@ subroutine ft8b(dd0,newdat,nQSOProgress,nfqso,nftx,ndepth,lapon,lapcqonly, &
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bmetap(i2)=r2
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bmetap(i1)=r1
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! Max log metric
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psl=log(ps)
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psl=log(ps+1e-32)
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r1=max(psl(1),psl(3),psl(5),psl(7))-max(psl(0),psl(2),psl(4),psl(6))
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r2=max(psl(2),psl(3),psl(6),psl(7))-max(psl(0),psl(1),psl(4),psl(5))
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r4=max(psl(4),psl(5),psl(6),psl(7))-max(psl(0),psl(1),psl(2),psl(3))
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@ -37,11 +37,6 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand,sbase)
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savg=savg + s(1:NH1,j) !Average spectrum
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enddo
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call baseline(savg,nfa,nfb,sbase)
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! savg=savg/NHSYM
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! do i=1,NH1
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! write(51,3051) i*df,savg(i),db(savg(i))
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!3051 format(f10.3,e12.3,f12.3)
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! enddo
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ia=max(1,nint(nfa/df))
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ib=nint(nfb/df)
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@ -49,6 +44,9 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand,sbase)
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nfos=NFFT1/NSPS ! # frequency bin oversampling factor
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jstrt=0.5/tstep
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candidate0=0.
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k=0
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do i=ia,ib
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do j=-JZ,+JZ
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ta=0.
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@ -95,20 +93,18 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand,sbase)
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iz=ib-ia+1
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call indexx(red(ia:ib),iz,indx)
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ibase=indx(nint(0.40*iz)) - 1 + ia
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if(ibase.lt.1) ibase=1
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if(ibase.gt.nh1) ibase=nh1
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base=red(ibase)
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red=red/base
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candidate0=0.
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k=0
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do i=1,200
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ji=iz+1-1
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if(ji.eq.0) exit
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n=ia + indx(ji) - 1
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if(red(n).lt.syncmin) exit
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if(k.lt.200) k=k+1
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candidate0(1,k)=n*df
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candidate0(2,k)=(jpeak(n)-1)*tstep
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candidate0(3,k)=red(n)
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do i=1,min(200,iz)
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n=ia + indx(iz+1-i) - 1
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if(red(n).lt.syncmin.or.isnan(red(n)).or.k.eq.200) exit
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k=k+1
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candidate0(1,k)=n*df
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candidate0(2,k)=(jpeak(n)-1)*tstep
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candidate0(3,k)=red(n)
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enddo
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ncand=k
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@ -123,9 +119,6 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,s,candidate,ncand,sbase)
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if(candidate0(3,i).lt.candidate0(3,j)) candidate0(3,i)=0.
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endif
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enddo
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! write(*,3001) i,candidate0(1,i-1),candidate0(1,i),candidate0(3,i-1), &
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! candidate0(3,i)
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!3001 format(i2,4f8.1)
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endif
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enddo
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