Merged master 8748
This commit is contained in:
Jordan Sherer
@@ -1,142 +0,0 @@
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program jt65
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! Test the JT65 decoder for WSJT-X
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use options
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use timer_module, only: timer
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use timer_impl, only: init_timer
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use jt65_test
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use readwav
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character c,mode
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logical :: display_help=.false.,nrobust=.false.,single_decode=.false.
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type(wav_header) :: wav
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integer*2 id2(NZMAX)
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real*4 dd(NZMAX)
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character*80 infile
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character(len=500) optarg
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character*12 mycall,hiscall
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character*6 hisgrid
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type (option) :: long_options(12) = [ &
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option ('aggressive',.true.,'a','aggressiveness [0-10], default AGGR=0','AGGR'), &
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option ('depth',.true.,'d','depth=5 hinted decoding, default DEPTH=0','DEPTH'), &
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option ('freq',.true.,'f','signal frequency, default FREQ=1270','FREQ'), &
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option ('help',.false.,'h','Display this help message',''), &
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option ('mode',.true.,'m','Mode A, B, C. Default is A.','MODE'), &
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option ('ntrials',.true.,'n','number of trials, default TRIALS=10000','TRIALS'), &
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option ('robust-sync',.false.,'r','robust sync',''), &
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option ('my-call',.true.,'c','my callsign',''), &
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option ('his-call',.true.,'x','his callsign',''), &
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option ('his-grid',.true.,'g','his grid locator',''), &
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option ('experience-decoding',.true.,'X' &
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,'experience decoding options (1..n), default FLAGS=0','FLAGS'), &
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option ('single-signal-mode',.false.,'s','decode at signal frequency only','') ]
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naggressive=0
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nfqso=1500
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ntrials=10000
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nexp_decode=0
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ntol=1000
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nsubmode=0
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nlow=200
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nhigh=4000
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n2pass=2
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ndepth=3
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do
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call getopt('a:d:f:hm:n:rc:x:g:X:s',long_options,c,optarg,narglen,nstat,noffset,nremain,.true.)
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if( nstat .ne. 0 ) then
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exit
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end if
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select case (c)
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case ('a')
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read (optarg(:narglen), *) naggressive
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case ('d')
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read (optarg(:narglen), *) ndepth
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case ('f')
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read (optarg(:narglen), *) nfqso
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case ('h')
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display_help = .true.
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case ('m')
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read (optarg(:narglen), *) mode
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if( mode .eq. 'b' .or. mode .eq. 'B' ) then
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nsubmode=1
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endif
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if( mode .eq. 'c' .or. mode .eq. 'C' ) then
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nsubmode=2
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endif
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case ('n')
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read (optarg(:narglen), *) ntrials
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case ('r')
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nrobust=.true.
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case ('c')
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read (optarg(:narglen), *) mycall
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case ('x')
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read (optarg(:narglen), *) hiscall
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case ('g')
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read (optarg(:narglen), *) hisgrid
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case ('X')
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read (optarg(:narglen), *) nexp_decode
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case ('s')
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single_decode=.true.
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ntol=100
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nlow=nfqso-ntol
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nhigh=nfqso+ntol
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n2pass=1
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end select
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end do
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if(single_decode) nexp_decode=ior(nexp_decode,32)
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if(display_help .or. nstat.lt.0 .or. nremain.lt.1) then
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print *, ''
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print *, 'Usage: jt65 [OPTIONS] file1 [file2 ...]'
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print *, ''
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print *, ' JT65 decode pre-recorded .WAV file(s)'
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print *, ''
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print *, 'OPTIONS:'
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print *, ''
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do i = 1, size (long_options)
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call long_options(i) % print (6)
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end do
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go to 999
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endif
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call init_timer ('timer.out')
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call timer('jt65 ',0)
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ndecoded=0
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do ifile=noffset+1,noffset+nremain
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nfa=nlow
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nfb=nhigh
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minsync=0
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call get_command_argument(ifile,optarg,narglen)
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infile=optarg(:narglen)
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call timer('read ',0)
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call wav%read (infile)
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i1=index(infile,'.wav')
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if( i1 .eq. 0 ) i1=index(infile,'.WAV')
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read(infile(i1-4:i1-1),*,err=998) nutc
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npts=52*12000
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read(unit=wav%lun) id2(1:npts)
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close(unit=wav%lun)
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call timer('read ',1)
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dd(1:npts)=id2(1:npts)
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dd(npts+1:)=0.
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call test(dd,nutc,nfa,nfb,nfqso,ntol,nsubmode, &
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n2pass,nrobust,ntrials,naggressive,ndepth, &
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mycall,hiscall,hisgrid,nexp_decode)
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if(nft.gt.0) exit
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enddo
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call timer('jt65 ',1)
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call timer('jt65 ',101)
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! call four2a(a,-1,1,1,1) !Free the memory used for plans
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! call filbig(a,-1,1,0.0,0,0,0,0,0) ! (ditto)
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go to 999
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998 print*,'Cannot read from file:'
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print*,infile
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999 continue
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end program jt65
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@@ -1,189 +0,0 @@
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=== Frequency Calibration
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Many _WSJT-X_ capabilities depend on signal-detection bandwidths no
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more than a few Hz. Frequency accuracy and stability are therefore
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unusually important. We provide tools to enable accurate frequency
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calibration of your radio, as well as precise frequency measurement of
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on-the-air signals. The calibration procedure works by automatically
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cycling your CAT-controlled radio through a series of preset
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frequencies of carrier-based signals at reliably known frequencies,
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measuring the error in dial frequency for each signal.
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You will probably find it convenient to define and use a special
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<<CONFIG-MENU,Configuration>> dedicated to frequency calibration.
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Then complete the following steps, as appropriate for your system.
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- Switch to FreqCal mode
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- In the _Working Frequencies_ box on the *Settings -> Frequencies*
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tab, delete any default frequencies for *FreqCal* mode that are not
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relevant for your location. You may want to replace some of them with
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reliably known frequencies receivable at your location.
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TIP: We find major-city AM broadcast stations generally serve well as
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frequency calibrators at the low frequency end of the spectrum. In
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North America we also use the standard time-and-frequency broadcasts
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of WWV at 2.500, 5.000, 10.000, 15.000, and 20.000 MHz, and CHU at
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3.330, 7.850, and 14.670 MHz. Similar shortwave signals are available
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in other parts of the world.
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- To cycle automatically through your chosen list of calibration
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frequencies, check *Execute frequency calibration cycle* on the
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*Tools* menu. _WSJT-X_ will spend 30 seconds at each frequency,
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writing its measurements to the file `fmt.all` in the directory
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where your log files are kept.
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- During the calibration procedure, the radio's USB dial frequency is
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offset 1500 Hz below each *FreqCal* entry in the default frequencies
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list. As shown in the screen shot below, detected signal carriers
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therefore appear at about 1500 Hz in the _WSJT-X_ waterfall.
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image::FreqCal.png[align="left",alt="FreqCal"]
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With modern synthesized radios, small measured offsets from 1500 Hz
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will exhibit a straight-line dependence on frequency. You can
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approximate the calibration of your radio by simply dividing the
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measured frequency offset (in Hz) at the highest reliable frequency by
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the nominal frequency itself (in MHz). For example, the 20 MHz
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measurement for WWV shown above produced a measured tone offset of
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24.6 Hz, displayed in the _WSJT-X_ decoded text window. The resulting
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calibration constant is 24.6/20=1.23 parts per million. This number
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may be entered as *Slope* on the *settings -> Frequencies* tab.
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A more precise calibration can be effected by fitting the intercept
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and slope of a straight line to the whole sequence of calibration
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measurements, as shown for these measurements in the graph plotted
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below. Software tools for completing this task are included with the
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_WSJT-X_ installation, and detailed instructions for their use are
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available at https://physics.princeton.edu/pulsar/k1jt/FMT_User.pdf.
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Using these tools and no specialized hardware beyond your
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CAT-interfaced radio, you can calibrate the radio to better than 1 Hz
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and compete very effectively in the ARRL's periodic Frequency
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Measuring Tests.
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image::FreqCal_Graph.png[align="left",alt="FreqCal_Graph"]
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=== Reference Spectrum
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_WSJT-X_ provides a tool that can be used to determine the detailed
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shape of your receiver's passband. Disconnect your antenna or tune to
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a quiet frequency with no signals. With WSJT-X running in one of the
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slow modes, select *Measure reference spectrum* from the *Tools* menu.
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Wait for about a minute and then hit the *Stop* button. A file named
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`refspec.dat` will appear in your log directory.
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[ ... TBD ... ]
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=== Phase Response and Equalization
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*Measure phase response* under the *Tools* menu is for advanced MSK144
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users. Phase equalization is used to compensate for group-delay
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variation across the passband of receiver filters. Careful application
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of this facility can reduce intersymbol interference, resulting in
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improved decoding sensitivity. If you use a software-defined receiver
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with linear-phase filters there is no need to apply phase
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equalization.
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After a received frame is decoded *Measure phase response* generates
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an undistorted waveform whose Fourier transform is used as a
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frequency-dependent phase reference to compare with the phase of the
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received frame's Fourier coefficients. Phase differences between the
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reference and the received waveform include contributions from the
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originating station's transmit filter, the propagation channel, and
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filters in the receiver. If the received frame originates from a
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station known to transmit signals having little phase distortion (say,
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a station known to use a properly adjusted
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software-defined-transceiver) and if the received signal is relatively
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free from multipath distortion so that the channel phase is close to
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linear, the measured phase differences will be representative of the
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local receiver's phase response.
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Complete the following steps to generate a phase equalization curve:
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- Record a number of wav files that contain decodable signals from
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your chosen reference station. Best results will be obtained when the
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SNR of the reference signals is at least 9 dB.
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- Enter the callsign of the reference station in the DX Call box.
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- Select *Measure phase response* from the *Tools* menu, and process
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the wav files. The mode character will change from `&` to `^` while
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_WSJT-X_ is measuring the phase response and it will change back to
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`&` after the measurement is completed. The program needs to average a
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number of high-SNR frames to accurately estimate the phase, so it may
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be necessary to process several wav files. The measurement can be
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aborted at any time by selecting *Measure phase response* again to
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toggle the phase measurement off.
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+
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When the measurement is complete _WSJT-X_ will save the measured
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phase response in the *Log directory*, in a file with suffix
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".pcoeff". The filename will contain the callsign of the reference
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station and a timestamp. For example: K0TPP_170923_112027.pcoeff
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- Select *Equalization tools ...* under the *Tools* menu and click the
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*Phase ...* button to view the contents of the *Log directory*. Select
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the desired pcoeff file. The measured phase values will be plotted as
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discrete circles along with a fitted curve labeled "Proposed". This is
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the proposed phase equalization curve. It's a good idea to repeat the
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phase measurement several times, using different wav files for each
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measurement, to ensure that your measurements are repeatable.
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- Once you are satisfied with a fitted curve, push the *Apply* button
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to save the proposed response. The red curve will be replaced with a
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light green curve labeled "Current" to indicate that the phase
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equalization curve is now being applied to the received data. Another
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curve labeled "Group Delay" will appear. The "Group Delay" curve shows
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the group delay variation across the passband, in ms. Push the
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*Discard* button to remove the captured data, leaving only the applied
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phase equalization curve and corresponding group delay curve.
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- To revert to no phase equalization, push the *Restore Defaults*
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button followed by the *Apply* button.
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The three numbers that are printed at the end of each MSK144 decode line
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can be used to assess the improvement provided by equalization. These numbers
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`N` `H` `E` are:
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`N` - Number of frames averaged,
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`H` - Number of bit errors corrected,
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`E` - Size of MSK eye diagram opening.
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Here is a decode of K0TPP obtained while *Measure phase response* was measuring
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the phase response:
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103900 17 6.5 1493 ^ WA8CLT K0TPP +07 1 0 1.2
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The "^" symbol indicates that a phase measurement is being accumulated. The
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three numbers at the end of the line indicate that one frame was
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used to obtain the decode, there were no bit errors, and the
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eye-opening was 1.2. Here's how the same decode looks after phase equalization:
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103900 17 6.5 1493 & WA8CLT K0TPP +07 1 0 1.6
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In this case, equalization has increased the eye opening from 1.2 to 1.6.
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Larger eye openings are associated with reduced likelihood of bit errors and
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higher likelihood that a frame will be successfully decoded.
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In this case, the larger eye-opening
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tells us that phase equalization was successful, but it is important to note
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that this test does not tell us whether the applied phase equalization curve
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is going to improve decoding of signals other than those from the reference
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station, K0TPP!
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We strongly advise you to carry out before and after comparisons
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using a large number of saved wav files with signals from many different
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stations to decide whether or not the equalization curve improves decoding for most
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signals. When doing before and after comparisons, keep in mind that
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equalization may cause _WSJT-X_ to successfully decode a frame
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that was not decoded before equalization was applied.
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For this reason, be sure that the time "T" of
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the two decodes are the same before comparing their end-of-line quality numbers.
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When comparing before and after decodes having the same "T", keep in mind
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that a smaller first number means that decoding has improved, even if the
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second and third numbers appear to be "worse". For example, suppose that the quality
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numbers before equalization are "2 0 0.2" and after equalization
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"1 5 -0.5". These numbers show improved decoding because
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the decode was obtained using only a single
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frame after equalization whereas a 2-frame average was needed before equalization.
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