Using
Writelog for PSK31
By
Dick Stevens, N1RCT 15 April '99
It's Just like RTTY .. Almost
First, be sure you have a good grasp of the PSK31
fundamentals ... I won't be covering it .. and there is no better explanation
than the one written by the PSK31 (and AMTOR) inventor, Peter Martinez
G3PLX. It's on Eduardo EA2BAJ 's site at:
http://aintel.bi.ehu.es/psk31theory.html
Information on the Writelog program is found on the homepage: http://www.contesting.com/writelog/ . Writelog is written by Wayne W5XD and is distributed by Ron K5DJ. I have used it for RTTY contesting for the past 20 months.
I have two PSK31 setups .. one
rig for QSOing and another for
2-rig contesting. I have an article on how
to save multiple setups for Writelog, and I will skip the
2-rig setup as those guys don't need any help .. First, you
need WLVersion 9.23 or higher. You must use the SB card used for WinRTTY
(stereo for 2-rigs). While the PTC-II is on the menu, it is not set
up for use.
You can use VOX or a PTT
circuit, as I do. VOX was very troublesome for me but no problem for
most ops. You must use either LSB or USB on your radio (No FSK here).
Most of the QSO's seem to be BPSK which can be on LSB or USB. For QPSK,
you must tell Writelog which sideband you are using. For Rig Control, you
must be in LSB (for now at least) and check, under "Bands", "LSB
is really FSK". The WL VFO display will say "FSK" but it
is really in LSB, which is necessary for the buffer keys to work.
The G3PLX manual insists that a attenuator
must be used between the SB output and the rig afsk input. Mine does not
need it after careful setup and high center frequency but you must be extremely
careful here and start out with the WIN95 Volume Controls set to minimum
per the Writelog manual, and you may want to use the audio transformer
isolators. However, your RTTY setup should work IF you stick to a high
center frequency (>1500 Hz). A way of monitoring all this is in my article
"Bad Vibes" ....
Still with me? Time to get a little complicated ...
Selecting your Center Frequency and Sideband
This is a major decision and may take a while to arrive at the best value for your situation. I am using 1800 Hz and LSB to fit my equipment. Your situation and preferences may well lead you to a different choice. The most common is 1000 Hz and USB. The trick is find the frequency that will be compatible with your CW filter, Bandpass range, and external DSP box. I have an article on how to do that also .... click here ... I would have liked a Center Frequency of 2210 so the filter would be at the same place as RTTY but my Timewave 599zx can only go up to 1800 with full bandwidth in the CW mode. I could have gone as low as 1200 and still permitted my IC756 bandpass control to center the radio CW filter, but chose the high end to minimize the chance of bad harmonics using AFSK. If you are using an external DSP filter, be sure it is a SINGLE filter, not a double as is normal in RTTY. PSK data is a single tone. A RTTY DSP filter would remove the PSK31 signal in the center of the bandpass. I use a DSP CW filter of 1800 CF and can turn the bandwidth down to "35 Hz" with no problem in desired signal attenuation. It is easier to set your CF intially by editing Writelog.ini, searching for "PSK", and putting in, say 1800, for RX and TX values in place of the default 1000 value. You can fine tune later on-screen.
Tuning PSK31 with Writelog
Writelog uses the G3PLX algorithms but displays the tuning data as a frequency distribution rather than the "waterfall" of the free software. The phase lock diagram is about the same. Here is the WL display:
Looks like I was about 1 Hz off when I snapped the picture. I could tune this in by turning the rig VFO, the RIT, clicking on the Rx arrow button, or mouse-clicking on the point I wanted tuned .. certainly enough rope to hang one's self. I find this display easier to fine tune (as when CQing) but harder when locating a station (S&P). The Phase display is a very fine tune and really not essential, as the frequency display is very small scale. The auto tune lock of the free software is not included but I do not miss it. There is another common signal display and it looks like:
Note that the green line goes to zero power at the center ... this is the "Idle" signal of PSK31 when it switches to a two-tone signal of 31 Hz shift. When you see this, the other guy has run his buffer empty and there is no data coming .. so it is a "don't panic" indicator. If all this "1 Hz" talk has you wondering, Yes, a 1 HZ VFO is very, very useful. Without it, you will need to do the mouse clicking thing to fine tune a few Hz with the 10 Hz VFO/RIT left in place. Of course, you must get familar with what a PSK31 signal sounds like to find them. The actual pitch will depend on what center frequency you have selected. Since I am in LSB with a 1800 Hz tone, to tune a true 14.070.00 MHz, I would set the rig VFO to 14.071.800. Remember this when making DX spots as the true RF frequency is standard.
Log Book Setup
For a contest, just use the closest RTTY contest for the exchange.
For QSOing, I started with the RTTY Roundup contest as a base, as it has
NAME and State/VE Prov already formatted. I add entry boxes for QTH (meaning
the city this time), power, and antenna which are the items I like to log.
This will permit IDing states if you ever want a PSK31 WAS. Here is how
it looks (sorry for the size, I use a 1280x1024 screen):
For those who have not had the fun, the WL Help
menu explains how to add extra entry boxes like this. It must be done before
you use the log and cannot be changed later. Basically, go to "Contest",
"Exchange Format Setup", "NO". This gives you the "Edit
QSO Exchange Fields" ... select "New"give it a caption of
"CITY "
with blank spaces to set the desired box size. For options, I would use
"lower" and "prompt" . Press save, then"NEW"
for the next desried Box.
If you make a mistake, you will have to start over from the very beginning.
Better read the WL manual page first.
Buffers .. the whole point ..
Buffers are set up much like
RTTY except you may use lower case where appropriate. There is no need
for beginning spaces as WL automatically begins with a little Idle synchronizing
signal. There is no need for dashes like 599-004-004 as there are no LTRS/FIGS
involved. For contesting, a full set of buffers will be useful; for QSOing,
very few are needed. I have used capital letters for callsigns and other
things where upper case is traditional for appearance although the Varicode
used in PSK31 would have a higher transmission rate in lower case (2X?)
. Contesters will want to think through the use of upper and lower case
and do some experimenting. I don't see any technical problem with using
lower case for everything; it all depends on how nice you want things to
look on the other guy's screen. For QSOing and contesting, lower case has
the possibility of having a lower error rate as there is a smaller time
period/character length in which any noise must appear. Here are mine for
QSOing:
The first one (F2) turns the transmitter on and starts a new line. They work by stringing together buffer keys .. For the first exchange I use F2, F3, F4, F3, F8 .. F8 simply turns the transmitter off after all buffers are sent. A little experimenting here with a dummy load will be needed. One caveat .. the %H HI command will send the name in Upper Case if your friend.ini file is in upper case. You may want to start a new one for PSK31.
Writelog does not permit you to use the alt-K buffer until you have finished the buffers and shut down the transmitter. This leads me to make the second exchange with alt-K only, just start typing. For the third exchange I may go back to buffers and send the brag tape F6. All-in-all, a bit clumsy in QSOing (but exactly like DX4WIN). Perhaps someday we will have a "alt-K" imbedded command for the buffers which will make it seamless to use buffers and manual typing together. Also, the backspace/correcting feature is not implemented.
And that is about it ... I will add stuff to this article over time so check again .. Thanks to Wayne W5XD for several constructive comments and help.