Monday, 28 May 2018

WSJT-X audio, tx period, timing plus a long 4m QSO

From time to time I get queries about WSJT-X and here are a few that came in recently:-

Why has my audio suddenly failed?

David GM4JJJ provided the solution to this one. I was away in Greece at the time so it had not caught up with me yet. Now that I am back and have installed the recent Windows 10 update my audio streams stopped working too. Thankfully I had David's advice - go to Settings, Privacy and select "Microphone" from the left bar. Turn "allow apps to access microphone" on, and then you might want to turn off all the other apps. WSJT-X is not listed but it is accessible if you turn the overall button "on".

Maybe it is just me. Although I write a blog I do like to keep some things private. I turn off the microphone because there isn't one on this PC anyway. I do it as routine on my laptop and tablet because I try to avoid giving anything to the collectors of "big data". So if this does not affect you then you are not as nutty as I am and you had your microphone turned on in the first place.

What does the selection Tx even/1st mean?

This is not really very clear in WSJT-X. It looks a bit like the choice is either even or first. What it actually means is that the choice is for or against even and first (versus odd and second).  Even and first are two ways of describing the same thing.
WSJT-X showing the period selection at the top
 To many people none of this matters at all. In FT8 clicking on a station calling will set it automatically. However, it is crucial to meteor scatter operators as it shows the direction the operator is seeking contacts. Also, it is common round here for local stations to use second period simply to stop us overloading each other's receivers. We can still reply to somebody by transmitting on first but we usually call CQ on second.

I am not about to go into the background about all this, which has its roots in meteor scatter and EME. Suffice to say that the labelling on WSJT-X is confusing some people. Choosing first (itself an odd number) means selecting the even period, whereas choosing second (obviously an even number) chooses the odd periods. The two terms made some sense when the periods were a minute long, but now that they are sometimes 15 second long it is all getting confusing.

This is one area which MSHV makes perfectly clear with a simple choice between two options....
MSHV showing a clear choice of period.
 Why am I seeing traces but nothing is decoding?

Could be many things, but almost certainly because your timing is wrong.

Data modes depend on accurate timing. The timing regime as supplied as standard with Windows is not accurate enough for this purpose. Most people use Dimension 4 or Meinberg to upgrade their timing to the necessary standard. See the link to Meinberg on the sidebar.

Not that these are totally foolproof. I have had quite a bit of trouble with Meinberg. I discovered it because I was using a different computer for 10m WSPR. The two PCs showed different times, even though both had Meinberg. I added the Meinberg monitor and what I expect to see is this - some yellow time sources found (suitable), one green one (the best one which Meinberg is using) and maybe a red one (not suitable). Then some will be white ("a survivor" but not one chosen) :-
Meinberg Time Server Monitor. One time source (green) is synchronised with 2 in reserve (yellow)
But many times none of the listed sources were synchronising and some were simply marked as survivors, meaning that Meinberg did not look for a replacement. If all six were like that the whole thing was stuck. This showed up as a several second difference between the two computers. I coloured those (otherwise white) sources purple to make them easier for me to see.
All sources unsuitable - this stayed like this for hours.
Another failure is if Meinberg software simply fails to start. I know of no way of testing for this other than by installing and using the monitor. Fortunately this fault often causes the time to default to the last time you turned the computer off, so it shows up fairly easily.

Either way, restarting the computer seems to be the only way to free these situations up as user starting and stopping of the software is turned off in the standard version of Meinberg.

Anyway, in my experience, just because I have installed Meinberg does not make everything certain.
Great QSO on 4m FT8 with Olli, DH8BQA, today (link to DH8BQA's blog on the sidebar). So much for 1 minute QSOs on FT8, this one took 40 minutes.

For the first 30 minutes or so I could not get a good bearing on a station which was showing up as a faint trace. Data modes don't help here, as unlike CW or SSB you cannot catch a bit of a callsign. I knew it was somewhere between 150 and 80 degrees, but that was as close as it got. It was very steady but very weak with occasional meteor pings and blips of Es. Eventually I worked out that it must be Olli. Only then did I occur to me to look and find that he had posted that he was hearing me on the cluster. He must have PSK Reporter logging turned off.

I was determined to complete this one as it was obviously not your normal 5/9+ Es QSO. At the time there was no Es QSO going on on 6m, and nothing on 10m WSPR so it was unlikely to be Es on 4m, or at least not entirely. The presence of a constant, weak, signal at about 1100km range suggests to me some underlying scatter mode, tropo- or iono- scatter. The meteor pings probably just served to spoil the FT8 decoding, but there were also occasional weak Es period superimposed on the weak trace. This weak Es was never long enough to allow a decode, so I had to wait for the weak steady signal to get through.

The QSO was easy enough once I knew exactly where to point the beam. I then mis-posted it as Tropo but I think it was a steady scatter mode, with a bit of assistance from Es and tropo, plus a wee bit of meteor scatter to mess it up.

I like that type of thing. Having spent hours on single meteor scatter QSO in the past, 40 minutes is not much time to spend on an interesting outcome.

I suspect that marginal paths like this are possible a lot of the time.
Finally, it has been a BRILLIANT Giro d'Italia. Quite the best bike race I have followed for 20 years or so. OK, so Dumoulin did not win this time, but the mountain climbing, the break aways, even the sprinting, had me on the edge of the seat every day. Wonderful.



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