Sunday, 21 January 2018

The tyranny of default settings

The tyranny of default settings.

Sounds menacing, eh?

Not too much to report, apart from a perfectly predictable 10m Es opening on 19 January following an increase in solar activity. The K number rose to more than 4, as predicted four days earlier by NOAA and also two days earlier by Solarham. This duly produced this result:-
10m Es spots on WSPR at GM4FVM on 19 January 2018
10m Es opening in January at the bottom of the solar cycle - nothing unusual to report there then. I had hope for 20 January too, but the enhanced solar activity faded away.

I have confirmed what was limiting my PC performance when using multiple instances of MSK144 mode. It does seem to be a bandwidth thing as mentioned previously as a theory. I now need just one computer. So the back up computer has gone to the further reaches of the shack, despite all the fettling I did to it.

But what has been intriguing me recently has been strange behaviour amongst some amateurs who use the "wrong" settings for MSK. I have distinctly heard four stations using 30 second T/R intervals, one fairly local, but the others in the 750 to 1000km region. If I can hear these stations in both receiving segments then something pretty serious is wrong.

Always providing that my timing is correct, and I use Meinberg software for timing, then is just not be possible to hear the same station in successive receive segments, unless of course they were transmitting in both. Maybe their timing is wrong. Or maybe they are actually deliberately transmitting in both.

I checked my timing by running two sets of Meinberg on two computers, and verified with the Meinberg NTP monitor that both were functioning correctly. They both showed the same time even though they were synching with different hosts.

At least one of these stations is using 30 second intervals because I can see that they also have "Auto Seq" ticked. I can tell because they transmit for 30 seconds, and then if they get a reply, Auto Seq switches them to the other 30 second segment.

This is bizarre behaviour. They are losing 50% of their receive time, making QSOs on average twice as long. They are also occupying both segments, meaning that any station close to them might as well give up. And half of their transmissions will be lost for a DX station using the standard 15 second interval, causing another 50% loss and making any QSO next to impossible.

I have been pondering all this. Why do such a thing when it will only (at best) lengthen your QSOs, or (at worst) lead to many QSOs failing to complete? And it will annoy every other amateur in your area who will be unable to operate while you are on the air.

Then the penny dropped. The last time I downloaded WSJT-X it came with the default setting as "T/R 30 seconds" and "FTol 20". Of course I reset those to 15 seconds and 100, as the User Guide suggests. Perhaps these people are just using the default settings. Perhaps they never looked at the User Guide.

At this point I could don the cloak of the "Old Timer". I could point out that my enforced period as a Short Wave Listener taught me the benefit of listening first. If I had listened first it would immediately be clear to me that other stations were using 15 second intervals.

However, I think it goes deeper than that. My instinct when downloading WSJT-X is to explore it and find out more about it. Maybe other stations just accept the defaults and think no more about it.

OK, every so often every station gets it wrong and transmits on the wrong segment. The "Tx even/1st" button is small and it is easy to forget to change when you turn the antenna. But to use the 30 second T/R constantly is shooting yourself in the foot - you miss, on average, 50% of the replies. And the other station misses 50% of yours, leaving the statistics of randomness to condemn you to fail most of the time.

In between the times when these stations have been wiping both rx opportunities for me I have worked a few stations during the supposed "dead period" (early January to April) for meteor scatter.
VHF meteor scatter contacts at GM4FVM 9 to 21 January 2018
Meanwhile, the stations using 30 second periods seem to be calling CQ a lot, and not getting many replies.

I wonder why.
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On a different tack, the issue about strength reports as opposed to meteor ping duration and number of pings has been mentioned elsewhere. Here is a nice clip from OZ1JXY Henning's 4m QSO of today today . Somehow my report of +03dB, although good, hardly goes far enough to describe this ...
That counts as quite a blast in this quiet period.
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Enough from me, but for what it is worth I will post the relevant section from the WSJT-X User Guide which I doubt if anyone involved will read. Ah well.

73

Jim
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To configure WSJT-X for MSK144 operation:
  • Select MSK144 from the Mode menu.
  • Select Fast from the Decode menu.
  • Set the audio receiving frequency to Rx 1500 Hz.
  • Set frequency tolerance to F Tol 100.
  • Set the T/R sequence duration to 15 s.
  • To match decoding depth to your computer’s capability, click Monitor (if it’s not already green) to start a receiving sequence. Observe the percentage figure displayed on the Receiving label in the Status Bar:
MSK144 Percent CPU
  • The displayed number (here 17%) indicates the fraction of available time being used for execution of the MSK144 real-time decoder. If this number is well below 100% you may increase the decoding depth from Fast to Normal or Deep, and increase F Tol from 100 to 200 Hz.
Most modern multi-core computers can easily handle the optimum parameters Deep and F Tol 200. Older and slower machines may not be able to keep up at these settings; at the Fast and Normal settings there will be a small loss in decoding capability (relative to Deep) for the weakest pings.
  • T/R sequences of 15 seconds or less requires selecting your transmitted messages very quickly. Check Auto Seq to have the computer make the necessary decisions automatically, based on the messages received.


Monday, 8 January 2018

Quadrantids meteor shower marks the end of the season?

3 January 2018 marked the peak of the Quadrantids meteor shower. The Quadrantids also mark a break in the procession of the main showers in the Northern Hemisphere until April.

At GM4FVM Quadrantids 2018 produced this result:-
VHF meteor scatter QSOs at GM4FVM 30 December 2017 to 8 January 2018




This year saw me working many of the usual stations, but it felt very different. Only one QSO was on 6m, the rest were evenly split between 4m and 2m. All were on MSK144 mode. This was the first year when I could call CQ on 2m MSK144 and get successful results.

For too long now 2m operators in Western Europe have been sticking with FSK441 mode. This time I watched PSK reporter carefully and I noticed several stations working into Russia, Belarus and Ukraine. As those Eastern stations were using MSK144, the people trying to work them had to use MSK144 as well. This gave me the opportunity to be heard, and it worked. If some people want to stick with FSK441 then that is their choice, but they are not going to work me.

I did hear stations from Belarus and Russia myself but I have never worked that far on meteor scatter (though I have worked Belarus on Sporadic E). I suspect that some of these stations run quite high power levels.

Perhaps I am beginning to find 6m meteor scatter "too easy". Well, not really, but when I call CQ I can see that I am heard by many stations but few answer. So maybe they find it too easy to work me, so they don't try. I find that on 2m there are fewer stations but a lot more of them are ready to reply and try to make a contact.

So that was a successful Quadrantids campaign to round off the VHF year.

I am still left wondering whether 10m would be any good for meteor scatter from here.

Between now and April there are still plenty of things which might happen. Random tropo and aurora events can be very good fun but they are impossible to predict until a day or two before they occur. There may be several or there may be none.

The NOAA 27 day Space Weather Outlook (which you can find here) suggests no recurrent auroral activity can be expected - or at least the test of Kp index over 5 is not predicted to be met in the 27 days from 8 January. However, this predictor only really lists recurring coronal holes; a solar flare could happen at any time, or not, as the case may be.


Meteor scatter will still work of course. Just because there are no major showers does not rule out taking advantage of minor showers or background meteor action.

Plus there could be some minor Sporadic E events.

I might try some Earth Moon Earth operation. More accurately I might try listening again. My station is not well suited to EME, but it might be worth trying. There is nothing to lose. I had an email from Gordon GM4OAS which has given me a nudge towards listening again.

I had a phone call from Keith, MM6KFE, asking for a test on the local 70cm repeater GB3BE. As I had no antenna I had to try to reach him on my £8 Baofeng hand held. Not a sophisticated rig and I ended up standing in the middle of the back garden in the rain. So I have relented as far putting a 2m dipole in the loft which works (badly) as a 3/4 wave dipole for 70cms. I have managed to work Keith on that so I am back on 2m and 70cms FM for now anyway. There followed contacts with Wallace, MM0AMV on BE and Paul GM0IQI on GB3DU. Active locals! Things are not as bad as they looked.

I am quite looking forward to a lull. This has been very eventful year.

73

Jim

GM4FVM