Amateurs - don't do as I say !!!

Amateurs - don't do as I say ... do what you want to do!

Please, I implore you - find your own way. Do not follow anyone's insistence, but learn from the many voices out there. Also, I encourage you to learn from what you do, and to progress in your own path.

And I know, that is me telling people what to do.

Irony, eh? Who needs it?

I recently posted an encouragement to VHF+ amateurs to try Q65, a splendidly efficient data mode devised by Joe Taylor and his merry tribe of creators. I did not say "give up your old modes". 

Here is a screenshot taken by Phil, EI9KP of our 2m QSO on Q65. Not bad at all - 479km on a flat band. We went on using Q65 successfully on 70cm. Eventually we tried 23cm, and although we did not complete a QSO there no doubt we will in due course. Q65 is good for contacts like this as it benefits from scatter enhancement such as that from aircraft. 

I think that it is best to use the best mode for the purpose, so for meteor scatter I use MSK144, for HF I would use FT8, and so on. Those were a great set of QSOs with EI9KP. You do not have to follow suit, but you can see how it can be done. As usual, click on the images to enlarge if you wish.

144MHz Q65-30B contact between EI9KP and GM4FVM on 25 March 2024 (Screenshot EI9KP)

Then I went on the 2m/70cm KST chat room [that is where you went wrong, Jim]. 

On KST someone asked for a meteor scatter contact and I explained that I can use MSK144. He then told me that I was wasting my time with MSK144 and I should install MSHV and use the JTMS mode instead. He said that there is "scientific evidence" from many hams to prove that JTMS was more efficient. 

What is the difference between me encouraging people to use Q65, and him telling me to install MSHV and use JTMS not MSK144. Is it just that I cannot take instruction, or learn from scientific evidence?

Well, I think not. I sincerely hope that everybody who reads this blog takes my ideas as representing what works for me. You can read about what I do, go away to your own blogs, and say the opposite. Or go to the local club and say that that old codger GM4FVM is talking nonsense. Sometimes I do talk nonsense. I can be wrong and I often am (source of ionisation for Es, for example). I can learn as I go along, and so can everybody else. I can even admit to being wrong.

Returning to the recent KST barney. I simply said that I use MSK144 on meteor scatter. This seemed to make things worse. After a blast in return I said that I respected his choice of mode and I hoped that he would respect mine. And then things calmed down a bit. I had some support from others on KST which I appreciate.

As for the scientific evidence, he did not say what he was talking about. Data modes for meteor scatter work on the principle that the meteor pings are short duration, thus the data rate is set so that the message fits into a very short timeframe. It is then repeated over and over again for 30 seconds in the hope that some of it will be transmitted at the same moment as a meteorite provides a tiny moment of propagation between the two stations. Different modes use different periods but from what I recall MSK144 repeats the message every 72 milliseconds. That would suggest that your message is repeated more than 415 times in your 30 second period, and almost all of those repeats is not detected by anyone.

The argument has been put that because the pings are of shorter duration at higher frequencies, then the time of repeat needs to be shorter too. That is a fair enough argument except that MSK is also up to about 8dB more sensitive than some other modes, and that affects the timing issue too. When you increase the sensitivity the pings are received for longer. This is because as the ping proceeds the amplitude declines, and with more sensitivity you can receive it further down the "tail" as it tails off. This means that the decode can lasts longer. Thus MSK does not need such a short timeframe. This is a benefit which some people use to argue against MSK, even though it is actually a benefit.

MSK144 is tailored for the 2m band and is probably over-engineered for 4m and 6m (so of course it works even better there). Maybe it would not be quite so good on higher frequency bands. The WSJT-X notes say it is designed for VHF bands so it would not be my choice for 70cm.

Anyway, I use MSK144 for another reason too. MSK144 has powerful error correction which other modes used for meteor scatter lack. I think that the reason why some people prefer other modes is because they produce less well corrected results which they interpret their own way. I do not criticise this, but I choose not to do it myself. I used older modes for years and I have had enough of looking at screens full of gibberish. Back then I quickly saw that I could interpret the results they produced in hundreds of different ways. To me that means anyone can interpret them in ways that suit them.

If you need some low-down on this you might find this from K5ND interesting:-

https://k5nd.net/2020/10/msk144-vs-fsk441-meteor-scatter-modes-my-scattered-compilation-of-data-points/

Before MSK, most modes used much weaker error correction, leaving operators to make sense of bits and pieces of decodes. The temptation to find evidence of success blinded quite a few to the fact that they were actually piecing together bits of decode provided by random noise.

70MHz FSK441 screen from 4 January 2016 showing partial decodes.

The example shown above is actually from a fairly long and successful period of reception on  4m - a band where results are better than on 2m. It looked like EA2BCJ was calling me, and this eventually proved to be the case. Maybe he was calling GM4F6M, which was also a possibility. Despite all the favourable factors, no single ping contained both correct callsigns together. In many cases there were screens full of garbage from which amateurs of the time would piece together the evidence they thought constituted a contact. Bill Somerville, G4WJS, is quoted in the K5ND piece in the link above commenting on those operators "who prefer to pick out a few relevant characters from a jumbled stream of uncorrected errors and decide that a QSO has been completed." Of course they can do that, but I do not want to.

Sadly Bill is now silent key and we miss his wisdom.

My simple decision was to use only MSK144 on meteor scatter. I think that I am free to decide that. Others seem happy to only use CW on Top Band, some only use 20 metres to have chats around Europe, still others just solder together circuits they never use. Fine business old men. You have that choice. I am not wasting my time doing what I want to do just because you do something else. I might say here that Q65 is going begging, but I don't tell people that they are wasting their time doing anything else. It is up to them.

We all think that our own set-up is the best. The only better one is the one we plan to buy when we can afford it. Most of us think that everybody else is barking up the wrong tree. Fine, but please don't preach to me.

I did not have the heart to tell this guy on KST that I already have MSHV installed here. I could run JTMS if I wanted to. I choose not to. As I said, mode is my choice, just as much as it is his. I could run some other meteor scatter mode, but give me proper error correction and lots of sensitivity every time.

Here is some advice from someone with years of experience - do not accept advice from people with years of experience. By all means listen to them, but form your own ideas yourself and go your own way.

Even if you go the wrong way, it is still your way. And, you can always learn some more and change later.

Finally, an 11 minute QSO from the good old days before strong error correction. Is this complete?

70MHz FSK441 contact between GM4FVM and SQ85PZK on 6 April 2015

Who decided that GM5JVM was wrongly decoded but GM4FVM was correctly decoded? Is this my QSO at all? I would rather leave decisions like that to the algorithms in WSJT-X.

73

Jim GM4FVM