First, there is no fuss about Q65. There should be.
Time for a question and answer session.
What is Q65? It is a data protocol in the WSJT-X suit, amongst others like FT8, MSK144 and JT65.
What does it do best? It allows radio amateurs to communicate in difficult situations by exploiting scatter and coping well with Doppler effects.
What is it designed for? According to the WSJ-X users guide "Q65 is designed for fast-fading signals: tropospheric scatter, rain scatter, ionospheric scatter, trans-equatorial propagation (TEP), EME, and the like."
Which bands is it best for? According to the WSJT-X website - "it is highly recommended for EME, ionospheric scatter, and other weak signal work on VHF, UHF, and microwave bands." I find that it can be helpful by bringing iono-scatter into play for 50 and 70MHz, using aircraft scatter on 144 and 432MHz, and various assistive scatter modes on 1296MHz (and probably higher).
Are amateurs using it? In general, no. The EME community are using it above 432MHz, but most EME on 2m is still using the outdated JT65. For other purposes such as scatter or other weak signal work you hardly ever hear it.
Have you seen the benefits? Yes. Switching to Q65 on 1296MHz during a tropo contact brings a huge benefit. However, this works for me simply because stations on 1296 are often in contact via email or KST. This allows me to ask to switch mode. On tropo on other bands I am not in contact with other stations so much.
How does it work? The WSJT-X model allows you to choose the most suitable submode for data rate and period length. So if you use Q65 submode B with a 30 second period you would call that Q65-30B.
How difficult is it to use? On WSJT-X you simply click the button Q65. Then you select the period and the submode. It does not seem to difficult to me.
Which submode should you use? That is up to you and you QSO partner. Perhaps 30A for 50MHz where you have time to exploit iono- or tropo-scatter, perhaps 15B for higher bands where you want to capitalise on short aircraft scatter events. I used 30C to complete a QSO with DJ8MS on 1296MHz on 12 January 2024. That was after trying FT8 and failing so we went for the most sensitive combination we could.
Anything else to look for? Just like other scatter modes, it is as well to turn up FTol. The default is 20. You can turn it up to as much as your computer can take - max is 1000. Once you have made contact with the other station you can turn it down again if you wish to narrow the receiver pass band. 20 is fine if you are on exactly the same frequency, but on the higher bands this is not always the case.
What is the problem with using it? I dunno.
Why are people sticking to FT8 and JT65 on VHF? I dunno that either.
Can you show a QSO where Q65 worked? Yes, for example this 432MHz QSO between GM4FVM and G0MJI. A 265km path over the Pennines which would not have been possible without some assistance from aircraft scatter. If you look at the traces you can see steep Doppler inclination. This contact simply would not have been possible using FT8 due to Doppler shift which disrupts FT8. It was easy on Q65-15B. From what I recall, Bri was running 35W.
 |
| Q65 QSO between GM4FVM and G0MJI on 29 January 2024 |
Q65 is a powerful aid for VHF, UHF and microwave amateurs. VHF QSOs are being missed needlessly. We are not learning how scatter modes can help us. We are not dealing effectively with fading. This is us scoring an own goal.
I have remarked before about a long lived trend in amateur radio to stick with the old ways. If that worked we would still be using spark to transmit plus cats whiskers and coherers to receive. If progress is to mean anything we need to be ready to try new ideas.
Q65 has been around for some years now. Joe Taylor and his band of helpers have created something very useful in Q65. And yet many VHF DX-ers hardly use it.
Anyone who wants to try Q65 on a marginal path between 50MHz and 1296MHz can feel free to contact me.
73
Jim GM4FVM
I've tried Q65 many times. But so far only a sked via KST chat with a German station was successful. I hope more stations will use it. But hey, JT9 was also a very high sensitive mode. It is so unfotunate no one is using it anymore. 73, Bas
ReplyDeleteBas, exactly. JT9 is a very good mode and in many ways so much better than FT8. Like you I used it a lot at one time. However, people seem to prefer FT8. Is this because FT8 works best on HF, and they just cannot realise that VHF is different? JT9 could still be useful in many situations where Q65 also works. This is like VHS vs Beta video battle. Beta was better, but the public chose VHS. Why? And then I could talk about how we elect our leaders .... ???? 73 Jim
DeleteQ65 is also a good mode for contacts via AU on VHF, I used it for the first time during the last Aurora and it worked well
ReplyDeleteJeremy
Very good work Jeremy. Glad you tried Q65 on auroral propagation. It would be very good to have that, even if it only worked partially - after all aurora is hard to use on any mode. I suspect that 6m and 4m would be best as the distortion gets a lot worse on 2m, but I would love to be proved wrong. Anyway, during the next auroral opening I will give that a try. Many thanks. 73 Jim GM4FVM
DeleteI've used Q65 on VHF and UHF and it works very well.
ReplyDeleteI find that FT8 can suffer with aircraft reflected signals, especially if the reflected signal crosses the main signal.
On 23cm I've found that FT8 is quite tricky to use and Q65 would probably be better.
As to why people stick with FT8, I can only asume that it is the same reason that I see posts in various VHF/UHF groups saying that (insert VHF/UHF band here) is only "Line-of-sight", or "Line-of site" as some seem to have decided it is called. They've been told that's tue, so they believe it...
Dave (G0DJA)
Dave
ReplyDeleteYou are fairly unique, being one of the few stations I have worked on Q65, on 1295MHz about a year ago. So I know you have got the right idea there.
Yes, I know somebody who got his licence and told me that he had been told by his trainer that VHF was "line of sight". I think that we have proved otherwise.
Thanks.
73 Jim GM4FVM