|
Hi,
?
I ordered my prebuilt QMX+ in October just after watching the video with the RSGB, which was fascinating and brilliant.
?
I mainly ordered it to use as a stand-alone WSPR beacon, having started at the QDX/QDX-M but quite liking the idea of not needing a PC connected, and a slightly more general-purpose unit, so ended up deciding on the QMX+. Also it was the QMX/+ that was discussed primarily in the RSGB youtube video.
?
Anyway, the SSB wasn't a "dealbreaker" but it was a nice future extra. Back in October, I looked at the sales queue and thought that perhaps by the time I received my QMX+ the SSB firmware might be out. I received my QMX+ in mid-Jan, and have now done some limited WSPR testing and am very pleased with it.
?
The serial terminal functionality in particular is like magic. Absolutely brilliant. And the diagnostic stuff; GPS sats and SWR is genius.
?
Tip for those using linux and "screen" as their terminal: "Ctrl+A" before issuing Q to quit inner functions.?
?
But...... it would be cool if there was any update on the SSB firmware??
?
I do know that people were asking a bit too much back in October, but quite a few months have passed since then, so it doesn't feel like it's wrong to see if there is any update? Even if it's "I've hit a snag, and it's maybe less feasible than first thought".?
?
Thanks for a very interesting and good quality product.?
?
Alex
M1AJB |
|
Hello Alex No problem at all to request an update. I am sorry it is taking a long time, but it is complicated and I want to get it right. NO snags have been hit! It is certainly?not less feasible than I first thought! It is going excellently and I am very pleased indeed with the performance. I have also implemented CESSB (Controlled Envelope SSB).? All the parts of the SSB project were completed (coded and tested) in isolation and the current task is to integrate everything into the main firmware without breaking anything and without missing anything. I have a list about half a page of A4 of sub-tasks that I needed to tick off and I am working my way through the list. All items are not equal. By far the biggest item was the calibration and optimization of the SSB modulation process.? I have developed a way of getting the QMX/QMX+ to measure its own PA phase distortion (means: different phase delay occurs at different amplitudes). I have developed a calibration tool which measures phase distortion at 60 amplitude points, for each band of operation, and stores it in EEPROM. These are applied as phase pre-distortion during the SSB modulation process, to cancel out the distortion inflicted by the amplifier. Note that amplitude linearity is already so good that I cannot improve on it by measurement and pre-distortion.? Then there's the synchronization requirement between the amplitude and phase modulation. Phase modulation is achieved by discrete frequency jumps of the '5351 synthesizer, amplitude modulation by commands to the microcontroller's DAC which then controls an amplitude modulator circuit. Both sides have inherent delays, and it's necessary to be able to slide one relative to the other to cancel out the net delay. I arranged for the 32x interpolated amplitude samples to flow through a circular buffer and I can tap this at any point, that gives me control over the amplitude delay relative to phase modulation in 1/32'nds of a 12ksps sample (2.6 microseconds resolution). I developed a calibration tool where the QMX can measure its own SSB transmission two-tone (standard 700?+ 1900 Hz test) intermodulation products then slide the synchronization and determine the best offset.? I attached a screenshot of these tools though there are still a few tweaks needed to the?appearance. The two-tone signal source is internally generated. It is important to note that these SSB self-calibration tools require NO hardware modifications and will work on any PCB revision of QMX and QMX+, so it makes it possible for every user to obtain the best calibration for his own transceiver (therefore taking into account any component tolerances or differences in build such as toroids etc).? The remainder of the task list is mostly composed of making sure, and modifying, various parts of the system to make sure they work for SSB mode - things like the AGC system, Power and SWR metering, S-meter, transmitting audio from the various sources (USB from PC, microphone, internal two-tone source). So it's all a bunch of little things, but they are important to get right.? Note also that contrary to some rumours, I do intend to release the SSB firmware as soon as it is ready, I am not intending to wait artificially for any particular event until Dayton FDIM/Hamvention in May. 73 Hans G0UPL On Mon, Feb 17, 2025 at 12:40?PM Alex via <alex.bloor=[email protected]> wrote:
|
|
Dear Hans,
?
Thank you very much indeed for the exhaustive detail in that reply. It is very much appreciated, and what you are doing is massively impressive. In particular, your method of detecting and cancelling out distortion... I saw a demo at Adelaide University years ago, where a guy doing his doctorate was analysing the microscopic defects on a glass lens/mirror, then creating a hologram from that and using it in conjunction with the imperfect lens to compensate/cancel those defects. For some reason this put me in mind of that.?
?
Having known engineers/firmware developers myself as a result of some of the work I am involved in, I have noticed (at least) a couple of different approaches to coding features; one is to deliver something rather "partial" very quickly, then revise, revise, revise. The other is to code into every single corner; every diagnostic, every circumstance, every plausible edge case, all documentation written up in full, before making a release. Both approaches have good and bad points! I would guess that you are the of the latter approach! Bravo.?
?
To repeat, SSB was never a primary need for me; the WSPR functions are outstanding, together with things like SWR make tuning up a small magloop disarmingly easy. But it will be amazing and novel to give this radio a whirl using my voice. All the same, it is great to know that there have been no "dead stops" though.?
?
Thanks again,?
Alex. M1AJB |
|
Hi Alex ?
I don't think I'm in that latter camp, if I was, I would have not announced or released QMX at all until SSB was ready... I am probably a mix of the two! 73 Hans G0UPL |
|
On Mon, Feb 17, 2025 at 02:16 AM, Hans Summers wrote:
I attached a screenshot of these tools though there are still a few tweaks needed to the?appearance. The two-tone signal source is internally generated. It is important to note that these SSB self-calibration tools require NO hardware modifications and will work on any PCB revision of QMX and QMX+, so it makes it possible for every user to obtain the best calibration for his own transceiver (therefore taking into account any component tolerances or differences in build such as toroids etc).? I'm going to assume that these tools will be part of the build/setup process for anyone wishing to use SSB and the manual will reflect that. And that we should assume that the patch notes for the next firmware update will also include a directive to perform these calibrations.
?
I'm wondering if the "default" for these calibrations will be adequate enough such that anyone who doesn't perform them will have a setup that works well enough. Also, will these calibrations need to be re-performed upon subsequent firmware updates or is it too soon to even guess at that? |
|
Hi Jason
Yes to all
Yes. If phase pre-distortion is not switched on and if the synchronization isn't optimal, then it kind of makes the difference between getting IMD3 of -30 to -35 dB PEP, or an improvement to -35 to -40 or more. It's a very nice improvement but the system still works very well even without it.? See for example the attached overall calibrarion result for the sync parameter. A value of 55 would not be far off optimum on most bands. And you can see that the curve is reasonably shallow, not a sharply optimized notch. FYI this curve represents the sum of the energy in the 3rd, 5th and 7th IMD products and after a lot of experiments, is the chosen optimization measure.?
No, it won't be necessary to re-perform calibration on firmware updates, it depends on the hardware. Well it's an interesting question, should "Factory Reset" wipe out the calibration? I suppose it should, really. In which case a new calibration would be needed. But in general a new firmware version doesn't require a factory reset.? 73 Hans G0UPL |
|
On Mon, Feb 17, 2025 at 08:25 PM, Hans Summers wrote:
No, it won't be necessary to re-perform calibration on firmware updates, it depends on the hardware. Well it's an interesting question, should "Factory Reset" wipe out the calibration? I suppose it should, really. In which case a new calibration would be needed. But in general a new firmware version doesn't require a factory reset.? My 5 cents: It would be intuitive, that a factory reset sets all configuration data, including calibrations, to factory defaults. Particularly, if there is any chance of the TRX not to work properly if that calibration is, for whatever reason, far-off. After a factory-reset (and subsequent basic configuration, if needed) a device should be guaranteed-to-work if the hardware is good. ?That's what factory-resets are mostly used for, besides resetting devices before vending or trashing them.
?
As you wrote 'self-calibration', I assume that it can be done by 'pressing a button '. If I'at feature to QMX. Even greater to know, that QMX+ will have a self-calibration tool so that every QMX+ will have the best calibration for that specific piece of hardware. This alone is worth waiting for :-) |
|
My last sentence got cut... Should be:
As you wrote 'self-calibration', I assume that it can be done by 'pressing a button '. If I'm wrong and it's considerably more work for the user, an export/import function via terminal might be worth a thought. On SSB: Great work, Hans! I love your update, that way I get a feeling for what it takes to get that feature to QMX. Even greater to know, that QMX+ will have a self-calibration tool so that every QMX+ will have the best calibration for that specific piece of hardware. This alone is worth waiting for :-) |
|
Hi Yes, it's just a button you press and the calibration happens by itself, and is specific to the actual hardware being calibrated. The only necessary pre-requsiites are:
Calibration takes some minutes because there are 12 bands (QMX+) or 5/6 (QMX) and each band measures 60 sync calibration points and typically 50 phase distortion points (depends on supply voltage); at each measurement the system sets itself up correctly and settles down then some averaging takes place to obtain sufficient accuracy. Each measurement point rakes a little over one second.? Calibration can be run either from the terminal or from the LCD menu without terminal; of course terminal is nice because of the ASCII-art graphing capability, it's fun to see the measurement curves. And yes I'll make Factory Reset put everything to defaults. 73 Hans G0UPL On Tue, Feb 18, 2025, 00:21 410733 via <410733=[email protected]> wrote:
|
?
A quick question on that one Hans:
?
If I have a 12V-build QMX but routinely run it at 9V to "underdrive" it (for a margin of safety), can I run the calibration at 9V or should I actually feed it with 12V for the calibration before going back to 9V operational? |
|
On Mon, Feb 17, 2025 at 11:16 AM, Hans Summers wrote:
I am not intending to wait artificially for any particular event until Dayton FDIM/Hamvention in May.Does that mean it's doable and could reasonably be expected before May? ;) ?
Heh, looks to me, this SSB thing is not just a feature users gonna get; it's the whole journey users enjoy with Hans. I personally like to read those from-time-to-time updates - issues that appear and solutions that come.?
? |
|
This is all amazing, and thanks again.
?
Just so that I can semi-get-my-ducks-in-a-row. . .?
?
I realise the QMX+ has an inbuilt microphone... which is excellent for testing, I guess, but maybe not something I'd want to use full time...?
?
Therefore, do you have (/have you been testing with) any hand-held mic that you'd recommend and I could pick up in advance??
?
Many thanks,
Alex. M1AJB.? |
|
I believe there was another thread where Hans discussed the pin-out (tip/ring/sleeve) for how the jack was to be used but said nothing about mic recommendations.
?
I'm sure that someone here has access to a large number of mics and will post some informed recommendations after the firmware is released. |
|
Hi Chris ?
I think in that case, if it is a 12V built QMX, I would still run calibration at 12V; that way you have the complete set of curves stored. In actual use it will only use the curves as far as 9V if you use a 9V supply, but you'll still have the full set of curves.? If you decide you prefer to only calibrate with 9V supply, if you are sure you will only ever use up to 9V supply, then that will also be viable.? Note that if a voltage beyond the end of the curves is used, the system extrapolates the curve anyway.? 73 Hans G0UPL |
|
Thanks Tony Good idea. I pinned it! 73 Hans G0UPL On Mon, Mar 3, 2025 at 3:03?PM Tony KA3ZPH via <tony=[email protected]> wrote:
|
|
Hi Hans,
?
Congratulations on the about to launch SSB transmission.?
?
The receiver works so well on SSB, as an SWL'er the hardest part is already accomplished. My QMX+ is a super receiver on SSB, and 99% of the time I am listening.
?
I notice that one of the biggest problems with QRP transceivers was in reception, not transmission. The QMX+ is a real value!? The low current drain makes it even more practical to use as a portable on vacation. It works great with a short whip. The room for six or eight alkalines
inside the case, makes the QMX+ ideal for air travel.?
?
TNX, & 73,
George
K3GK
?
? |
Jason KE8WSI
Steve H
Tony KA3ZPH
Bill, N4QA/QRP