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#qmx #firmware 1_00_017 AGC, S-meter, LPF sweep #qmx #firmware

 

Hi all

I have released firmware 1_00_017 at

The most important features are the AGC and S-meter.?

S-meter: it appears in the 3 characters to the right of the mode indicator character, when S-meter is enabled. The 15 vertical bars are worth 6dB each and therefore correspond to levels from S0 to S9 (9 bars) and?on up at S9+6dB, S9+12dB etc to S9+36dB when all three are full solid. The scale is calibrated in real decibels, but the accuracy of S0 relative to an actual signal input depends on the level of the gain setting you set for various bands in the Band Configuration terminal menu.?

AGC: it's a quite complex sub-system and I have documented the concepts and parameters in the 1_00_017 operating manual at , section 5.21 pages 52-57 inclusive. Briefly...?

AGC operates in the decibel domain, not linear. There is an AGC threshold below which AGC does not operate, it's a parameter specified in S-meter units. There's an impulse noise filter whose duration is configurable. The AGC slope is configurable so you can adjust it to your taste, you can have a gentle AGC action where strong signals are louder than weak ones, or an aggressive one where the AGC system makes everything the same volume. Hang time and recovery rate are also configurable.?

The AGC system creates an audio sample delay line, which it analyzes for impulse peaks then applies the calculated AGC gain (attenuation) to the sound samples in the delay line. The action of the AGC is therefore effectively instant; no matter how strong the incoming signal, the time taken for the AGC to react to it and protect your ears is always zero,?no piece of strong signal reaches your ears. The length of the delay line is configurable and needs to be a minimum 1.3ms for CW. SSB has a lower minimum audio frequency so a longer delay line is required; the maximum configuration is 6ms which would be able to handle signals down to 83 Hz. Either way, it's a very small latency.?

The S-meter also has a configurable "AGC action" display; if enabled, the S-meter looks like the Power/SWR meter function (during transmit) with two bars. The upper bar is the S-meter and the lower bar is the AGC action, with a configurable number of dB per pixel. It just helps you to see when AGC is active.?

The S-meter configuration parameters were moved to their own sub-menu under the Display/controls menu, and include an S-meter update interval parameter.?

I created a short demonstration YouTube video? . In this video I used a QCX, with about 150cm of wire attached to the antenna port, to generate a strong CW test signal. The BS170s in the QCX are toasted so this just produces very little actual power output but of course we are in close proximity, so the signal level "received" by the QMX is enormous, approx S9+30dB. In the video you can see heavy clipping when the AGC is off, which would no doubt generate a gigantic headache if you had earphones on; when I switch AGC on the signal is reduced to a comfortable S9 level.?

I also tested the QMX with AGC on 40m at night, tuning around for strong signals with and without AGC and I believe it is highly effective.?

The system is highly configurable, I suspect it may be TOO configurable; I will look forward to your feedback and suggestions on how it may be improved, and in particular it may be possible to remove some of these configurations, or derive or calculate them. The attached screenshot shows the configuration I used for the video. I must say though that it does not appear to be a delicate act, balancing parameters carefully; it seems generally to be very effective and insensitive to the exact settings.?

I do highly recommend though that you read the operating manual pages 52-57 carefully; initially all the parameters will be zero and you need to set it up carefully, before enabling AGC. At the moment there are no default values. So let's see.?

Other than that, I also added an LPF sweep tool (see example attached), which was discussed some time ago here. It "transmits" at 1/4 full power, into a dummy load (DO connect a dummy load!) while sweeping the transmit frequency, and plots the measured power output, after conversion to dB and normalizing the center frequency measurement as 0dB. It's indicative only, but quite interesting to see and educational, perhaps useful for debugging too.?

Plus a couple of bug fixes; change list is:
  1. Bug fix: '5351 synth code for setting TX params could lock up in some circumstances
  2. New LPF Sweep application in the terminal
  3. Added S-meter
  4. Added AGC implementation and supporting configuration menu parameters
  5. Bug fix: Parameter corruption (incl IQ Mode setting lost) in Digi config menu
So that's my week's work here.?

73 Hans G0UPL
Re: IQ mode Enabled on version 16 #qmx

 

Thanks mate, very nice of you to give this attention.
73 de ZR6TM
Timo
Re: QMX locks up during keying practice

 

Is there a reason you're not merely using Practice Mode?

You could check your dummy load using an SWR meter or a NanoVNA to make sure it truly is 50 Ohms.
--
72/73 de Steve, K9NUD
Re: oscilloscope use

 

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Is this book only available as a kindle version? I would prefer good old fashioned paper if it is available!

On 14/02/2024 06:39, Fernando TUSELL via groups.io wrote:

I found this little book of use:

McClanaham, J.??? Oscilloscope Applications for the QRP Enthusiast

Not really on-line, but quite cheap, even more so for the Kindle version.? Available at Amazon and probably many other places as? well.
Re: An interesting diagnosis

 

Great work, Jeff, and good luck with the micro replacement!

73 JZ KJ4A?

On Fri, Feb 16, 2024, 2:34?AM Andrew Lenton <a@...> wrote:
A very interesting write up well done, not sure if I would have got there!!

Re: PWR/SWR meter with FW #16

 

Hi,
I am using this PWR/SWR setting:
Update = 30ms,
TX to RX = 20ms
And it works well for me at around 22 WPM.
--
73 Bojan S53DZ
Re: QMX V3? What does V3 bring?

 

?Hi?Gottfried

Is it advisable to add mods 2, 3, 4, 6, 7 and 8 to old Rev 1 boards as well?

There aren't any documented problems attributable to these issues on Rev 1 boards. The modifications 2, 3, 4, 6, 7 and 8 would work fine on a Rev 1 board. However - when you replace SMD parts there's a risk of damage to the board. Therefore I would in general, stop short of recommending these modifications be made to Rev 1 boards. In general I find that remembering "if it ain't broke, don't fix it" normally works very well for me.?

73 Hans G0UPL
#qmx #shipping update #shipping #qmx

 

Hi all

QMX kits: FINALLY after some UNNECESSARY delays and FedEx FRUSTRATION Arrrggghhhh we finally got the 8 boxes of 1,000 QMX Rev 3 boards yesterday afternoon. My team are building two for testing right now. I don't expect any issues. My team are also flashing the bootloaders. The other components and enclosures are already prepared. Subject to successful testing we'll begin shipping the pending QMX kit orders today; there are around 250 orders pending so it will not happen instantly, but I hope we can clear the backlog within a week.?

QMX Assembled (and QCX-series, QDX-series): See attached: we are making good progress on reducing the size of the backlog. The assembled radio waiting list is here: and I update it normally every weekday unless I have a brain lapse. It currently stands at 815 orders, down from a peak of 906.?

Any urgent requests, please let me know.?

We have two new employees starting on Monday. Which reminds me I need to order some new soldering irons and solder today otherwise that's not going to help us much, is it :-/? ?And we have a carpenter building two new 90 x 270cm tables for our 4'th room up here in QRP Labs towers.?

73 Hans G0UPL
Re: An interesting diagnosis

 

A very interesting write up well done, not sure if I would have got there!!
Re: IQ mode Enabled on version 16 #qmx

 

Hi all

I resolved?this issue in the forthcoming 1_00_017.

73 Hans G0UPL



On Wed, Feb 14, 2024 at 9:41?PM <timo.vandermerwe@...> wrote:
Thanks Adrian and Jim,
Glad I am not the only one.? Being a CW wannabe, but no where close to actually using it effectively, the SDR functionality is quite important to me, and seriously, the QMX pulls stations from everywhere.? It is absolutely great.??
No worries - will stick to V-14 until our guru "Hans" presents a solution.
73 de ZR6TM
Timo

Re: PWR/SWR meter with FW #16

 

Ok....Roger that Hans. I'll go check it out now. Thanks.

Tim - K5DEZ
Re: PWR/SWR meter with FW #16

 

Hi Tim

It isn't a bug, it's a change to the way the power meter operated; in 1_00_016 there are some additional parameters in the new "Pwr/SWR display" configuration screen (see attached). The reason you don't see power on dits is because the update interval you have, is too long, and the dits are fitting in between the power?meter updates; just make the update interval a bit shorter and it will fix it.?

73 Hans G0UPL



On Fri, Feb 16, 2024 at 9:19?AM Tim Keene via <k5dez=[email protected]> wrote:
?I'm not sure if it has already been reported or noticed yet but I have a low band Version 1 QMX and a High band V2 QMX. With FW #14 the PWR/SWR meter works fine but when I install FW #16 the pwr/swr meter only works "normally" with the Dah paddle. If you hold the Dit paddle only one line of pixels come up and does not show the power or swr correctly. If I reinstall FW #14 again all is well. Can anyone else produce this "bug"?? Let me know please.

Tim - K5DEZ

PWR/SWR meter with FW #16

 

?I'm not sure if it has already been reported or noticed yet but I have a low band Version 1 QMX and a High band V2 QMX. With FW #14 the PWR/SWR meter works fine but when I install FW #16 the pwr/swr meter only works "normally" with the Dah paddle. If you hold the Dit paddle only one line of pixels come up and does not show the power or swr correctly. If I reinstall FW #14 again all is well. Can anyone else produce this "bug"?? Let me know please.

Tim - K5DEZ
Re: oscilloscope use

 

I don’t have a lot of scope experience. I bought this one 4 or 5 years ago and it is much nicer than the old tube scopes I have used. It is recommended in these groups often ?

?

Siglent Technologies SDS1202X-E 200 mhz Digital Oscilloscope

?

--
Colin - K6JTH?
Re: oscilloscope use

 

Thanks for suggesting "Oscilloscope Applications for the QRP Enthusiast." Just what I was looking for.

I don't have an oscilloscope yet and the one that McClanahan bases his text on, the "Rigol DS1102E 100 MHz digital" seems to be out of production. The book was first published 2015, so I'm guessing there are a lot of newer oscilloscopes on the market.

Does anyone have a suggestion for an inexpensive digital oscilloscope? I don't have any experience with which to choose one and there are many available on Amazon and other sources. At this point, I don't really have a need for a very complex instrument, just something suitable for analyzing my herd of QRP radios and test gear. Thanks.

Cheers, Michael KE7FZD?
Re: QMX V3? What does V3 bring?

 

Is it advisable to add mods 2, 3, 4, 6, 7 and 8 to old Rev 1 boards as well?
Thanks,
Gottfried OE1IRA
OCX+ T1 Toroid Continuity Process

 

Greetings and thank you for indulging a rookie question. I'm new to complex kits.

I have wound, then soldered T1 onto the board, and have continuity in each of these points:? 1 to 2, 3 to 4, 5 to 6 and 7 to 8.

Does this mean I successfully installed T1 and can proceed with construction?? I just want to know the precise continuity steps.

- Bill

W3WJ
Re: An interesting diagnosis

 

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That is an interesting failure mode - deep inside the cpu. After all that meticulous soldering I can understand the sentimental attachment. Good luck and thanks for all you do! 73, Sandy KB3EOF

On 2/15/24 19:21, Jeffrey W Moore via groups.io wrote:

Recently a fellow ham sent me a QMX rig to fix.??This is to be my 100th QMX that I have fixed - assuming that I accomplish that with this one.???I wanted to share the journey.??I found this one interesting.??This is a Rev 2 QMX with rev 14 firmware.??Wound for 12V.??This is the first part of a story - the diagnosis and how I arrived at it.??I wanted to share because this is more interesting than most and it may help someone else.??More will be posted later.

?

?My usual routine with a new rig is to disassemble, inspect, clean??and inspect again.??I use a 10x stereo microscope for everything with very bright side and overhead lights.??I scrape flux off, use 99% isopropyl alcohol to clean with an extra soft toothbrush.??Then I inspect again.??I can fix almost all rigs this way.??There are always solder blobs, solder balls, cold solder joints in every rig that comes to me.

?

This rig came in very clean.??No excess flux, no bad solder joints, no solder splashes.??It did have a few long pins that ended up shorting to the case, adjacent boards and wreaked a bit of havoc.??I fixed those before proceeding.

?

After applying power at 7V with current limits, it came up only with top row black boxes.??No backlight, nothing on PUTTY.??Looking with a scope I could see the 3.3V rail was good and 3.3V PWM was within range.??But the 5V rail was sitting at about 5.8-5.9 V and the 5V PWM was at about 78% as measured on my scope.??Not Good!??But I knew the CPU was running enough to produce PWM signals for the SMPS boards.??Thats good!

?

I tested the SMPS power boards on my homemade test fixture.??They were fine.??I tested for near shorts or low resistance on the 5V rail.??It looked fine also.

?

I put the SMPS boards back into the rig and plugged in the controls board.??I also installed the jumper to force the QMX into firmware update mode.??That worked.??The QMX came up wit the “disk drive” on my Linux desktop.??I installed rev 16 firmware knowing that Hans had fixed a bug in initializing the EEPROM.??I thought the forced factory reset upon installation of Rev 16 might shed some light.??It did.??Now the rig came up immediately into Diagnostic mode.??It’s the only screen that will come up in PUTTY if something is seriously wrong.??I could see that the 5V rail was at 78% duty cycle as I saw on my scope but the reported voltage to the CPU was only 4.8 volts.??The CPU was trying its hardest to reach 5V but it maxed out at 78% and couldn’t get there.??I measured the ADC_5V signal on the board and my scope read 2.4V.??That is consistent with the diagnostic screen reporting 4.8V since there is a 2x divider in the circuit.

?

ADC_5V only goes from the SMPS board to the CPU.??Something was clamping it at 2.4V.??It had to be a short on the SMPS (no, because I tested those separately), the main board in the traces (possible, but unlikely), or in the CPU (UGH!).??I lifted pin 32 of the cpu and confirmed that indeed the CPU was clamping that line at 2.4 volts.??After lifting that pin, the board showed 2.95V for ADC_5V.??And that CPU pin 32 in the air showed 2.4V.??Proof enough for me.

?

So this means that replacing the CPU is the only option.??This rig has sentimental value to its owner, so he said please proceed.??I have a few bare boards with programmed CPUs that I have just for this kind of occasion.

?

Tomorrow I will proceed with the operation.??I have to accomplish that in the morning when I am at my best and after only 1 cup of coffee.??I’ll post my progress here.

?

73 for now

Jeff

W1NC
Re: An interesting diagnosis

 

I’m sure it’s due to an inadvertent short circuit somewhere along the path of assembly. ?I suspect the extra long pins that weren’t trimmed short enough to the board shorted against the case, ?this is a very tight assembly that needs close attention to lots of details. ?I never blame ESD. ?It’s almost always some small human error. ?


Jeff
W1NC
Re: An interesting diagnosis

 

Amazing writeup Jeff thanks so much for sharing.? Do you think this is an anomaly (a single cpu that's bum from the factory), or a case of assembly mishap (errant and highly unusual? static discharge, or something else really crazy like that)?
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