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Topic: [solved] Receiving strong sigs 12.KHZ (Read 14167 times)
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DD4WH
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #106 on: 03. September 2018, 11:03:25 »
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Thanks, Andreas!
Totally agreed!
Lets see what the problem looks like in Chucks and Francois´ radios when they use the same test conditions.
73 Frank
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DD4WH
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #108 on: 03. September 2018, 11:11:47 »
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Andreas, I think we have several issues mixed here:
* decimation/Hilbert filter software issue (I found a minor filter problem in the firmware and will test an improvement in the next days)
* maybe an EEPROM setting issue (I sent an Email to Danilo for that)
* maybe IQ settings issues (lets see the outcome of the tests by Chuck and Francois)
Lets see :-)
73 Frank
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F4HTX
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #110 on: 03. September 2018, 12:22:49 »
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Hi Friends,
@ Andreas : I did not say the meter measurement is unreliable, I was just asking if the birdies problem, because it’s a locally generated artifact, might elude the s-meter measuring in the signal processing chain. But this might be not relevant because my ignorance about the software architecture, please forgive...
@ Frank : Hereunder a link for the two videos you asked for (sorry 600MB, I should find sometime a way to compress those vids) :
https://wetransfer.com/downloads/f1a3122969e8be3c1a77bebb66c7744e20180903110426/138a4684914b84e908a4ab0f6b26961520180903110426/aec5cd
This time +12kHz and RxIQon, I reseted the codec multiple time on the second video.
I would like to add a couple word about the history : I crafted two mchf v0.6, gifted one to my friend F6DPT (50 years experienced ham), and we were very happy playing with those TRX. After few months I noticed that I listened multiple occurrences of strong signals on a x12kHZ modulo. It was new and loud and I am quite sure I would have noticed it if it existed earlier. A few time later my friend called me because he noticed the same problem. We were doing the firmware update when they appeared and I am totally unsure when the change occurred. But we noticed this almost at the same time, and it appears on the web shortly later. I do agree (because of the firmware downgrade tests we did yesterday) that this is probably a long time existing problem rising up because of the better AGC. We could push the dust under the rug, but, for sure, it will came out again.
The question I would love to get an answer is : which part of the processing is able to generate such artifacts (nx +/-12kHz birdies) ? Does the maths predict this or is that a coding issue ?
There is also a possibility of hardware generated artifacts, ADC and DAC are far from perfect, and their implementation could be very tricky when you are playing with large dynamic range (routing, decoupling, tracks coupling, etc.). So far, we have no control on this aspect of the mchf.
I understand how frustrating and annoying this issue might be for the lead team, but without knowing where it does come from, I think we have a time bomb in the uhsdr.
Once again, we have to go « where no man… » And remember, people in red uniform die first !
73’s
François
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DD4WH
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #111 on: 03. September 2018, 12:56:58 »
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Hi Francois,
excellent! Thanks a lot for the videos, that is extremely interesting!
I had to watch the videos three times each to write down what is happening there . . . because on the second video the behaviour is different!
1st video: with automatic IQ correction, 3k6 BPF:
* what you can see is the following:
10.053kHz very faint signal
10.065kHz loud unwanted signal, but not visible
10.077kHz loud unwanted signal, but not visible
10.089kHz NO SIGNAL
10.101kHz wanted signal with -74dBm
10.113kHz NO SIGNAL
10.125kHz NO SIGNAL
10.137kHz NO SIGNAL
10.149kHz NO SIGNAL
--> no unwanted signals above the wanted signal
--> exactly TWO unwanted loud signals below the wanted signal spaced 12kHz in a distance of 24kHz of the wanted signal
--> unwanted signals NOT visible (and no dBm display possible)
2nd video: with automatic IQ correction, 3k6 BPF:
* what you can see is the following:
10.053kHz very faint signal
10.065kHz loud unwanted signal, but not visible
10.077kHz loud unwanted signal, but not visible
10.089kHz loud unwanted signal, but not visible
10.101kHz wanted signal with -74dBm
10.113kHz loud unwanted signal, but not visible
10.125kHz NO SIGNAL
10.137kHz NO SIGNAL
10.149kHz NO SIGNAL
--> YES, unwanted signal above the wanted signal
--> exactly FOUR unwanted loud signals below the wanted signal spaced 12kHz in a distance of 12kHz of the wanted signal, three below and one above
--> unwanted signals NOT visible (and no dBm display possible)
Honestly, I have no idea what that problem is!
It has nothing to do with the things I discussed above in this thread. You can easily see that the problems in your former video posted above in this thread were 100% caused by the IQ correction that was set to OFF. They have disappeared. But I cannot explain the new problems noted above with any software issue.
The most probable solution that comes to my mind is an erroneous codec that does what it wants depending on the reset.
You could do the following:
* set VFO to one of the unwanted signals and listen to the loud tone
* go into the menu and reset codec
* if the tone goes away (and maybe changes its position), the problem has to do with the codec hardware
Where did you buy the codecs that are inside your machine and the machine that you gave to your HAM radio colleague?
Maybe other OMs have an idea how this could be caused by software? I have no clue at all.
73 Frank
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F4HTX
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #113 on: 03. September 2018, 14:21:02 »
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Hi again Andreas and Frank,
@ Frank : my usual configuration is with -12kHz, so I am not familiar with the +12k test I performed, but I concur on the fact : WTF !!
I did the codec reset, here is the video (Spoiler : you will LOVE this one. This is fun, hold on to your wigs !!) :
https://we.tl/t-XIUe8XkEhX
When the codec reset seems to be efficient, the birdy goes down to where it should stay, in the noise. But, most of the time, it is like the reset is not performed correctly.
It might be hardware problem of the codec. All my components came from large reseller, in this particular case the codec is from Mouser. I might buy from another source and swap the chip. This seems to be a long shot as two mchf with two UI with the same chip problem...
I attached a pic of this area of the UI board I shot on Nov.2017. I will tear apart the mchf and put the UI board under my binocular. Two codecs wrongly soldered… Why not...
@ Andreas : here is the vid you requested with Xlate off
EDITEDIT:
I try to look into the future:
Using Xlate=off you do not see any spurs...
Nope : unfortunately your crystal ball needs upgrade 
https://we.tl/t-bGBuLDbGj2
73’s
François
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WD8BXS
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #115 on: 03. September 2018, 14:52:39 »
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Hello Andreas,
How can it be a hardware issue if you can load a config file in your radio and get it to happen?
If you do not have the issue, send me a copy of your config file and I will test it here.
Chuck
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Thanks,
De WD8BXS vy 73
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DD4WH
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #117 on: 03. September 2018, 14:59:13 »
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Hi Francois, hi Andreas,
thanks a lot for your efforts!
fully agreed ;-). Nice video with a multiresistent codec (although you seem to be a little fast on the encoder, give the automatic IQ correction a little more time to do its job properly before resetting again ;-))
It seems the cause has now been identified as hardware-related. Whether the software can deal with this, is another question. But if the codec is so resistent to reset and the shift seems to be randomly distributed (as can be seen in your two videos having different frequencies with unwanted signals), software correction is not straightforward.
I have seen the same phenomenon with a totally different codec (SGTL5000), so this seems to be common and as Andreas said, would go totally unnoticed in every quality control at the chip factory.
It is really good, Francois, that you built two mcHFs, because that was the final clue that put us on the right track with the codec ;-).
So, yes, hardware check (soldering) or even codec exchange would be the right solution here, I think.
The good thing is, that in the course of the search for a firmware issue I detected a bug in the audio chain, so maybe this will improve suppression of birdies a little more, but that has to be tested. We will keep you informed, if and when a new version is issued.
73 Frank
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DD4WH
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #118 on: 03. September 2018, 15:05:42 »
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Hi Chuck,
it would be very interesting to have a look at your problem and decide whether it has the same cause. Could you make a video of your machine with the following settings ? :
* inject a signal at 10100kHz into your radio
* IQ auto correction ON (because we have to eliminate the possibility that it is just a malaligned IQ phase/amplitude); alternatively you can show me on the video that your IQ phase and amplitude is perfectly manually calibrated at 10100kHz
* set frequency translation to +12kHz
* set display to spectrum display only
* could you tune slowly from 10100kHz to 10126kHz and down to 10074kHz
* after that, could you navigate to one of the unwanted signals and listen to the tone
* then go into the menu and try to restart the codec many times (leave some time after the restart for the automatic IQ correction, one second is enough)
* if it is the same issue, the tone will disappear after a restart (it could be that many restarts are necessary --> see the video by Francois)
Thanks a lot in advance!
73 Frank
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F4HTX
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Re:[not solved] Receiving strong sigs 12.KHZ
« Reply #119 on: 03. September 2018, 15:08:59 »
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Hello Andreas and Frank,
Thanks for the explanations, so, this is what I will do now :
1. Thorough exam of my UI board under the binocular
2. I will swap the codec with one of the ovi-40 kit still not soldered
3. Report to the team…
Many thanks for your dedication folks.
Best Regards,
François
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