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Digital Distortion Compensation for Measurement Setup
Digital Distortion Compensation for Measurement Setup
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Old 4th June 2019, 06:50 AM   #191
phofman is offline phofman  Czech Republic
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This simple adapter version is suitable for compensated measuring of non-balanced circuits. No output/input level equalization is available. Only one (fixed) output channel is calibrated/compensated.

Using only one input channel would be too much of a compromise because in single-ended measurements it is also important to subtract the ground-loop noise and/or ADC artefacts. Yet only one input channel (right channel in the diagram) needs to be calibrated/compensated, the non-calibrated/non-compensated left channel is used solely for subtracting the common-mode noise.

In measurement mode both output and input soundcard channels are available for any uncompensated usage.
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Last edited by phofman; 4th June 2019 at 07:02 AM.
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Old 5th June 2019, 07:35 AM   #192
KSTR is offline KSTR  Germany
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Meh, tried to install and use Ubuntu 18.04/Mint 19 but failed miserably.
I found out the hard way that 18.04 doesn't like Dell laptops like mine, overheats the hardware rather quickly (with no easy fix unless you're a total geek), causing a severe system stall (no way to shutdown gracefully, had to cut power) and when that happens in wrong moment it corrupts the file system so much that even booting in recovery mode ends with a kernel panic and no way to repair it. Game over :-(
Might try an older 16.x version instead?

Puppy Linux isn't useful either because it is so stripped down that the usual tools are simply not present (apt-get, gcc, ...). Installing anything is cumbersome with the supplied packet manager because almost everything ends up in fails with endless lists of missing libraries... I couldn't make it...
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Old 5th June 2019, 07:57 AM   #193
phofman is offline phofman  Czech Republic
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Interesting. Honestly, I have never had a problem like that, I just stick a live USB flash into some PC/NTB, boot from it and it has always worked OK.

What is exact model of your NTB?

I am thinking of dumping my drive with clonezilla to create a completely-installed image for download.
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Old 5th June 2019, 08:30 AM   #194
KSTR is offline KSTR  Germany
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It's a Dell Studio 1537 pp33l, 8GB RAM but only 2GHz Intel Core 2 Duo T6400 which might be on the edge of CPU power anyway.

The overheating with some Dells seems to be a known issue, has to do with the graphics chip/driver. Probably a bootable image of your system won't help, therefore.

There are ways to fix this it seems, people have managed to cope with it, but I must make sure I can step through the process in less than 20 minutes or so before the system stalls again. Being a Linux noob this is difficult, I have to google every silly simple thing

Anyway, thanks for your help!
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Old 5th June 2019, 08:45 AM   #195
phofman is offline phofman  Czech Republic
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I see, that is the old ntb you mentioned. I do not think the CPU is really up to the task, you will need 3 octave processes + arta + the system all running without xruns. I have quite bad experience with Core 2 CPUs (+ slow DDR2), they hardly keep up with modern web sites.

Is there any other machine you could use? Refurbished good brand laptops (Dell, HP, Lenovo) with i3/5 gen2/3 run at 150 EUR, with SSD/mSATA they work very nice, I use a few of them.
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Old 5th June 2019, 09:14 AM   #196
thumb is offline thumb  Europe
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Quote:
Originally Posted by KSTR View Post
It's a Dell Studio 1537 pp33l, 8GB RAM but only 2GHz Intel Core 2 Duo T6400 which might be on the edge of CPU power anyway.
Make a USB stick with this one: Try it | Antergos Linux
It is Archlinux base not Debian/Ubuntu. It is a live Image you can install if you like. With that you can easy test/check if your labtop works

In antergos/archlinux is Octave 5.1 pre-build package

Last edited by thumb; 5th June 2019 at 09:23 AM.
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Old 5th June 2019, 09:59 AM   #197
phofman is offline phofman  Czech Republic
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Archlinux is definitely a great choice, provided the user knows his way in linux/archlinux. I am just afraid the problem with this particular NTB will be the same as in ubuntu live USB used for installation.
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Old 5th June 2019, 01:44 PM   #198
thumb is offline thumb  Europe
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Okay, I have not build your interface box yet but, octave and playrec.mex setup works.
How do I get your gui up ? Via octave --gui ?
Sorry I'm very new to octave
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Old 5th June 2019, 02:40 PM   #199
thumb is offline thumb  Europe
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Ahh... run : octave mainCtrl.m
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Old 5th June 2019, 02:48 PM   #200
phofman is offline phofman  Czech Republic
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Very good.

Plus:
One terminal - octave mainPlay.m - that is the playback side
Another terminal - octave mainRec.m - that is the recording side

These two processes are sending zeromq messages to mainCtrl which controls and displays UI.


Please update the latest version (git pull).

The configs have been recently renamed to final name - configRec.m, configPlay.m (.example versions are stored in the repo).

First please configure playrec device IDs in nonlinear-compensation/configRec.m.example at master * pavhofman/nonlinear-compensation * GitHub , nonlinear-compensation/configRec.m.example at master * pavhofman/nonlinear-compensation * GitHub + the corresponding devices in the other direction nonlinear-compensation/configPlay.m.example at master * pavhofman/nonlinear-compensation * GitHub (all in .m versions, of course).

What does your octave mainListPlayrecDevs.m say?

Last edited by phofman; 5th June 2019 at 02:54 PM.
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