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Sample rate confusion
PostPosted: Thu Jul 19, 2012 2:04 pm Reply with quote
tuuca
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Joined: 19 Jul 2012
Posts: 7




Gentlemen,

I have encountered a frequency shift of a peak in the Spectrum view...

Background:
Used SW: SysTune
Used HW: AUBION X.8, Bruel & Kjaer microphone, Bruel & Kjaer calibrator.

The calibration signal frequency is 1000 Hz. But SysTune's Spectrum view shows 900 something (sorry, did not write down the exact number - next opportunity to work with the measurement setup will not come before the second week in August Confused ).

To fix the frequency scaling I have to go to the device settings (Configure > Select device...) and change the sample rate from whatever is set to something else (and switch back if I want to work with the original sample rate). After this, everything is alright and the peak is located prerfectly at 1000 Hz where it should be.

Looks like there is a sample rate confusion after SysTune starts up. Changing the sample rate and changing it back to the original value fixes the problem but it is rahter uncomfortable and the customer complains about it.

Could you please help me with that? Any ideas for test procedures to locate the problem closely? I will try to do some more investigation in two weeks.

Thanks
Jan
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PostPosted: Thu Jul 19, 2012 10:28 pm Reply with quote
Bruce
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Joined: 19 Apr 2005
Posts: 459
Location: Minneapolis, MN, USA




This is an issue with the Aubion X.8 and older SysTune versions. It has been solved in SysTune 1.2.6.

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Best Regards,
Bruce C. Olson
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PostPosted: Fri Jul 20, 2012 1:17 pm Reply with quote
tuuca
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Joined: 19 Jul 2012
Posts: 7




Thanks Bruce,

as soon as I get to the CP with the program installed I'll check the version installed and try to update.

Cheers
Jan
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PostPosted: Fri Aug 03, 2012 10:42 am Reply with quote
tuuca
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Joined: 19 Jul 2012
Posts: 7




Hello again,

I finally got to the problematic system and here is the summary:
1) the version of SysTune installed is 1.2.6.416
2) the sampling problem persists. I dont know all the circumstances, relationships, dependencies and so on but here is how I reliably replicate the fault state.
2b) Set the sample rate to 44,1 kHz in SysTune
2c) Exit SysTune
2d) Turn off computer
2e) Turn off Aubion
2f) Unplug mains power from Aubion
2g) Reconnect mains
2h) power up computer
2i) power up Aubion
2j) launch Aubion daemon
2k) launch SysTune
2l) connect calibrator and see the wrong position of the peak

The procedure surely can be simplified but as I tried it sometimes the sampling was right. This way it was always wrong.

If I set the sample rate to 48 kHz in 2b), everything works fine. So I can work with 48k. But there is a problem somewhere...

Regards
Jan
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PostPosted: Fri Aug 03, 2012 3:22 pm Reply with quote
Bruce
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Joined: 19 Apr 2005
Posts: 459
Location: Minneapolis, MN, USA




Hello Jan,
What is the version and firmware that is on the Aubion?

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Bruce C. Olson
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PostPosted: Fri Aug 03, 2012 3:31 pm Reply with quote
Bruce
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Joined: 19 Apr 2005
Posts: 459
Location: Minneapolis, MN, USA




Jan,

Thank you for the detailed steps. I can recreate the problem. I will enter this in our database and have the developers work on it.

Bruce

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Bruce C. Olson
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PostPosted: Sat Aug 04, 2012 9:03 pm Reply with quote
AFMG Pedro Lima
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Joined: 05 Jun 2010
Posts: 266
Location: Germany




Jan,

Please allow me to make an important question:

After restating the PC you have started AUBION daemon and then launched Systune. When Systune started had AUBION already been recognized by the system? One way of testing that is checking in he AUBION GUI if the meters react and if there is a device connected.

If you start Systune BEFORE AUBION is recognized by the system the sample rate problem can occur. That happens because Systune currently does not recognize sample rate changes made externally (as via the ASIO device control). Changes to sample rate have to be done via Systune. This is actually schedule to be implemented in subsequent versions.

Would you be so kind to verify that for us?

I think it is possible that AUBION sample rate has been reverted to the default 48.00kHz after being recognized by the system. But at the time Systune was already open.

Best Regards,
Pedro
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PostPosted: Sun Aug 05, 2012 7:53 am Reply with quote
tuuca
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Joined: 19 Jul 2012
Posts: 7




Gentlemen,

thank you for replies and additional questions...

Quote:
Hello Jan,
What is the version and firmware that is on the Aubion?


The AUBION GUI "about" says: version is 1.0.5.95, service: r878. But the screenshot I have was taken with "no connection". I have to take a look next time I get to the machine.

Quote:
When Systune started had AUBION already been recognized by the system?


Yes. I always wait for all automatic procedures to end before I go to the next step.

Quote:
If you start Systune BEFORE AUBION is recognized by the system the sample rate problem can occur.


I surely can play around with that some more but I don't have an everyday access to the machine. So it will take 2 or three weeks to get the facts. So if you come up with a detailed test procedure in the meanwhile there is no problem to give it a shot.

Jan
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PostPosted: Mon Aug 06, 2012 1:00 pm Reply with quote
AFMG Pedro Lima
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Joined: 05 Jun 2010
Posts: 266
Location: Germany




Hi Jan,

You have helped a lot already. No need for further investigations from your side, thanks.

For the meantime, please use this workaround suggested by Bruce Olson:

1) Use ST Select Device to switch to 48k SR.
2) Close Select Device dialog.
3) Use ST Select Device to switch to 44.1k SR.
4) Close Select Device dialog.

After both 2 and 4, the correct frequency is shown in Spectrum.

Best wishes,
Pedro
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PostPosted: Mon Aug 20, 2012 2:00 pm Reply with quote
tuuca
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Joined: 19 Jul 2012
Posts: 7




Sorry for the delay. I am glad I could help. This is the workaround I use from the beginning Wink Looking forward to the fix.

Thank you
Jan
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