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ETS problem

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ETS problem

Postby maxsca » Mon Oct 18, 2010 7:38 pm

I'm using the PicoScope 2204, with version 4.6.92, to take a measure of sine wave of 1.8 MHz.

When i select the AUTO trigger the waveform of the signal is not stable, but the frequency mesured is correct; if I select the ETS the wave becomes stable but the frequency, and the waveform show, becomes exactly half of the original, 900 KHz.

It's correct ??
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Re: ETS problem

Postby ziko » Wed Oct 20, 2010 9:42 am

Two problems; one the measurement is wrong, but the main problem is that the waveform is jittering. I have managed to recreate your problem. This is a bug in the driver you should not have to put ETS on. I have reported it as a bug. Thanks for pointing it out.
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Re: ETS problem

Postby maxsca » Wed Oct 20, 2010 10:29 am

Thanks for the analasys !
Others informations: the same problem occurs with a Picoscope 3224 (same software 6.4.92) and the signal applied comes from a reference generator, therefore it's jitter free.

Massimo - Italy
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Re: ETS problem

Postby ziko » Thu Oct 21, 2010 2:11 pm

Hi I cannot recreate the problem on the 3224 what I think you are seeing is the Sin(x)/x interpolation.

With linear interpolation this connects the dots between the sampled points and you normally need a significantly higher sample rate to get a very good looking signal. Using Sin(x)/x interpolation this algorithm (used by many scope manufacturers) means that you do not need to sample as high to get a good looking waveform.

By default Sinx(x)/x is on and the trigger looks as if it is jittering, If you switch of sin(x)/x interpolation you will see the that the waveform is triggering correctly.

You can switch this off by going into Tools-> Preferences and then selecting the sampling tab and switch it off

Let me know if this makes a difference?

Kind regards
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Re: ETS problem

Postby maxsca » Fri Oct 22, 2010 9:01 am

Hello,
i tried to disable the sin (x) function but the defect remains!
I learn that even if activated the second channel B, the 1 MHz signal 1 becomes stable (see. Two_channel_without_defect.psdata), but with only active the channel A the defect is always present (see One_channel_with_defect.psdata)


Reference -> Picoscope 2204, SW 6.4.92, signal 1MHz sine.
Massimo -Italy
Attachments
One_channel_with_defect.psdata
(30.38 KiB) Downloaded 138 times
Two_channel_without_defect.psdata
(30.45 KiB) Downloaded 136 times
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Re: ETS problem

Postby maxsca » Tue Oct 26, 2010 3:20 pm

Hello,
do you have any idea about solving the problem ??

Massim - Italy
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Re: ETS problem

Postby ziko » Wed Nov 03, 2010 10:46 am

Hi yes we have fixed the problem for the 2204 which will be out in the next release, but what I was saying about Sin(x)/x was for the 3224.
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Re: ETS problem

Postby maxsca » Wed Nov 03, 2010 11:13 am

Ok,
i'll check the solution of the problem in the new SW release !.

Thanks
Massimo - Italy
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