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External Triggering with 5203

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External Triggering with 5203

Postby acerussi » Mon Jan 23, 2012 8:44 pm

Im having some trouble using Pico 6 and an external trigger. Using a reference signal in channel B I can trigger a Sample signal in channel A very well using the "auto" triggering options.

but when I use the same signal in external trigger it wont trigger properly.

the scope I am using is the 5203 and the signals are 20 MHz pulses. I had noticed an earlier post with a user having similar difficulties using a different scope. sounded like it was a driver/software issue.

any help with this would be appreciated.
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Re: External Triggering with 5203

Postby Martyn » Tue Jan 24, 2012 2:50 pm

When you say it wont trigger properly what exactly do you mean ?

Does it trigger sometimes or will it not trigger at all ?

If you chose repeat or single trigger, rather than auto which will get data on a timeout without a trigger, are you able to trigger ?
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Re: External Triggering with 5203

Postby acerussi » Thu Feb 02, 2012 9:31 am

Thanks for the reply (I thought Id be notified at a reply but something went wrong)

What I mean by "not triggered" is that the waveform is not stable in time as drawn on the screen. When I use B as a trigger reference for A, I can see the phase/time relationship between these signals is preserved. In other words, trace A and trace B are drawn the same way on the screen with each sweep.

But when I switch the triggering to external (using the exact same signal B as above), the A trace now bounces all over the screen (in time) - the waveform is drawn differently with each sweep.

I haven't tried the single trigger yet - will give that a go.
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Re: External Triggering with 5203

Postby Martyn » Mon Feb 06, 2012 9:02 am

Rather than using auto, as this supplies the data every second even when the signal doesn't trigger and therefore will jump about, I would try using repeat trigger. I have just tried this on a a 5203, using Picoscope R6.6.16, and received a stable signal when the trigger input signal was moved between Channel B and EXT.
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Re: External Triggering with 5203

Postby acerussi » Sat Feb 11, 2012 2:34 am

I tried this and it did not work for me. I can use the Rapid trigger on either A or B and the triggering is OK. But when I switch A to the EXT and try to trigger off that it does not draw a trace. Im using software 6.6.16.12.

any suggestions? Thanks.
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Re: External Triggering with 5203

Postby acerussi » Mon Feb 13, 2012 1:03 am

I tried the rapid trigger and the same problem exists. the software is up to date (according to the updater).

Has anyone else had this problem before?

Perhaps the structure if the trigger signal is an issue: Im using a 20 MHz pulse as the trigger (not a square wave or sawtooth etc). When I use this signal in channel B with the other trigger modes it seems to work fine -it is just the EXT that seems to struggle.
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Re: External Triggering with 5203

Postby Martyn » Mon Feb 13, 2012 2:34 pm

Can you use File->SaveCurrentWaveform and chose to save as a .pssettings file and post this file here so that we can look at your settings.

Additionally what are the exact characteristics of the 20MHz pulse you are using.

Thanks
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Re: External Triggering with 5203

Postby acerussi » Tue Feb 14, 2012 9:22 pm

There are 3 examples using various triggers (all channel B). N is the signal that when I use EXT it doesnt seem to work.

Thanks for taking a look.
Attachments
master_repeat.psdata
(12.09 KiB) Downloaded 109 times
master_rapid.psdata
(12.14 KiB) Downloaded 108 times
master_ETS.psdata
(99.08 KiB) Downloaded 108 times
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Re: External Triggering with 5203

Postby Martyn » Wed Feb 15, 2012 11:41 am

Can you repeat the process, but with a slower trigger signal, say something in the 100kHZ to 1MHz range and see if you can trigger on the normal channels and the EXT channel. If it does then we need to look at the characteristics of your signal which may be at the limits of the EXT input circuitry.
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Re: External Triggering with 5203

Postby acerussi » Thu Feb 16, 2012 8:03 am

I tried using a 2 MHz square wave (1V) and that seems to work with the EXT trigger.

Are there differences between the EXT trigger input and the other channels - perhaps a voltage threshold or frequency limitation for the EXT trigger?
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Re: External Triggering with 5203

Postby Martyn » Thu Feb 16, 2012 1:28 pm

The pulses in the waveform you posted are narrow and it is possible that they are not being seen by the EXT input trigger on all occasions and so causing the jumping around. If you try a 20MHz square wave do you get a more stable trigger albeit with a little bit of jitter ?
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