Trigger when transmissions start or stop

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creed
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Trigger when transmissions start or stop

Post by creed »

Our team has been attempting to setup triggers that reliably trigger when transmissions either start or stop on a channel. We need one trigger to fire only if transmissions start. We need a second trigger to fire only if transmissions stop. We have looked at the Trigger resources in the User Guide, online, and in the PicoScope 6 software itself, but are still struggling to find these two types of triggers. I am attaching screenshots of what we need, these were captured using our hardware to output a logic high on Channel A when the event we need to trigger off of happens, but this is not a viable solution for the times when we are using hardware that we do not have this type of control over and still need to trigger when it starts or stops transmitting. Hopefully the screenshots make it clear what we are looking for, please let me know if you need more information.

Example of needing a trigger on Channel B when transmissions start:
trigger_when_transmissions_start_on_CHB.png
Example of needing a trigger on Channel B when transmissions stop:
trigger_when_transmissions_stop_on_CHB.png

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

You can trigger on rising and faling edge of a signal.
2022-06-24_07-32-18.png
Direction on Rising or faling.

Be aware that if the faling edge is shortly after the end of the capture of the start, the faling edge will not fire because the scope is busy transferring data to the PC and not reading the inputs.
If you want to accomplish that you can use the rapid trigger in stead of the repeat trigger (do not use auto trigger)

Benno

creed
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Re: Trigger when transmissions start or stop

Post by creed »

This would trigger on every edge though, which would have a bunch of triggers we don't want and can't have happening for our use case. I need it to only trigger on the types of events shown in the images. A rising or falling edge trigger would trigger millions of times before that as well as the signal is PAM3 so it has tons of edges.

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

That is on CH b
but CH-A looks only edges on start stop or am I missing something ?
Benno

creed
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Re: Trigger when transmissions start or stop

Post by creed »

Yes as I said in my post I used our hardware that we can control a logical signal on channel A to go high at the same time that we stop transmissions (or start them) in order to show what we need to be able to trigger on. However, we need to be able to trigger on the Channel B type event in the screenshot since with the other hardware we do not have that kind of control and the start or end of transmissions can happen at a varying time. Those screenshots trigger on channel A solely to show the behavior on Channel B that we need to be able to trigger on. If we used an edge trigger on Channel B it would trigger repeatedly which is not what we want, we only want it to trigger at the start or stop of transmissions (but not both, one trigger for each type).

Let me know if that still doesn't make sense.

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

can you post a psdata file of the signal you want to capture.

Benno

creed
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Re: Trigger when transmissions start or stop

Post by creed »

I have two files one with the start of transmissions example and one with the end of transmissions example. I would like the trigger to be based on Channel B starting transmissions in the one and on Channel B stopping transmissions in the other. However, they are too large to attach here and zipping them did not reduce their size significantly. Is there somewhere I can share them, they are ~43MB zipped together.

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

https://wetransfer.com/

if you don`t want them on a public I can send you a FTP login.

Benno

creed
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Re: Trigger when transmissions start or stop

Post by creed »

Please send an FTP login.

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

Login send via PM.

Benno

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Re: Trigger when transmissions start or stop

Post by bennog »

Ok I got the files

Can I publish them here on the forum so the people can also have a look at them ?

Looks like some form of QPSK.
Are there stuff bits in the signal ?
So the longest time the signal is below 50 mv is always less than e.g. 64ns.

Benno

creed
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Re: Trigger when transmissions start or stop

Post by creed »

Yes, you may publish them here. The signaling is PAM3 and in theory, the longest period of 0's in normal signaling could be up to 120 ns plus a small tolerance. So anything greater than that we would consider stopping transmitting for that trigger. The starting transmitting trigger is obviously just as soon as the signaling goes above or below a threshold range (as you stated it seems to be +/- 50 mV in these captures, but could be different for different devices).

bennog
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Re: Trigger when transmissions start or stop

Post by bennog »

The PSDATA files are these 2.

https://www.ans-net.nl/picotech/exCHBst ... ons.psdata
https://www.ans-net.nl/picotech/exCHBen ... ons.psdata

The end of transmission is not a big problem but triggering on the start and the end looks challenging.
Maybe someone from picoscope can tel something about it.

Benno

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Re: Trigger when transmissions start or stop

Post by bennog »

I have found 2 options to trigger 1 for entring and 1 for exiting.
but not a option to trigger on both situations.

Benno
Attachments
2022-07-26_22-17-47.png
2022-07-26_22-09-51.png

creed
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Re: Trigger when transmissions start or stop

Post by creed »

We have attemted to use Pulse Width for start of transmissions, the issue we find is that it has a ton of false triggers. From the description of the trigger it seems it shouldn't so maybe this is a bug in the software. We have assumed this is a likely case as it is not consistent. Sometimes we get false triggers and sometimes we don't even with the same settings. This can sometimes be fixed by changing to Positive Pulse for a moment and then changing back to Negative Pulse however this does not always fix it. We also need to have the time set much lower (we have used 700 ns in the past but would like to be able to use around 200 ns but 200 ns doesn't seem to work ever) and this also might be connected to this bug.

I will try out the Level Dropout suggestion for End of Transmissions and get back to you.

Thank you for your help with this ask.

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