Trigger holdoff testing - Solved

[atferrari]

Trying to grasp the concept of trigger holdoff, using my Owon DSO, I would like to generate some kind of signal allowing me to understand how it works.

What signal should I get from my 10 MHz Siglent function generator?

Do you use it in Auto, Normal or both?

Thanks for any help.

 

[gophert]

You use it if you want to look at a waveform is short in duration but long after the trigger that causes it. Which means, if you set the standard sweep width of your scope to include both the trigger signal (far left edge of screen) and the signal you wish to view (far right side of screen), the waveform your looking at is so slender that you cannot see the shape.
Now, if you know the trigger and signal are 2mSec apart, you can set the delay to 2 mSec and look at the wac
Waveform that is 500nSec wide.
Or in the case of your 10MHz scope, you might want to look at some waveform that is 1 mSec after a trigger but only 10 microseconds duration.

 

[Reloadron]

Maybe try to visualize trigger hold off in older analog thinking. We have a horizontal display 10 cm wide. Sweep time is set for 1 mSec/Div. We use internal triggering set for a vert channel. Two opposing voltage sawtooth waveforms are applied to our horizontal deflection plates. I start a sweep at some point on my incoming signal. which is a .5 KHz square wave (2 mSec) I trigger on a + Slope at some level. That trigger starts my sweep, my saw tooth waves have a 10 mSec rise time (1 mSec/div). The problem is I can't have my next incoming waveform initiate another trigger to begin a sweep until my sweep of 10 mSec is complete. So I Hold Off any additional triggers until my sweep is complete. If you look at an old analog scope schematic, like the old Tek 545 series you will see exactly how trigger hold off is done and it will make sense. You can't initiate another sweep trigger till the existing sweep is complete,

Ron

 

[atferrari]

Thanks to you both. Well noted.
Off for a coffee and to start the testing.

 

[dr pepper]

It makes your screen wider, imagine something is happening off the right of the screen, turning the delay moves the screen to the right, shoving what you'd normally see off to the left.

 

[atferrari]

It makes your screen wider, imagine something is happening off the right of the screen, turning the delay moves the screen to the right, shoving what you'd normally see off to the left.

Gracias Dr.

Explained as it was in this thread, the concept is easy to grasp. Yesterday I spent some time trying to generate a signal with my Siglent generator to see the holdoff in action but I couldn't.

Anyway, now I know it means "sense the trigger, wait [holdoff] seconds (or whatever) and display the signal.

What I consider awful is the holdoff control itself (Owon scope). You need the hell of knob turns to reach the desired value (from the default 100 ns until the sec range).

 

[kubeek]

It looks like you are talking about trigger delay, which is a different thing than holdoff. Holdoff sets how long it takes after the first trigger before it can trigger again. You would typically use it to trigger on start of a long train of pulses and not to retrigger in the middle, e.g. i2c communication.

 

[atferrari]

It looks like you are talking about trigger delay, which is a different thing than holdoff. Holdoff sets how long it takes after the first trigger before it can trigger again. You would typically use it to trigger on start of a long train of pulses and not to retrigger in the middle, e.g. i2c communication.

Agustín going back to square one. Revising the manual to see what it says ( delay, no, for sure).

 

[dr pepper]

I might have got it wrong.
however I'm a thinking that holdoff may mean different things on different 'scopes.

 

[atferrari]

To you all that replied, thanks and forgive me for wasting your time and patience:

After reading several definitions in the Web (some of them confusing if not contradictory) I've read my OWON scope's manual:

Holdoff: The holdoff time is the oscilloscope’s waiting period before starting a new trigger. The oscilloscope will not trigger until the holdoff time has expired.

Pretty clear.

Programmed my function generator to output a 45-pulses burst of 1 ms each with a repetition rate of 50 ms. I adjusted the holdoff time between 46 and 49 ms, getting a stable display on the screen.

I am done.