Rigol 1054 triggering

[sndchaser]

Question with a problem (likely user error) I'm having with my Rigol 1054 that I didn't have with my Tektronix scopes.  I'm edge triggering, have the trigger level set, and on some signals I get the expected triggering (1st picture) and on others I get a blur (like the other pictures).  I'd appreciate it if someone could point out what I'm doing wrong.  Thanks

[sndchaser]

Persistence is on Min.  I put it on normal triggering and still get the blur.  With single triggering I see that my duty cycle is irregular, so I guess this triggering behavior for auto and normal is as intended? 

[tautech]

I put it on normal triggering and still get the blur.  With single triggering I see that my duty cycle is irregular, so I guess this triggering behavior for auto and normal is as intended?

This looks like a data stream and your rising edge triggering probably isn't helping for a negative going signal.
Also if it is a data stream it's not a repetitive waveform and therefore triggering will not be stable without additional trigger parameters being set.
The clue is a blurry waveform that it's not repetitive and confirmed with the Single shot.

[sndchaser]

Surprisingly, it's actually not a data stream, it's an apparently defective frequency divider IC (it should take the 500kHz signal from the stable shot and divide it down to each frequency in an octave of musical notes).  I've seen the blur on other analog signals with this scope, just curious what other triggering parameters I could be trying to get stable triggering?

[Fungus]

just curious what other triggering parameters I could be trying to get stable triggering?

Your trigger is stable. It's the signal that's wonky.



If you pick a random rising edge in that signal then the data on either side is unpredictable.

[sndchaser]

Yes, the chip is an MK50240 from the 1970's:

http://www.datasheetspdf.com/datasheet/MK50240.html

It really just divides a square wave into 13 slower square waves.   Way before I2S was even dreamed of.   The triggering wasn't working as I expected it to because the chip has failed. 

[David Hess]

Automatic triggering just means that after a period of time without a valid trigger, the acquisition or sweep is started anyway so at least something is displayed.  Normal triggering always waits for a valid trigger.  On a Tektronix you can check this condition via the trigger indicator; I don't know if Rigol includes this.

You should have gotten the same results with a Rigol or Tektronix oscilloscope.