EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Mechatrommer on January 31, 2016, 09:44:30 am
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can someone experience this? 10X probe connected to CAL signal (the 1KHz 3Vpp square wave that we use to compensate probe respond at far right bottom of the DSO). set trigger to lower than 600mV or 0.6V, and in my case BAM!, unlocked signal output goes all over the screen (as attached)
(https://www.eevblog.com/forum/testgear/rigol-ds1054z-unable-to-trigger-cal-signal-at-lt-0-6v/?action=dlattach;attach=198047;image)
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That's normal. You'll find that the trigger has some hysteresis, so you need to move it up a little if triggering on rising edge, or down a little on falling edge.
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Mine does the same.. At 620 mV or lower, the waveform is just garbage. At 640 mV or higher it triggers normally.
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Are your scopes unlocked to 100 MHz bw? I don't know if this makes any difference... but....
Mine triggers just fine down to 260 mV, which is 13 steps up from the baseline. Each step is 20 mV. It loses the trigger at 240 mV.
Of course it also depends on the Vertical Scale setting. At 500mV/div mine triggers stably down to 100 mV. Each step is now 10 mV.
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Mine is unlocked.
It seems, that the more zoomed in you are (Volts/div - don't know the correct term), the trigger gets better.
I managed to trigger at ~140 mV
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Mine triggers just fine down to 260 mV, which is 13 steps up from the baseline. Each step is 20 mV. It loses the trigger at 240 mV.
mine is "DSER upgraded". istr last time this bug occured but then later it dissappeared, triggering at low level was just fine, i dont know what i did to make this bug dissappear. this is not "everytime" bug, sometime it goes off.
That's normal. You'll find that the trigger has some hysteresis, so you need to move it up a little if triggering on rising edge, or down a little on falling edge.
no this is not normal.. 0.6V is too large of hysterisis, my older DS1054E didnt have this kind of hysterisis. just imagine what hysterisis left to us to move up and down for a 0.5Vpp signal to trigger correctly? none. non-trigger at selected level of transition means miss capture and is no good, Type I Error: very heavy punishment... the DSO is unable to fullfill its core business, show the signal at the right moment..
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It seems, that the more zoomed in you are (Volts/div - don't know the correct term), the trigger gets better.
The datasheet does say that.
Page 7 in the linked document.
"Trigger Sensitivity[1] 1.0div (below 5mV or noise rejection is enabled)
0.3div (above 5mV and noise rejection is disabled)"
Document taken from:
http://www.batronix.com/pdf/Rigol/Datasheet/MSO1000Z_DS1000Z_Datasheet_EN.pdf (http://www.batronix.com/pdf/Rigol/Datasheet/MSO1000Z_DS1000Z_Datasheet_EN.pdf)
So better try to reproduce their parameters and see if it holds to the specs - or not.
Beware of the footnote...
Cheers
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Do you have trigger noise rejection on?
My DS1074Z triggers at ~0.3div (~300mV in your case) and at ~0.6div (~600mV) with trigger noise rejection on.
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It could be due to the trigger levrel calibration being off/drifted.
A easy way to verify this is to show a trangle wave in near-full vertical scale. Now move the trigger level up and down and check whether the intersection point of the vertical "T" marker line and the horizontal "T" marker line are always on the waveform trace.
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ok i shutted down the ds1z fw minutes ago. turned back on, now it can trigger at ~0.3V correctly. pressing the trigger menu, NoiseReject turned out to be at OFF state (remember this is after reboot). when i turn ON NoiseReject, it goes back to the OP problem, trigger only at > 0.6V weird, maybe some unseen noise going on? i have computer turned ON next to it.. trigger gets better at NoiseReject OFF.. but earlier when posting the capture above, i havent touch NoiseReject menu, so its weird... maybe the earlier boot, the NoiseReject is at ON position by some luck... and now the second reboot, the NoiseReject is at OFF, also by some luck, i dont know what was going on...
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It could be due to the trigger levrel calibration being off/drifted.
do i have to self-cal frequently? man this new generation X scope calibration is a pita half an hour or so, not like older ds1e which takes only minutes..
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I remember seeing in the manual that if the ambient temperature changes by more than a couple of degrees you should recalibrate. Takes 17-18 minutes on my scope. Scope should be warmed up for half an hour if you are doing quantitative work anyhow.