Author Topic: New Rigol DS1054Z oscilloscope  (Read 1404242 times)

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Offline ruggb

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Re: Vertical position
« Reply #4425 on: Yesterday at 08:04:07 am »
new (last month) 1054Z with all upgrades and SP4 firmware.
When viewing a PWM square wave -
single channel, AC coupled, triggered @ ~ 50%, Vert = 100mv/, waveform centered.
As the pulse width of the signal is changed, the position of the waveform on the screen changes.
50% - waveform is centered
60% - waveform moved down 50mv
70% - waveform moves down another 50mv
40% - waveform moves up 50mv
30% waveform moves up another 50mv

no settings changes on the scope, it is AC coupled, so why does it move?
 

Online ebastler

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Re: Vertical position
« Reply #4426 on: Yesterday at 08:10:14 am »
no settings changes on the scope, it is AC coupled, so why does it move?

It moves exactly because it is AC coupled. The average voltage of your signal changes as you vary the PWM duty cycle. And AC coupling puts this average voltage at the center of the scale.
 

Offline ruggb

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Re: Vertical position
« Reply #4427 on: Yesterday at 08:57:48 am »
no settings changes on the scope, it is AC coupled, so why does it move?

It moves exactly because it is AC coupled. The average voltage of your signal changes as you vary the PWM duty cycle. And AC coupling puts this average voltage at the center of the scale.

I am trying to teach this old dog new tricks. thank you for your enlightnement
 

Online David Hess

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Re: New Rigol DS1054Z oscilloscope
« Reply #4428 on: Yesterday at 09:38:49 am »
That is one of the reasons I like the peak-to-peak automatic triggering modes in old Tektronix oscilloscopes; the trigger point does not change as the duty cycle changes but it still tracks level changes.
 

Offline Fungus

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Re: rise time
« Reply #4429 on: Today at 03:38:59 am »
new (last month) 1054Z with all upgrades and SP4 firmware.
When viewing the cal signal - as I change the time base, the displayed rise time changes.
The signal does not change so why does the displayed rise time change?

Because all calculations on a DS1054Z are done using the "on screen" data. You get most accurate numbers when you zoom in.
 

Offline ruggb

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Re: rise time
« Reply #4430 on: Today at 06:44:20 am »
new (last month) 1054Z with all upgrades and SP4 firmware.
When viewing the cal signal - as I change the time base, the displayed rise time changes.
The signal does not change so why does the displayed rise time change?

Because all calculations on a DS1054Z are done using the "on screen" data. You get most accurate numbers when you zoom in.
Thanks, so for sample shown the 3.00┬Ás is the closest, except that is most affected by the sample rate so it varies a lot
If the sample rate is 1Gs/S, what variation should I expect? It seems like it varies more that the sample rate would indicate. What else affects it?


« Last Edit: Today at 07:10:23 am by ruggb »
 


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