The DS1000Z series only uses "digital grounding" , i.e, it disregards the output oft the ADC and displays the line at 0V. That's worth nothing regarding the noise problem. I would simply try out the scope in a different location with a mains supply from a different distribution point. If the noise is still there, return it for a replacement.
Good luck,
Thomas
The DS1000Z series only uses "digital grounding" , i.e, it disregards the output oft the ADC and displays the line at 0V. That's worth nothing regarding the noise problem. I would simply try out the scope in a different location with a mains supply from a different distribution point. If the noise is still there, return it for a replacement.
Good luck,
Thomas
Ah, I didn't know that. Where did you find this information about "digital grounding"?
Perhaps that helps to explain how the scope is able to calculate and display a large RMS voltage measurement value even though the channel input is "ground coupled" and the display is showing a flat line at 0V.
Somehow this "feature" of the DS1000z series leaves me rather cold.
Maybe the Engineer who designed this feature was a digital person & regarded the analog circuitry as a sort of "pipeline" feeding the signal to the ADC.
Or perhaps he was the "bunny" who had to come up with a "quick fix" after the analog guys forget to provide a proper
ground switch.
Ah, I didn't know that. Where did you find this information about "digital grounding"?
Perhaps that helps to explain how the scope is able to calculate and display a large RMS voltage measurement value even though the channel input is "ground coupled" and the display is showing a flat line at 0V.
Somehow this "feature" of the DS1000z series leaves me rather cold.
Somehow this "feature" of the DS1000z series leaves me rather cold.
Does that mean that the inputs of the Rigol scope can be made "floating" given that the analog guys forgot to provide a proper ground switch?
I hate tracing these things out, but I guess that's all part of the job/hobby.
When you said you tried it in "different locations" I thought you meant you tried it in two different buildings.
When you said you tried it in "different locations" I thought you meant you tried it in two different buildings.
Yup. Two buildings a mile apart. Just typical we had the same power bank in use at both locations.
Somehow this "feature" of the DS1000z series leaves me rather cold.
So cold that you couldn't help bringing it into the middle of a completely unrelated thread?
Uhuh.
Hi all,
Back again. I've found it.
The noise is external and getting in everything. I borrowed another scope last night and dragged it home to test. Both had the same noise.
On closer investigation the "I unplugged everything" was proven correct, however there was a USB powerbank device that was switched on and remained so even with power removed from everything else. I sniffed it out using a long power cable and walking the property with the scope.
It just happens that my friend also has that same power bank (Generic Ebay) and his was also broadcasting a noise both out the USB ports and the charging cable. The rapid switching appears to be the power bank just topping off the capacitors as when power is drawn from the device the noise became much more constant as the switcher was working harder.
So now we're down to a normal noise floor with some smaller switching noise still present.
I hate tracing these things out, but I guess that's all part of the job/hobby.
Thanks for all of your time/efforts testing at your end.
Robert
Maybe the Engineer who designed this feature was a digital person & regarded the analog circuitry as a sort of "pipeline" feeding the signal to the ADC.
Or perhaps he was the "bunny" who had to come up with a "quick fix" after the analog guys forget to provide a proper
ground switch.
Does that mean that the inputs of the Rigol scope can be made "floating" given that the analog guys forgot to provide a proper ground switch? Or did I misunderstand? What part is not properly grounded? The analog input of the ADC, or the digital output of the ADC?
The "earthing" switch referred to shorts the non-earthed side of the input to the earthed side.
This is commonly used to establish "zero volts" to set the zero line of the display to whatever graticule line is required.
The "earthing" switch referred to shorts the non-earthed side of the input to the earthed side.
This is commonly used to establish "zero volts" to set the zero line of the display to whatever graticule line is required.
Isn't this only relevant for analog oscilloscopes?
The "earthing" switch referred to shorts the non-earthed side of the input to the earthed side.
This is commonly used to establish "zero volts" to set the zero line of the display to whatever graticule line is required.
Isn't this only relevant for analog oscilloscopes?
Why would it be? I regularly move the trace to different parts of the graticule on my DSO.
The "earthing" switch referred to shorts the non-earthed side of the input to the earthed side.
This is commonly used to establish "zero volts" to set the zero line of the display to whatever graticule line is required.
Isn't this only relevant for analog oscilloscopes?
Why would it be? I regularly move the trace to different parts of the graticule on my DSO.
I do that too. But my DSO (as, I believe, the vast majority of digital scopes) has channel indicators on the side of the screen, which show where the 0V level is. So I agree with pascal_sweden that switching the input to GND mode to get your bearings is a bit redundant with DSOs. (While in analog scopes it was the only quick way to establish where 0V are.)
... my DSO (as, I believe, the vast majority of digital scopes) has channel indicators on the side of the screen, which show where the 0V level is. So I agree with pascal_sweden that switching the input to GND mode to get your bearings is a bit redundant with DSOs. (While in analog scopes it was the only quick way to establish where 0V are.)For those that don't want the display cluttered with on-screen measurements the need for grounding the input is necessary when setting the waveform zero level exactly to a graticule so that waveform amplitudes can be quickly observed.....a methodology for many that is a carry over from the days of no OSD on CRO's.
Not all use set methods of scope use and manufacturers know this.
Many owners of the DS1054z will have noticed that the displayed "zero volts baseline" rarely lines up exactly with the channel baseline indicators, and in some cases can be way off.
This is an uncorrectable DC offset and should be factored into any interpretation of Measurements that reference the channel baseline values. It also can move around, depending on whether you have run the self-cal routine at your present lab ambient temperature.
Many owners of the DS1054z will have noticed that the displayed "zero volts baseline" rarely lines up exactly with the channel baseline indicators, and in some cases can be way off.
This is an uncorrectable DC offset and should be factored into any interpretation of Measurements that reference the channel baseline values. It also can move around, depending on whether you have run the self-cal routine at your present lab ambient temperature.Not at all uncommon for DSO's but not the end of the world either.
Self Cal after an appropriate warm up time should get any zero offset down below a mV, then if this amount matters you are really using the wrong tool for the job.
Many owners of the DS1054z will have noticed that the displayed "zero volts baseline" rarely lines up exactly with the channel baseline indicators, and in some cases can be way off.
This is an uncorrectable DC offset and should be factored into any interpretation of Measurements that reference the channel baseline values. It also can move around, depending on whether you have run the self-cal routine at your present lab ambient temperature.Not at all uncommon for DSO's but not the end of the world either.
Self Cal after an appropriate warm up time should get any zero offset down below a mV, then if this amount matters you are really using the wrong tool for the job.
Thanks, tautech. And the offset values alesatonkin's scope is showing are indeed all around 0.25 mV (assuming that all channels were set for 10x probes, as indicated in the screenshot for channel 4). Nothing to worry about, I would say.
You must admit it is an elegant solution,if you don't anticipate the above "bugs".
Maybe the Engineer who designed this feature was a digital person & regarded the analog circuitry as a sort of "pipeline" feeding the signal to the ADC.
Or perhaps he was the "bunny" who had to come up with a "quick fix" after the analog guys forget to provide a proper ground switch.
Thanks, tautech. And the offset values alesatonkin's scope is showing are indeed all around 0.25 mV
Thanks, tautech. And the offset values alesatonkin's scope is showing are indeed all around 0.25 mV??
More like a couple of mV. He has his 'scope set to 20mV/div.
He has the scope configured for 10x probes. So that's 20mV/div at the (presumed) probe tip, but 2mV/div at the scope's BNC input. Hence, the offset at the actual scope input is well below a mV, right?
The "earthing" switch referred to shorts the non-earthed side of the input to the earthed side.
This is commonly used to establish "zero volts" to set the zero line of the display to whatever graticule line is required.
Isn't this only relevant for analog oscilloscopes?
On closer investigation the "I unplugged everything" was proven correct, however there was a USB powerbank device that was switched on and remained so even with power removed from everything else. I sniffed it out using a long power cable and walking the property with the scope.