Smoothing function - Fluke 87V Max - Keysight U1270 - U1280 Series

[Kiriakos GR]

Smoothing function this is one addition at DMM manufacturing industry since the year 2005, when Fluke 87V this shown in the market.

Long story in short, the documentation this coming from Fluke Corporation, this talking about use of Smoothing function at AC Voltage measurements.
And in the frequency range of 10Hz up to 1KHz.

There is a number of specific recommendations.
a) FLUKE recommends Smoothing function at all ACV measurements below 30 Hz.
b) With Low-Pass Filter engaged, FLUKE recommends Smoothing function for VFD systems within the frequency range 15 – 200 Hz

Generally speaking, Smoothing function this more an assistance to human eyes, when measurement reading this fluctuates allot.
HIOKI Corporation this implemented a similar technique, at their DT4282, due a front panel button, the user can activate a Slow display update rate.

Agilent/Keysight this when a bit further, and their Smoothing function, this has configurable settings.
 
All text above this is my summary and a mini chart, regarding Smoothing function and DMM models these supporting such a functionality.
At my next message, I plan to present more in depth details. 

[Andrew-88]

What is amazing, this is that in the past 15 years, owners of Agilent/Keysight DMM, they ask to find more about Smoothing function, and do not find answers.
When owners of FLUKE 87V DMM ( this be out for 20 Years), and no one shared any clues with the other group.

I have long time to write RTFM especially for the fanatics of the yellow team. 
About Agilent/Keysight, their scientific thought, turned the user manual in to a hard to solve puzzle.

And now Kiriakos decided to activate his spot light, so even this detail to become understood.
Why you were waiting that long?

[overvolt]

HIOKI Corporation this implemented a similar technique, at their DT4282, due a front panel button, the user can activate a Slow display update rate.

From HIOKI DT4282 Instruction Manual, SLOW function this is also shown with ACV screenshot.
And there is a second reference at DC (DCµA, DCmA, DCA).

(When the measured value fluctuates and cannot be read, it is possible to stabilize the value, due 5 times averaging.)

[Kiriakos GR]

And now Kiriakos decided to activate his spot light, so even this detail to become understood.
Why you were waiting that long?

1) I wanted all those wannabe DMM product reviewers (at YouTube) to stay in the dark.
2) I wanted Agilent/Keysight them to stop handing over, DMM samples at unworthy hands.

@overvolt were motivated to look at HIOKI work so to find more clues, and this is a wise thought. 


 

[Kiriakos GR]

I have to share interesting news, I am now in communication with Keysight EU technical support team. 
(Keysight Technical and Application Support (KTAS) team) (Keysight Technologies).

They are willing to research and find for us, all details about Smoothing function.
Because they did also acknowledge, that the currently offered documentation this is lacking clarity.

   

[Andrew-88]

This is really interesting, when ever Kiriakos show-up at Keysight Technologies castle, it doors always open up for him. 

[Kiriakos GR]

This is really interesting, when ever Kiriakos show-up at Keysight Technologies castle, it doors always open up for him. 

Thank you for the compliment
But in this case, I did hand over at their engineers, a pile of facts that its hard for them to ignore. 
 
Today I did some testing with my U1272A, and the Smoothing function.
I did use my stabilized AC power source, and I use Smoothing so to check of how it behaves.
At 299,80 ACV,  I wanted to see better stability at the last two digits.
The DMM It was had a rapid fluctuation at xxx.45 ~ xxx.85 

Even by the settings of 0002E, 0003E and or 0004E, it did appeared, Smoothing this to have some positive influence.
But with settings of 0010E or higher, display settling time issues appear. 
The higher Smoothing settings in use, cause a slower settling time, from zero volts to 230V.

I hope Keysight this to be able to better explain, their own text this relative to the functionality and or correlation, of Smoothing settings and of Auto-Hold settings.
Do we need to adjust both for having optimal results at Smoothing?

[Kiriakos GR]

While I did exchange eight messages with Keysight and  Mr. Dumitrescu Application Engineer, within a month time, only a small amount of clarifications was the benefit.

Here are the results in a form of a FAQ:

a)  Is this 0001 to 0009 at Smoothing, another one input point for tweaking the variation count setting?
The smoothing does not change the variation count. It only changes the refresh rate for averaging.
 
b)  Is this 0500 setting at AutoHold feature, just another one input point for tweaking the variation count setting?
Yes, the AutoHold feature set the variation count.
U1271A/U1272A Handheld Digital Multimeter User’s Guide (English, French, Italian and Spanish) P.133 Changing the variation count
 
c)  Is Smoothing designed so to assist at AC or DC measurements, or in all measuring functions of the DMM?
The smooth mode applicable for all function not just ACV/DCV.

In summary, I am now convinced that the actual behavior of Smoothing, in hardware level, this does not come close to customer expectations.
Its not completely a gimmick, but neither this is a life saver.
Keysight might thought that this gentle form of Smoothing this might shown as useful.
Refresh rate for averaging this is a function available also at digital oscilloscopes, but neither in them it helps much, as plain mathematical function.

Personally I will stick to Min,Max,Average function when there is high fluctuation at the measured DUT.

[Kiriakos GR]

Today May 10 2025,  due my active communication with Mr. Dumitrescu Application Engineer, we both came in to a dead end. 

We both verified due lab testing, that the information supplied due Keysight R&D engineers back to us,  this is just a theory of operation.
While the DMM, the hardware, this is not responding according to this theory of operation.

Long story in sort, Keysight U127xA User manual documentation, this implying that Smoothing function ... this might be assisted by the Ahold Setting.
In Theory:
Smooth setting  0007 along with Ahold Setting 0500 = Two adjustments and or, two points of control, these as combined...  will help the DMM display,  at the delivery of a more stable reading.
..............................................................................................
At ITTSB lab, I did run tests with U1272A.
Mr. Dumitrescu he run tests with U1271A.

We both came down in to identical conclusion.
a) Smooth settings range 0007 up to 0050 , these offer a minor improvement.
b) Ahold Settings range, no matter the input value, these are ignored by the hardware. 

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In conclusion, something when very wrong withing Agilent / Keysight, back in time that U127xA series this was still under design / development.
Human error of other?  Smooth this does not work as expected at the specific DMM series.

Final word of Keysight R&D, Consider AVG Feature: If the environment has significant noise, the AVG feature could help stabilize the readings more effectively.

AVG Feature = Min/Max DMM Function.