Rigol DHO804 Test and Compare Thread

[ballsystemlord]

That's not an AC sine wave, but thanks! That was informative.

[ballsystemlord]

I am just warming up the siglent sdm3065X, the rigol scope and the dmm ref.plus source...

Just for the sake of my own sanity, the SDM3065X, was it NIST calibrated like I had asked or not?

[tautech]

I am just warming up the siglent sdm3065X, the rigol scope and the dmm ref.plus source...

Just for the sake of my own sanity, the SDM3065X, was it NIST calibrated like I had asked or not?

Official statement:
https://siglentna.com/service-and-support/calibration-certificate/

[Mechatrommer]

i see tea'ism comes to the party now, after siglenism... find Dave's video in the early age... DSO is not for Vdc accuracy... why this has to happen so many times? why?

[asmi]

Official statement:
https://siglentna.com/service-and-support/calibration-certificate/

"We swear on the Bible that our calibration is good! (since we're not Christians we can say whatever we want )"
"Oh, actually, it's soooo goood that it's not only good on delivery, but also for up to 180 days".
"Hmm, nevermind 180 days - 18 months sounds even better! (it's still mostly BS but now we can sell even super-old crap for pennies that nobody wants to buy, so it collects the dust in the warehouse)."
    

[tautech]

Official statement:
https://siglentna.com/service-and-support/calibration-certificate/

"We swear on the Bible that our calibration is good! (since we're not Christians we can say whatever we want )"
"Oh, actually, it's soooo goood that it's not only good on delivery, but also for up to 180 days".
"Hmm, nevermind 180 days - 18 months sounds even better! (it's still mostly BS but now we can sell even super-old crap for pennies that nobody wants to buy, so it collects the dust in the warehouse)."

Such are the realities of worldwide distribution chains or is that too complex to get your head around. 

[asmi]

Such are the realities of worldwide distribution chains or is that too complex to get your head around. 

Wouldn't it be easier to perform calibration before sending out units to the end users? Most places which care about calibration will not accept any manufacturer's calibration anyway because who knows what happens to the unit during transport, storage, handling, etc, and will want to do a proper calibration anyway - and at some place which is independent of manufacturer. And for the rest of the buying public it doesn't matter anyway, so manufacturer can write whatever.
At the end of the day cars to undergo a pre-delivery inspections, and some of the scopes cost in the same ballpark as cars - so why not?

[tautech]

Such are the realities of worldwide distribution chains or is that too complex to get your head around. 

Wouldn't it be easier to perform calibration before sending out units to the end users?

No.
To do so would mean every reseller worldwide would require a Cal lab.

Most places which care about calibration will not accept any manufacturer's calibration anyway because who knows what happens to the unit during transport, storage, handling, etc, and will want to do a proper calibration anyway - and at some place which is independent of manufacturer. And for the rest of the buying public it doesn't matter anyway, so manufacturer can write whatever.

Dunno what other brands do but every Siglent unit Cal sheet specifies the factory calibration equipment used, the model and SN# and its Cal expiry date.
Is that not enough to convey accurate calibration that meets datasheet spec ?

At the end of the day cars to undergo a pre-delivery inspections, and some of the scope cost in the same ballpark as cars - so why not?

Every end seller is different and may not do PD checks, but we do.

[asmi]

To do so would mean every reseller worldwide would require a Cal lab.

Or have a contract with one.

Dunno what other brands do but every Siglent unit Cal sheet specifies the factory calibration equipment used, the model and SN# and its Cal expiry date.
Is that not enough to convey accurate calibration that meets datasheet spec ?

It doesn't guarantee that nothing happens to it between factory cal and actual delivery to the end user. And you should know better than most how shipping goes sometimes.

Every end seller is different and may not do PD checks, but we do.

If I would be the manufacturer I would require resellers to do it. Because I do care that my customers get what I advertise. Here in Canada we have an official Rigol rep which does all of this, but to my knowledge there is no Siglent rep in the country at all. Which is kind of annoying, and part of the reason why I opted for a Rigol scope many-many years ago (I think it was in 2016 or something like that) when I bought my MSO2022A, which still works to this day btw!

[tautech]

To do so would mean every reseller worldwide would require a Cal lab.

Or have a contract with one.

To add additional cost and delay to equipment supply ?

Dunno what other brands do but every Siglent unit Cal sheet specifies the factory calibration equipment used, the model and SN# and its Cal expiry date.
Is that not enough to convey accurate calibration that meets datasheet spec ?

It doesn't guarantee that nothing happens to it between factory cal and actual delivery to the end user. And you should know better than most how shipping goes sometimes.

Don't have such issue here, however I trust border Customs far less.
OTOH I have a 26.5 GHz VNA to deliver 1500km away which I will be doing in person where in some effort to minimise risk, airline baggage handlers are the only unknown.

Every end seller is different and may not do PD checks, but we do.

If I would be the manufacturer I would require resellers to do it.

Of any/all brands ?
Fail to see advantage of such when gear has been tested to remain within spec for a considerable period post manufacture.

Because I do care that my customers get what I advertise.

So do we however we have no reason to distrust Siglent Cal anymore than a Cal from any other TE producer.

Here in Canada we have an official Rigol rep which does all of this, but to my knowledge there is no Siglent rep in the country at all.

You need update your knowledge.

From the US 'Partners' map:
Canada
ACA TMetrix
800-665-7301
 www.tmetrix.com
 info@tmetrix.com

RCC Electronics
800-668-6053
 www.rcce.com
 sales@rcce.com

Techno-Test
 450-681-5777
 www.Techno-Test.com
 info@techno-test.com

[asmi]

To add additional cost and delay to equipment supply ?

That depends on your organization of this process. You can forecast a demand and have some units pre-caled within a week let's say.

Don't have such issue here, however I trust border Customs far less.

I've seen it all - from light damage all the way to near full destruction.

OTOH I have a 26.5 GHz VNA to deliver 1500km away which I will be doing in person where in some effort to minimise risk, airline baggage handlers are the only unknown.

Unfortunately they are known. And not in a good way.

Of any/all brands ?

Of my brand. Why would I care what they do to other products?

Fail to see advantage of such when gear has been tested to remain within spec for a considerable period post manufacture.

I know how testing works all to well too believe that. Statistics don't work when we talk about one specific unit.

So do we however we have no reason to distrust Siglent Cal anymore than a Cal from any other TE producer.

Those who care don't accept any mfg's cal for the same reason.

You need update your knowledge.

From the US 'Partners' map:
Canada
ACA TMetrix
800-665-7301
 www.tmetrix.com
 info@tmetrix.com

RCC Electronics
800-668-6053
 www.rcce.com
 sales@rcce.com

Techno-Test
 450-681-5777
 www.Techno-Test.com
 info@techno-test.com

This is what representative looks like: https://www.rigolcanada.com/
Note branding, localized prices, support (which has been superb even with my relatively cheap unit BTW! they loaned me much more expensive unit for free until the unit I ordered arrived from mfg), lack of stuff from other brands, etc.
What you linked are resellers, not representatives.

[tautech]

What you linked are resellers, not representatives.

Then Siglent NA in Ohio are your reps.

[asmi]

Then Siglent NA in Ohio are your reps.

Now you see the problem. Apparently Siglent is not interested in our market enough, unlike Rigol.

[Martin72]

Just for the sake of my own sanity, the SDM3065X, was it NIST calibrated like I had asked or not?

It is calibrated(June 2023), I was a little disappointed with the one sheet of paper that came with the meter and explained that the meter had been calibrated and everything was fine - anyone can write that.
But since the serial number of my meter was listed, it occurred to me that Siglent might have a database with the calibration values of each device.
And I was right...
I got this data and so it is clear that the explanation on this one sheet of paper can actually be trusted.
Calibration intervals are usually 12 months (e.g. ISO), for higher calibration methods (e.g. DAkks) the intervals can be extended to e.g. 24 months.
As mentioned, the calibration of my meter was about 4 months ago, so I'm still "full" in it.
What actually does not matter with the tolerance of an oscilloscope, so "bad" the meter can not become, unless it is defective.
Nevertheless, it must be said that the Rigol has made a very good figure, in the comparison measurement.

[nctnico]

i see tea'ism comes to the party now, after siglenism... find Dave's video in the early age... DSO is not for Vdc accuracy... why this has to happen so many times? why?

Agreed. A DMM is the wrong tool to measure oscilloscope accuracy anyway. For that you need a calibrated signal (AC) source which can also output tens to several hundred Volts.

[tautech]

Then Siglent NA in Ohio are your reps.

Now you see the problem. Apparently Siglent is not interested in our market enough, unlike Rigol.

Have you worked with your Canada ppl ?
Is their support substandard or something ?

[Martin72]

Agreed. A DMM is the wrong tool to measure oscilloscope accuracy anyway. For that you need a calibrated signal (AC) source which can also output tens to several hundred Volts.

I cannot imagine that it just happened to fit so well in this case(it was a comparison of the measured values, not more).
The levels of the sine signals from the fluke calibrators often used in calibration laboratories go just above 5V(squarewaves up to 200Vpp).
Depending on the frequency, you can also use an ac signal that has not been calibrated, as long as the measuring device used to determine the level is much more accurate than the specifications of the scope.

[Fungus]

It seems pointless to measure "AC accuracy" on a 'scope. If the DC accuracy is good then "AC accuracy" is down to the user settings.

On a DMM it makes sense because they have TRMS converter chips inside them and they don't work the same way oscilloscopes do.

[2N3055]

It seems pointless to measure "AC accuracy" on a 'scope. If the DC accuracy is good then "AC accuracy" is down to the user settings.

On a DMM it makes sense because they have TRMS converter chips inside them and they don't work the same way oscilloscopes do.

What you say might hold in some very low frequency range close to DC.

You do realize scope has a BW of DC-100 MHz. Or DC-1GHz. Or DC-100GHz... ?

It's frequency response will be complex curve..

BW is specified at -3dB point.  So scope with 100MHz -3dB response, will at 100MHz have amplitude error of 29 %
And in between DC and -3dB point it will be some falloff.

So yeah, scope needs to be checked for AC accuracy.

[Martin72]

The DMMref plus reference has two calibrated ac signals, 100hz and 10khz.
"Low enough" to be measured accurately with any good multimeter and therefore I think you can still compare, but of course this says nothing about the scope accuracy as a whole.
A nice comparison, nothing more.

[KedasProbe]

Some IR view compare DHO914S (top) vs Hameg HMO1022 (bottom)
The hot part behind it is the USB power adapter

Looks like it's even heating up the Hameg next to it.

zip file is the same 3 pictures but original .bmp with extra info in it from UTi260B

[ebastler]

Heating up the Hameg next to it from the inside? That seems counter-intuitive, to say the least... Is the Hameg powered off?

[KedasProbe]

They are both on for a while, in the front image you see the left side of the Hameg to be warmer receiving heat from the rigol. (but would need to test it with rigol off to be sure.)

edit: The hameg has an USB stick in the front, the rigol USB mouse.

[ballsystemlord]

i see tea'ism comes to the party now, after siglenism... find Dave's video in the early age... DSO is not for Vdc accuracy... why this has to happen so many times? why?

The selling point of 12bit DSOs is that they're more accurate than 8 bit DSOs. IIRC, Rigol marketing said 60%. So, it seemed to me that testing the accuracy would be interesting. I sought to determine if the DSO was truly accurate or just had improved dynamic range.

[mawyatt]

i see tea'ism comes to the party now, after siglenism... find Dave's video in the early age... DSO is not for Vdc accuracy... why this has to happen so many times? why?

The selling point of 12bit DSOs is that they're more accurate than 8 bit DSOs. IIRC, Rigol marketing said 60%. So, it seemed to me that testing the accuracy would be interesting. I sought to determine if the DSO was truly accurate or just had improved dynamic range.

Gave a quick look at our clients 824 (we haven't delivered yet, as client is tied up) using our in-house derived squarewave generator (precision duty-cycle and amplitude squarewave derived from precision 5 volt reference).

https://www.eevblog.com/forum/testgear/ac-rms-dmm-tests/msg3940957/#msg3940957

Results were very good wrt using a precision squarewave from above at 250Hz. Reference source confirmed with our latest KS34465A (we have 3) and our DMM6500. We periodically use this reference source to quickly check each DMM (also SDM3065X, HP34401A, AG34401A) to make sure that one isn't issuing rouge rogue readings.

DHO824 measured with 1000 averages.

Vavg = 2.5001VDC
Vrms = 2.5092Vrms

BTW why is this important for us? We often employ a DSO to view & measure complex waveforms and often these waveforms are beyond the frequency range where one would expect the DMMs to render a decent measurement, so we employ the built-in DSO measurements. This all boils down to KTI (Know Thy Instruments) and where and how to apply such. For our work having measurements, statistics and such that "One Can Rely On" is a great asset these modern DSOs possess, same goes for the FFT and Bode Functions

Stated before these are complex data acquisition systems, disguised as scopes, that can do so much more within the hands of experienced users 

Side Note: When we acquired our 1st DSO here at the Labs a few years back, it was a Siglent. One of the first things we did was evaluate the measurement capabilities, and how they behaved. Needless to say we were impressed then as we are now with the Rigol DHO824 measurement capabilities, altho the FFT needs some polish, however our client isn't interested in the FFT (nor Bode Function) so for us a moot point in that respect.

Best,