New Rigol DS1054Z oscilloscope

[Meka77 wd]

This thread has really been sidetracked, there's been hardly any discussion of how great it is that all the major bugs seem to be fixed now.

Koombiah. But then again if it is an easy fix to eck out even better results - why not?

Sure, but three days ago the RMS thing even wasn't on the radar. The only things being discussed were the math offset and the measurements freezing.

It's amazing how fast things can change. 

3.FFT works nicer than before

In what way?

I sent it to Rigol a few days ago. I actually got a response - but before you get hopes high - a response that says where did I get the scope from? So since I got it from Tequipment I assume I'll get a follow up from Rigol NA sometimes in the near or mid or distant future.

Hi everone...

@Fungus

FFT is become sluggish  with 4.3SP2, in 4.4 more responsive and seems correct regarding RMS level (I didn't do detailed analysis yet)

@Assafl

Actually i'm contacted to Rigol Turkey in March about this RMS and other 4.3SP2 related issues. And i got responses too...

meka: houston we have a problem!

rigol: are you hacked your scope?, becasue if you did it, it's gonna out of warranty and scopes do this kind of problems when hacked. (trying to ditch warranty )

meka: no, i'm not! (beacasue it's true, it came already updated from former user... in the background *UninstAll  )

rigol: ok. please send your serial number and your problem description

meka: mailed full sysinfo and detailed explanation of all issues i know of in 4.3SP2, and told him if possible i wish return to former firmware asap (March 8 )

rigol: i'm sending your information to rigol germany (becasue we're closer to europe?  )

rigol: hi meka, rigol germany told this to me:  "Could you explain the problem with RMS measurement and FFT more in detail? Regarding the voltage level. Has he done a self-cal?" can you help me with more data? (March 15)

meka: i'm called rigol turkey directly and told him i have other scopes which don't have any problems like this. Again told him if possible i wish return to former firmware asap!

rigol: ok i'm gonna explain them your experince on this matter, but unfortunately there is no chance going back former firmware builds. Btw. they know about other issues and working on it (freeze bug, math bug etc.)

meka: ok. i'll wait then. And called about month later is there any update yet.

rigol: they cannot reproduce your issue in their devices (regarding what?  )

meka: i'm very annoyed about this and uploaded a youtube video regarding RMS and FFT issue (April 16)

rigol: ok. i'm sending them your video link and information again.

meka: thanks again.

Btw. i'm called rigol turkey couple of times (most of my calls dropped or blocked), ask to is there any update yet and he said expected in beginning on June. And seems rigol China unable to see youtube videos, because website is blocked in China (how professional). I uploaded my video to another website which isn't blocked by Chinese gov. and send to him  my new link.

In first two weeks in June he directly blocked my calls (Some times he send me stupid automated sms ie. i'm out now, please call again later. Within 1 seconds later after my call dropped  )

Then i hided my number  and called him again, he immediately answered (gotcha  )... (July)
I cornered him down and unfortunately he said; "we are just selling their stuff like apple and orange, there is nothing i can do about it except wait for them to act    ." Then i asked him; can you please check your one of devices regarding this issue, if it's ok i'm willing to pay extra for exchange?. He said; Sorry, i can't do that.

This is my adventure with rigol so far.

Thanks for your patience and sorry about long post. 


Edit: Some date correction.

[canibalimao]

So, just to simplify: the last update is really worth, right?

There doesn't seem to be any downsides to updating.

But ... the old curmudgeon in me would like to say, "If it ain't broke, don't fix it".

Don't upgrade just to see the version number change on screen. There's always a non-zero chance that a failed firmware update will brick a device (any device!)

If the bugs aren't affecting you and you don't need the new XY mode then wait for the next one. You can always apply this update if one day you need to use the math functions (or whatever).

I wasn't able to reproduce the freeze bug yet, so I'm not affraid of that. I'll just upgrade to this new version to have a nicer XY mode. I just want to know in which firmware version the RMS problem started, or if it is an issue since the beggining.

[Fungus]

I wasn't able to reproduce the freeze bug yet, so I'm not affraid of that.

Only 40% of people could reproduce it in the poll that was done here.

I'll just upgrade to this new version to have a nicer XY mode. I just want to know in which firmware version the RMS problem started, or if it is an issue since the beggining.

Probably since the beginning.

If you're on an older firmware you can easily check yours before upgrading. That way you'll know if upgrading will make it worse. All you need is two probes and the test signal on the front of the 'scope.

[canibalimao]

I wasn't able to reproduce the freeze bug yet, so I'm not affraid of that.

Only 40% of people could reproduce it in the poll that was done here.

I'll just upgrade to this new version to have a nicer XY mode. I just want to know in which firmware version the RMS problem started, or if it is an issue since the beggining.

Probably since the beginning.

If you're on an older firmware you can easily check yours before upgrading. That way you'll know if upgrading will make it worse. All you need is two probes and the test signal on the front of the 'scope.

Thanks. I'll check that and if the RMS issue appear in my firmware version I'll upgrade it anyway. I haven't noticed it before, but I think I just got lucky by measuring only with one channel in use.

[David Hess]

Thanks. I'll check that and if the RMS issue appear in my firmware version I'll upgrade it anyway. I haven't noticed it before, but I think I just got lucky by measuring only with one channel in use.

Meka77's post contrasting the RMS voltmeter and oscilloscope measurements makes me question the accuracy even when using one channel.

[canibalimao]

Thanks. I'll check that and if the RMS issue appear in my firmware version I'll upgrade it anyway. I haven't noticed it before, but I think I just got lucky by measuring only with one channel in use.

Meka77's post contrasting the RMS voltmeter and oscilloscope measurements makes me question the accuracy even when using one channel.

I've allways been warned that you should never fully trust a scope voltage measure. They are good for "measure" voltage over time, not very accurate measuring just voltage, and those errors with just one channel doesn't seem so off to me, or am I seeing it wrong?

[Fungus]

Meka77's post contrasting the RMS voltmeter and oscilloscope measurements makes me question the accuracy even when using one channel.

I'm sure it doesn't help that the waveform is clipped at the bottom even though we've said about a million times that the Rigol works with on-screen data.



Even if it wasn't: It's a 8-bit DAC with a very sensitive, very high impedance input and a slight DC offset error. It can only ever be about 5% accurate.


The reading looks entirely reasonable to me when the wave isn't clipped.

[David Hess]

I've allways been warned that you should never fully trust a scope voltage measure. They are good for "measure" voltage over time, not very accurate measuring just voltage, and those errors with just one channel doesn't seem so off to me, or am I seeing it wrong?

Those measurements should be accurate to within the oscilloscope specifications but they are not even that.  They are also not wrong in a consistent way which points to an algorithm or design problem instead of a calibration problem.  The stuff with phantom measurements on other channels is just broken.

There have been other discussions about measurement problems with these Rigol oscilloscopes where measurements change depending on trace positioning and scaling.  I suspect that is a problem of design where measurements are made on the display record instead of the acquisition record.

As far as the expected accuracy of a DSO, my old DSOs are all well within their specifications after warming up and automatic calibration.  So are my analog oscilloscopes which have measurement capability.

[Meka77 wd]

I'm sure it doesn't help that the waveform is clipped at the bottom even though we've said about a million times that the Rigol works with on-screen data.

Even if it wasn't: It's a 8-bit DAC with a very sensitive, very high impedance input and a slight DC offset error. It can only ever be about 5% accurate.


The reading looks entirely reasonable to me when the wave isn't clipped.

@Fungus

I'm sorry but you are looking this completely wrong way...

UT181A multimer and scopes Ch2 is connected at amplifier OUTPUT TERMINAL, only Ch1 connected paralel to amplifier INPUT TERMINAL!!!

In the first picture amplifier volume pot at MINIMUM, so multimeter shows about 50mv RMS noise and 1054z Ch2 (blue) showing 10.3V RMS!!! (Suppose to show "Ch2's own RMS noise" x "probe attenuation setting" x "vertical div setting" + "amplifier's outpu noise" = 500mv approx!!!)

In the second picture amplifier volume pot at MAXIMUM, multimeter and scope are showing closer value, BEACUSE Ch1 IS GROUND COUPLED!!! (That means RMS phantom error voltage does not affect Ch2 anymore) 

Btw. signals never clipped any way, but 1054z's large font setting is chopping visible area of sinewave. ( Doesn't  accuracy depend on ADC full scale, i.e fit your signal 95 percent vertically for best accuracy level measurement in rigol's spec iirc 3 percent?)

Regards

Edit: Added clarity...
 

[metrologist]

I've allways been warned that you should never fully trust a scope voltage measure. They are good for "measure" voltage over time, not very accurate measuring just voltage, and those errors with just one channel doesn't seem so off to me, or am I seeing it wrong?

Those measurements should be accurate to within the oscilloscope specifications but they are not even that.  They are also not wrong in a consistent way which points to an algorithm or design problem instead of a calibration problem.  The stuff with phantom measurements on other channels is just broken.

There have been other discussions about measurement problems with these Rigol oscilloscopes where measurements change depending on trace positioning and scaling.  I suspect that is a problem of design where measurements are made on the display record instead of the acquisition record.

As far as the expected accuracy of a DSO, my old DSOs are all well within their specifications after warming up and automatic calibration.  So are my analog oscilloscopes which have measurement capability.

The first image that Fungus quoted is not technically clipped, the labels just overlay the trace. If you change the font size, I really hope that does not affect screen measurement data.

Out of spec? How do we calculate RMS of a DC offset sine wave? It's hard to tell because of the label overlay, but it looks like the sine wave is DC offset around 0 volts with a peak voltage of 3.6 divisions (0.720Vp). According to spec, the actual Vp could be  0.698mV to 0.742mV. Oops, it should be ±3% of full scale (±60mV), or 0.640mV to 0.780mV.

This is my understanding, I would translate the Vp range above into the below formula to see if we are out of spec. We do not know what the actual voltage is, however, so we can only verify the calculation:

RMS = SQRT(DC^2+Vp^2/2)

RMS = SQRT(0^2 + 0.720^2/2)

RMS = 0.509 mV

Is my understanding wrong? It does not seem all that bad considering I am interpreting a peak voltage from a fuzzy trace on an actual picture of an instrument display from the other side of the planet.

I forgot what the DMM is connected to, but it is set to measure AC and shows 54mV and the scope is in DC mode; just as an observation...

What about the second image? Out of spec too?

[metrologist]

In the second picture amplifier volume pot at MAXIMUM, multimeter and scope are showing closer value, BEACUSE Ch1 IS GROUND COUPLED!!! (That means RMS phantom error voltage does not affect Ch2 anymore) 
 

Why would you be unhappy with this result? Aside from reiterating the same bug over again, which we understand, the scope seems to make the measurement fairly well.

[Meka77 wd]

With all respect i'll give up!

If you don't understand what i'm saying or showing, it must be me myself have a problem.
And i'm very sorry to share this confusing issue with you.

Whatever. Anyone curious about that problem click on my profile and read about it from my older posts.

I'm tired, and again i'm sorry.

Have a nice life.

[metrologist]

With all respect i'll give up!

If you don't understand what i'm saying or showing, it must be me myself have a problem.
And i'm very sorry to share this confusing issue with you.

Whatever. Anyone curious about that problem click on my profile and read about it from my older posts.

I'm tired, and again i'm sorry.

Have a nice life.

Meka, I don't think anyone is saying they do not see the problem. I am merely trying to point out a better way to set up for a measurement because of some of the wild claims. You pointed out several ways to work around the issue. The end result is that you can get an accurate measurement result. There are certain caveats and pitfalls that should not exist, but they do. It will be great when Rigol fixes it, and even when they do, my points will still be valid, and are valid for any scope.

I feel it is important to understand these things, and also address blanket statements that a result is out of spec. when in fact it is not. Other than the fact that you want to use channel 1 and 2, the fact that you have to ground ch1 to get an accurate result is merely an unfortunate caveat, the  bug. The measurement from the DSO in this condition, however, is not  IMO.

If you needed to use three channels with the simultaneous measurement, well then, there is no work around 

[Assafl]

With all respect i'll give up!

If you don't understand what i'm saying or showing, it must be me myself have a problem.
And i'm very sorry to share this confusing issue with you.

Whatever. Anyone curious about that problem click on my profile and read about it from my older posts.

I'm tired, and again i'm sorry.

Have a nice life.

Meka77 - I sent your bug to Rigol as well so I understand the problem.

But why is it so important to you? You know to measure CH1 & CH3. You know to be careful. What do you care what others think?

[Fungus]

It's a 8-bit DAC with a very sensitive, very high impedance input and a slight DC offset error. It can only ever be about 5% accurate.

The reading looks entirely reasonable to me when the wave isn't clipped.

@Fungus

I'm sorry but you are looking this completely wrong way...

Fair enough, but the point about 8-bit DAC, etc. still stands.

If you only turn on a single channel or if you only measure on channels 1 and 3 then are the RMS readings reasonable?

If you own a decent true RMS multimeter then make the RMS measurements with that.

Use the scope to look for distortions, clipping, etc., in the output.

[bitseeker]

So, just to simplify: the last update is really worth, right?

There doesn't seem to be any downsides to updating.

It does seem like the new version is a good one from what I've seen thus far in several threads. The current RMS discussion seems to also occur on the SP1 version I'm using, so no change there. I may upgrade after I get some other projects out of the way.

[2N3055]

It's a 8-bit DAC with a very sensitive, very high impedance input and a slight DC offset error. It can only ever be about 5% accurate.

The reading looks entirely reasonable to me when the wave isn't clipped.

@Fungus

I'm sorry but you are looking this completely wrong way...

Fair enough, but the point about 8-bit DAC, etc. still stands.

If you only turn on a single channel or if you only measure on channels 1 and 3 then are the RMS readings reasonable?

If you own a decent true RMS multimeter then make the RMS measurements with that.

Use the scope to look for distortions, clipping, etc., in the output (ie. what it's meant to be used for).

You are repeating yourself... It is tiresome and you are not right.....

First let's see specs from manual:

DC Gain Accuracy: <10 mV: ±4% full scale >10 mV: ±3% full scale
DC Offset Accuracy: ±0.1 div±2 mV±1% offset value
Channel to Channel Isolation: DC to maximum bandwidth: >40 dB

This means following: no 5% is not right , it has to be less than ±4% full of scale on sensitivities of less than 10mV/DIV, and better than  ±3% of full scale on more than 10mV/DIV...

And 8 bit ADC converter can be 0.00001% accurate... It will have a resolution of 256 discrete steps form 0 to max value. But every single step can in theory be 1 ppm accurate.. It would have to have fantastic linearity but yeah it can be that accurate... Kelvin Varley divider with 3 decades will have a resolution of one thousand but can be sub PPM accurate on each of it's steps...

And I checked , each channel individually does fairly good RMS... 2.09 RMS applied to input (that is amplitude of scope cal on my Rigol, measured by separate 6.5 digit true rms voltmeter) shows 2.09 to 2.06 on all channels, each by itself... So accuracy of RMS measurement in not a problem and quite within scope specs...
Offset is also quite better that guaranteed specs..


Problem is in the third spec: channel separation.... Channel separation should be on order of 10000x, meaning that 10000 mV (10V) connected to one channel, should not induce (yes induce, trough parasitic capacitors and inductances inside scope) more than 1mV of phantom signal in other channels, and that's from DC to 100MHz...

And looking at the traces it seems that scope does that better then specs too, electrically at least.....

Except in RMS measurements.
In which, channel separation between consecutive channel seems to be cca 7.7dB (cca 2.43 times voltage difference) because of stupid software bug...

You connect 2.09 VRMS on  CH1 and on CH2 with nothing connected you measure 854mV. That is 0,854 of a division, 10.6% of  error induced by software bug..

So there you are.. No , it's not within scope specs.

And my scope does it from CH1 to CH2, from CH2 to CH3, and CH3 to CH4.  CH4 does not interfere with other channels.

So if you need to measure RMS, you can do it with only 2 channels simultaneously, CH1 and CH3,  CH1 and CH4 or CH2 and CH4.. All other combos will have errors..

And if you work with switching PSU design and repair, RMS on a scope is used a lot... especially on several MHz and up, and waveforms with high crest ratios and complicated shapes , where no multi-meters will have enough bandwidth.. On those scope with good RMS implementation and 3-5 % percent error is much better than 30% errors you will get with multi-meter..
And I don't have one of those fancy thermal RMS converter based types with 100MHz bandwith that could do the job..

So none of your reasons to downplay this have merit.. I know you just want to make sure all is right and precise and relevant and such..
Thank you for a nice discussion that I hope now resulted in good explanation of what is wrong and why this is important and need to be fixed.. Much more than that HUUGe "pulses/pluses" bug 

Attached are photos of screen and RMS measurements, voltage applied to each channel separately.. note the spillover to following channel.. All channels were set equally...

[alsetalokin4017]

@2n3055:
Thank you for your thoughtful and correct discussion of this RMS issue. It's nice to see someone who understands the difference between "precision" and "accuracy" and who is willing to discuss the shortcomings of the scope rather than turning a blind eye to them.

But there is one thing: You can make nice screenshots of your scope very easily, simply and clearly by using several different methods. The resulting screenshot (if you select the PNG default format) is less than 1/5 the filesize of the photos you posted and displays at a reasonable and easy to read 800 pixels wide. Just put a USB thumbdrive into the front panel jack and press the green "print" button underneath the Help button.

Of course it may take a while for the image to be saved to the USB drive.... but the result is generally much better than taking a photograph of the screen.

 

[bitwelder]

Actually i'm contacted to Rigol Turkey in March about this RMS and other 4.3SP2 related issues. And i got responses too...

meka: houston we have a problem!

rigol: are you hacked your scope?, becasue if you did it, it's gonna out of warranty and scopes do this kind of problems when hacked. (trying to ditch warranty )

meka: no, i'm not! (beacasue it's true, it came already updated from former user... in the background *UninstAll  )

rigol: ok. please send your serial number and your problem description

Ah, so Rigol helpdesk script is currently like:

1) Greetings
2) ask "Have you hacked your scope?"
3) if NO, ask "What's your problem?"

Interesting... 

[Assafl]

Channel to Channel Isolation: DC to maximum bandwidth: >40 dB

...

Problem is in the third spec: channel separation.... Channel separation should be on order of 10000x, meaning that 10000 mV (10V) connected to one channel, should not induce (yes induce, trough parasitic capacitors and inductances inside scope) more than 1mV of phantom signal in other channels, and that's from DC to 100MHz...

And looking at the traces it seems that scope does that better then specs too, electrically at least.....

Except in RMS measurements.
In which, channel separation between consecutive channel seems to be cca 7.7dB (cca 2.43 times voltage difference) because of stupid software bug...
...
So none of your reasons to downplay this have merit.. I know you just want to make sure all is right and precise and relevant and such..
Thank you for a nice discussion that I hope now resulted in good explanation of what is wrong and why this is important and need to be fixed.. Much more than that HUUGe "pulses/pluses" bug 

A few notes:
1. That the 3rd spec is the problem is not saying it like it is. The specification is for the analog front end (where noise floors are established and most channel leakage are created). In fact - the trace for CH2 looks fine even if the RMS text has an error. The problem is not in the 3rd spec - it is in the mathematical function that does the RMS calculation.

Once Math gets involved (any math) there can be a dependency between channels. For example, A+B or AxB or any other function negates the 40dB for the participating channels.

2. In my screenshot I picked a scenario in which the error was over 500% - clearly unacceptable. Everyone on this forum does (or should) accept that a 500% error is not right. While the signal no longer takes up the FS - I have shown in another post that the number would need a worse than 10% DC Gain for worst case scenario.

3. Nobody is down playing - (I even sent this to Rigol and will resend my email if I don't hear back from them) - I think the question is what do you do in the meantime. Is this scope No Good? Depends. Certainly, if you must have the ability to measure 4 channels RMS - then this scope, with current firmware, is NO GOOD TO YOU. If you can do with less channels, then I guess what we "down players" (as you call them/us) say is PLEASE DO NOT MEASURE RMS using CHX and CHX+1 until (and if) Rigol issues a software fix. 

For me, I personally think all scopes are SH*T - they all have quirks, and you learn to work around them. But this is based on my experience working at a university fab and then at a defense research lab both with unlimited funds (10 years of working with Tek and HP and Anritsu and B&K and many other brands) - over time realizing - or being mentored to realize - that getting a useful physical property from a DMM or a Scope is always hard and needs attention to endless details for the measuring chain. Good research lab rats are always 100% sceptics - for a good reason.   

[2N3055]

@2n3055:

But there is one thing: You can make nice screenshots of your scope very easily, simply and clearly by using several different methods. The resulting screenshot (if you select the PNG default format) is less than 1/5 the filesize of the photos you posted and displays at a reasonable and easy to read 800 pixels wide. Just put a USB thumbdrive into the front panel jack and press the green "print" button underneath the Help button.

Of course it may take a while for the image to be saved to the USB drive.... but the result is generally much better than taking a photograph of the screen.

 

Thanks for info , i know that, this was quicker 

Nice to met you, cheers!!

[2N3055]

Channel to Channel Isolation: DC to maximum bandwidth: >40 dB

...

Problem is in the third spec: channel separation.... Channel separation should be on order of 10000x, meaning that 10000 mV (10V) connected to one channel, should not induce (yes induce, trough parasitic capacitors and inductances inside scope) more than 1mV of phantom signal in other channels, and that's from DC to 100MHz...

And looking at the traces it seems that scope does that better then specs too, electrically at least.....

Except in RMS measurements.
In which, channel separation between consecutive channel seems to be cca 7.7dB (cca 2.43 times voltage difference) because of stupid software bug...
...
So none of your reasons to downplay this have merit.. I know you just want to make sure all is right and precise and relevant and such..
Thank you for a nice discussion that I hope now resulted in good explanation of what is wrong and why this is important and need to be fixed.. Much more than that HUUGe "pulses/pluses" bug 

A few notes:
1. That the 3rd spec is the problem is not saying it like it is. The specification is for the analog front end (where noise floors are established and most channel leakage are created). In fact - the trace for CH2 looks fine even if the RMS text has an error. The problem is not in the 3rd spec - it is in the mathematical function that does the RMS calculation.

Once Math gets involved (any math) there can be a dependency between channels. For example, A+B or AxB or any other function negates the 40dB for the participating channels.

3. Nobody is down playing - (I even sent this to Rigol and will resend my email if I don't hear back from them) - I think the question is what do you do in the meantime. Is this scope No Good? Depends. Certainly, if you must have the ability to measure 4 channels RMS - then this scope, with current firmware, is NO GOOD TO YOU. If you can do with less channels, then I guess what we "down players" (as you call them/us) say is PLEASE DO NOT MEASURE RMS using CHX and CHX+1 until (and if) Rigol issues a software fix. 

For me, I personally think all scopes are SH*T - they all have quirks, and you learn to work around them. But this is based on my experience working at a university fab and then at a defense research lab both with unlimited funds (10 years of working with Tek and HP and Anritsu and B&K and many other brands) - over time realizing - or being mentored to realize - that getting a useful physical property from a DMM or a Scope is always hard and needs attention to endless details for the measuring chain. Good research lab rats are always 100% sceptics - for a good reason.   

Hi, thanks for an interesting points.. Exactly on spot.. So let me answer you :

1. You are actually correct as I did point that out... But in the same time you're not. You are correct about problem not being analog and not seen on trace, I said that.. If you don't use RMS all is fine..
But for the RMS measurement , what we see is a channel separation error.. Except for RMS parasitic influence happens in software...
How come I have this attitude: If you buy a separate RMS voltmeter, you don't care what signal path it has and where correction and calibration is done. From BNC to screen, all is the same to you.. Accuracy and all other specs apply to results as seen on the screen.. Who screw up, software or hardware guys, is company's problem.. To me instrument is not within specs..
And I know that is how MY customers look at my products...  Don't get me wrong, it's not that I say what you say is stupid, it 's just not seeing the whole picture..

A note about mesurements and math.. Measurements and math in this case are used in Rigol terminology context.. Measurements are "thingies" you can quick access on the left of the screen and trough <Measure> button. These are exclusively SINGLE channel measurements. And RMS is one of them and no channel interaction should be possible..
Math, as accessed by pressing <Math> button is normal channel mathematics, that can get quite crazy, and can have any result between minus infinite to plus infinite, depending on creativity of said mathematician.. We're not touching any of that here.... 

2. I have no comment

3. Is actually the source of misunderstanding here and a reason for the lenght of this discussion. It is because there are several issues here:

- Firstly, thank you fro reporting a bug to Rigol.. Much appreciated..
- Secondly, I newer said scope was crap or unusable.. I'we been doing this for more than 35 years.. I worked with scopes that didn't have cursor measurements, to the fancy digital mixed signal ones.. I know how to improvise to make do with what I have. And as you said right, now that I know about bug, i will find a way to measure it (i have another scope if nothing else). But it should be fixed anyways and it seems we all agree on that.
- Personally I think scopes are magical machines that makes electronics feel alive.... But I don't trust them blindly...
To be honest in general work, I usually don't pay attention to last digit of measurement on any instrument as a general rule...  Precision measurement is a complicated process... Scopes are more like 3 1/2 multi-meters for general troubleshooting, to check things approximately... Is it oscillating ?...I check wtih scope... Ok it does, let me connect a counter to see what EXACT frequency is that...

Measuring anything to precision must be controlled experiment, and properly designed..
But I digress.. 

Anyways, thanks for a discussion, despite misunderstanding, i do think we pretty much agree on conclusions here, despite coming from a different point of view..

To reiterate, scope great, RMS bad, need fix RMS, make scope more great... I think even Google translate could translate this to chinese 

P.S. When writing this I pressed something  and it got posted incomplete... I went back and finished..  Sorry for that.

[Karel]

Problem is in the third spec: channel separation.... Channel separation should be on order of 10000x, meaning that 10000 mV (10V) connected to one channel, should not induce (yes induce, trough parasitic capacitors and inductances inside scope) more than 1mV of phantom signal in other channels, and that's from DC to 100MHz...

You made a mistake here. 40dB = 10000x in terms of power ratio.
It is, however, 100x in terms of voltage ratio...

[JPortici]

Actually i'm contacted to Rigol Turkey in March about this RMS and other 4.3SP2 related issues. And i got responses too...

meka: houston we have a problem!

rigol: are you hacked your scope?, becasue if you did it, it's gonna out of warranty and scopes do this kind of problems when hacked. (trying to ditch warranty )

meka: no, i'm not! (beacasue it's true, it came already updated from former user... in the background *UninstAll  )

rigol: ok. please send your serial number and your problem description

Ah, so Rigol helpdesk script is currently like:

1) Greetings
2) ask "Have you hacked your scope?"
3) if NO, ask "What's your problem?"

Interesting... 

Not really.
Happened all the time when everybody wanted to root their smartphone and threatened to sue the retail store and the manufacturer when we found out (after they lied to us) and refused to repair them under warranty.
You have modified the software. We have no idea of what else you did when you touched where you weren't supposed to *washing both hands*


(To be fair the reason was that everybody rooted their phone not because of MUH FREEDOM but because they read on the interned that they could play better games by rooting and becoming super hackers like neo in the matrix, by then installing a piece of software that controlled the voltage applied to the core.. and so their crappy phones would crap out from months of constant overheating)

[2N3055]

Problem is in the third spec: channel separation.... Channel separation should be on order of 10000x, meaning that 10000 mV (10V) connected to one channel, should not induce (yes induce, trough parasitic capacitors and inductances inside scope) more than 1mV of phantom signal in other channels, and that's from DC to 100MHz...

You made a mistake here. 40dB = 10000x in terms of power ratio.
It is, however, 100x in terms of voltage ratio...

Absolutely correct Karel.. thanks!! It was late, im defense...    But all reasoning is nevertheless correct..
Cheers!!