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.
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.
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.
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.
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?
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.
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.
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)
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.
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.
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...
So, just to simplify: the last update is really worth, right?
There doesn't seem to be any downsides to updating.
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).
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
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
@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.
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.
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...
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...
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...