Author Topic: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope  (Read 68278 times)

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Online luma

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #700 on: March 27, 2019, 01:38:54 am »
So you have 10 MS/sec and 10 Hz resolution bandwidth...

What do you think how fast screen should refresh on this FFT ?

In order to have 10 Hz RBW  on 10 MS/s you need to have 1Mpoints FFT. So this is FFT on 1 Mpoint.
And also, in order to get 1 Mpoint at 10 MS/sec , you need 0.1 sec to acquire data for single FFT.

So if FFT took no time to calculate at all, at those setting you would have maximum 10 refreshes per second.

And 1 Mpoint FFT will take a bit of time.
So few times per second is realistic... Even once per second is definitely not slow for a 1 Mpoint FFT at that sampling speed....

As it was mentioned many times before, measurement instruments don't measure anything. Operator does, using instruments.
Know the theory, know how instrument operates and work within it's operating principles and hardware limits.

Regards,

Yeah I'm comparing against dedicated analyzers which is probably not a fair basis of comparison.  Your point is well taken.  Overall I'm pretty stoked about the capabilities of this device, and for the price it's a great solution for my own needs.

edit: To better illustrate the point, as a dumb operator I was doing a dumb thing which was impacting the measurement on the instrument - the RG316 cable was crossed over itself as it sat on the bench.  Simply repositioning the cable on my bench has removed some of the spurs shown in the previous capture.  Here's how it looks now.  Idiot operator == idiot results! :D

« Last Edit: March 27, 2019, 01:53:48 am by luma »
 

Online 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #701 on: March 27, 2019, 01:52:38 am »
Yeah I'm comparing against dedicated analyzers which is probably not a fair basis of comparison.  Your point is well taken.  Overall I'm pretty stoked about the capabilities of this device, and for the price it's a great solution for my own needs.

Dedicated spectrum analyzers use overlapped FFT, so they can provide continuous running FFT update after initial block is loaded..
No scope does that AFAIK.. If some does it would be good to know..
 

Offline nerdineer

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #702 on: March 27, 2019, 08:57:10 am »
Does anyone know of a quicker way to remotely read large waveform raw data from the scope? Right now I have managed to use USBTMC to grab the data but its painfully slow (minutes). This is with raw samples (e.g. bytes, not ASCII).
I'm assuming the protocol adds a lot of weight...

Saving binary files to memory (e.g. a memory stick or the internal memory) is much faster. However then you need to manually remove the USB stick from the scope and plug it into the PC. All possible but annoying and I dont want to wear out the one USB port.

I'm wondering (perhaps with the hacked firmware) if it would be possible to secure FTP into the scope and simply browse and download the scope captured over Ethernet? Or if there are any other ideas or solutions?



 

Offline Commodore8888

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #703 on: March 31, 2019, 08:09:48 am »
For those with the sketchy overshoots from the wonky low freq cal on some MSO5000s and DS/MSO7000s, I've been in touch with Rigol USA over the last month.

As noted by Martin earlier when he contacted Rigol UK, Rigol as a whole appears to know there's an issue. I've been informed there's a fix coming in the form of a new firmware rev.
When, I'm not sure, but hopefully I have more info next week from Rigol USA. It's good to hear considering the group I work with has some analog work rolling up (and it'd be nice not fighting for the sole Tek MDO 3k  :box:), as well, some companies/groups make sending things out for RMA a completely asinine process...
Mike D
 
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Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #704 on: March 31, 2019, 08:54:02 am »
Yes, rigol took everything in this case seriously.
For example, they know and work around about the weak display brightness (although, of course, they couldn´t change the angle view via software).
I wrote to them, different math trace colours were a good and useful thing to have, they answered you´re right, we tell it to the R&D Department and so on.
Or bode plot function ( will come).
Or my problems with getting a pwm signal displaying stable….
They asked me about the nature of the signal, after a few days they told me to set the holdoff time for triggering to ms instead of ns...and it works.
Really good support.
 
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Offline bitseeker

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #705 on: March 31, 2019, 09:17:18 am »
It's good to hear they're responding to the reports. So, this may be like the DS1054Z where they will be fixing issues as they're found and reported. The 1kZ took a while to get sorted, but they took care of it (even "pluses" eventually got corrected :horse:).
I TEA.
 

Offline Commodore8888

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #706 on: March 31, 2019, 10:19:12 am »
Yes, rigol took everything in this case seriously.
For example, they know and work around about the weak display brightness (although, of course, they couldn´t change the angle view via software).
I wrote to them, different math trace colours were a good and useful thing to have, they answered you´re right, we tell it to the R&D Department and so on.
Or bode plot function ( will come).
Or my problems with getting a pwm signal displaying stable….
They asked me about the nature of the signal, after a few days they told me to set the holdoff time for triggering to ms instead of ns...and it works.
Really good support.

Good to know their R/D takes this stuff seriously. Seeing as this chipset is now in multiple scopes, and they're trying to be big players now with ASICs seems like, time to step up the support effort. Especially if new features are just some simple software tweaks. Quality of life stuff.

Screen brightness? In what way, is there a regulator running the backlight in there somewhere?? :popcorn: Or is it just a software image brightness deal. Still would be nice if they do something to bump it a tad. It's not bad in an office environment though. Side by side with our 7000s it IS a little dimmer.

Here's hoping the overshoot/bad cal thing gets sorted soon-ish though. It sort of crosses off our new scopes for serious analog work :(
Difference between new features vs. "cannot be used" :(

Auto bode function seems neat. This using the internal AWG with an internal trigger like how you might with a stand alone AWG, wide time base, and trig out?
Mike D
 

Offline tautech

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #707 on: March 31, 2019, 10:47:46 am »
................
Or my problems with getting a pwm signal displaying stable….
They asked me about the nature of the signal, after a few days they told me to set the holdoff time for triggering to ms instead of ns...and it works.
Yes of course.
User error and nothing to do with the scope at all.

All DSO's can struggle with obtaining a stable triggering with PWM unless Trigger Holdoff time is adjusted to greater than the max pulse width.
These Holdoff triggering issues also arise in some decoding work too where sometimes Holdoff needs be longer than an entire packet.
Pretty basic stuff.
Avid Rabid Hobbyist
 
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Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #708 on: March 31, 2019, 07:54:10 pm »
Yeah, but if you hadn´t the need to adjust the trigger in this way before, you think it´s a bug.
On LeCroy and Siglent models, you don´t have to adjust the trigger timeout - and we got LeCroy only and since a couple of time a Siglent.
So I was surprised using the 5000 for the first time and measure a pwm signal.
 

Online 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #709 on: March 31, 2019, 08:57:21 pm »
Yeah, but if you hadn´t the need to adjust the trigger in this way before, you think it´s a bug.
On LeCroy and Siglent models, you don´t have to adjust the trigger timeout - and we got LeCroy only and since a couple of time a Siglent.
So I was surprised using the 5000 for the first time and measure a pwm signal.
That is because of very fast wfm/sec rate (short blind time) on new Rigols. After getting Keysight 3000T  I also had to start adding holdoff where I didn't have to use it before...
Slower scopes have "built in holdoff"   ^-^
 

Offline hhappy1

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #710 on: March 31, 2019, 10:30:15 pm »
Thanks sir.!!

One more question.

Why it is different THD. Moving the vertical offset.

https://drive.google.com/open?id=1uJyffuycF8e_rt2JvaoOCzDjRx_0lUL4

This is 1Khz Sine wave and 2nd , 3nd, more distortion.

Tek & R&S is Not different.
« Last Edit: March 31, 2019, 11:11:10 pm by hhappy1 »
 

Online luma

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #711 on: April 01, 2019, 01:01:48 am »
Or bode plot function ( will come).

Wait, are you saying Rigol has directly stated that bode plot is coming?
 
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Offline David Hess

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #712 on: April 01, 2019, 03:24:05 am »
Why it is different THD. Moving the vertical offset.

https://drive.google.com/open?id=1uJyffuycF8e_rt2JvaoOCzDjRx_0lUL4

This is 1Khz Sine wave and 2nd , 3nd, more distortion.

Tek & R&S is Not different.

Other automatic measurements also change when the vertical position is adjusted.  I think this is because the Rigol makes measurements on the display record instead of the processing record.  The same thing also explains why automatic RMS measurements are not accurate for noisy waveforms.

In the general case, there are three different waveform records but in some cases they are combined to save money or increase performance:

The acquisition record is what is actually produced by the digitizer and is often limited to the digitizer resolution like on the Rigol where high resolution mode produces an 8-bit result.  On older DSOs, it may be limited to the length of a dedicated bank of fast memory but modern DSOs tend to capture the acquisition record directly into the processing memory.  Early DPO style DSOs captured directly into display memory but I think they do it a different way now. (1)

The processing record is what the processor works with and is often the 8-bit acquisition record promoted to 16-bits like on older Tektronix DSOs.

The display record is what actually gets displayed and may or may not be stored in the processing memory.

(1) I think modern DPO designs capture a histogram into acquisition memory and then the processor transfers this to the display memory which is how I would do it now.  Peak detection is a very limited early example of this.
 

Online 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #713 on: April 01, 2019, 03:44:55 am »
I think this is because the Rigol makes measurements on the display record instead of the processing record.

It doesn't..New ones don't.
 

Offline David Hess

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #714 on: April 01, 2019, 03:58:38 am »
I think this is because the Rigol makes measurements on the display record instead of the processing record.

It doesn't..New ones don't.

Then that is an even more peculiar behavior.
 

Online Bud

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #715 on: April 01, 2019, 04:12:01 am »
Thanks sir.!!

One more question.

Why it is different THD. Moving the vertical offset.

https://drive.google.com/open?id=1uJyffuycF8e_rt2JvaoOCzDjRx_0lUL4

This is 1Khz Sine wave and 2nd , 3nd, more distortion.

Tek & R&S is Not different.
Vertical offset is DC voltage that is mixed with the signal BEFORE the ADC digitizes it. The digital waveform produced by the ADC will include the effect of the DC offset on the pre-ADC circuit (distortion).
 
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Offline Fungus

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #716 on: April 01, 2019, 11:34:38 am »
Or bode plot function ( will come).

Wait, are you saying Rigol has directly stated that bode plot is coming?

Apparently so. See the dedicated topic:

https://www.eevblog.com/forum/testgear/rigol-oscilloscopes-with(out)-bode-plot-feature/msg2308233/#msg2308233
 
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Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #717 on: April 07, 2019, 05:57:07 am »
Does anybody know which 9" Display are used on the rigol, name, model ?
Dave did it a fully teardown but I´m sure he wouldn´t notice it.

 

Offline mabl

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #718 on: April 08, 2019, 06:47:42 pm »
Ok guys,

so I've been wondering on why you think that HIRES does not work on the DS5000. To my understanding, HIRES will runn a box car averaging filter over the samples, potentially resulting in more resolution if the noise is gaussian.

On the display side, multiple acquired wave forms overlay and result in a gradient display. If the waveform differs from shot to shot, the trace will look wider, even if the ADC had perfect resoultion.

The new Rigols are special in a sense, that they have very high update rates, even in HIRES mode. So what I would expect is:
  • Gain of significant digits when using HIRES
  • Trace getting thinner when reducing update rate via trigger holdoff
  • Potential influence on display grading depending on vector mode or point display mode. With points enabling to see the higher vertical resolution
  • In the best case I'd like to be able to specify the averaging filter shape etc. Rigol does not allow this.
So what I just did is looking at a 15MHz "square" wave from the wave form generator and going through these options, see attached images. I do believe to see a vast improvement of the waveform. The grading is "better" in case of dot display mode (instead of vector), and if I reduce the wave form rate, things narrow down and get clearer.

Is this not what one would expect from the HIRES mode? Once we account for the high frame rate and the easy saturation of the gradient display.
« Last Edit: April 08, 2019, 06:50:28 pm by mabl »
 

Online 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #719 on: April 08, 2019, 07:04:19 pm »
To take update rate out of equation, one should try single capture without and with HIRES.
 

Offline mabl

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #720 on: April 08, 2019, 07:19:32 pm »
To take update rate out of equation, one should try single capture without and with HIRES.

Fair enough. But I wanted to point out the effect of the high update rate and the difference between dot and vector display.

I have added single shot measurements to this post as well. Due to the high ADC sample rate, it would definitely be useful to change the box size. But in general, my laymen's sense is that the HIRES mode does work but the results look bad in case of graded display and vector display mode.   
 

Online 2N3055

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #721 on: April 08, 2019, 08:08:22 pm »
Problem is with the fact that it is not specified how HIRES is done and that you have no control over how many averages (how many bits) HIRES is doing. They might be doing it with filter of length 2 which would only give 0,5 bit enhancement which would pretty much be not visible.
It should be made like averaging so you can set how many bits of enhancement you want and it should correspondingly show effective sampling rate AND effective bandwidth with that filter setting..
 
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Offline Martin72

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #722 on: April 09, 2019, 03:27:30 am »
Yeah, like the filtering in 0.5 bit steps by lecroy or siglent.

Quote
They might be doing it with filter of length 2 which would only give 0,5 bit enhancement which would pretty much be not visible.

Exactly, see also:

https://www.eevblog.com/forum/blog/new-rigol-scope/msg2266332/#msg2266332

And:

Quote
The hi-res mode is active on the 5000, but somehow too "weak".

https://www.eevblog.com/forum/blog/new-rigol-scope/msg2233980/#msg2233980
 

Offline MegaVolt

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #723 on: April 16, 2019, 09:42:18 pm »
Maybe someone knows?

1. Can the generator produce PWM signals? Or PFM or some other modulation for a square wave?

2. Is there any possibility to use external synchronization? I know that there is no separate entrance for this. But how can it be possible to use one of 4 inputs for this?
 

Offline MegaVolt

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Re: EEVblog #1146 - New Low Cost Rigol MSO5000 Oscilloscope
« Reply #724 on: April 17, 2019, 07:12:13 am »
Digitized generator output good instrument. And I found small spikes on any generated signal. Perfectly visible on rectangular pulses. The frequency is somewhere 20 Hz. The amplitude is 0.15 mV.

This is all?
 


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