REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol

[Teneyes]

@TP, re "Measure" , I have FW 1.00.02  and measuring the 1kHz Test, I get Freq =1.000KHz with scan set up to 5ms/div, that is 5 pulses per div.
 Now at 10 ms/div ,IE 10 pulses , DSO shows Freq > 1.000kHz
 and  at 20 ms/div ,IE 20 pulses , DSO shows Freq > 0.833kHz
 and  at 50 ms/div ,IE 50 pulses , DSO shows Freq = ****
BUT
    by pushing <SCALE>  and going into Zoom mode , then narrowing the Zoom back to 5.000ms the Freq = 1.000kHz , BUT no Hanging of DSO
  I will next try your test with a Modulated source at 1MHz

[marmad]

A simple test to check for the 'looping' bug on the DS2000 - without using my RUU software - which makes it easier - but could make you think my software is causing it 

1) Set scale to 2ms/div (this allows for just 6 frames to be recorded - or it might be different on your scope due to memory settings - if so, select a scale that gives <10 frames)
2) Go to Utility -> Record -> Mode -> Open
3) Press 'Run/Stop" to stop recording.
4) Go to Utility -> Record -> Mode -> Playback
5) Set 'Interval' to 500ms
6) Set 'Play Mode' to loop.
7) Press '|| >' button and watch 'Current Frame' counter on Menu as it tries to loop. For me, sometimes it will count 1,2,3,4,5,6 - sometimes 1,2,6 - sometimes 1,6 - sometimes just 6! Or any other possible permutation... I can't see any pattern to the bug.

To quickly repeat test over and over, just repeat:
8 ) Press '[]' to stop playback.
9 ) Press '[]' again to enter 'Record Open' mode.
10) Press 'Run/Stop' to record.
11) Press 'Run/Stop' again to stop.
12) Press '|| >' to playback.

I get a different 'pattern' of looping with almost every test 

I have already sent this on to drieg for reporting to Rigol. They have confirmed the previously reported trigger setting bug and plan to fix it.

[Teneyes]

Record open, playback in loop mode Interval 500mS , I get  Frames 1,2, 6 allways
like Marmad
I changed mem.Depth to 1.4Mpts and get 62frames max.  then playback
I get all frames 1-62.
I am using normal trigger , and touch finger for 60Hz and touch test 1KHz for  half of the frames .

Oops
  now looping differently
   1-20   all 60Hz then   21 start of 1kHz  then JUMP to frame  62 1KHz end of Frames ,then Loops to 1

BUT if I use waveFinder knob , it goes to pause and if I scan to Frame 23 and "RUN" then
displays 23-62 then Loops back to 1,

If I 'wavefind' to Frame 22 and Press 'RUN' in JUMPS to 61 and loops to 1

Seems like Frames 22 causes the jump to End ,Frame 62
Bugging!!

[marmad]

Record open, playback in loop mode Interval 500mS , I get  Frames 1,2, 6 allways like Marmad

Thanks for confirming the bug in 01.00.02, Teneyes.

[TP]

On my scope the "Measure" box can get hung requiring a reboot.  If I input a 1 MHz signal and resolve the cycles the "Measure" box gives correct data.  If I slow down the time/div, say to see modulation of the RF carrier, the "Measure" box will get confused and quotes, say, freq > something.  If I speed up the time/div to see the 1 MHz cycles again the "Measure" box will remain hung with bad data and nothing I tried gets it working again except a power down.

@TP: I was unable to replicate this error on my scope, either using the individual Frequency measurement or the 'Measure All' box. I have to conclude that it's either a firmware version 01.00.02 bug - or that there was an added variable in your setup/scope settings that I don't know about that provoked the bug.

Well, I can't replicate it now either.  That first day the scope was definitely acting weird.. maybe first day jitters .  Anyway, it works perfectly now.

[marmad]

OK, I caught it, before I was only recording 1 group . this time I recorded 2 groups , frames 1- 450 , and 451-2449, and have space for 8127.
and yes playback plays and loops only in the 1-450 group , but if I move into the second group with the Wavefunder 'big' knob then go to run from pause.It will play to 2449 then jump into the 1-450 group and loop there.

@Teneyes - I've been trying to do what you mentioned here, but no luck.
I set scale to 1us = 4065 frames.
First I record all 4064 frames.
Then I change end frame to 1000 and record 1 - 1000.
But how can you move from 1 group to the other? The scope seems to only let me playback 1 -1000 - and the big Navigation Knob won't let me move out of that group.

I can't see how it's possible to have two groups of frames recorded - and move between them - because you can't specify a 'start frame' for recording - only an 'end frame'.

[marmad]

Well, I can't replicate it now either.  That first day the scope was definitely acting weird.. maybe first day jitters .  Anyway, it works perfectly now.

It might be a certain hard-to-repeat selection of settings and/or inputs - if you see it again, please note down as many variables (scope settings, etc) as possible. In any case, I'm glad it's working for you now 

[TP]

A simple test to check for the 'looping' bug on the DS2000 - <cut>

I can confirm that my scope does the same as yours in Record Open mode and that it works properly in straight record mode (i.e. just pressing the record button).  I also get 7 frames in Record and only 6 in Record Open.

[larsie]

Hi. I am new to this forum. Thanks for some very interesting posts on the DS2000 series. I've just ordered a DS2022 thanks to this information. I'm wondering if the trial feature timing is based on how many hours the scope is on, or if it's a real-time-clock from when I turn the scope on the first time. So, basically will turning it off make it last longer? Thanks. 

[Teneyes]

@larsie, Yes the trial version timer is only the DSO ON time, so when the wife calls be sure to shut it off. Oops lost another 200 minutes ,Enjoy.  and Watch the Self-Cal feature as it removes the trial version  options!

[EV]

. I've just ordered a DS2022 thanks to this information. ...

Maybe you mean DS2202?

[larsie]

. I've just ordered a DS2022 thanks to this information. ...

Maybe you mean DS2202?

Oops... yes 

[tigerwillow1]

I have a question about RMS voltage measurement.  I'm checking out my brand new DS2072, which I chose based on all of the good info on the forum.  Either I'm doing something wrong or the RMS measurement function doesn't work very well.  Here's the setup: Channel 1 connected to the scope's calibration square wave, probe on x10, vertical 100 mV/division, horizontal 100 uSec/division, DC coupling.  V min  reads -4.0 mV and V max is 308 mV.  These are ok.  V rms reads 211 mV, which is bogus.  I think it should be 156 mV.  Am I maybe doing something incorrectly?   With AC coupling the RMS value is closer but still quite a bit off.  I just got the scope from Tequipment, software version is 00.00.01.00.02 .

[larsie]

I think it might be correct. Isn't the formula Vrms= Vpk*sqrt(f*T) for a positive square wave? Maybe not?

Edit: I think I mean Vp / sqrt(2)

[marmad]

I have a question about RMS voltage measurement.  I'm checking out my brand new DS2072, which I chose based on all of the good info on the forum.  Either I'm doing something wrong or the RMS measurement function doesn't work very well.  Here's the setup: Channel 1 connected to the scope's calibration square wave, probe on x10, vertical 100 mV/division, horizontal 100 uSec/division, DC coupling.  V min  reads -4.0 mV and V max is 308 mV.  These are ok.  V rms reads 211 mV, which is bogus.  I think it should be 156 mV.  Am I maybe doing something incorrectly?   With AC coupling the RMS value is closer but still quite a bit off.  I just got the scope from Tequipment, software version is 00.00.01.00.02 .

As far as I can tell, it's reasonably accurate (which is about the best you can say about most measurements on an oscilloscope):  The calibration signal is a 3V 1kHz positive square wave with a 500us duration = 2.121Vrms.

Check it with this online calculator.

[tigerwillow1]

As far as I can tell, it's reasonably accurate (which is about the best you can say about most measurements on an oscilloscope):  The calibration signal is a 3V 1kHz positive square wave with a 500us duration = 2.121Vrms.

Thanks.  I feel like I'm at an AA meeting having to say "I'm an electrical engineer and I don't know how RMS works".  It has always seemed intuitive to me that a square wave with its minimum voltage at zero has the same RMS value as a square wave symmetric about zero.  Now I see that the math says otherwise, and I even found a couple of web sites that incorrectly agreed with me.  I think it has to do with the DC component, it's just hard to suddenly break with decades of wrong thinking.  So it's correct that the RMS value of the calibration signal is different with AC coupling vs. DC coupling.  The scope's calculation isn't stellar accuracy, but close enough for my purposes.

[marmad]

Thanks.  I feel like I'm at an AA meeting having to say "I'm an electrical engineer and I don't know how RMS works".  It has always seemed intuitive to me that a square wave with its minimum voltage at zero has the same RMS value as a square wave symmetric about zero.  Now I see that the math says otherwise, and I even found a couple of web sites that incorrectly agreed with me.  I think it has to do with the DC component, it's just hard to suddenly break with decades of wrong thinking.  So it's correct that the RMS value of the calibration signal is different with AC coupling vs. DC coupling.  The scope's calculation isn't stellar accuracy, but close enough for my purposes.

Don't worry - most of us here - especially myself - have posted many things that we either missed, didn't understand in the first place, or still don't fully understand   Just remember that most lower cost DSOs perform measurements on the display data (not the raw sampled data) so the more that the event you're trying to measure fills (but doesn't overflow) the display, the more accurate it will be - and if you need super-accurate measurements, break out a DMM or another instrument. The exception to this is the hardware frequency counter (under the 'Measure' menu) which doesn't care if one or more cycles fill the screen.

BTW, one limitation of the measurements is the number of digits - limited to 3 on the display. I've already written software which pulls chosen measurements to the PC screen - while allowing you to set the number of digits of accuracy up to 6 (see attachment in post below). I think all measurements are stored inside the scope as 64-bit double-precision floating-point numbers.

[marmad]

I put an Marconi signal generator(2019a) on my ds 2072, ( 70 mhz  to the book ) and these were the results,

112 mhz -3 db at 100 milliVolts, the rms on the scoop 70 mV
175 mhz -6 db
232 mhz -9 db
292 mhz -12 db
349 mhz -15 db still triggering and rms still working.
403 mhz -18db
437 mhz -20 db still good trigger and stable
497 mhz game over

Very interesting... thanks for that info!

[marmad]

Anyone who can verify ??

I can't verify your scientific data (no adequate signal generator), but if you want anecdotal evidence that the 2072, 2102, and 2202 are identical in terms of hardware, I can tell you that I've seen a 'firmware modified' 2072 running and behaving precisely like a 2202.

Merry Xmas!

[marmad]

BTW, for those wanting to hack their 2072 (or 2102) to a 2202, I imagine the trick is to figure out how to change the backup copy of the data. Unlike the DS1000, the DS2000 series keep their vital information (such as model number) backed up in another section of memory (with, I assume, a checksum - or something similar). It appears that if the bootloader sees that the normal copy of the information has been corrupted (or changed), it reverts to the backup copy.

EDIT: As clever as Rigol is at making good-quality, inexpensive test equipment - I don't think (luckily for us) that they're very clever at creating hacking preventive measures

[marmad]

The scope's calculation isn't stellar accuracy, but close enough for my purposes.

Attached is an image of the scope displaying the RMS of the calibration square wave (with 3 digits of resolution) - with an inset snipped from my PC display showing the actual measurement read from the DSO with SCPI (in scientific notation) and displayed with 6 digits of resolution.

[EV]

Rise time measured with tunnel diode pulse generator for Rigol DS2202. Generator is connected with BNC cable and 50 ohm terminator. Average value is 1.56 ns. It gives bandwith: 350 / 1.56 = 224 MHz (in specs given 200 MHz).

[marmad]

...and between the 2202 is the 2 nsec timebase.

And the 100MHz BW limit setting - which you would think would be set "ON" all the time on the 2072/2102.

[AndyC_772]

The rise time of a 200 MHz sine wave just is what it is, it's not telling you anything about the bandwidth of the scope. You can infer the scope's bandwidth by either measuring the rise time of a square pulse, or by measuring the displayed amplitude when you feed a sine wave into the scope.

[Wim13]

And the 100MHz BW limit setting - which you would think would be set "ON" all the time on the 2072/2102.
[/quote]

If that was the case,
the 2072 has a 20 Mhz limit knob, that gives at 40 Mhz -6 dB and on 80 Mhz -12 dB,
translated to a limit on 100 Mhz, should give at least -6 db on 200 Mhz, but that is
not what i measured, i got -3 dB on 200 Mhz.