Gw Instek GDS2204E (200MHz 4 channel DSO) review

[nctnico]

That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems.

Yep, the devil is in the detail.
For the new Siglent X-E series:

Offset ranges 1x input.
500uV~118mV/div: ±2V
120mV~1.18V/div: ±20V
1.2V~10V: ±200V/div

2V/div will give sufficient offset for DougM's needs and using the minor divisions ~250mV resolution.

That only works if the Siglent doesn't have overdrive recovery problems just like the Rigol. Designing for a DC offset is easier than for a large signal swings.

[DougM]

Even though my excuse for getting a better 'scope for home use has been undermined by finding that my Rigol works a lot better at 1x probe setting, I've read this entire thread and am being sorely tempted to get one of these scopes!

Thanks for the detailed review and discussion.

Doug

[2N3055]

For DS1000Z:

Offset Range (Probe ratio is 1X)

1 mV/div to 499 mV/div: ±2 V
500 mV/div to 10 V/div: ±100 V

As far as I could see, DougM wants to look at part of 40V P-P signal at better than 1V/DIV or less..
No digital scope I know of will have dynamic reserve of 200x of full screen sensitivity... And probably only +-8 to 10 DIVS...

That depends entirely on how the input circuit is designed and it is not 200x but 5x (40V/8V full display range @ 1V/div = 5x). If the oscilloscope allows a large offset then the input circuitry should be designed to handle a signal which swings between the maxima of the offset. It seems the Rigol has a design flaw and thus has overdrive problems.

Yep, the devil is in the detail.
For the new Siglent X-E series:

Offset ranges 1x input.
500uV~118mV/div: ±2V
120mV~1.18V/div: ±20V
1.2V~10V: ±200V/div

2V/div will give sufficient offset for DougM's needs and using the minor divisions ~250mV resolution.

Tautech, thanks for the info..

It is not about offset. That was mentioned in passing, not relevant for original question. It is a good reminder to the fact that all scopes are different, though..
For instance from 500mV to 1.2V Rigol has 100V offset compared to Siglent 20V. If that is of significance to anybody...

But that is only relevant if you have a small AC component riding on top of a large DC component. In which case you can use AC coupling too.

Most of the time, DC offset is simply used to move channels vertically on screen for visual separation.

Problem is something else.

If you have 10 vertical  DIVs on screen... you put in 40V AC P-P, and put it on 5V/div you see nice +/-4 divs signal.
Then you realize a small something, maybe 100mV anomaly at zero cross. So, you put it on 50mV/div so anomaly would be at least +/-1 div (2 div P-P) vertically so you can have a better look. At this point, full screen dynamic range of input is +/-500 mV (1V P-P).. You are overdriving it 40X... On top and bottom.. not where you are looking.   

Old analog CRT scopes had different circuitry, working on much higher internal voltages (even full solid state integrated ones). They had to actuate electrostatic plates on CRT tube. That gave them much larger linear dynamic range and also many times a more graceful clipping and recovery... They were better at this. 

Regards,

Sinisa

[rhb]

Heating of the input attenutator network, especially the capacitors, is a big deal.  Someone at Tektronix derived an analytic solution which was held as a closely guarded trade secret for a long time.  There was a reason "scope" and "Tektronix" were synonymous for a long time.

I have an article about it in a book somewhere, but it was not in the ones by Jim Williams and Bob Pease where I expected to find it and my library is a bit too large to justify a search.  As I recall it was a Bessel series expansion.  I remember thinking when I read it the article what a tremendous amount of work (i.e. months) it must have been to derive.

Each setting in the attenuator network is expecting a particular voltage range.  So if you drop off the higher voltage attenuators the remaining stages get severely overdriven.  Unlike analog scopes which had to generate the deflection plate voltages, a DSO reduces the voltage before feeding the signal to the ADC if it is above the ADC range.  An amplifier is only needed for voltages below the ADC range and to buffer the input. 

Sadly despite the fact that component level repair would be much easier on a single board SMD DSO than something like a Tek 465, the tradition of providing proper service information to the user has died.  As a consequence, few people are aware of the details of DSO circuit designs.

Getting a believable presentation of something like high frequency ringing after a 40 V step is not easy.  The only way I can think of to do that would be to apply an external bias,  AC couple the scope and use an external comparator to switch the signal on and off.  Otherwise the opposite swing would cause heating and non-linearity.  This would be rather difficult to implement if the step had a fast rise time.

[seronday]

For anyone who may be interested, it is possible to install a license file in the GDS-2000E series to upgrade the bandwidth.

I have recently used an experimental license file generator created for the GDS-1000B series by EEVblog member,   wgoeo  ,  to upgrade a GDS-2074E (70Mhz) to 200Mhz bandwidth.
The Info on the license file generator and how to use it, is in this thread :-
     https://www.eevblog.com/forum/testgear/possible-gw-instek-gds-1000b-hack/

When the license file is installed, an additional entry appears on the " Utility - System - System Info " screen.

Also a new file called  "  OptionConf  ", is created in the GDS-2000E file system under   /home/dso .
The option license can be removed by deleting or renaming this file.
Note that in the current FW ver 1.34,  ssh access has been disabled, so it is necessary to install an earlier FW version to gain access to the internal file system.

The attachments show the additional info on the System Info screen and the frequency response before and after the 200Mhz license file installation.

Regards

[rhb]

How did you collect the data for the plot?

[seronday]

Using the DSO voltage measurement function to measure the displayed signal level from a calibrated RF signal generator at various frequencies.
The reference is the level measured at 1Mhz.

[CC555]

I can't update the oscilloscope to v1.35: https://www.gwinstek.com/en-global/products/detail/GDS-2000E

it seems the .upg file is not valid for my oscilloscope (gds-2000e)  , upgrading by safe mode.

[wraper]

I can't update the oscilloscope to v1.35: https://www.gwinstek.com/en-global/products/detail/GDS-2000E

it seems the .upg file is not valid for my oscilloscope (gds-2000e)  , upgrading by safe mode.

Are you sure you did not download wrong or corrupted file? Sounds like you want to brick your scope.

[CC555]

Thx for the reply,

I think the .upg file is good, I downloaded it several times.

Did anyone update the oscilloscope to v1.35?

Current version in my oscilloscope v1.34.

Thanks

[rhb]

I just updated my GDS-2072E from 1.35b4 to 1.35 using "safe mode".  The MD5 checksum is:

9a38e230f4a2168fd602aaef8352a71a  FW_GDS-2000E_V1_35.upg

I had the USB drive inserted when I turned it on.  I had only one file on the drive.  In "safe mode" the update file *must* be the first file in the output from "/bin/ls".  If it's not, the program to update the FW can't find the .upg file. I ran into that issue at some point, so I now just have a single file on the USB.  It's a practical use for a 512 MB SD card.

Has anyone sorted out how to generate the CRC for a .upg file?  It doesn't seem to match any of the CRC programs on the scope.

[CC555]

Thanks rhb, I am going to try to update the oscilloscope again.

[CC555]

I did the update using a 8 GB memory instead a 16 GB memory, with the 16 GB memory didn't work.

[rhb]

I decided to fool around with the BW hack from the hack thread.  It works.  I've got a 40 pS pulser from Leo Bodnar.  Excellent piece of kit!

 I reverted to 1.28 so I could log in via ssh, applied the 200 MHz  BW upgrade. The 300 MHz is BS as that's above Nyquist of 250 MHz. I did the 200 MHz and then the 300 MHz just to see if there was a difference in single channel mode when Nyquist is 500 MHz.  No change.  All the other option hacks from the 2000B are already installed.

Interestingly, the 2074E as delivered had the same BW as the "100 MHz" after the hack.  It's actually about 85 MHz by the traditional rise time metric, so  not better than 70, but not quite 100.

I then updated the 2072E to 1.35 again and saved screenshots from the 2204E and the 2072E.

I need to quite fooling around like this and start working on FOSS FW for these.  That's what I bought the 2072E for.  I'm not about to risk bricking my MSO-2204EA.

[nctnico]

I did some experimenting with the license generator from this post on my GDS-2204E:
https://www.eevblog.com/forum/testgear/possible-gw-instek-gds-1000b-hack/msg1256089/#msg1256089
I downgraded to version 1.21 because version 1.34 doesn't accept the licenses but version 1.21 does. The power analysis options doesn't seem to enable anything but the 300MHz option does work! The bandwidth went from 288MHz to 314MHz and now there is a 200MHz bandwidth limit option. Sure the 300MHz option isn't useful when using 4 channels but for that you can still enable 200MHz. All in all not bad! 

Edit: the 300MHz remained when I installed firmware version 1.35 (currently the most recent).

[rhb]

Interesting.  I wonder if they removed the 300 MHz option between 1.21 and 1.28.

How did you measure the BW?

[nctnico]

Interesting.  I wonder if they removed the 300 MHz option between 1.21 and 1.28.

How did you measure the BW?

I installed version 1.35 afterwards and the 300MHz option is still there. I measured using an RF generator and a 50 Ohm feedthrough. I referenced the bandwidth from the signal amplitude at 20MHz.

[Mortymore]

On the 2074E (70MHz) with v1.21b6 the 300.lis is accepted but it does nothing that the 200.lis hasn't done yet.
After reboot it still says "Bandwidth upgraded to 200MHz. Which is just fantastic per se.
Maybe the 300MHz.lis works on the 100MHz scope. In the 200MHz is confirmed.

This is just me guessing...
Because there's an option in the hack to enable "Power Analysis"... isn't this option directed to the 3000 series scopes?
Any of the 1000 and 2000 doesn't has the ability to enable this tool, right?
Correct me please if I'm mistaken.

[nctnico]

I tried to install the power analysis license as well but it is not accepted. I'm not aware of any power analysis option being available. Can you check if you have a 200MHz bandwidth limit in the channel bandwidth menu? If it is there I'd expect that the 300MHz option is active.

[Mortymore]

Hi nctnico!

There's no 200MHz bandwidth limit option available. Only "Full", 20MHz and 100MHz.

About the "Power Analysis" option available in the lis.html... if it's there... my suspicion is that the hack may also be directed to the 3000 series. I think those have that tool as optional.

[rhb]

With all channels enabled, they're being sampled at 500 MSa/S. You can only do 300 MHz on two channels of a 4 channel, or one of a two unless all you want to do is look at it.

I was quite amazed to discover that a 2 GS/S scope channel can go as high as 1.5 GHz, a mere 50% above Nyquist.  It works.  It's a LeCroy and it gives  220-230 pS with one of Leo's pulsers.  Both sampling at 2 GSa/S and 4 GSa/S.   But the overshoot is "<20%"!!!

[Mortymore]

For those who haven't noticed, there's a new firmware version 1.37 for the GDS-2000E series (released at 2018-11-28)

https://www.gwinstek.com/en-global/products/detail/GDS-2000E

Version 1.37
1.Fixed the  crash issue for  the "bus decode" function
2.Fixed the "peak table" data storage issue for the SA mode.
3.Added the new "SA:LIST? SCPI" command.
4.Changed the data transmission format of "SEGMents:MEASure:TABle:LIST?" (SCPI command) to  the "block data" transmission format.
5.Changed the data transmission format of " LISTer:DATA?" ( SCPI command) to the "block data" transmission format.
6.Improved the measurement high-low(histogram) calculation method.
7.Fixed the correspondence problem of frequency value for the  Math FFT Detail CSV of "Save All Waveform" function.

Have a great 2019

[Mortymore]

This scope doesn't stop!

Yesterday I updated to the latest firmware version v.1.38 (2019-01-26) and manage to activate a licence for the Spectrum Analyzer option.

After fooling around a bit with the SA functionality, I realize that I have a 70MHz oscilloscope (IDS-2074E), "upgraded" to 300MHz (EDIT: upated from 200MHz), "upgraded" again to a Spectrum Analyser with a frequency span of 500MHz 

Attached 3 screen captures in SA mode. 2 of them from a 60MHz sinusoid (SDG1032X) with a span of 500MHz, and another from a 1MHz sinusoid with a span of 10KHz. Neat 

Stretching the rope, I wish Santa could make FRA APP work with an external function generator so it could run on the GDS scopes.

[nctnico]

Hmm, you didn't install the 300MHz license key? 

[Mortymore]

Hmm, you didn't install the 300MHz license key? 

It didn't work on my 70MHz scope. But I'm happy with the 200Mhz anyway.

PS: What is the frequency span of the SA on your stretched 300MHz scope?

UPDATE: Now I manage to have the 300MHz working. But had to clear first the file OptionConf to clean the 200MHz BW licence instaled