Author Topic: The Siglent SDG2042X Thread  (Read 279555 times)

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Online pigrew

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Re: The Siglent SDG2042X Thread
« Reply #925 on: April 17, 2018, 10:28:56 pm »


Can one of you guys confirm this behaviour as a feature and not an hardware bug of my unit? (I also tried with same results chanels coupling, chanel copy and eqphase functions)
Thanks to all
Denis

I saw a similar thing happen when I first tried to replicate this, but then I realized that my BNC cables were different lengths, and not 50 ohm terminated.

Once using equal length cables (even without 50 ohm termination), the phases were aligned.

The propagation delay in the cables should be around 1.5 ns per foot.

You should also play with using a BNC tee and equal length cables to verify your oscilloscope has calibrated timebases between channels.

-Nathan
 
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Offline Gixy

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Re: The Siglent SDG2042X Thread
« Reply #926 on: April 18, 2018, 06:12:31 am »
Thanks a lot Nahan to point this. You're right, my cables are of different lengths and I tried to swap them but I believe I remember that the result was the same; nevertheless I have to recheck that the deviation was not inverted. Let me see. They are 50 Ohm cables, one of them being the one provided with the unit. Thinking of it, the length difference should be around 2 feet, so 3ns, which is the problem: I will check as soon as possible!
Thanks again  :)
 

Offline Gixy

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Re: The Siglent SDG2042X Thread
« Reply #927 on: April 18, 2018, 10:12:36 am »
Shame on me! You're right Nathan, it's the cable length... I'm now trying to cut the longest one and put a new BNC connector on it.
 

Offline tautech

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Re: The Siglent SDG2042X Thread
« Reply #928 on: April 18, 2018, 10:24:25 am »
Shame on me! You're right Nathan, it's the cable length... I'm now trying to cut the longest one and put a new BNC connector on it.
There's no shame in this.....we're all learning.  :)
Look harder at all the different coax types and you'll see there's different propagation speeds for all of them.
So while you might have leads all the same length, it doesn't mean they'll all have the same signal propagation characteristics. Modern DSO's provide deskewing of the channels to allow for different propagation characteristics.
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Offline McBryce

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Re: The Siglent SDG2042X Thread
« Reply #929 on: April 18, 2018, 11:35:06 am »
That why I always buy cables in pairs :)

McBryce.
 
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Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #930 on: May 01, 2018, 02:21:11 am »
Does anyone compared output signal fidelity of SDG2042X and SDG2122X?

Previously Timpert reported that the DAC markings had been ground off on his SDG2042X:
https://www.eevblog.com/forum/testgear/the-siglent-sdg2042x-thread/msg942145/#msg942145

This is very strange, because review of SDG2122X from Dave Jones shows the DAC with normal marking AD9122.
So, probably it looks like SDG2042X uses different DAC, or even rejection samples which doesn't meet with AD9122 specs.
And this is may be the reason to ground off the marking on the DAC.
 

Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #931 on: May 06, 2018, 07:17:18 am »
Can someone test SDG2042X with spectrum analyzer?
Are there any problems with spectral purity of the signal?
 

Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #932 on: May 11, 2018, 10:12:38 am »
According to the datasheet, there are two revision for DAC AD9122.
Revision 2 has a consistent and lower spur level.
While revision 1 has a variable and higher spur level.

The difference in chip marking.
The chip with date code < 1001 is revision 1.
The chip with date code >= 1001 and with no TxDAC label is revision 1.
The chip with date code >= 1001 and with TxDAC label is revision 2.

Is it possible that SDG2042X uses revision 1 with higher spur level, while SDG2122 uses revision 2?

I'm just want to buy SDG2042X, but I'm not sure if it's output is as good as indicated in the SDG2122X review...
« Last Edit: May 11, 2018, 10:39:59 am by radiolistener »
 

Offline Qw3rtzuiop

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Re: The Siglent SDG2042X Thread
« Reply #933 on: May 11, 2018, 11:04:25 am »
Is it possible that SDG2042X uses revision 1 with higher spur level, while SDG2122 uses revision 2?

Unfortunately noone is able to answer that question because they removed the markings.

Dave had an early unit. Maybe they started to remove the markings later. Or they just remove them at the sdg2042x units.
« Last Edit: May 11, 2018, 11:07:01 am by Qw3rtzuiop »
 

Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #934 on: May 11, 2018, 11:45:17 am »
It looks that they removed the marking of AD9122 for SDG2042X.
I think there is only one reason to hide it - because it has much worse spec.
As result, all measurement from Dave review is not applicable for SDG2042X.
Because Dave performed it for SDG2122X with good AD9122.

So, there is need for a measurement of the SDG2042X model. It may be very different from Dave results...
 

Offline tautech

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Re: The Siglent SDG2042X Thread
« Reply #935 on: May 11, 2018, 12:05:05 pm »
Can someone test SDG2042X with spectrum analyzer?
Are there any problems with spectral purity of the signal?
Next week I'll check one with an SSA3032X when I have more in stock......remind me.
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Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #936 on: May 17, 2018, 12:47:06 pm »
Next week I'll check one with an SSA3032X when I have more in stock......remind me.

any news?
 

Offline tautech

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Re: The Siglent SDG2042X Thread
« Reply #937 on: May 17, 2018, 07:35:15 pm »
Next week I'll check one with an SSA3032X when I have more in stock......remind me.

any news?
Thanks, I should have them in a few days but I've lent my SSA3032X to member hendorog who wants to do some deeper checks on it's performance after comparing it last weekend against his new acquired 22GHz HP and 6 GHz Signalhound. He's got some nice stuff.  :)
So either I'll have to rock by his place next weekend or he'll come to me to return my SA.
Either way we'll get the sreenshots you want but it'll be another week, sorry.
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Offline rfspezi

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Re: The Siglent SDG2042X Thread
« Reply #938 on: May 18, 2018, 06:31:15 am »
During the development of my GPSDO, i compared the 10 MHz reference output of the SDG2042X with two high quality OCXOs.
I noticed that the 10 MHz output is permanently shifting frequency - like lacking phase over about 5 seconds and then hurrying up again.
As expected, this instability is also visible on the synthesized signals.  :-\
Can somebody confirm that and does anybody know what frequency the internal reference oscillator is running at?
 

Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #939 on: May 18, 2018, 11:44:05 am »
does anybody know what frequency the internal reference oscillator is running at?

according to Dave review of SDG2122X, there is 10 MHz oscillator. It looks, that it can be easily replaced with more stable OCXO.
But there is need to perform frequency calibration after replacement, I'm not sure how to do it.
 

Offline rfspezi

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Re: The Siglent SDG2042X Thread
« Reply #940 on: May 18, 2018, 12:38:36 pm »
Calibration can be easily done through the service menue.
However, where is that annoying phase shifting coming from?
Is the correction of the 10 MHz xtal done digitally and not through a voltage trimmable TCXO?
If so, i don‘t like it at all.
 

Offline Gixy

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Re: The Siglent SDG2042X Thread
« Reply #941 on: May 18, 2018, 10:47:00 pm »
I use my GPSDO (BG7TBL) as ext. ref. for both my SDG2042X (2122x...) and my TF930 frequency counter: no drift, and no need for calibration (imo).
 

Offline flash2b

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Re: The Siglent SDG2042X Thread
« Reply #942 on: May 22, 2018, 12:15:16 pm »
I have made a transistor Curve Tracer out of my Siglent SDG2042X and posted this on the Dutch CO forum.

Read the English version (via Google Translate) here: https://translate.google.com/translate?sl=nl&tl=en&js=y&prev=_t&hl=nl&ie=UTF-8&u=https%3A%2F%2Fwww.circuitsonline.net%2Fforum%2Fview%2F141079&edit-text=&act=url

Very versatile this 'little' function generator !
 
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Offline exe

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Re: The Siglent SDG2042X Thread
« Reply #943 on: May 22, 2018, 03:25:35 pm »
It is a cool device! Did something similar to measure transition frequency of power BJTs. Unfortunately, 50ohm output might not be enough, so I used external supply (to have collector current around ~1A).
 
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Offline tautech

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Re: The Siglent SDG2042X Thread
« Reply #944 on: June 02, 2018, 07:36:05 am »
Next week I'll check one with an SSA3032X when I have more in stock......remind me.

any news?
Thanks, I should have them in a few days but I've lent my SSA3032X to member hendorog who wants to do some deeper checks on it's performance after comparing it last weekend against his new acquired 22GHz HP and 6 GHz Signalhound. He's got some nice stuff.  :)
So either I'll have to rock by his place next weekend or he'll come to me to return my SA.
Either way we'll get the sreenshots you want but it'll be another week, sorry.
Here's those SA screenshots I promised a couple of weeks back.
Hendorog was kind enough to run my SSA3032X back and even grabbed them for us while we were having a good chat. Anything else you need please ask.

20 MHz sine, into 50 ohms.


40 MHz sine
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Offline tangram

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Re: The Siglent SDG2042X Thread
« Reply #945 on: June 02, 2018, 12:11:25 pm »
Guide for Dummies

1. Plug in ethernet cable and turn on unit
2. Press Utility -> Page 1/2 -> Interface -> LAN Setup -> DHCP ON
3. On you computer telnet (Windows use Putty, OS X and Linux can just use telnet on the CLI) to the IP Address that's displayed. (If you need to manually specify the port it's 23)
4. mount -o remount,rw ubi2_0 /usr/bin/siglent/firmdata0
5. cp /usr/bin/siglent/firmdata0/NSP_system_info.xml /usr/bin/siglent/firmdata0/NSP_system_info.xml.orig
6. vi /usr/bin/siglent/firmdata0/NSP_system_info.xml
7. Use the down arrow to navigate to the line which has '<license><bandwidth_update_license>xxxx</bandwidth_update_license></license>'
8. Press dd to delete the line. Press ESC. Type :wq then hit enter (write quit)
9. Turn unit off and on again

Works a treat!  Thanks so much :-)
"All specifications are subject to change!"
 

Online pigrew

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Re: The Siglent SDG2042X Thread
« Reply #946 on: June 03, 2018, 04:15:01 pm »
Here's those SA screenshots I promised a couple of weeks back.
Hendorog was kind enough to run my SSA3032X back and even grabbed them for us while we were having a good chat. Anything else you need please ask.

These are are pretty good results. There are 1 MHz offset spurs on the 40 MHz plot. Where could these be coming from? Perhaps they would go away with an external 10 MHz reference?

Based on my understanding of the device errata, I don't think that the measurements would tell us anything. It says that there should be spurs at f_data +/- f_out. f_data is 1.2 GHz, I think? f_out is your carrier frequency, so we really should be looking for signals around 1 GHz. However, these would be filtered out in the analog front-end. We might be able to see mixing products ((f_data + f_out) mixing (f_data - f_out)) which would result in a spur at 2*f_out, and more generally the even harmonics. Though, my feeling is that non-linearities in the PA would add to the THD much more than these spurs. So, I don't think that we should be able to see any effect.

To measure the above, we'd probably need to probe before the filters/PA. The spurs might be independent of the signal power, so it should be measured in the bottom of an amplitude range (to reduce the relative power of the desired output signal). The measurement probably should be done with a 800 MHz or so high-pass filter, or a notch filter to block the programmed output frequency. There may also be an effect in the phase noise of the output signal (or the phase noise of the 1.2 GHz spur).

All in all, I don't think that it will have any real-world effect on instrument performance.

I'm much more interested in UI improvements/firmware updates (I noticed that the SDG6000X has separate 10 MHz ref in and out ports... I like that. (Another aside, why don't instrument manufacturers label the ports with their impedance and signal levels? I don't like having to dig that information out of the datasheet)).
 

Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #947 on: June 04, 2018, 06:40:58 am »
Here's those SA screenshots I promised a couple of weeks back.
Hendorog was kind enough to run my SSA3032X back and even grabbed them for us while we were having a good chat. Anything else you need please ask.

Thanks. As I can understand these pictures are taken for SDG2042X, is it right?
Could you please take the same pictures also for SDG2122X (for comparison)?

Also, I'm interesting to see two additional pictures:
1) 20 MHz sine with span 200 MHz
2) 20 MHz sine with minimum possible RBW
 

Offline tautech

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Re: The Siglent SDG2042X Thread
« Reply #948 on: June 04, 2018, 08:11:36 am »
Here's those SA screenshots I promised a couple of weeks back.
Hendorog was kind enough to run my SSA3032X back and even grabbed them for us while we were having a good chat. Anything else you need please ask.

Thanks. As I can understand these pictures are taken for SDG2042X, is it right?
Could you please take the same pictures also for SDG2122X (for comparison)?

Also, I'm interesting to see two additional pictures:
1) 20 MHz sine with span 200 MHz
2) 20 MHz sine with minimum possible RBW
Only have 2042X sorry and previous were at 40 (max) and 20 MHz.
I mucked around for quite a while to try and show more than 2 harmonics so more than those displayed are right down in the noise floor.
1)


2)
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Offline radiolistener

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Re: The Siglent SDG2042X Thread
« Reply #949 on: June 04, 2018, 09:30:16 am »
Only have 2042X sorry and previous were at 40 (max) and 20 MHz.
I mucked around for quite a while to try and show more than 2 harmonics so more than those displayed are right down in the noise floor.

Thanks a lot.
Now it will be interesting to compare it with SDG2082X, SDG2122X and with Rigol DG4102 in the same condition. 
Any chance you can do it in the future? ::)

Also, it will be great if you will test SDG2042X for this modulation issue:
« Last Edit: June 04, 2018, 09:32:36 am by radiolistener »
 


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