Measuring Distortions with the Scope:What you see is not what you really have..

[Martin72]

Hi folks,

I got a sdg1062X(formerly 1032X...) and I´m quite happy with it.
But the day will come I´ll need more than 60Mhz from time to time, so I decided to buy a SDG2042X and (try to) doing the upgrade to the 120Mhz.
With a little bit luck, the generator will arrive on saturday - my personal christmas gift..
My sdg1062X I´ll sell it because two gens I don´t need.
But I got an idea, as long the both are here, I could make some comparisions between the two.
Last year I had to decide to take the 1000X or 2000X - And I´m sure I was and am not the only one..
Both models are popular among hobbyists.
So my idea is, tell me what I should compare between the two and I´ll post it here.
I could set both to say 1khz sinewave and measure with my HD scope the distortion for example, or, or, or...
This is my idea.
Will post here again when the other gen has arrived.

Martin

[BillyO]

When you generate keys for a SDG1032X it gives you a license key for 120MHz.  It would be interesting to see if that would work and compare the results to an SDG2000 "improved" to 120MHz.

[Martin72]

Hi,not sure if I want to do this on the 1032X, must think about it.

Meanwhile, a "few" hours later, the SDG2042X has arrived...
I let it acclimate a while..

[rf-loop]

Hi,not sure if I want to do this on the 1032X, must think about it.

Just don't. (these simple license generators don't really understand anything about these devices. If they generate 120MHz license for SDG1000X ... well, mad(software) can do what mad(software) do.)

[Martin72]

I got twins....nearly. 
Building quality is absolute the same, which is good to know for the ones, who wants to buy the 200 bucks cheaper 1032X.
System menu got one feature more I didn´t notice on the 1032X so far, "Multi Device Sync", must rtfm to understand what this means.
The SDG2042X got a touchscreen which is in my opnion not really necessary - And it´s a little bit annoying when trying to touch it in the upper/lower areas of the screen - Maybe my fingers are too fat, I better use the knobs...
So...next thing I´ll try is to hack the 2042X to 120 Mhz, must read the threads for it.
To be continued.

[tautech]

I got twins....nearly. 
Building quality is absolute the same, which is good to know for the ones, who wants to buy the 200 bucks cheaper 1032X.

Not quite as there are some crucial differences and in some corner cases the 1000X is better.
However it cannot beat the 16 bit and longer Arb waveform depth of the 2000X however if we want a faster edge a SDS1000X has that.

Even with a much shorter Arb waveform depth capability if it fits within memory it can be made to loop for xN cycles or continuously.

[Martin72]

Hi Rob,
With twins the outside was meant...

[pope]

Interesting thread. Thanks!

[electr_peter]

1) Basic test would be to see if there is any second/third/... edge jitter when frequency is not "nice". There should be none.
2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.
3) Also check FM modulation drift w.r.t. SYNC. SDG2000X definitely drifts in FM mode even with the newest firmware (many other AWGs drift the same for some reason).
4) Max frequency of SYNC on SDG2000X is only 10MHz. How does it compare with SDG1000X?
5) SDG2000X has new FW release which seem to improve rotary encoder performance. It would be a good comparison with SDG1000X variant.

[BillyO]

Hi,not sure if I want to do this on the 1032X, must think about it.

Meanwhile, a "few" hours later, the SDG2042X has arrived...
I let it acclimate a while..

I just got back home and tried the 120M license key on my SDG1032X (improved to SDG1062X) and it simply did not accept it.

Oh well.  Never ventured, never gained.

[Martin72]

Hi,

So...next thing I´ll try is to hack the 2042X to 120 Mhz, must read the threads for it.

That was pretty fast:
https://www.eevblog.com/forum/testgear/siglent-sdg2042x-hack-door-closed/msg4599439/#msg4599439

Now I got a SDG2122X...Nice.

[Martin72]

1) Basic test would be to see if there is any second/third/... edge jitter when frequency is not "nice". There should be none.
2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.
3) Also check FM modulation drift w.r.t. SYNC. SDG2000X definitely drifts in FM mode even with the newest firmware (many other AWGs drift the same for some reason).
4) Max frequency of SYNC on SDG2000X is only 10MHz. How does it compare with SDG1000X?
5) SDG2000X has new FW release which seem to improve rotary encoder performance. It would be a good comparison with SDG1000X variant.

Aha....And indeed I wondered about why the encoder is so...slowish and "stuttering"...Thanks for the hint!

[tautech]

2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.

Are datasheets too hard to read ? 
(Square wave) Jitter (rms), Cycle to cycle
SGD1000X    300 ps + 0.05 ppm of period
SDG2000X    150 ps
SDG6000X    100 ps
SDG7000A     20 ps cycle to cycle rms, >10 kHz,1Vpp, 50 Ω load

[Martin72]

FFT with 1khz sinewave, 2.85vpp...
Separate, then both together using both mathchannels, unfortunately the top of the tables are "cutting off" by the screenshot..

[Martin72]

Short video of the setup...

https://youtu.be/ekRBBR1Xj0k

[Roger Need]

Attached is a pdf document which compares the SDG1000x to SDG2000x.  One feature I like in the 2000x is that you can trim the internal 10 MHz. reference from the service menu using a software DAC control.  This gives much better synthesizer output frequency accuracy. 

Roger

[tautech]

unfortunately the top of the tables are "cutting off" by the screenshot..

Save/Recall/Save PNG/Keep menus visible. 

[electr_peter]

2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.

Are datasheets too hard to read ? 
(Square wave) Jitter (rms), Cycle to cycle ...

There is no harm in testing, isn't it? SDG1000X shows some significant cycle to cycle jitter on page 13 in PDF comparison linked above. Devil is in the details, AWGs have many modes, so testing helps to clarify things.
Cycle to cycle refers to CH1/CH2 output. Is it the same spec for SYNC?

[2N3055]

2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.

Are datasheets too hard to read ? 
(Square wave) Jitter (rms), Cycle to cycle ...

There is no harm in testing, isn't it? SDG1000X shows some significant cycle to cycle jitter on page 13 in PDF comparison linked above. Devil is in the details, AWGs have many modes, so testing helps to clarify things.
Cycle to cycle refers to CH1/CH2 output. Is it the same spec for SYNC?

Acronym of the day here is NCO.. Inherent in their operating principle is fractional relation between generated frequency and clock. At certain frequencies CH1/CH2 will have 0 phase jitter to SYNC. On other frequencies it will have rounding errors in phase comparison. There is also a fact that at certain settings, a slight phase dithering will produce cleaner spectrum of the output signal (instead of few large peaks, harmonics gets dithered into wideband noise and into noise floor).

AWGs are great because they are universal. That comes with certain tradeoffs.
They will not have same pulse specifications as specialized pulse generators, but will be good enough for many uses.
They will not have distortion as low as audio analyser but will have very low one, better than many old "legendary" audio sources (my SDG6000X has 0.02% THD at 1kHZ, -10dBm. SDG2000X is actually slightly better because of smaller BW. Those are very respectable numbers),
SDG6000X has CCJ of 2.9ps (that's picoseconds) at 10MHz.. That includes built in TCXO and NCO engine.
These are absolutely fantastic numbers for a simple AWG.

[mawyatt]

@ 2N3055

And why we have (2000 & 6000) and use them, they are that good

People bitch and complain about the UI (granted it's poor), but the "end product justifies the means" 

Best & Happy Holidays

[Martin72]

unfortunately the top of the tables are "cutting off" by the screenshot..

Save/Recall/Save PNG/Keep menus visible. 

I know it but in the moment I´ve made the shots, it wasn´t set...Now it is. 

[tautech]

2) Try looking at jitter of CH1/CH2 vs SYNC. I think SDG2000X does not have jitter, but that would be interesting to know for sure.

Are datasheets too hard to read ? 
(Square wave) Jitter (rms), Cycle to cycle ...

There is no harm in testing, isn't it? SDG1000X shows some significant cycle to cycle jitter on page 13 in PDF comparison linked above. Devil is in the details, AWGs have many modes, so testing helps to clarify things.
Cycle to cycle refers to CH1/CH2 output. Is it the same spec for SYNC?

Okay sorry but you need become more familiar with your instrument as you can tune phasing for better channel edge alignment however it only allows for precise alignment at the tuned frequency and if you change frequency you will need to realign for precise phasing.
First we lock phasing then apply phase + corrections.

[electr_peter]

@tautech, maybe CH1/CH2 in text was not clear enough, I meant single channel CCJ. As I understand, CCJ specs refers to a single channel. Relationship between CH1 and CH2 is a separate question (but both channels should have the same CCJ).

What I am asking it to check jitter between CH1 and SYNC output, as it is not directly mentioned in specs. In my experience, SDG2000X does not exhibit any issues in this area, but on SDG6000X thread there were some questions about this (maybe wrong test setup, I am not sure  ).

[rf-loop]

Attached is a pdf document which compares the SDG1000x to SDG2000x.  One feature I like in the 2000x is that you can trim the internal 10 MHz. reference from the service menu using a software DAC control.  This gives much better synthesizer output frequency accuracy. 

Roger

This comparison is obsolete and extremely poor -- today also partially false.

Years ago example SDG1000X series have get TrueArb function.
(2019-02-25 FW 1.01.01.33R1: Supported TrueArb: 2~16 kpts)
True arb jitter SDG1000X 300ps, SDG2000X 150ps

https://www.siglenteu.com//wp-content/uploads/dlm_uploads/2022/06/SDG1000X_DataSheet_DS0201X_E01I.pdf

Then also quite fun to see that square wave performance is not at all included in this ([www.batterfly.com] stamped) comparison what was "big" advantage in SDG1000X series after older SDG2000X series. If this is Siglent made comparison it looks like they somehow "compete with them selves". Sad there is not any datecode in this obsolete pdf.
(of course SDG2000X is better in many other things).

Btw, it is good question why it is so many times seen that some publications do not have any date and/or version with history (changelog).
 
SDG2000X series max is 25MHz (all models) and rise/fall 9ns
SDG1000X series max is 60MHz (32X 30MHz, 62X 60MHz) and rise/fall 4.2ns (3.8ns @1Vpp)

These are of course out from box. (for compare, factory specs are suitable and recommended to use)

Example my 1062X have 11.8ns pulse rise and fall time minimum. After Siglent it was 16,8ns and example max sweep time is now 100000s when it was 500s after factory (Because one day I needed slow 24 hour sweep so 100ks was nice number) and some other "tweaks".

[Hexley]

Btw, it is good question why it is so many times seen that some publications do not have any date and/or version with history (changelog).

Agreed.

Which invites a comment on Siglent's own documentation -- I look forward to the day when  Siglent steps up to the next level of documentation standards for their products, not only including change logs but also having an index at the back, displaying chapter numbers in the footer, updating the manuals to keep them consistent with firmware changes, etc. 

Maybe 2023 will be the year for that. I can't wait.