The Siglent SDG1000 and SDG800 thread

[jimon]

Arb max frequency setting is 5MHz. Nowhere is told Arb produced maximum frequenxcy is 5MHz.

Sounds like overkill for me, main reason why one want's to buy DDS unit is too have proper UX (like UI, specs, etc), otherwise one can just buy analog devices DDS-on-chip solution and add glue logic to control it.

[rf-loop]

Arb max frequency setting is 5MHz. Nowhere is told Arb produced maximum frequenxcy is 5MHz.

Sounds like overkill for me, main reason why one want's to buy DDS unit is too have proper UX (like UI, specs, etc), otherwise one can just buy analog devices DDS-on-chip solution and add glue logic to control it.

Do you think it do not have?
Here

What is "overkill"? Just normal use of multifuction/arbitrary waveform generator.
Exept that building quality, signal quality and features are overkill in this price class.

[rf-loop]

Repeated my previous tests. (because result was so good that hard to believe)

About SDG805 audio THD.


SDG805 sinewave 20Hz to 20kHz (Keithley 2015THD works only with these limits)

Signal with 50ohm cable to Keithley 2015THD and before test both equipments powered up 1 hour.
Kethley input banana/BNC adapter - 50ohm feed thru terminator.
Level set for 0dBV
Keithley set for 10 counting  filter with moving average.

Result:
20Hz THD 0.009%
200Hz THD 0.007%
1kHz THD 0.006%
5kHz THD 0.005%
20kHz THD 0.005%

Result is agen around same if produce sinewave using Arb function. And now also carefully checked that not mistake with level using Arb vs. Sine mode.

Also checked with some other signal generator if my Kethley is out of order. No, they give same kind of results still what I remember and still some (very)old Wavetek is as poor as it have always been (due to its circuits working principle).


NOTE:  With Arb function SDG00 displayed Vrms is not at all ok for sinewave. It looks like it really do not calculate it from waveform used.

If in Arb mode  level is set using V p-p it is of course ok.

[Mike Warren]

Every time I try to load a CSV arb file from a USB flash drive my SDG1020 locks up and I have to power cycle it.

The waveform is loaded when it boots back up, so it's not the end of the world.

Firmware: 1.01.01.36R1
Hardware: 02-00-00-22-24

Anyone else experiencing this?

[Hugoneus]

Every time I try to load a CSV arb file from a USB flash drive my SDG1020 locks up and I have to power cycle it.
The waveform is loaded when it boots back up, so it's not the end of the world.
Firmware: 1.01.01.36R1
Hardware: 02-00-00-22-24
Anyone else experiencing this?

Does it ever freeze when connected to the USB interface and trying to upload a waveform?

[Mike Warren]

Does it ever freeze when connected to the USB interface and trying to upload a waveform?

I just tried it. That works fine. But I don't normally have it connected to my computer.

[rf-loop]

Every time I try to load a CSV arb file from a USB flash drive my SDG1020 locks up and I have to power cycle it.

The waveform is loaded when it boots back up, so it's not the end of the world.

Firmware: 1.01.01.36R1
Hardware: 02-00-00-22-24

Anyone else experiencing this?

I have tested several SDG1000 series ands never meet this problem. Also SDG5000 and SDG800.
(exeption: I have meet some problems when I have used my own selfmade  .csv files (using example OpenOffice calc, where something is wrong in .csv file structure.)

Where from these .csv files are. From EasyWaveX? From Oscilloscope?
From some third parties softwares?

Can you attach here one .csv file what do not work without reboot.
(just modify filename.csv so that forum accept it. Example add .txt after filename -->  filename.csv.txt)

[Mike Warren]

Where from these .csv files are. From EasyWaveX? From Oscilloscope?
From some third parties softwares?

The files are from EasyWave. I even tried one one you uploaded.

What I haven't tried is a different USB flash drive. I'll do that today.

[Mike Warren]

What I haven't tried is a different USB flash drive. I'll do that today.

Yep, the first drive was a 16GB SanDisk Cruizer Switch, but a 1GB Imation drive works fine.

[rf-loop]

What I haven't tried is a different USB flash drive. I'll do that today.

Yep, the first drive was a 16GB SanDisk Cruizer Switch, but a 1GB Imation drive works fine.

I do not exactly(!) know if in some Siglent equipment still have some limits with USB stick.
Many times I have recommended to use 8Gb or less size USB2.0 sticks.
FAT32 default cluster size is 4k for 256Mb - 8Gb  and  8k for 8Gb - 16Gb  and 16k for 16Gb - 32Gb.

Yes, this table what Microsoft have puplished is really fun. If I look this table then I will ask. Which one is default cluster size exactly for 8Gb  4k or 8k? Or is it random variable both or just "who knows - who cares".

I have not perfect answer what are exactly supported USB stick specifications with SDG1000, SDG800, SDG5000 or other Siglent equipments but it is sure:
When I have used 4Gb USB2.0 sticks I have not meet any problem. (this is why I keep this still this practice) Knowing what is, is more easy than knowing what is not. 

If ask from chinese there need first ask. Then get answer, then ask more accurate, get answer, then after new answer need agen made new question more and more deep details... this iteration loop is endless and finally other or other part gives hands up. It is almost impossible to get a fully comprehensive and precise answer.

[rf-loop]

Issues (unsolved)
*SQUARE WAVE GLITCH....

Why this is marked as unsolved?
As far as I know this HW related thing have solved long time ago. 
There is NOT Square wave glitch problem. (But there was time ago in some manufacture lots/HW)

There is not Square wave jitter problem. 
What there is,  is normal quality of square wave what meets specifications and what are quite normal in this circuit principle where square wave is derived from sinewave. Of course  time error  rise when go more and more low frequencies. (It is 0.1% error in cycle time Typical at 1kHz).  This is normal and this is told in specifications and it is natural. Previously there was more this jitter before there was some fine adjust in HW By Siglent.

Square/rectangle wave  (just before and up to) start of rise corner and (just before and up to) start of fall corner glitch problem is also HW related and partially origin from same reason with square wave cycle to cycle jitter with low frequencies (long time periods).  As far I know these very small changes in HW around square wave PECL comparator  have done By Siglent long time ago.

[rf-loop]

Images clarify the previous message.
1 .Square wave (using Square function) cycle - cycle jitter. 1kHz.

2. Square wave (using Square function) glitches before rising edge. Zoom 100x
3. Square wave (using Square function) glitches before rising edge. Zoom 1000x

4. Old (January 20, 2013, 06:08:29 PM) EEVBlog member "BlueLaser"  image about glitch issue in SDG1020.
This >2 years old hardware issue is totally obsolete  but the old news and beliefs circulating over and over again, creating a modified truth.

Today SDG1000 serie is very clean from any major issues in signal quality, building quality or functions. My message to Siglent is: Do not repair a well-functioning device, it can only get worse.
(there is some minor things what can and need do if want it even better but is it WISE to push power for it. Because it IS good or even leader in its price class.)

[Lightages]

I just received my SDG1025. I like the feel of it and it seemed OK until I started playing with the sweep function. It arrived with the latest firmware that I see on the Siglent site, with version 3 bootloader. The sweep function was messed up. It didn't matter which direction I set the sweep, it would always start at the highest frequency set and then ramp down, and then back up again! I played with this for a bit and then got the idea to try and reflash the latest firmware. I was surprised that it actually fixed the problem It now sweeps as per the settings and only in the direction requested, not up and down continuously. The bootloader changed to 5.....

I am now happy with it so far. The output drops a bit as it passes 15MHz but I was too tired to quantify the drop. The sweep seems to be "smooth" enough if the sweep time is set to a realistic time based on the sweep range, lin and log.

[rf-loop]

I just received my SDG1025. I like the feel of it and it seemed OK until I started playing with the sweep function. It arrived with the latest firmware that I see on the Siglent site, with version 3 bootloader. The sweep function was messed up. It didn't matter which direction I set the sweep, it would always start at the highest frequency set and then ramp down, and then back up again! I played with this for a bit and then got the idea to try and reflash the latest firmware. I was surprised that it actually fixed the problem It now sweeps as per the settings and only in the direction requested, not up and down continuously. The bootloader changed to 5.....

I am now happy with it so far. The output drops a bit as it passes 15MHz but I was too tired to quantify the drop. The sweep seems to be "smooth" enough if the sweep time is set to a realistic time based on the sweep range, lin and log.

This version of 1.01.01.36R1 what is now downloadable from Siglent there is repaired this terrible mistake what they make in previous version with sweeps. (I do not remember if there was same name R1 short time what was broken, but so or so...this newest 36R1 (Published?2014-11-27) works)

Phase continuing stepping log sweep works now. (perhaps if possible I hope they change it so that with wide freq span sweep it use different step increment math) 

New features:
-Channels lock (slave follow master as master freq is changed. There can also be fixed freq offset between master and slave channel or phase offset.)

-Output load setting was previously Hi-Z or 50ohm.
Now if user select this load (previousluy fixed 50ohm) user can adjust load value from 50ohm to 10kohm.

[alterbaron]

I just received my SDG1025. I like the feel of it and it seemed OK until I started playing with the sweep function. It arrived with the latest firmware that I see on the Siglent site, with version 3 bootloader. The sweep function was messed up. It didn't matter which direction I set the sweep, it would always start at the highest frequency set and then ramp down, and then back up again! I played with this for a bit and then got the idea to try and reflash the latest firmware. I was surprised that it actually fixed the problem It now sweeps as per the settings and only in the direction requested, not up and down continuously. The bootloader changed to 5.....

I had experienced the same issue. My unit shipped with the 1.01.01.36 firmware and had the sweep issue. Flashing 1.01.01.36R1 fixed the problem, and now it works a treat.

[Lightages]

OK, just measured the frequency response. The claim is that it is within ±0.3db with reference to 100kHz at 5 volt output. There is no mention of what load it is measured with. I made a log sweep and recorded the screen with a 50 ohm load, 100kHz to 25Mhz at 5VPP. That is the first image. It does just meet the spec in this case as it drops by about -0.27db. With a 3VPP output it drops closer to -0.95db, second image.

With no load, or rather 1Megohm scope input, the 5VPP is about +0.21db and so is the 3VPP output setting.

So it does meet its spec, but be aware that the curve changes based on load and output and is closer to 1db out or more worst case.

I will qualify more of the output response over more conditions it a bit more later.

[rf-loop]

OK, just measured the frequency response. The claim is that it is within ±0.3db with reference to 100kHz at 5 volt output. There is no mention of what load it is measured with.

"...at 5 volt output. There is no mention of what load it is measured with."

With 50ohm load 5V output is 2.5V.



Here you measure  your whole system frequency response, not SDG1000 output freq response.
Your cable+oscilloscope input is not 50ohm true impedance with over 100kHz to 25MHz band. (yes you can put external 50ohm or internal if oscilloscope itself have but it is not pure 50ohm load, not even with 25MHz. Also there is oscilloscope itself freq response. Then, with different measurement you have changed oscilloscope settings so not even these pictures can not compare with each others. If you have reference signal generator what really have flat response over this range you can make reference with it and then compare result with SDG (using exactly same test setup)

Simplified: With your test can not classify SDG1000 output if it is in specs or not with enough true accuracy.


Atteched how it can classify.  (also if you have SDG1000 with real calibration certificate it need pass this and other specs in SDG1000 calibration manual when cal lab do measurements for certificate)
(Other method is real professional quality spectrum analyzer with known level accuraacy and flatness (these both (power meters and good spectrum analyzers) mostly have real enough accurate 50ohm impedance instead of only 50ohm DC resistance.)

Edit: Added attachment image how to adjust freq response of SDG1000

[Lightages]

Hmmm, I see what you are saying, but I am not sure I agree that my inline load and cable are not flat enough at 25MHz bandwidth. If what you say is true, then adding another length of cable should show a difference again if the cable is at fault. I will try that tomorrow and see if I get a result that would indicate that my cable and/or load are at fault. I will also do it with the same input settings on the scope.

Please excuse my naivety with this frequency realm as I never really dealt with things like this above 10MHz and sometimes I played with things around 25MHz but not with any precision.

[rf-loop]

Hmmm, I see what you are saying, but I am not sure I agree that my inline load and cable are not flat enough at 25MHz bandwidth. If what you say is true, then adding another length of cable should show a difference again if the cable is at fault. I will try that tomorrow and see if I get a result that would indicate that my cable and/or load are at fault. I will also do it with the same input settings on the scope.

Please excuse my naivety with this frequency realm as I never really dealt with things like this above 10MHz and sometimes I played with things around 25MHz but not with any precision.

You can not really check your load impedance with changing cable lenght. You may see some change but can not classify what is really going on. Your test method is somehow ok, this I do not push to garbage.  But your test accuracy is not enough for claim if SDG1000 is in specs or not. You can only tell that "my setting this and that show this and that image. But starting claim part of decibels... (I can see there is even 1/100 of dB  resolution in your numbers but your system really can not be even close with this needed accuracy)

This next example  is not true in this test setup but just for give some weak light for thinking dB's and 0.1dB's and 0.01dB's

Think pure resistance 50ohm (not RLC hybrid)
Then connect 20pF pure capasitance parallel with it.
Next can not exactly do due to many reasons but if we forget phaase etc things and simply think that C is "resistance" with some other than just DC.

Lets look reactance map. With 25MHz this example 20pF  reactance is 318 ohms.
(btw with 100kHz it is 79.6 kohm and with 100MHz 79.6ohm)

Lets do deep simplification. 50ohm parallel with 318 ohm is 43.2ohm. 
Is your load impedance now 50ohm. Not. What it means  with dB's. (you can calculate)

(in real system there may be things what make situation more or less bad due to other R and LC reactances in total setup. Example: Oscilloscope input is RLC hybrid... there is RLC Network what may or may not affect more os less with different frequencies together with cable)

In real life things are much more complex. Due to other reactances of course.
This kind of "simply thinking calculkation" give only imagine what may happend and if it affect lot of or perhaps less. But it is well enough for tell that 0.01dB's are sure total garbage.
 
Oscilloscope like Rigol (and most of other simplemachines) do have only 50ohm +/- something resistor connected parallel with input by relay. It is not true 50ohm impedance over freq span.  HF power meters heads are totally different "animals" and also example good spectrum analyzer inputs. And even more bad it go if we use  coaxial T and external 50ohm terminator. Feed thru terminator is some amount better but still there is scope input reactance with it.

My point is only for accuracy. If we talk 0.1dB or even 0.01dB things in flatness your measurement is not valid.  Using 50ohm termination and 50ohm cable and oscilloscope is ok for many kind of measurements. But it need understand what kind of error sources it may have. And just forget 0.1dB and 0.01dB thins.

[Lightages]

I just did some more testing and I could not recreate the differences I saw before. I think, perhaps, that the internal relays on the outputs were not making good contact the first few times I did this. Maybe now they are making better contact after a couple of cycles and everything is more stable. I am not even sure the relays I hear inside are on the outputs but there is a difference from yesterday in the performance I see.

Yes I see small differences now between a coax with a termination on the end connected directly to the scope, and the termination directly on the output and sampled with a 10x probe with a BNC adapter.

Either way, I am very happy with this AWG, at least as a function generator. I have yet to still use the AWG function.

[Lightages]

Well another update. I had purchased a 25MHz TCXO to replace the simple crystal as demonstrated in the links in the first post. It is a 0.3ppm TXCO. All went well and apparently it improved the frequency accuracy. Before a 10MHz output would read 10.00014MHz on my frequency counter and 10.0002 on my DS1054Z. Now all three instrument agree on the frequency except the frequency counter shows 1 count out sometimes.

[rf-loop]

Well another update. I had purchased a 25MHz TCXO to replace the simple crystal as demonstrated in the links in the first post. It is a 0.3ppm TXCO. All wen well and apparently it improved the frequency accuracy. Before a 10MHz output would read 10.00014MHz on my frequency counter and 10.0002 on my DS1054Z. Now all three instrument agree on the frequency except the frequency counter shows 1 count out sometimes.

Do you have datasheet about this TCXO or manufacturer and model.

[kwass]

Well another update. I had purchased a 25MHz TCXO to replace the simple crystal as demonstrated in the links in the first post. It is a 0.3ppm TXCO. All wen well and apparently it improved the frequency accuracy. Before a 10MHz output would read 10.00014MHz on my frequency counter and 10.0002 on my DS1054Z. Now all three instrument agree on the frequency except the frequency counter shows 1 count out sometimes.

Do you have datasheet about this TCXO or manufacturer and model.

I bought one of these:

http://www.ebay.com/itm/221589387690

only one left, however.  (I'm not sure what happened to the picture on ebay, the crystal is  marked MDD).  Checked it against my calibrated Racal Dana 1992, it was better than .1ppm without adjustment.  It works great on my SDG1025.

[Lightages]

This is the one that I purchased:
http://www.ebay.com/itm/141421463923?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
The data sheet supplied is below.

[Lightages]

I have been playing around with all my equipment tonight and realized the the rotary knob has a push function. I cannot find any use for this. Anyone?