EEVblog #806 - Siglent SDG2000X Arb Function Generator First Look - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: October 10, 2015, 06:09:12 am
content: Dave takes a look at the new Siglent SDG2122X / SDG2042X Arb Generator and compares it to the Rigol DG4162 and the older Siglent SDG5082. Including some performance measurements on the Tektronix MDO3000 spectrum analyser.

author: tautech
author_rank: Super Contributor
timestamp: October 10, 2015, 07:00:09 am
content: Thanks Dave, nice overview and well done.Nice to see it measures up well against competition.

author: EEVblog
author_rank: Unknown
timestamp: October 10, 2015, 07:06:38 am
content: If the license on the $499 40MHz version is hackable, it'll sell like hot cakes.

author: sergey
author_rank: Regular Contributor
timestamp: October 10, 2015, 07:38:32 am
content: Thanks Dave for the review!Wondering if 40MHz gen will also have distortion at the top frequency ranges. Anyone to measure this?

author: Chipguy
author_rank: Unknown
timestamp: October 10, 2015, 07:45:30 am
content: Is it this thread for questions to the Siglent CEO who plans to visit you in December?Here is one: Is he aware that the green LEDs on the buttons are very dim and if they are going to do anything about it?Maybe giving him this questions before his visit would be a good idea, so he can consult with staff and prepare.... just sayin....

author: bktemp
author_rank: Super Contributor
timestamp: October 10, 2015, 07:56:17 am
content: It was funny when Dave was unable to synchronize the phase of the two 10Hz square wave signals because the delay was limited to 100ms.

author: Tim F
author_rank: Regular Contributor
timestamp: October 10, 2015, 10:41:39 am
content: On the Rigol set the pulse frequency to something appropriately high to allow you to set a low lead edge/rise time, then enable a 1 cycle burst and use the burst period to set the frequency you desire.

author: Rasz
author_rank: Super Contributor
timestamp: October 10, 2015, 05:03:41 pm
content: You accidentally whole EEVblog #805CEO question: rust, WTF mate?

author: German_EE
author_rank: Super Contributor
timestamp: October 10, 2015, 05:24:48 pm
content: European prices from the Siglent website are as follows:SDG2042X 40 MHz 475 EuroSDG2082X 80 MHz 589 EuroSDG2122X 120 MHz 855 EuroTempting, I wonder how Rigol will respond to these prices?

author: Groucho2005
author_rank: Regular Contributor
timestamp: October 10, 2015, 05:55:58 pm
content: Quote from: German_EE on October 10, 2015, 05:24:48 pmThese are ex. VAT. The 2042X for example would be 565,25 Euro (Batronix) for a private customer.

author: xthexder
author_rank: Newbie
timestamp: October 10, 2015, 10:41:40 pm
content: I just had a play along myself with the Arb function gen built in to the MDO3000. It doesn't quite have the features of these dedicated boxes, but the performance is pretty decent:Using the same 10MHz 500mVpp input signal:The maximum output of the Tektronix scope is 50MHz sine, but it still looks pretty clean compared to the Siglent at it's maximum.

author: rs20
author_rank: Super Contributor
timestamp: October 10, 2015, 10:46:39 pm
content: Quote from: Tim F on October 10, 2015, 10:41:39 amI wonder if this is what Siglent are doing internally to implement their feature. Regardless, what you describe isn't exactly user friendly -- seems like a bit of a garden path to have to go down just to get an occasional pulse.

author: Tim F
author_rank: Regular Contributor
timestamp: October 10, 2015, 11:21:15 pm
content: Quote from: rs20 on October 10, 2015, 10:46:39 pmWith the Rigol basically what most of the inbuilt functions (triangle, pulse, harmonic, etc) are doing is allowing you to create a 16K (16384) sample waveform by setting the various parameters relevant to the type of waveform, and set the sampling rate. The output just becomes the 16K samples repeated over and over at the desired sample rate. When you enable burst all it is doing is creating dead time between outputting each 16K waveform. Obviously you now lose a fair bit control over where the falling edge is placed since it has to be contained within the same 16K samples as the rising edge. e.g. If you set the 'Pulse frequency' to 10MHz to achieve a fast rise time and then use the Burst function to set the period t=1ms to achieve 1kHz, the falling edge can't be more than 1/10MHz = 100ns after the rising edge.Strangely, on the lower frequencies the rigol does not allow you to set the rise/fall time low enough to achieve a rise/fall over 1 sample which is why you get the 'stair steps'. You could get around this by creating a custom arb waveform if you really needed to. On the Square function the Rigol does always transition in 1 sample and the DAC always runs at maximum bandwidth so you achieve the fastest rise/fall time at every frequency.What the Siglent seems to have on the pulse function is the ability to 'pause' at the high and low parts of the waveform so it can always run the edges at maximum sample rate, possibly dedicating as many samples to the edges as possible. I'd be interested to know how it handles edges >8.4ns. E.g. can it handle 12ns correctly, or does it only do 8.4ns increments or possibly even larger increments? That will tell a lot more about how it is achieving that functionality.

author: nbritton
author_rank: Frequent Contributor
timestamp: October 10, 2015, 11:38:05 pm
content: Quote from: Rasz on October 10, 2015, 05:03:41 pmI understand the rust, that's actually the one thing I don't fault them on. Sea air is highly corrosive. Short of plating the steel in a corrosive resistant metal such as nickel the chassis is going to rust. Normally things like machine tools get get coated in a layer of waxy grease prior to shipment, but they obviously can't grease up electronics equipment. They build the units down to a price, so I guess that means the enclosures don't get anti-corrosive nickel plating. Iron redox reactions are a real pain in the ass to deal with.

author: rs20
author_rank: Super Contributor
timestamp: October 11, 2015, 12:45:06 am
content: Quote from: nbritton on October 10, 2015, 11:38:05 pmPrecisely. If you want your money to be put towards making the chassis (which you can't see) prettier rather than putting that same money towards more capable electronics, then you have the Rigol SigGen available to you. I know which I'd prefer.

author: alank2
author_rank: Super Contributor
timestamp: October 11, 2015, 02:34:53 am
content: The rust would bother me, how much does it cost to put it in a plastic bag with some desiccant?edit-I didn't know they had the bag/desiccant, it sounds like they need to keep the cases out of a humid environment instead or prep them to handle it.

author: tautech
author_rank: Super Contributor
timestamp: October 11, 2015, 02:59:43 am
content: Quote from: alank2 on October 11, 2015, 02:34:53 amThat's exactly how Siglent products are shipped.I've never seen rust on Siglent products other than those posted here and they all seem to be on the cut edges of the plated chassis.I have a Tek TDS2012B that has rust on the cut edges of the chassis too.The first I heard of rust was it seems from poorly plated sheet steel from Siglents chassis suppliers.Siglent has replied in various threads that this has been rectified.

author: German_EE
author_rank: Super Contributor
timestamp: October 11, 2015, 09:12:28 am
content: How difficult would it be to either zinc dip or paint a chassis after construction but before electronic assembly? The other option of course is to make the chassis out of aluminum.

author: tautech
author_rank: Super Contributor
timestamp: October 11, 2015, 09:23:00 am
content: Quote from: German_EE on October 11, 2015, 09:12:28 amThere has been much todo of Siglent rust and it is likely they do that now, I'm sorry I don't know.In saying that one also must understand the process of zinc cathodic protection, it seems not many EE's do.https://en.wikipedia.org/wiki/Cathodic_protection

author: nctnico
author_rank: Super Contributor
timestamp: October 11, 2015, 11:24:11 pm
content: I'm wondering how the high frequency measurements at the end where done. Without the scope set to 50 Ohm it is likely the input capacitance messes things up and the measurement is not very relevant at these frequencies.BTW If Siglent's CEO visits give him a 'Programming for dummies' book and some Hammerite

author: Chipguy
author_rank: Unknown
timestamp: October 12, 2015, 05:33:57 am
content: Quote from: nctnico on October 11, 2015, 11:24:11 pmLOL I see that little rust spot really upset many users here.The serious question about this would be something like:"Do they know on what point the housings have been stored or handled in such a moist or harsh environment that some started developing rust spots""Have they taken measures to prevent this from happening in the future"Many manufacturerers have outsourced the production of these parts and buy them from specialized manufacturers.I use to call them "sheet metal benders"(of course german: Blechbieger)Here is one of them:http://www.psw-umformtechnik.de/index.php?article_id=5&clang=1A visit and inspection of the production facilities is usually a good thing to do when you contract one of those.However that is all guessing, depending on the production volume it's sometimes cheaper to make these things in house.

author: pascal_sweden
author_rank: Super Contributor
timestamp: October 12, 2015, 05:48:48 pm
content: Hello Dave,You mentioned that the Rigol has more built-in arbitrary waveforms than the Siglent.But even the Siglent has quite a wide range of arbitrary waveforms, like mathemical, etc.Maybe it's a good idea to highlight the specific use of some of these arbitrary waveforms in an actual use case. Specific circuit or application which needs to be tested, and for which you need to have a specific arbitrary waveform on the input... I am a bit blank on this area, and would like to have a better understanding of the specific use of these pre-built arbitrary waveforms. If possible a coverage of several categories, and each time a specific use case illustrated on a specific circuit or application.Believe that this will be very helpful to the bigger audience.I have only used a signal generator in school for measuring out filters, but never used any of these built-in arbitrary waveforms. Not available at my time AFAIK

author: nctnico
author_rank: Super Contributor
timestamp: October 12, 2015, 07:41:53 pm
content: The Siglent X series seems to be much cleaner. But it would be interesting to take a look at the harmonics from the Marconi generator Dave used as a comparison as well. Usually RF generators are not that clean when it comes to harmonics. Having the 2nd or 3rd harmonic at -30dB or worse is not an exception.

author: cnkz
author_rank: Contributor
timestamp: October 13, 2015, 06:58:35 am
content: Quote from: Tim F on October 10, 2015, 10:41:39 amI have attached screen-shots from 15ns risetime dwonto 9ns rise time in 1ns steps using the SDG2042X. So you can see it does 1ns increments at least. I have not checked shorter increments yet...

author: cnkz
author_rank: Contributor
timestamp: October 13, 2015, 12:18:42 pm
content: Quote from: sergey on October 10, 2015, 07:38:32 amNo, looks clean.

author: EEVblog
author_rank: Unknown
timestamp: October 15, 2015, 10:58:38 pm
content: Siglent have just fixed the bugs I found, and new firmware is going out to dealers. Super quick response

author: German_EE
author_rank: Super Contributor
timestamp: October 16, 2015, 10:39:03 am
content: This company continues to impress me.

author: TrioTest
author_rank: Contributor
timestamp: October 16, 2015, 10:59:34 pm
content: Dave,to get both edges of the different generators aligned easily, (around 16:35 in the video) there's a function on some analog scopes called "Alternate Channel Triggering." I think even the old HP1740 you rescued from me has it too.If you use that function then the scope triggers off the channel it is sweeping so you do not need to try to phase lock the generators to compare the rising (or falling) edges. You can even have 2 different frequencies and both waveforms will be rock solid.Those old classics like the HP1740 (and some of us who used and remember them) still have a few useful functions left in them yet!!Let me know if you wish to try it and I'll get the SDG2122X back to you with the updated firmware.

author: cnkz
author_rank: Contributor
timestamp: October 19, 2015, 09:27:34 am
content: Quote from: EEVblog on October 15, 2015, 10:58:38 pmWhere can we get this firmware? I didn't find it on the siglent web-page....

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 19, 2015, 11:23:38 am
content: Quote from: cnkz on October 19, 2015, 09:27:34 amProbably will come out soon.

author: alank2
author_rank: Super Contributor
timestamp: October 21, 2015, 07:27:10 pm
content: I'm going to give the SDG2082X a spin. Hopefully tequipment will get it to me quickly once they get it from Siglent.The updated firmware has been posted here:http://www.siglentamerica.com/gjjrj-xq.aspx?id=1472&tid=16From the revision notes:1. Supported adjustable noise bandwidth2. Supported harmonic3. Added some built-in arbs, so the number of arb types increased to 1964. Fixed some bugs

author: smarteebit
author_rank: Contributor
timestamp: October 27, 2015, 02:57:58 am
content: Dave, thanks for the video.I think it is a little unfair to compare the SDG2122X with the DG4162 on the 120MHz sine wave, because SDG2122X was outputting a 10Vpp amplitude but DG4162 was outputting a ~4.3Vpp amplitude. I believe if you set the SDG2122X to output 120MHz @ 4Vpp, the waveform will look much better.Generally in an AWG the last stage circuit is a high-speed current feedback amplifier. It's hard to require the amplifier to output a sine wave with both high frequency and high voltage at the same time. What's addition, amplifiers generally are sensitive to the capacitive load at their output. Large capacitive load could cause unstability, so the cable connected to the output should be as short as possible.

author: alank2
author_rank: Super Contributor
timestamp: October 28, 2015, 01:13:17 am
content: The SDG2082X arrived tonight and it is a keeper for me. In contrast, I tried the DS1074Z-S a few weeks ago and was very disappointed with just about everything with its signal gen.My first impression is that it is compact and solid. Feels really nice.I checked its internal clock against my GPSDO and it is 0.160 ppm fast which isn't bad at all. Also, the built in frequency counter is really great because it offers 8 digits and also has a PPM calculation feature which is super. I had considered getting a dedicated counter like the BK 1856D, but this one has so many features that there is no need. If they would add a min/max/average to it, it would be awesome.Unlike the Rigol -S signal gen, the arbitrary waveforms worked really well - at least it would load files and display the right wave, and the controls were responsive and didn't require you to change other controls to become active.I made up an arb wave with 10 sine waves in it and while my unit is an 80 MHz unit, I could easily take it up to 120 MHz. It will not however go past 120 Mhz well at all, even 130 MHz:Output set to 50ohm, 1 Vpp, BNC cable direct to DS4014 CH1, 50ohm enabled10 Mhz = 1.018 V50 Mhz = 1.000 V100 Mhz = 1.006 V120 Mhz = 0.981 V130 Mhz = 0.631 V140 Mhz = 0.200 VI only did a 256 points per sine wave (2560 points total), but it looks really great at 120 MHz.It is my first signal gen, but so far I love this thing.

author: rs20
author_rank: Super Contributor
timestamp: October 28, 2015, 02:06:51 am
content: Quote from: alank2 on October 28, 2015, 01:13:17 amLooks like your oscilloscope and siggen are rolling off together there; after all you'd expect -3dB rolloff from your 100MHz scope at 100 MHz...

author: alank2
author_rank: Super Contributor
timestamp: October 28, 2015, 11:34:50 am
content: A closer look at what I thougth was a bug may not be a bug after all, but the way the DDS chip works. If you setup a small arb wave with the minimum number of points, and you create one like this:-10 -10 -10 +10 -10 -10 -10 -10You will see a triangle type pulse in the middle of it when it transitions from the 3rd sample to the 4th, and then transitions from the 4th to the 5th. This shows that the DDS does an interpolation between samples which is pretty neat. But that interpolation does NOT work on the first and last samples.If you move that +10 to the beginning:+10 -10 -10 -10 -10 -10 -10 -10No more triangle with a rising ramp and falling ramp, you get a straight up line and then a falling ramp. It is not interpolating between the last and first samples.If you move that +10 to the end:-10 -10 -10 -10 -10 -10 -10 +10Now there is a rising ramp and a straight line for the falling. Again, no interpolating.Perhaps this is the way the DDS IC is designed? I haven't looked at the datasheet, but I can't say it is a bug as it works on the front and back of the waveform.With a decent number of points you wouldn't notice it. Also, adding the first sample to the end will cause it to transition back to the first sample as well.

author: alank2
author_rank: Super Contributor
timestamp: October 28, 2015, 05:42:02 pm
content: In case anyone is interested, the .bin format can be loaded directly with no conversion issues and is simply an array 16 bit signed integers. 0x7FFF (32767) is the highest value and 0x8000 (-32768) is the lowest value. It can also go as low as 2 samples, not 8 as the spec says.With the 8M of sample memory, you could load 8*1048576/10=838,860 UART characters and play them back at some baud rate you want.

author: tautech
author_rank: Super Contributor
timestamp: November 12, 2015, 02:51:49 am
content: Link tobillfernandez's Siglent SDG2042X thread:https://www.eevblog.com/forum/testgear/the-siglent-sdg2042x-thread/

author: Electro Fan
author_rank: Super Contributor
timestamp: November 13, 2015, 02:56:53 am
content: Quote from: alank2 on October 28, 2015, 01:13:17 amCongrats on the new SigGen. Did you make the arb through the front panel or via a computer?

author: alank2
author_rank: Super Contributor
timestamp: November 13, 2015, 03:06:39 am
content: Quote from: Electro Fan on November 13, 2015, 02:56:53 amFront panel via USB stick.

author: FaultlineAudio
author_rank: Unknown
timestamp: November 19, 2015, 04:04:55 pm
content: I order my Siglent SDG2122X this morning. According to Siglent the newest firmware update adds the following features:Harmonics Function, 140 or so more ARB waveforms for a total of 193 or so and an adjustable bandwidth to the Noise function.This firmware update was released on 10/28/15Siglent should thanks Dave for his review, it was instrumental in my decision to buy the Siglent over the Rigol.

author: bson
author_rank: Unknown
timestamp: December 06, 2015, 10:11:09 am
content: Has anyone used this with an external 10MHz reference yet?

author: digitaladdictions
author_rank: Contributor
timestamp: April 26, 2017, 02:59:57 am
content: Picked up a SDG2042X in April of 2017. "Upgraded" it to the 120MHz version. I know they released new firmware multiple times by now. Just wanted to point out specifically at 120MHz my sine wave looks better than what Dave was getting in the video on his original release firmware. Maybe not perfect but much better. However, I am only getting 7.24Vpp when set to 10Vpp.

author: tautech
author_rank: Super Contributor
timestamp: April 26, 2017, 03:07:56 am
content: Quote from: digitaladdictions on April 26, 2017, 02:59:57 amCan you just check you haven't got the amplitude value set for Vrms ?

author: rf-loop
author_rank: Super Contributor
timestamp: April 26, 2017, 05:19:20 am
content: Quote from: digitaladdictions on April 26, 2017, 02:59:57 amHow you know what is level in SDG output? Right level is or (mostly) is not on your scope screen. With this kind of frequencies there start grow many errors. Do you have trusted leveled generator for make some compare. Also accurate RF power meter connected directly to SDG input is good way (because we know there is not so much harmonics power).

author: nctnico
author_rank: Super Contributor
timestamp: April 26, 2017, 12:02:18 pm
content: I'd be surprised if a relatively low cost generator can reach 10Vpp at 120MHz into 50 OHm. Better check the specs first to see if there aren't any limits on the maximum output level versus frequency. Another problem might be the generator's 50 Ohm series resistor and the scope's input capacitance forming a complex voltage divider if the 1M Ohm input setting is used. 7.2V would indicate an input capacitance of around 14pf.

author: digitaladdictions
author_rank: Contributor
timestamp: April 29, 2017, 02:15:25 am
content: I really did not think much of the reduced voltage at the high frequency since Dave was getting similar effects and stated that is just par for the course essentially. Basically, I just wanted to report in that the latest firmware seems to be giving a better sine wave than what he got in the video although the peak to peak voltage has dropped.I do not have a power meter (it's on the wish list). I was going off what is displayed on the generator and the measurement provided by the scope. I just repeated the measurement right now and am getting 7.36Vpp. The current screen shot shows the measurement.The waveform generator has a HiZ and a 50ohm option. I had it set to high impedance but I tried changing it to 50ohm. The amplitude automatically drops to 5Vpp when set to 50ohm but at HiZ it allows 10Vpp. What is odd though is I saw no noticeable difference on the scope either in the reported measurement or the displayed waveform. Despite the generator changing the amplitude from 10Vpp to 5Vpp the waveform stayed the same.I can change it to 1Vpp and see the scope change. If I put it back to 10Vpp it gives me a warning that it can only do 5Vpp but actually gives me the same 7.36Vpp. If I go back to HiZ I can change it back to 10Vpp but there is no difference in the output.

author: digitaladdictions
author_rank: Contributor
timestamp: April 29, 2017, 03:38:53 am
content: OK I was not changing the scope to match the generator which explains the lack of difference when switching between 50ohm and HiZ on the generator.Generator set to 5Vpp (max setting) and 50ohm with the scope also set to 50ohm I get 4.2Vpp reading from the scope.Generator set to 10Vpp (max setting) HiZ with the scope set to 1Mohm I get 7.[2-4]Vpp.

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2017, 12:45:02 pm
content: The high-Z and 50 Ohm setting on the generator only affects the amplitude the generator display. The generato's output resistance stays the same: 50 Ohm. In 50 Ohm mode the generator assumes the load is 50 Ohm so the amplitude across the load is half of what the generator's output amplifier is delivering.