Comparaison Générateur de fonction Rigol DG1032Z et GW Instek AFG2125 - Page 1
Forum section: electronics / testgear

author: Electro Fan
author_rank: Super Contributor
timestamp: November 16, 2014, 10:17:35 pm
content: Hi French (& English) Speaking EEVers,Just checking to see if anyone who speaks French would be up for summarizing the conclusions of this comparison?Thanks! EF

author: old gregg
author_rank: Regular Contributor
timestamp: November 16, 2014, 10:52:01 pm
content: to summarize, he sends back the GW and keeps the Rigol.The GW has an offset error on the output (21.2V for 20V output) whereas the Rigol is more precise.The rigol is built in a better fashion, the LCD is clearer but hard to view at an angle. The encoder seems a bit fragile and the fan is loud.The GW is supposed to output a 25Mhz square but start to look ugly at 7Mhz (at the 7th minute). At 25Mhz it looks like a (funny-looking) sinus with a reduced amplitude (which is quite amusing). It seems to be tedious to set the GW (arbitary fonction)The GW has a 10bits output whereas the Rigol has 14bits.The Rigol seems to be clear winner for him despite the price difference.

author: miguelvp
author_rank: Super Contributor
timestamp: November 16, 2014, 11:00:01 pm
content: Old greg you spoiler, I'm translating the video, here is what I got so far first 6 minutes 30 seconds:I'm going to present two function generators dg1032z and gw Instek afg2125on the isntek I found some faults in particular as I showed in a previous video I found that the outputs are not that good, for example I put the voltage to be 10 volts when I look in the scope I see 17/18 volts (wasn't too clear because he said it fast but he probably is 11-12 volts)When I set it to 20 volts it outputs 21-22 voltsIt doesn't matter much because it's not a lot and the instruments are not supposed to be that precise, but never the less, 6% error between the generator and the scope is quite a bit.I didn't have bnc cables until now so I thought it was due to the cable.I received my rigol today so I could use the cable that came with it on the instek1khz 10 v set, that is easy, output engaged, impedance 50 ohms, what do we see in the scope, press auto, I don't know if you can see it 16-17 volts not quite 10 if I maximize the wave its still that but it's not too much and the signal looks good.Now to compare i'm going to unhook the instek and put the bnc in the rigols output, it's hard because it's too new, there.frequency 1khz i'm already at 10 v, then he talks about how the screen looks as in angles. i'm going to enable the output and there you go, 2% error between the scope and the generator and that's more acceptable.I'm also going to show you something that shocked me a little the instek can do up to 25MHz output square wave, i'm not going to show you how this looks because...(lost that), so i'm going to input then a square signal and i'm going to start with a frequency of 500 khz i'l leave it at 10 volts (hmm he forgot the cable is still plugged into the rigol)Continued:auto press, there we have a square signal, not perfect but reasonable, now i'm going to increase the signal little by little, 500khz, 600, 700, 800, 900, 1Mhz, now to 2Mhz, 3Mhz4, 5, 5Mhz it doesn't quite look like a square wave. It looks more like a rectangular wave (don't think he knows what he is doing/saying)So I continue, 6Mhz 7Mhz 8 9 10 11 .. 12 13 14 15.. now it looks like in between a triangle wave and a sine wave, 16 17, oh, have you seen that? 19 20 21 22 23 24 25Mhz.Well at 25 Mhz what we have a signal that is no longer rectangular, this is not spectacular (then he goes to say something that I didn't pay much attention)For comparison I'm goign to leave it like it is and change it to a sinusoidal wave... 25Mhz, here is at 25MHz sinusoidal and if I press square, puf there it goes. (the amplitude changes), No super top (it's an expression meaning not top notch).(time so far 10 minutes)Then he changes the scope to 1 khz at 10v and we are going to see what it shows in the scope, I'm going to regulate the scope to show a little trick ... oh not on a square signal....(I'll finish it later have to do something.)Then he complains a bit that it did reset the frequency because the generator is not capable of generating all the signals at 25MHz so now I'm in sinusoidal at 1khz 10 volts, I go back to the scope, and here.. 11:45 ... ahh there it is you can see the ladder now close up and there it is. 1021 values of ascension (I bet he meant 1024) he saids it right, right after.Now going to show the difference with the Rigol (12:38) the Rigol uses 14 bits 2^14 that is 16384 possibilities so that gives a precision 16 times better.I'm going to disconnect the bnc from the instek and plug it into the rigol, there is done and now not touching a thing if you look at the scope you'll see the signal is not stepped (I think that's what he said crenelee no idea what that means) it is perfect, and if I go farther, but the trigger is giving him problems14:00Going to attach it to the intek and there you go it makes a difference, it's not the same price because the instek list price is 139 euros with 20% discount, so 115 euros, the rigol list price is 198 euros, then goes about the store and price difference.Rigol has 2 independent outputs up to 30 Mhz, construction quality is in par of the instekI think then he complains about the tilting vale and the fan that is blows too hard (I guess that's for the fan being loud on the rigol)This is all I want to show ,ee..... what else can i show. I'm going to press the auto button (16:22) there you go the sinusoidal wave generated by the instek (he apologizes about the video shaking because he is using his iphone)Then he goes to show all the signals you can do on the instek (16:52) we are at sinusoidal, square, ramp then sets it to 1Mhz and zooms in.Then I think he says he can't go higher than 1Mhz so goes down to 800, 700, 500.Then we have a signal of noise, and there is no frequency setting it's just noise and you only can set the voltage output.And then the arbitrary wave generation. Here I'm going to say that I'm a little surprised, I don't know how with this equipment (refering to the instek) I can create my signals, I did try, but it's complicated, you have to enter the signal a point at a time (deep exhalation 18:38) and I don't have the patience to do that. The equipment came with a little CD that allows you to input the signal from a computer and then upload it to the generator but meh.Me I only care about the square and sinusoidal waves. Then he mentions that there is the possibility of doing a sweep between two frequencies.19:42, I could show you and example, for example I'm going to input a sinusoidal signal... so we are going to enter the sweep mode.starting signal I'm going to input 100KHz and sweep of 5 milliseconds, amplitude I'm not touching it.. and now we are going to look at it on the scope (20:50)Lets see what that gives... the signal well it's imposible to trigger on the signal. So I can't show you and I'm going to stop the acquisition, the sweep starts here (21:24)If I zoom we can see the wave is present here. so that's the sweep function, it is useful to measure resonant frequencies, fo an oscillating circuit or a capacitor by itself.So the only problem with this piece of equipment (instek still) is that we can't change the period, the duration of the sweep, I didn't measure it or figure out how to do it but on the rigol that I just got you can change everything, the frequency the duration, all.That's it for this video and I hope that you like it.

author: dentaku
author_rank: Frequent Contributor
timestamp: November 16, 2014, 11:03:31 pm
content: Let's see if I can understand the not terribly good iThingy audio and the very European accent- He was surprized at how inaccurate the GW was at the start when he compares a 1kHz, 10Vpp signal with 50ohm impedance he gets 10.6V and the Rigol is better giving him 10.2V with the same settings.- The GW is supposed to be able to generate a 25MHz square but as you see in the video it's not square at all when he cranks it up a bit past 5MHz and more of a sine at 18MHz- It can output a clean sine wave at 25MHz though- He zooms into the GWs signal to show the stairsteps then switches to the Rigol to show how it's not blocky (at around 13:00 min)- The GW has a sweep function which he demonstrates at the end of the video but he doesn't like that you can't control the speed of he sweep unlike the Rigol.Ha! old gregg beat me to it

author: Electro Fan
author_rank: Super Contributor
timestamp: November 16, 2014, 11:37:23 pm
content: Quote from: miguelvp on November 16, 2014, 11:00:01 pmWow, thanks for the very quick French language support! Thanks old gregg, miguelvp, and dentaku!migeulvp, in the part you translated above it sounds like the video poster was trying to demonstrate the Instek's challenges with displaying a square wave - but it sounded like maybe he forgot to move the cable from the Rigol to the Instek? By the time the translation gets to "Continued: auto press, there we have a square signal...." had he moved the cable back to the Instek?What was the maximum frequency the Rigol displayed a good looking square wave? Any other notable finds regarding the Rigol?Thanks, EF

author: miguelvp
author_rank: Super Contributor
timestamp: November 17, 2014, 12:22:04 am
content: I just finished it, the thing is he didn't focus any effort on the Rigol signal generator in my opinion.Just assumed everything is perfect with itJust by watching his video it doesn't give me much confidence on being a good detailed reviewer. Although it wasn't a waste, I used it to practice my french which I haven't used for over 25 years (well maybe a handful of times and a movie now and then).Edit: I used to be able to think in French, now English took over that, but every time I stop by France it just takes me a day or two to get it back so I don't need to translate the words one by one and it automatically engages, but it's pretty dormant lately.Maybe the Unibroue Maudite beer I was drinking while translating helped a little

author: miguelvp
author_rank: Super Contributor
timestamp: November 17, 2014, 12:41:52 am
content: Quote from: Electro Fan on November 16, 2014, 11:37:23 pmYes that was at 6:44 in the video, he was mainly focusing on the InstekQuote from: Electro Fan on November 16, 2014, 11:37:23 pmHe mentioned 30MHz, but he didn't do a lot of testing of the Rigol, if any at all.

author: old gregg
author_rank: Regular Contributor
timestamp: November 17, 2014, 11:40:13 am
content: I've no merits, I'm a froggy-coustaux myself (as I heard recently).yes the reviewer seemed to not be very keen on the GW compared to the Rigol. But the Rigol costs 200euros more.The review is more focused on the (relative) poor performances of the GW. The 25Mhz sinus-like square is really silly.You don't have much to hear about the Rigol, it's mainly about the reason why he sends back the GW.

author: anotherlin
author_rank: Frequent Contributor
timestamp: November 17, 2014, 01:27:16 pm
content: miguelvp, your translation is basically correct, your understanding of french is goodI don't think the poor voltage precision is that much of a problem. As long as the generated signals are good (sine wave is actually a sine wave, a square is a square). It would be best if the requested voltage is spot on, but you may just adjust for it. If you intend to use the generator using programming, that's a big problem though.The 25MHz square which is a sine wave on the Instek, that's very bad.Regarding arbitrary waveform generation, 10-bit (Instek) vs. 14-bit (Rigol), I'd rather think the problem is that the Instek doesn't apply a low pass "reconstruction filter" hence you see "stairs". "Zooming" enough, 14-bit would also show stairs without filtering. Also, planning to enter an arbitrary waveform by hand doesn't make sense. If there's a CD with a program (Instek), use it !

author: rf-loop
author_rank: Super Contributor
timestamp: November 17, 2014, 02:35:10 pm
content: I do not try tell Instek is ok. It have very low grade specifications in all meanings.But when we tal that sine must be sine and square need be really square.I can see real square waves only in books.You take Hewlett.Packard old ancient 20MHz function generator and adjust it for 20MHz square. What you see. Nearly as (badly) distorted sinewave. I take old HP pulse generator where is risetime around 1ns . I run it for 100MHz Square and look with example 500MHz oscilloscope. Signal shape is far away from square.Now if we read this Instek generator specifications there read:Quote25MHz whole cycle time (period) is 40ns.50% duty it means it is 20ns high and 20ns low.Now think specifications. (and even more, all know that normally rise and fall time is measured between 10% and 90% levels. )Draw it using these specifications to piece of paper and think. With these specifications it need not even rise to to top level or fall to bottom level.Ok other way.How much bandwidth is needed if look 25MHz square wave so that it also looks square or nearly square.Perfect squarewave can think produced by infinite count of mother frequency (25MHz) odd harmonics (with different amplitudes).If we take 1. , 3. and 5. harmonic it do not yeat look square wave but not total crap. How if we add 7. harmonics. Well it is better, then 9. more better. 11. harmonic, and agen better but still not as ideal square wave in book. But normally it can think that 5.-9. odd harmonics with around right level is enough for normal use.Who really think that there is 0-300MHz linear amplifier inside. Of course there is not.I do not know if this Instek meet evcen they specifications but specifications tell exatly that there is NOT 25MHz square wave and not even "squarewave".Im so lazy that I do not want even take equipment for test if I can clearly see in specifications that there is not any reason to look it. And with this Instek it really can see. Instek have told that it do not generate 25MHz square wave at all. Not even close.Rigol specs tell that Square risetime is <10ns.Overall just reading specification can immediately know that these equipments are really far away from each others. Compared to Rigol this Instek is like some kind of joke or toy if seriously talk about 25MHz function/Arb signal generators.Also if look example Amazon price for this Instek. Nearly USD 500.If look example Siglent SDG1025 it is in same Amazon around USD 350 and it is far far over this.In its price class it is good tool, really good. Perhaps best what you can get in its price class.Siglent low end serie SDG1000 (example this SDG1025) is not just as good as this Rigol DG1032Z but Rigol price is also double.