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Siglent SDS2000 new V2 Firmware

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Performa01:

--- Quote from: Wuerstchenhund on December 27, 2015, 12:18:14 pm ---Or so you hope! :-DD  Don't forget that this scope is on the market for almost two years now, and still suffers from bugs that make it pretty useless for any real type of work.

--- End quote ---

What bugs are you talking about, that make it ‘pretty useless for any real type work’?

I have used the SDS2000 to troubleshoot, repair and redesign some older test gear, including some high precision stuff, and as a DSO, it didn’t let me down. I just had to use a separate LA as the digital channels were not working with the initial V2 beta firmware.

Other brands are big companies that have built gear for decades and have a big R&D department with lots of firmware developers. The firmware for a complex piece of gear like a modern MSO isn’t that easy to develop from scratch with just a handful of people.



--- Quote ---In short, you pretty much bought a half-finished (ok, 70% finished) scope and agreed to work as a beta tester for free.  :-+

--- End quote ---

What’s left, if nobody else does? ;)

Siglent claims to aim for making affordable test gear available for everyone. Many private users out there certainly welcome that. Do we reach that goal by just bashing Siglent for some immaturities in their firmware, or is it more likely to achieve something by reporting any bugs we find?

I could understand if people get angry for instance about bugs in a Rigol 4k, as these start approaching the prices of A-brand scopes in the same class, also with the various software options. If we have to pay big money like for an established A-brand, we expect a mature product indeed.



--- Quote ---Yes, the WaveAce is shit (guess who made them?) but there are many other alternatives which aren't.

--- End quote ---

Oh, of course. If you you’re willing to pay 5k or more for the basic scope, plus another 1k for each and every software option, even if it’s a serial decoder for just a single protocol, and still make do with relatively short memories, than I’m sure you’ll find ‘many other alternatives’.



--- Quote ---Most of them? The Keysight DSOX2k has a hires mode (10bit), as does the R&S HMO1000 (up to 16bit?). If I remember right even the Rigol DS2k/DS4k have some working hi-res modes.

--- End quote ---

Maybe. I have the impression that resolution enhancement wasn’t that common until recently.



--- Quote ---That's nonsense, sorry. FFT does not need 12bit vertical resolution to "make sense", and is a pretty useful facility even on 8bit scopes, assuming of course the implementation isn't crap (like Rigol's limit of a few thousand points only) and works correctly (which it does on other scopes).

--- End quote ---

For spectrum analysis, I personally just cannot think of too many use cases, where I would want to have less than at least 70dB of dynamic range.



--- Quote ---Reliability is certainly an issue, but frankly what accuracy do you expect from a scope with a timebase that is spec'd with +25ppm? Without an external clock reference (i.e. GPSDO) the accuracy will be limited by nature.

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I don’t think I expect something unreasonable. Every single quartz crystal oscillator I’ve used so far was pretty much spot on within a couple ppm of its nominal value at room temperature, despite the specs that usually say +/- 100ppm. So it is somewhat strange if an oscillator in a scope is close to the limits of its accuracy spec. right from the start.

The much bigger problem is the lack of resolution anyway, due to its not implemented as a reciprocal counter, which is all the more incomprehensible, given all the computing power in such a scope.



--- Quote ---Reliability is certainly an issue, but frankly what accuracy do you expect from a scope with a timebase that is spec'd with +25ppm? Without an external clock reference (i.e. GPSDO) the accuracy will be limited by nature.

--- End quote ---

I don’t think I expect something unreasonable. Every single quartz crystal oscillator I’ve used so far was pretty much spot on within a couple ppm of its nominal value at room temperature, despite the specs that usually say +/- 100ppm. So it is somewhat strange if an oscillator in a scope is close to the limits of its accuracy spec. right from the start.

The much bigger problem is the lack of resolution anyway, due to its not implemented as a reciprocal counter, which is all the more incomprehensible, given all the computing power in such a scope.



--- Quote ---Y out was pretty much only available in a few specific Tek scope models and was also bandwidth limited, so it was only really useful for very specific cases.

--- End quote ---

To put it in your own words: that’s nonsense, sorry.

But on this topic I discovered something interesting:

http://blog.hameg.com/?p=622

So while I thought Y-out has gone with the introduction of digital scopes, apparently Hameg/R&S provide a Y-output (again) at least for their HMO series. That’s great news, and makes these scopes attractive for people who want an accurate trigger frequency display. And it is exactly like it used to be with the analogue scopes – the y-output follows the triggered channel. And no, it was NOT bandwidth limited at all.

I have no doubt though, that the built in frequency counter of an HMO has true 6 digits of resolution and would be fairly accurate (like even on the ancient Rigol 1054E), so there is much less need for an y-out just to feed a proper external frequency counter anyway.

nctnico:

--- Quote from: Performa01 on December 27, 2015, 05:13:33 pm ---Maybe. I have the impression that resolution enhancement wasn’t that common until recently.

--- End quote ---
That depends on your definition of recently. The Tektronix TDS500/700 series which was introduced around 1990 has high-resolution mode as standard.

Performa01:

--- Quote from: nctnico on December 27, 2015, 03:15:41 pm ---The V2 firmware doesn't look like it is much better than the V1 firmware. Just more things plastered over. If you want to use an oscilloscope's FFT function to check the spectral waveform purity of the signal generator than you are clearly using the wrong tool.

--- End quote ---

Oh? I’m a bit confused right now. What do we use in order to check the spectral purity of a signal? A spectrum analysis tool, don’t we? And what is an FFT analyser then?

So you probably meant to say I should have used a _proper_ spectrum analyser instead, right? You’re absolutely correct about that – I just don’t have one here at the moment (and the one I have in my second lab only starts at 500kHz, so there would have been a gap anyway).

So you’re basically suggesting that FFT on an 8 bit scope is not the right tool to do a proper spectral analysis. That’s certainly correct, mainly because of the severely limited dynamic range.
 And that’s exactly what I said all the time.



--- Quote ---Either way the value for money the SDS2000 offers just isn't good because a lot is severely limited at best. You can buy a used DSO for the same amount of money which has proper FFT and works as advertised.

--- End quote ---

Is it really that limited? Just because average and Eres modes aren’t very useful right now? And just because of the FFT? Why do we need FFT on a scope anyway, when you yourself stated it’s not the proper tool for doing spectrum analysis?



--- Quote ---The added value of the SDS2000 is in the MSO, protocol decoding and advanced features but it is those that cause most of the headaches. If I didn't need protocol decoding I'd never bought the SDS2000 to begin with!

--- End quote ---

That’s fine, but not everyone is like you.

There are also folks like me, who want a scope with reasonably high bandwidth, high signal fidelity and a reliably working, jitter-free trigger system. And deep memory of course, so we don’t run into aliasing troubles when looking at signals that contain LF and HF components at the same time.
Ah – yes, we also want a reasonable high waveform update rate, so that we can see what’s going on with a dynamic signal.

All the additional bells and whistles are nice, but it’s not the world if there are still some flaws in them.
Particularly for protocol decoding I have no problems to stick with my LA if needed. The nice thing of an MSO is that it’s so easy to correlate analogue and digital signals, where digital in my case mostly means control signals and not a serial bus, even though this would certainly also be very useful for some cases, e.g. troubleshooting A/D or D/A converters with a serial interface.



--- Quote ---Also your remarks about averaging and high res being OK with a short memory is nonsense.

--- End quote ---

Thank you. Where and when did I ever say it is ok?

The best thing I’ve ever said about average mode is that it’s kinda usable, but would be much more useful if only we had more memory available. What I said is that we should be able to live with the slow wavefrom update rate, as there is no hardware support available in this mode.

For Eres mode, I’ve even stated that the way it is implemented now I cannot think of any useful application. But on this one I was not quite right, because it can still serve as a noise reduction tool for non-repetitive waveforms. But having said that, please don’t argue sometimes in the future that I’ve made a remark that Eres is ok, ok? ;)

What I finally said is that there are still scopes in the same price range that do not have long memory in the first place.



--- Quote ---They are very handy to clean a signal up so you can make accurate cursor measurements. I made good use of that in one of my recent projects on a trace which was several seconds long.

--- End quote ---

Yes, as it is now you couldn’t use it for that, except when the signal frequency stays below some 250Hz.



--- Quote ---Still I'd like to see how the protocol decoding works in the V2 firmware and whether you can zoom (using the s/div knob) into the bits of a message without losing the decoding. And does zoom mode work together with decoding in the V2 firmware?

--- End quote ---

I’ll certainly do that, but I have to set up something that generates a serial data stream first. Unfortunately I don’t have anything ready to use at my hands at the moment.

nctnico:

--- Quote from: Performa01 on December 27, 2015, 06:36:27 pm ---
--- Quote from: nctnico on December 27, 2015, 03:15:41 pm ---The V2 firmware doesn't look like it is much better than the V1 firmware. Just more things plastered over. If you want to use an oscilloscope's FFT function to check the spectral waveform purity of the signal generator than you are clearly using the wrong tool.

--- End quote ---
Oh? I’m a bit confused right now. What do we use in order to check the spectral purity of a signal? A spectrum analysis tool, don’t we? And what is an FFT analyser then?

So you probably meant to say I should have used a _proper_ spectrum analyser instead, right? You’re absolutely correct about that – I just don’t have one here at the moment (and the one I have in my second lab only starts at 500kHz, so there would have been a gap anyway).

So you’re basically suggesting that FFT on an 8 bit scope is not the right tool to do a proper spectral analysis. That’s certainly correct, mainly because of the severely limited dynamic range.

--- End quote ---
Stop moving goal posts / twisting what I wrote! A good LF sine wave generator will have a harmonics well below 40dB so it rather is obvious that an 8 bit FFT isn't going to cut it but an 8 bit FFT is still perfectly useful for checking filters, system bandwidth, distortion, EMC issues, etc. Your claim FFT is on an 8 bit scope is useless is just nonsense.

--- Quote ---
--- Quote ---The added value of the SDS2000 is in the MSO, protocol decoding and advanced features but it is those that cause most of the headaches. If I didn't need protocol decoding I'd never bought the SDS2000 to begin with!

--- End quote ---
That’s fine, but not everyone is like you.

There are also folks like me, who want a scope with reasonably high bandwidth, high signal fidelity and a reliably working, jitter-free trigger system. And deep memory of course, so we don’t run into aliasing troubles when looking at signals that contain LF and HF components at the same time.
Ah – yes, we also want a reasonable high waveform update rate, so that we can see what’s going on with a dynamic signal.

--- End quote ---
With those requirements the SDS2000 simply is the wrong choice; a second hand DSO from an A-brand would be a much wiser choice! How many hours did you waste doing tests on your SDS2000? If you would have put those hours to better use you may have made enough money to cover the price difference between the SDS2000 and a scope which works.

smarteebit:

--- Quote from: nctnico on December 27, 2015, 10:29:56 am ---

... Same goes for Eres and averaging. Without long memory they are utterly useless because at some point you will want to zoom in on a long signal. ...


--- End quote ---

For Eres I agree with you, but for averaging why is long memory so important? It must be a periodic signal to apply the averaging, a single peroid contains all the information you need. I think in most of cases kpts memory and >60 wfm/s update rate are enough for average mode.

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