For novel ideas about building embedded systems (both hardware and firmware), join the 35,000 engineers who subscribe to The Embedded Muse, a free biweekly newsletter. The Muse has no hype and no vendor PR. Click here to subscribe.
Episode 23: Review of Siglent's new SDS5000X Oscilloscope.
July 10, 2019
(Go to the complete list of videos)Siglent's new top-of-the-line scopes offer a ton of value. Here's a short review.
Hi, I'm Jack Ganssle, and welcome to the "Embedded Muse Video blog," which is a companion to my free "Embedded Muse" newsletter. Today, we're going to take a look at Siglent's new line of SDS5000X digital oscilloscopes.
What's the most important thing that you want in a scope? Bandwidth is important, sample rate is important, but ultimately, it all comes down to being able to see a signal. I knew a guy back in the 1960s, a really well known inventor, who had a 1-inch oscilloscope. What can you possibly see on something like that? Siglent's new scopes offer a tremendous screen. Look at the size of that thing. It's just enormous. And it's been sort of the trend in oscilloscopes, to make screens bigger, and it lets us see the signal. How big is it? Let's check it out.
Here's my 100-foot tape measure. So here's the scope displaying a signal. If I hold up my tape, you can see it. That is about a 10-inch screen. Pretty impressive.
This particular scope is 350 MHz, although models are available up to one gigahertz with two or four channels. It has a five gigasample per second acquisition rate, which is pretty impressive, and a 250 megapoint buffer. You know, waveforms per second is about 110,000 captured, and there's an optional 16-channel digital input as well.
As you can see, across the top of the screen are a number of drop-down menu items which control pretty much everything the scope can do. For example, I can say, "Measure" and "Menu." It will pop up, by default, all the measurements that are available. You can see a huge, huge number of measurements. You can turn the measurements off. And to clear that menu, you just press anywhere else on the screen.
If you care not to use a touch screen, there's a touch button that disables it, so that you'll only be able to use the buttons. But in truth, there's an awful lot of functionality you will not be able to get to. You can plug a mouse in, and with a mouse it will give you complete control of the oscilloscope. But practically speaking, I think most of us are going to rely on the touch screen. If I go to, for example, "Cursors," I can pop up set of cursors. I can move them around any way I want like that, just by touching the screen. And that works really well. I like that a lot. If I turn those off, likewise, you can adjust the vertical gain and horizontal by touching and pinching and squeezing.
I find the act of adjusting the horizontal sort of cumbersome. You have to twist your hand in a way that, at least for someone with arthritis, is not very comfortable. What's really interesting is that a number of menu items on the screen can be moved around, just like you would on an iPad or on a PC. So, for example, if I go to the "Trigger" menu and select the "Holdoff Time," it pops up this, so I can type in whatever holdoff I want. I can grab the top bar, slide it around, whatever is convenient. Pretty cool, huh?
I'm not much of a fan of touch screens on PCs and the like. I find that they're more annoying than anything else. But I'll tell you, on this scope, the touch screen works really well, and after I got used to it, I found I'm using it all the time. It's a very natural way of operating the scope.
I like this "Plus" item here. It allows you, very quickly, to pick another channel, which can get added to it. And that can be even a math or a reference signal can get added. It supports a number of triggering modes.
You can see them illustrated here. One of the interesting trigger modes is the so-called "Zone" trigger, which I see on some of the fancier scopes, like the Tektronix. It allows you to draw, on the screen, a box in which the trigger happens. I do find it's a little bit cumbersome to draw that. I think somebody with more agile fingers would have no trouble. And there is a facility in order to enter the data numerically.
There's an optional 16 digital channels. In this case, I've connected them here, and they're sampling some data from a little micro-controller board I put together. I can turn on the digital channels as easily as doing this. Bam. And you can see them there. Of course, the data is all kind of hosed because we're not triggering on anything. If I go to this "Pattern" trigger, I can set that up. And now, I'll say what source I want. Let's just say D1, data bit one being high. I'm going to turn off the analog because that doesn't really do much for us here. Crank the sweep right down a little bit. And there you have it. There's the digital things.
All mixed-signal scopes, of course, have this feature. And the really important thing about a mixed-signal scope is that you can look at both the analog and the digital at the same time to see how they interreact, and you can trigger on either the digital or the analog channels. With this Pattern trigger, it's pretty nice because you can have it exclude certain time periods. So if you have combinatorial logic, for example, which is in some weird state for a few nanoseconds as it's switching, you can tell the scope to ignore those strange states.
A very interesting feature of the scope is the ability to set the relative skew between vertical channels. In this case, I'm sampling a digital signal on channels two and channel three, and they're both connected to the same node, except that, on channel three, it's going through about 18 inches of wire. So given the speed of light, you can see that they're not quite lined up in time. I can go ahead and select that channel, go to the "Deskew," and in 10-picosecond increments, adjust the relative skew between the two signals, so that they actually do line up in time.
Another feature you can see on the same menu is an adjustable input impedance. Most scopes support a 1-meg ohm input impedance, which is ideal for probing most circuits. But if you're working with transmission lines, you're typically working with 50-ohm cable, and it's very important to match the scope to that transmission line, which you can do easily, just by pressing that button.
The scope also supports segmented memory. With segmented memory, you can divide the memory buffer up into numerous little chunks, as many as 100,000 on the scope. And every trigger fills one of those chunks. What that does is it allows you to sample a signal at a very high rate, but something that happens infrequently. And I've described this in much more detail in my Embedded Muse number 315.
Another interesting and somewhat puzzling feature is in the histogram. You can go to "Histogram" there, and here you can set a region of what is being displayed, what's being histogrammed. But to tell you the truth, I have no idea with this histogram means. The axes are unlabeled. It just doesn't mean much to me. The statistics are kind of nice, though. You can get mean, max, standard deviation, and all the rest of it.
A lot of scopes give you the ability to display what is basically a digital voltmeter, and this scope is no exception. If I can turn it on here, you get that.
Here, I'm measuring the frequency of channel one and you can measure all kinds of different things, and that's all very cool, but hardly new. What is new is the ability to put up a bar display, a histogram, a trendline. And if I go up to my waveform generator and change frequencies, you can see the frequency changing. You can see the trendlines, giving an an idea of what has happened over time. This is really, really cool.
The ability to plot data is truly a game changer. Scopes traditionally gave you just a snapshot in time. With this plotting capability, it acts a data recorder. You can configure the scope to acquire data over a long period of time, overnight, over a week. You walk away, you come back later, and you can see exactly what your system did during the, perhaps, very long acquisition period.
The scope is available with a number of different configurations. You can get a 2-channel, 350-megahertz version for about $2,900, all the way up to a 4-channel, 1-gigahertz version for about $7,300. The digital channel option adds about $800 to that. And a scope's configuration that I tested is about a $4,700 scope.
I've been using a Keysight MSO3054A for quite a few years here, and it's a fantastic instrument. I really love it. The specs are similar to that of the Siglent, similar bandwidth and number channels and whatnot. But the Siglent has more features. It's a more modern scope. But the Keysight is three times more expensive than the Siglent. This scope offers a tremendous amount of value, and I'm super impressed with it.
The Keysight's a pretty prettier scope. The knobs look better, but a pretty face is less important than a heart of gold. This is one of the more expensive Chinese oscilloscopes, but that's because it offers so much value. I can recommend it very highly. So that's it. That's the review of the SDS5000X series from Siglent.
Thanks for watching, and feel free to go to www.ganssle.com for over 1,000 articles about better ways of building embedded systems.