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Episode 13: Is GW Instek's GDS-1052 Oscilloscope Worth the Price?
|April 30, 2015|
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GW Instek's GDS-1052-U oscilloscope is, at $300, a bargain, It offers 50 MHz dual channel digital performance. This 8 minute video gives a tour of the best (and worst) features of the scope.
Hi, I'm Jack Ganssle, and welcome to the Embedded Muse video blog, which is a companion to my free online Embedded Muse newsletter. Today, we're going to take a quick look at GW Instek's new GDS-1052 Digital Oscilloscope. It's a 50-megahertz bench unit for an unbelievable price. It used to be that, if you wanted to get an oscilloscope, you're talking about something the price of a small Toyota or even more. Today, you can actually spend a half a million bucks on a really high-end oscilloscope, but over the last handful of years a number of Asian manufacturers have come to the market with pretty decent units for really incredible prices. The GW Instek is one of these, and I think you'll be interested in what it has to offer.
Here's a close-up of the scope. As you can see, it has all of the usual features of a bench scope, two vertical channels with separate controls for each, a horizontal channel, of course, full triggering, and the usual digital controls. The screen has a 234x320 pixel display, and the resolution is really nothing to brag about. If we zoom in here, we can see that a little bit better. It's not bad, but it's entirely adequate. I found some of those little letters above and below the trace were a little hard to read, but that might be to my myopia more than the scope. This menu that's on the right displays a number of different items depending upon what you're working on, but it can never be erased, it's always there. So that eats up a bit of screen space.
It has all the usual trigger modes, which are selected by this menu button, but it also has a nice pulse trigger mode. With a pulse trigger mode you can set conditions so that the trigger happens when an event is less than some amount of time, greater than some amount of time, equals, or not equals, and at time can be adjusted using this variable control here.
Like every scope on the market, of course, it has a scope probe compensation output, which is this here. On every other scope I've used, that's a one-kilohertz square wave, which is the default mode on this scope as well. One thing that I really like about this scope is that there's a probe compensation menu, and you can actually set the frequency to any frequency from 1 to 100 kilohertz. What's even cooler is you can program in the duty cycle as well with the signals, so that you get a poor person's pulse generator with this thing.
The supplied X1 and X10 probes are adequate, nothing fancy. We'll see how they hold up over time. But remember, with this scope for $300 you're getting both the digital scope and a pair of probes. My Agilent probes cost on the order of $400 a piece.
There are three acquisition modes, which are selectable here, normal, average, and peak detect. Normal, of course, there's not much to say about. Average, you can select an average of 2, 4, 8, all the way up to 256 samples that are averaged together. There's also this peak detect mode, which is supposed to detect the largest and lowest values of a waveform, but I couldn't make that work.
There's another odd bit of functionality in this. Of course, this knob controls the horizontal sweep, but as you crank this knob slower and slower, once you get down to 50 milliseconds per division, as we are right now, the trigger no longer works. You can see it says, "Not support this operation", really well-written English, which means that you can't trigger on very slow signals. Now, I did find that with a 25-millisecond-per-division sweep rate, which is where trigger is supported, I could actually display the full cycle of a 4-1/2-hertz waveform. So this only affects the very slowest of operations.
I also didn't really care for the vertical position knobs. You can see as you move the thing around, it gets all bouncy. Everything, the signals just disappear for a while. See them flashing? It's not very attractive. It's not a problem, but it's sort of a nuisance.
It's got a nice zoom feature which is really easy to use. You just go to the horizontal menu, and you say, Window to select a window, and you use the horizontal knob to create this variable-sized window you can see here. Then you press Window Zoom, and voila, that signal is exploded. Now, bear in mind, this does not work in stop mode. It only works when the scope is acquiring signals.
The thing supports a million kinds of measurements, more measurements than most obvious would certainly ever use. Here's a list of all of them: Vpp, Vmax, Vmin, you name it, Frequency, Period, Rise and Fall Time, all kinds of stuff. It's quite handy.
It also, of course, has a math menu like all scopes do today. You can display basically three things, the sum or difference of the two channels, or the Fast Fourier transform, the FFT of one of those channels. That's what I'm showing here. You notice what you don't see. You don't see any display across the bottom indicating what the frequency is, so this really gives us very little information. I'd call the FFT features pretty much useless, since you can't figure out what the frequencies are of the various frequency components.
Here's a nice sine wave coming out of my fancy HP signal generator, looks beautiful. As I crank the frequency up, you see it responds fairly slowly, but hook up to, say, 30 megahertz, and you can see the signal's getting a little ragged because of pixilation in there. The screen doesn't have a huge amount of resolution, and so even though that waveform is actually a perfect sine wave, it looks somewhat less than perfect on the GW Instek.
The following chart shows a frequency response to the instrument. I hooked it up to my HP signal generator and took a bunch of data, and you can see that it is pretty flat. The scope's right at 50 megahertz, so this is pretty good response. In fact, this instrument got to the -3dB point at 72.5 megahertz. These measurements I took using the supplied probes, so this is a reflection of the total system bandwidth.
I bought this scope from Saelig when they were having a sale on it, and I got it for $259. What a price. The sale is over, but it still goes for $299 from Saelig and probably some other vendors as well. While this is not a professional scope, it's a great scope for a awful lot of people, and every engineer can have one, even firmware developers that normally don't need a scope that much. As a hobbyist, I'd be pleased to have something like this.
This is the URL for a contest. We're giving this scope away. I've got plenty of scopes around here and don't really need it, so some lucky reader of the Embedded Muse newsletter can win this oscilloscope. The contest closes June 1, 2015. If you miss that contest, go to the URL anyway, because we're almost always giving something away.
So there you have it, a pretty decent oscilloscope for an incredibly decent price. You just can't beat that price. Or maybe you can. I can't wait to see if the prices continue to decline.
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