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Keysight DSOX1102G Oscilloscope Review by Nicholas Vinen A few years ago, Keysight brought two new series of InfiniiVision oscilloscopes, named DSOX2000 and DSOX3000, at prices that were previously unheard of for the performance they offered. This was thanks to their MegaZoom IV integrated circuit which is basically the guts of a high-performance scope on a single chip. Now they've put that same IC into a more compact and even more affordable scope. A fter reviewing the then brand-new MSOX2000 and MSOX3000-series scopes in the April 2011 issue, I was so impressed that I subsequently purchased an MSOX3014A 4-channel mixed signal oscilloscope to use at home. By comparison to the Agilent DSO7034A we were already using at the Silicon Chip lab, it has less bandwidth and a smaller screen but was also considerably less expensive and included a lot of new features and what I still think is outstanding performance. It's also more compact. Having just one modern DSO in our lab sometimes causes contention, so eventually I ended up bringing in siliconchip.com.au my own scope and it isn't exactly a hardship when I end up relegated to the smaller unit. In fact, despite the screen size disadvantage, I think mine is somewhat nicer to use. If you haven't read the 2011 review, to summarise, the MSOX2000 and MSOX3000 series scopes are the same size, with the same screen and look virtually identical. Both come with either two or four analog channels and a mixed-signal option with 8 digital channels for MSOX2000 or 16 for MSOX3000 series scopes. The main difference between the two is in the waveform update rate and the fact that the MSOX3000 offers more stand- ard and optional features. Until recently, the entry-level MegaZoom IV-equipped scope from Keysight was the MSOX2012A, with two 100MHz channels. At around $2500, we think it's good value but there are a lot of people who simply can't justify spending that much money on a scope. Hence the new DSOX1000 series, launched just last month, represented by the mid-range DSOX1102G reviewed here. Note that the DSOX1000 series is distinct from the Keysight DSO1000A/ DSO1000B models; the latter have been available for some time but do not use the MegaZoom IV IC and so April 2017  79 Scope 1: we found this Frequency Response Analysis feature tucked away in the “Analyze” menu. The blue trace shows the frequency response of the LC filter network connected between the arbitrary waveform generator (AWG) output and scope inputs, from 100Hz up to 25MHz. do not have comparable performance. The one advantage the A/B series models seem to have is the option for four channels; to get that with MegaZoom IV, you need to look at the DSOX2000 series. Similarities and differences Some of the similarities and differences between the DSOX1000 and DSOX2000 series scopes are immediately obvious. The DSOX1102G is clearly more compact than the DSOX2000 or DSOX3000 series, at 310mm wide, 170mm high (with feet retracted) and 140mm deep (including knobs and connectors). By comparison, my MSOX3014A is 380mm wide and 210mm high; its depth is similar. The difference in weight is less than you might expect. The DSOX1102G is a relatively hefty 3.2kg while my four-channel MSOX3014A is only a tad heavier at 3.9kg. Another difference that I immediately spotted is the lack of a logic probe interface on the front panel of the DSOX1102G. That's because there is no mixed signal option – it's a plain vanilla two-channel scope. Powering up the DSOX1102G, the interface is immediately familiar. Despite the slightly smaller screen (175mm/7” diagonal compared to 225mm/9”), the resolution appears to be the same and once you get used to the different button layout on the front panel, its operation is familiar. While some things have been rejigged, the interfaces and functions available on the 1000-series scope mostly parallel those on the higherspec models and other than some of 80  Silicon Chip Scope 2: using the scope's built-in Fast Fourier Transform (FFT) capability to analyse the 460kHz sinewave from the arbitrary waveform generator. You can see that the second harmonic (920kHz) and fourth harmonic (1840kHz) are the strongest. The other peaks are probably AM radio stations. the more advanced options such as plotting using complex mathematical equations, nothing really seems to be missing. Another difference I noticed immediately is that the fan on the DSOX1102G is a little louder than the fan on my MSOX3014A; not so much that it would drive you crazy but you certainly can hear the fan spinning, while the noise from the MSOX3014A is barely audible in a typical lab or workshop environment. Acquisition performance of the 1000-series scopes is pretty much on par with the 2000-series scopes; both have a waveform update rate of around 50,000 per second, which is not quite as good as the 3000-series or 4000-series (at over 1 million per second) but it's still right up there for an entrylevel scope. Like the 2000-series and 3000-series, the 1000-series scopes have the option for a single channel arbitrary waveform generator (AWG) output, which is quite handy to have. The 1000-series also has an option for serial protocol analysis that's equivalent to the one available on the 2000-series. However, there is no waveform search option for the 1000-series; something that's nice to have but I personally rarely use it. Interestingly, 1000-series scopes include standard features that cost extra on the more expensive models. This includes Digital Voltmeter (DVM) functionality, segmented memory and mask/limit testing. Sampling rate is 1Gsample/second for 2-channel models and 2Gsample/ second for 4-channel models which is more than adequate given the band- width choices are 50MHz, 70MHz and 100MHz. Educational models, accessories and upgrades While we don't have a lot of details at this stage, there are special “cutdown” scopes in the DSOX1000 series for the educational market with smaller sample memories (100kpoints maximum rather than 1Mpoint) and no standard segmented memory or mask/ limit testing features. These changes are unlikely to have much effect for educational use and we expect prices for educational models will be lower than the standard models. The DSO1000-series scopes are supplied with two suitable probes and a power cord. Presumably you will also get a user manual/CD although the sample unit we got to review did not have either. Some time after I bought my MSOX3014A, I upgraded its bandwidth from 100MHz to 200MHz and added a number of extra features including power analysis and segmented memory, at a time when Keysight had a 2-for-1 upgrade sale on. This was a relatively painless process and the extra features have come in handy from time to time. The DSOX1000-series scopes are also upgradeable, both in terms of bandwidth, memory and software features. The main difference is that they “top out” with lower specifications than the DSOX2000-series (which in turn, can't be upgraded as far as the DSOX3000-series) so upgrading after purchase can only take you so far before you have to buy a better scope. siliconchip.com.au Scope 3: another quite handy feature of the scope is the lowpass filter option. At top in yellow is the output of the AWG set for a sinewave at 10mV peak-to-peak using a 1:1 probe. Below it is the same waveform after having gone through a digital 1MHz low-pass filter. Conclusion While there are a lot of compact, low-cost scopes on the market, many of which would undercut the Keysight 1000-series on price, we doubt if any of them could compete with the sheer performance of the MegaZoom IV chipset. So if you just need a basic two-channel scope, but want one with the speed and features of a much more expensive unit, you certainly should take a good look at Keysight's offerings. Our only real criticism of the DSOX1102G applies also to the DSO/MSOX2000 series and DSO/ MSOX3000-series (including my own personal scope), which is that its in- Scope 4: shorting out the channel 1 probe and cranking up the vertical sensitivity gives this result, with bandwidth limiting enabled. This reveals the presence of a few millivolts of noise that could otherwise mask very low-level analog signals. put noise is not particularly low. While you can change the vertical scale to 5mV/div with a 10:1 probe, the result is a rather thick trace (see Scope 4). In fact, on the DSOX1102G, when you go to 5mV/div, channel bandwidth limiting is automatically activated to reduce noise. The practical effect of this is to make measuring low-level analog signals difficult. One simple solution is to use a 1:1 probe but then you have to swap probes depending on the signal you are measuring, which is a little frustrating. Depending on how you use the scope, you may never run into this and you can also pretty much solve this by using “high resolution” mode (or averaging, for repetitive signals). But we would like to see future Keysight scopes pay more attention to reducing input noise for better sensitivity. Regardless, we would have to say that the entire series of “InfiniiVision” scopes from Keysight is probably the most capable and well-rounded of any manufacturer, which is why we use them ourselves. Pricing and availability To get a price, enquire about one of these scopes or make a purchase, contact Trio Test & Measurement by ringing 1300 853 407 or e-mailing sales<at> triotest.com.au They are located at unit 4, level 1, 8 Century Circuit, Norwest Business Park, Baulkham Hills NSW 2153. SC The back of the set is quite bare in comparison to the front. However, there is one USB and an optional LAN port tucked away on edge of the set which can be used to connect the scope to other devices, such as a computer. siliconchip.com.au April 2017  81