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Keysight MSO-X 3104T oscilloscope has a touch screen By Nicholas Vinen This updated version of Keysight’s midrange scope adds a number of new features, including a touch-screen, without a price increase. Nor is there any need to return the unit to a service centre to upgrade the bandwidth all the way from 100MHz to 1GHz. A S YOU MAY have noticed, Agilent’s test equipment division has now been renamed to Keysight. So this unit is the immediate successor to the 3000A-series scope that we reviewed in the April 2011 issue. That unit dramatically raised scope performance within the budget of advanced hobbyists, educational institutions and freshly minted engineers. By that we primarily refer to its astounding waveform update rate of one million per second. When the 3000A-series was launched, a typical competitor had an update rate of around 10,000 per second. siliconchip.com.au The new 3000T-series has the same specification and still leads its class, although not by as much as the 3000A did in 2011; its appearance forced competitors to “lift their game”, so to speak. Even so, Keysight’s “MegaZoom IV” ASIC (application specific integrated circuit) technology has kept them in the lead. So even though this is an update to a scope released three years ago, it’s still state-of-the-art. The additional features only serve to sweeten the deal. Hardware upgrades While the most obvious change with the 3000T is the touch screen, there are quite a few other improvements. Sampling rate for all bandwidths is now 5GHz compared to 4GHz for the 3000A (except for the 1GHz model) and 4Mpoints segment memory is now standard rather than being an extracost option. All models come with 500MHz passive probes. This makes it easier to upgrade the bandwidth via software key; otherwise you would need to buy new probes. The logic analyser cable has also been improved, now being thinner, lighter and more flexible, so it’s easier to work with. Timebase stability is now 1.6ppm April 2015  89 Fig.1: this demonstrates the display of eight different measurements at the right side of the screen. The touch-screen controls to drag the measurements around and access other displays on the sidebar are visible above them. Here the new FFT mode (now separate from “math”) is enabled. Fig.2: thanks to the touch-screen, it’s now possible to input figures such as signal generator frequency using an on-screen numeric keypad. compared to 25ppm for the older model and the calibration period is three years rather than two. Software improvements There are many software improvements in the new model. Our favourite is that you can now turn off the channel information in the sidebar, making room for up to eight measurements at a time. Hallelujah! See Fig.1. Since there is now a touch-screen, that means an alphanumeric keypad can be used for entering values such as waveform generator output frequency (see Fig.2). This is a great feature. It also allows for zone-based triggering; you draw a box on the screen and it will 90  Silicon Chip trigger whenever the waveform crosses into that box. This is quite handy for searching for occasional out-of-spec signal glitches. The “Advanced math” option now comes as standard – another money saver and quite a useful feature. Also, the built-in counter (which can be used for accurate frequency measurements etc) has eight digits rather than five. Some of the major software improvements have been made to the spectral analysis (FFT function). This function now has a dedicated front-panel button and can be enabled simultaneously with one of the “math” options, whereas before you could have only one or the other. The FFT display is now cor- related with the time domain, so that as you scroll through the traces, the FFT display updates to show the spectrum of the data visible on the screen. This is a feature previously seen mainly in “Mixed Domain Oscilloscopes”. While this FFT feature does not quite have the performance you get with an MDO or dedicated spectrum analyser, it is one step closer and much more useful than the FFT function in most scopes. Its dynamic range can exceed 70dB, depending on how the data is being sampled. The FFT now has a peak search feature, akin to the cursors on a spectrum analyser and will display a list of the peaks with their frequency and power. It can also do averaging on the spectral data (a common feature in spectrum analysers but not scopes) as well as minimum/maximum hold. The serial protocol decoding options have been expanded, adding three new automotive protocols to its already extensive list: CAN-FD (CAN with flexible data rate), CAN-dbc (CAN with symbolic triggering and decoding) and SAE J2716 SENTbus. The scope’s user interface has been revamped to take advantage of the touch-screen, although you can still perform all the functions without it if desired (there’s even a button to disable it). These changes include the ability to drag various controls and displays out to their own “window”, such as the DVM readout, measurements, channel summary, numeric keypad etc. Given the relatively limited screen space and the fact that most of it is taken up by the graticule, in our opinion this is not that useful although there are occasions where we would use it. Features Our April 2011 review was specifically on the MSO-X 2024A although we did cover the MSO-X 3000A-series which was launched simultaneously and which had many similarities. Both the MSO-X 2000A and 3000A series (including the new 3000T) can be had with either two or four analog channels, with or without a logic analyser and with bandwidths from 100MHz up to 500MHz and 1GHz respectively. The base models (ie, 2-channel 100MHz) are quite affordable and since they can be upgraded later, give purchasers both an attractive starting price and an upgrade path. The bandwidth can be upgraded at siliconchip.com.au any time and the cost is now just the difference in price between the two models. The logic analyser (ie, digital inputs) can also be added to non-MSO models. However, two-channel models can not be upgraded to four channels so that is a decision that must be made up-front. There are also many software options that can be added to the scope later, including the single-channel arbitrary waveform generator. The main differences between the 2000-series and 3000-series are waveform update rate (50k/sec vs 1M/sec), number of logic analyser channels (8 vs 16), sampling rate (2GS/sec vs 5GS/ sec), maximum bandwidth (500MHz vs 1GHz) and some software options are only available on the 3000-series. The 3000A-series scopes are still available but there’s no point in buying one any more since the 3000T has all the same features and more. The rear panel of the demo unit, which was supplied with the optional LAN & VGA interface module installed. Besides this, the only connectors are the mains input, USB host & device ports and BNC external trigger inputs and outputs. There’s also a Kensington lock and calibration access hole. Fig.3: the new Event Lister, at right, shows the time stamps of events such as trigger locations in the waveform record, along with triangles showing their positions at the top of the graticule. A similar lister is available for showing spectral peaks when FFT mode is enabled. Impressions Overall, the MSO-X 3104T is a joy to use. Its interface is responsive and the fast update rate is very noticeable. This is especially true if you have averaging enabled as the fast acquisition rate means that enough waveforms are captured to update the average after a change in timebase, so that it stabilises very quickly. While the screen isn’t as large as higher-end scopes, it’s sufficiently large that it doesn’t feel cramped and the graduated intensity display gives an excellent picture, especially for smooth waveforms (ie, with little noise). The controls are generally intuitive, with separate vertical controls for each channel plus six soft buttons below the screen to control most functions, in combination with the dedicated mode buttons. Overall it is an improvement compared to earlier Agilent DSO models and is among the more logically laid-out scope interfaces we’ve used. The front panel button layout on the 3104T has been changed only slightly compared to the 3000A-series, with the Serial button function replaced by FFT, an added illuminated “Zone” button above the general purpose knob and an added illuminated “Touch” button to enable/disable the touch-screen. If we look hard for something to criticise, while maximum vertical sensitivity is slightly better than average at 4mV/div (5mV/div being quite typical), there are now low-cost DSOs available which will do 1mV/div or siliconchip.com.au even 500µV/div. While this sort of sensitivity isn’t often called for, it is handy to have. Sometimes when we’re probing for low level signals (eg, from a microphone) we have to resort to using 1:1 probes and even then, there are times when more sensitivity would be worthwhile. We should point out that while this scope does have 2mV/div and 1mV/ div settings, they are just a “software zoom” on the 4mV/div signal. Perhaps Keysight would have had difficulty getting such sensitivity with the higher bandwidths and this would have significantly increased the unit cost. But we hope to see a larger range of input sensitivity in future models. Conclusion I was so impressed with the 3000-series scopes after our 2011 review that I subsequently purchased an MSO-X 3024A for use at home (although it spends most of its time at our office!). The MSO-X 3000T-series is even bet- ter again; I wish it had been available at the time so I could have gotten all these extra features but I don’t regret the purchase! Despite the intervening four years, the situation hasn’t changed; these scopes still offer the best bang-foryour-buck in their segment with a combination of ease of use, very high performance, upgradeability, a suite of great software options and a good starting price. Yes, you can buy a decent mixed signal scope for well under $1000 these days but it won’t come close to matching the performance of the Keysight offerings. Prices for the DSO-X/MSO-X 3000AT series range from $3759 + GST (DSOX3012T; 100MHz, two analog channels) to $17281+GST (MSOX3104T; 1GHz, four analog + 16 digital channels). For enquiries or to purchase a scope, contact Trio Test & Measurement at sales<at>triotest.com.au, visit www.triotest.com.au or phone 1300 SC 853 407. April 2015  91