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Agilent Infinii MSO-X 2024A 4-Channel Mixed Signal Oscilloscope The new Agilent InfiniiVision DSO/MSO 2000X and 3000X series oscilloscopes will certainly stir up the scope market. They combine high performance and a wide screen format with ease of use – something that is not always a feature of today’s digital scopes. Review by Nicholas Vinen T he great thing about these new models is that they fill the gap between low-end, entry-level digital oscilloscopes and scopes with much higher performance, such as the Agilent 7000 series which have more daunting price tags. There are 26 new Agilent InfiniiVision models ranging in price from about $1328 plus GST to over $12,000. The particular model we tested is somewhere in the middle. And like high performance cars there are lots of options such as serial decoding modules (for the mixed signal oscilloscopes), a built-in signal generator, VGA and LAN connectivity, GPIB (General Purpose Interface Bus) and more. First impressions Turning now to the 200MHz MSO-X 2024A we tested, the immediately outstanding features are the large screen, a 21cm 800 x 480 LCD panel and the fast waveform update rate (50,000 acquisitions per second). Not only is the screen large and crisp 70  Silicon Chip but it is immediately obvious that the analog front-end is well-designed. The waveforms look clean, even if you set it to maximum sensitivity (which with the provided 10:1 probes, is 20mV/division). At that level you can see a little noise from the acquisition circuitry but it is kept well under control. This isn’t to say that the actual noise being measured has gone away – you can still see it but it is shown as a smooth band around the centre of the trace, thanks to the many sampled waveforms which are overlaid due to the rapid capture rate. The higher screen resolution contributes to the crispness of the displayed waveforms. If signal noise is an issue, one of the excellent features of the InfiniiVision series (which we make use of regularly on our DSO7034A) is the “high resolution” acquisition mode. This uses oversampling to provide noise reduction similar to averaging mode but without introducing any delays or removing much high frequency information (aside from the noise, obviously). Waveform averaging is also supported, as is peak-detection mode. The 2000X series oscilloscopes have a high sampling rate: 2GS/s (interleaved mode) or 1GS/s (noninterleaved). The advantage of noninterleaved mode is that each channel is sampled at exactly the same time but then the sampling rate is halved. The waveform memory is quite large at 100,000 points. The 3000X series has an even more impressive 2,000,000 points memory (with an option to double it). What does the high acquisition rate mean for you, the user? You obviously can’t see 50,000 waveforms per second. Well it turns out that this is actually a very useful feature because the scope averages many sampled waveforms and uses the result to vary the intensity of each pixel. This is similar to what an analog scope with phosphor decay does. In essence, if the waveform is not perfectly consistent, you can see the spread of voltage levels since some areas will be brighter than others. This makes it easier to see “glitches” (ocsiliconchip.com.au iVision casional deviations from the expected pattern) as well as giving you a better impression of just how much noise and jitter there is in the signal. It’s not just a matter of trying to make the number more impressive – this is a true improvement in usability that was previously limited to very expensive DPOs (Digital Phosphor Oscilloscopes). User interface A major benefit of the new models is the uncluttered control layout. Because they are taller than the Agilent 1000 series, they can fit a lot more controls (including the four side-byside vertical adjustment knob sets) without being much wider. There are a lot of buttons on the front panel but they are clearly labelled and grouped logically. Overall, this makes the interface easy to use. Here are some of the benefits from the extra buttons. The “Force Trigger” is useful when the acquisition is in “Normal” mode (as opposed to “Auto”). In normal mode, the display siliconchip.com.au does not update unless the trigger condition is met. This can be useful for catching occasional signals but it’s annoying if isn’t triggering since you can’t see why. Now you can easily force it to trigger and then adjust the trigger conditions as necessary. The “navigate” button cluster includes a left and right arrow with a “stop” button in the middle. These allow a constant-speed pan across the timebase, akin to turning the time offset knob at a particular rate. There are several speed settings which are stepped through with multiple presses of the arrow buttons. This is more convenient than using the knob if you have zoomed in to view the details of a complex waveform. There is also a “Quick Action” button; the action is set by the user. We set it so that a press will save the screen to a PNG file on the USB flash drive. It can also be configured to show all possible measurement values (“snapshot measurement” mode), print the screen, recall a saved configuration, freeze the display, change the trigger mode or clear the display (when persistence is enabled). The “Zoom” mode on this unit works quite well and there is a dedicated button at the top, which looks like a magnifying glass, to toggle it on and off. In this mode, the horizontal adjustment knob changes the zoom factor while the delay knob, as well as the navigate buttons, allow for the expanded portion of the waveform to be moved (see Fig.2). All the knobs also have a pushbutton action and in most cases this either resets the value to zero or else toggles the vernier (fine adjustment) mode on and off for that control. Nice touches Agilent have put quite a lot of thought into the usability of these models and they have a number of small details which improve the user experience. For example, you can attach a text label to each channel which is then shown in various places on the display (eg, when selecting a channel to April 2011  71 Here’s a view of the back of the scope. Of most interest is the right side, revealing two USB ports (device and host), trigger out and trigger in sockets and below them the optional LAN/VGA port, which we’ll look at more closely shortly. measure). You can select from a list of built-in labels or enter your own. This makes it much easier to remember which waveforms correspond to which points in your circuit (or to indicate it on printouts or screen grabs). You can position a small “time reference” triangle which is relative to the trigger point and then use this to calculate delays and such. It’s like a horizontal cursor but less obtrusive. There is also a “probe skew” setting which allows you to adjust for cable delays in the probes. The optional “Mask” mode can be used to check whether a signal is within a particular range. The mask can either be loaded from a PC (say, from a USB drive) or it can be derived from a captured waveform in combination with a tolerance setting (see Fig.3). A waveform can also be stored and used as a reference. In this case it is displayed as an orange trace, for comparison to live data. As with other traces, it can be changed in scale or offset. It can also be moved along the timebase (“skewed”). In zoomed mode, measurements can be taken from the main or zoomed window (or the selection left on “auto”). You can also make measurements from digital inputs and computed (“Math”) traces, although with some exceptions. There is a “snapshot all” option which shows a large number of instantaneous measurements for the selected channel in the middle of the screen (see Fig.4). The measurement selection menu is particularly good, as not only is the selection of measurements compre- Fig.1: using the test unit to make an amplifier distortion measurement, with the distortion residual at the top and the test waveforms underneath. Note the measurements at the right side of the screen with the orange dashed cursor indicating the peak-to-peak measurement points. 72  Silicon Chip hensive (eg, you can even select how many cycles RMS values are computed over), each selection is shown adjacent to a small picture indicating what the measurement represents. Measurements are also grouped under sub-headings according to type. So selecting the appropriate measurement to display is easy (see Fig.5). If you turn the soft-button menu (at the bottom of the screen) off, using the Back button, in its place is displayed the coupling mode for each channel, the offset voltage setting for that channel and the probe attenuation ratio. To the right of the channel information is the current time and date. No screen space is left unused. There is also a “file explorer” feature which allows you to view and navigate the contents of the USB flash drive plugged into the host port as well as view files stored in the scope’s internal memory. In addition to the normal and XY display modes (where channels 1 and 2 are plotted relative to each other as a Lissajous figure), there is also a “roll” mode where the screen scrolls from right to left and new data is constantly added to the right-hand side. This can be useful for viewing slowly changing voltages but is limited to relatively slow time bases (it would be impractical otherwise). Triggering These new Agilent scopes have the basic triggering options – edge, pulse width and video – as well as pattern triggering, which is mostly useful for use with the logic analyser. Unfortu- Fig.2: the zoom mode is easy to operate, especially with the navigation buttons which perform constant-speed panning across the captured waveform. The large memory and low noise allow small details to be seen in the zoomed view. The scope updates at the full rate when in zoom mode. siliconchip.com.au Along with the four 10:1 probes (one for each channel) comes a generous assortment of bits: the usual hook probe adaptor, earth alligator and spring clips, colour coding bands, spare points, RF connector adaptor and IC pin probes. nately, there is no alternate/sequential triggering to allow each channel to operate with its own timebase or any advanced, configurable analog trigger conditions. However there are some handy options such as adjustable trigger coupling (DC, AC and high-pass filtered), noise rejection, a low-pass trigger filter (“HF reject”) and a configurable hold-off setting, adjustable from 40ns to 10s, which prevents immediate retriggering. The video triggering mode has all the usual bells and whistles to select particular lines to trigger on, alternate fields etc. We have to wonder though, how many people are still using oscilloscopes to work on analog video equipment. Not many, we would guess. “Math” modes These new Agilent scopes have the usual add, subtract multiply and FFT modes (see Fig.6). But one very nice aspect is that there are dedicated scale and offset knobs which allow you to easily move and scale these “virtual” channels, just like you can with the regular channels. Those knobs are used for the same purpose with the logic analyser (in Serial or Digital mode) and the reference waveform. With other oscilloscopes (including some high-end models!) doing this is quite awkward as it involves pressing the soft buttons (below the screen) and twiddling the general adjustment knob. In the past this has been very frustrating but with this model, it is easy. Also, since you can set the units for each channel to Volts or Amps, if you use the “Math” feature to multiply two waveforms, it displays the correct units (V2, A2 or W, depending upon the units of the source channels). This is a nice touch. Ports and connectors The front panel sports the typical Fig.3: the mask testing mode. The mask was made from channel one and is being applied to the signal on channel three. The number of failures (ie, excursions outside the mask) is displayed, which could be very handy for use in production testing. siliconchip.com.au And there’s even somewhere to store them: there is a flipdown lid on the rear panel which reveals this handy storage compartment. Or it could be used to store the IEC mains lead, which is supplied with the scope. line-up of connectors: a BNC input connector for each channel, a probe calibration square wave output, a BNC output connector for the signal generator module (which only works if you have that option), the logic analyser port and a USB host port for flash drives and such. At the rear are the BNC sockets for the trigger input and output, mains connector and expansion port. There is an additional USB host as well as a USB device port on the rear. This allows for connection to a printer as well as a PC to control the oscilloscope functions. Accessories Standard 1.2m-long, 10:1 probes are provided for each channel. Each probe comes with a generous assortment of bits: the usual hook probe adaptor, earth alligator and spring clips, colour coding bands, spare points, RF connector adaptor and IC pin probes. Another nice feature is the clip-on Fig.4: the “snapshot measurement” mode which shows all the vital parameters in once place, for a single channel. This avoids fiddling with the measurement menu when you want to check a single figure. The problem is that this obscures the displayed waveforms themselves. April 2011  73 moulded plastic cover which protects the scope while you are carrying it but it also keeps dust off the knobs and screen when not in use. Also provided are a mains power cord, user manual (on a flash drive) and calibration certificate. For the mixed signal models, the appropriate logic analyser dongle and test clips are provided. The user manual is very well-written and is quite detailed; so many scope manuals are not. Another excellent design feature is the compartment located at the top of the unit, to the rear. With some careful arrangement, four probes with hook adaptors and earth leads can be stored inside. This is great for transporting the scope and should also reduce workbench clutter when the oscilloscope is not in use. The provided probes have autosensing support but the 2000X series oscilloscopes do not. Since they have a fixed 10:1 attenuation and this is the default setting, it isn’t really a problem. If you use different probes then it is necessary to manually select the attenuation factor for correct voltage scaling. Logic analyser The logic analyser on the mixed signal models has eight channels on the 2000X series and 16 channels on the 3000X series models. They have all the typical features and voltage threshold levels can be set anywhere between -8V and +8V. The channels can be displayed and used for triggering, including a “pattern” trigger which waits for a certain state to appear on some or all of the lines. Here’s how that optional LAN/VGA module connects into the scope – the snapout cover is removed and the module simply slides into place. The ring and socket on the left side is for a Kensington lock which prevents both the scope and module from being stolen. The digital inputs can be grouped arbitrarily into one or two buses, with the content of each bus displayed as binary or hexadecimal values. You can then set the pattern trigger to occur when a particular value appears on a particular bus. The bus can then be displayed in addition to the individual digital channels that it comprises (see Fig.7). Optional features In addition to the mixed signal models, quite a few options are available. This includes an inbuilt signal genera- Fig.5: the new measurement selection window, showing how measurements are grouped and the diagrams which indicate how they work alongside. This prevents confusion over what you are actually measuring. 74  Silicon Chip tor, a GPIB module, an ethernet/VGA module and serial decoding modules for the 3000X series MSOs (I2C/SPI, RS323/422/485/UART and CAN/LIN). Our review model was provided with the signal generator and ethernet/ VGA modules. The signal generator option is particularly handy as it gives you all the usual features without the need to have a separate unit on your workbench. All related functions are accessed via a “WaveGen” button which lights up blue when the generator is active. The waveform choices are sine, Fig.6: in this screen shot we are using the “math” menu to generate a third trace which is the sum of two captured waveforms. The multiply mode is especially useful for power measurement. siliconchip.com.au square, ramp (triangle), pulse, DC and white noise. In all cases the DC level (offset) is adjustable and except for DC, the amplitude can be set, either as a peak-to-peak voltage or by defining the minimum and maximum voltage levels. Frequency/period can be set for all modes except DC and noise. There are other parameters too like square wave duty cycle, ramp symmetry and pulse width. The waveform generator can be synchronised with the oscilloscope trigger system or it can produce a separate sync pulse. It can also be synchronised with the mask system. The maximum generator frequencies are 20MHz for sinewaves, 10MHz for square and pulse (which are no longer quite square at maximum frequency) and 100kHz for ramp. The amplitude is generally adjustable from 20mV to 5V peak-to-peak. The 1kHz sinewave output has around 0.2% harmonic distortion which is not unreasonable given its large frequency range. The combined Ethernet/VGA module slides into the rear of the unit and clips in place, providing the two additional ports without taking up extra space. The VGA port duplicates the LCD content on an external display and this could be useful for those with vision problems or in training/educational situations as the output can be connected to a projector. The Ethernet port allows for remote control and for data to be loaded onto and off the device. But USB connectivity is so convenient, this does not seem especially useful. It could be handy in automated test and production envi- ronments or for long-term logging and testing. Interestingly, with the LAN module, the oscilloscope can provide a web interface. Another option provides “segmented memory”, which allows multiple waveforms to be captured separately, in sequence. You can then switch between them for display and analysis. Possibilities for improvement With this new range of oscilloscopes, you get a very capable unit for a reasonable price. But there are a few areas in which we feel software changes could make it even better. For example, while the screen is large, you cannot actually use its full width to display waveforms. Instead, to the right of the screen is permanently displayed information such as the acquisition mode and rate, the probe division ratios and the quick measurements. While this is all useful, it isn’t always vital and we would like to use the full width of the screen just for the waveforms. No such option is in evidence. And with such a large screen it should be possible to show more than four measurements. Again, this may mean hiding the acquisition and probe data but we would happily do so to be able to show eight or ten measurements at once, without obscuring the waveform area. The 3000X series For more money you can get a scope in the 3000X series, which is physically quite similar but has some important improvements, some of which have already been mentioned: Fig.7: a demonstration of the Mixed Signal Oscilloscope mode with bus support. This shows the usefulness of channel labelling. With the serial decoding options, serial buses can also be displayed. siliconchip.com.au 16 digital channels, serial decoding options and the substantially larger sample memory (2Mpoints). In addition, there is more bandwidth (up to 500MHz), a doubled sampling rate of 2/4 gigasamples per second and the waveform update rate sky-rockets to one million per second. The 3000X series also has support for active probes, probe auto-sensing capability and waveform search and navigation. Educational features These scopes have a number of features tailored for the educational market, especially electrical and electronic engineering labs in universities and technical schools. We already mentioned the VGA output option but there is also a “training mode” option (called the Education Oscilloscope Training Kit). With this, it is possible to configure the scope’s signal generator to produce a series of waveforms which present students with particular challenges. These signals are available at the “Demo 1” and “Demo 2” terminals at the front of the scope (one of which doubles as the calibration signal source) and the separate waveform generator option is not necessary to use this feature. Note that some of the training signals use two channels, hence the two outputs. For example, the “phase shifted sine” option presents two sine waves with a phase difference between them at each of the two training (demo) outputs. Some of the other signals include occasional errors, either “glitches” (occasional deviations in pulse width Fig.8: here the “math” FFT mode has been applied to a 1kHz sinewave. Its resolution is limited at low frequencies so this mode is more useful for RF signals than audio signals. The FFT configuration menu can be seen at the bottom of the screen. April 2011  75 or rise/fall-time) or “runts” (pulses with lower than normal peak voltage). Students can use this mode to learn how to adjust the scope in order to observe these occasional phenomena. See Fig.9 for an idea of the training signals available. As mentioned earlier, one of the major advantages of having a scope with a fast update rate is the ability to catch glitches more easily, so the training mode also gives a good demonstration of the capabilities of this series. Agilent recognise the educational potential of these new models and are offering literature for teachers and students, to guide them through this process. These documents are downloadable, free of charge. In educational situations, it is also possible to disable the “Auto Set” button so that students learning how to use the various systems can’t take a shortcut. Trio Smartcal are currently offering a special deal for educational institutions when purchasing 2000X or 3000X-series oscilloscopes. The signal generator and training mode options will be included at no additional cost, in addition to their normal 15% discount for educational institutions. They plan to keep this deal running for as long as possible. Additional benefits Past contributor David L. Jones made an interesting point at the launch event: the training mode is useful for experienced scope users too. If you are trying to capture a glitch which occurs very infrequently, you want to be sure that you have set the scope’s trigger system up properly. If it is not set correctly, you could wait all day and then miss that one glitch. Using the built-in glitch generator in the training module, you can check that the trigger is activating properly, then simply swap the probe(s) over to the prototype. Users who are debugging high speed digital logic circuits (where occasional glitches can be an issue) may wish to purchase the training module for this reason. Upgrade path Earlier, we mentioned that there are several options available and we are glad to say that these can be purchased at any time. But have not yet revealed just how upgradeable these scopes are. While there are 26 new models, in reality you only need to decide between four main options. These are the 2- and 4-channel 2000X-series models and the 2- and 4-channel 3000X-series models. You can then purchase and apply upgrades at any time, even going to a wider bandwidth after having purchased the scope! Other upgrade possibilities are more memory, adding the signal generator or logic analyser (turning a DSO into an MSO), adding the segmented memory option and so on. This has not been possible with any previous scopes (officially, anyway). If you know exactly which features you want, you can purchase the particular model and options up-front but even then, you still have the possibility to upgrade it further. Almost all the upgrades are performed by entering a code so there is no need to send the unit out. The exception is when a 3000 X-series scope is upgraded to from 100200MHz to 350-500MHz bandwidth. One interesting option we have Fig.9: the menu (accessible via the Help button) which allows the user to select from the available training signals, if that option is installed. This list is incomplete, as you can see from the scroll arrow at the bottom of the menu. 76  Silicon Chip not mentioned yet, which is only available with the 3000X-series, is a “power measurement and analysis application”. This could be quite useful for those designing or fixing power supplies. Conclusion These are cheaper scopes than these available. There are also more capable scopes available. But there really isn’t anything right now that offers so much performance for so little money. These two new Agilent scope series are a major leap forward in terms of the performance and ease-of-use, available at a very reasonable starting price. The large range of models and options allows you to customise the oscilloscope to your needs and even the most basic models have an excellent set of features. The model we have reviewed, the MSO-X 2024A, costs $3580 plus GST. The signal generator option is $539 plus GST (771 for the 3000X); training mode is $539 plus GST and the LAN/ VGA module is $426 plus GST. If this seems expensive, do not fret because the 2-channel, 70MHz DSOX 2002A is $1328 plus GST and the 4-channel, 200MHz DSO-X 2024A (without logic analyser) is $2824 plus GST. At the other end of the scale, the deluxe MSO-X 3054A with 4 channels, 500MHz bandwidth and 16 channel logic analyser is $12,514 plus GST. There are 26 models in all, not including the options. For further information on the models, or to make a purchase, contact Trio Smartcal. Call 1300 853 407 or visit www.triosmartcal.com.au SC Fig.10: the blue trace is the output from the generator which has been connected back to channel 3 and the yellow trace shows the distortion residuals as measured by an Audio Precision System One analyser, at 0.15%. siliconchip.com.au