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Agilent’s new 5000 series digital scopes have a simple control layout that belies their very high performance. It is the closest thing we have seen to an intuitive scope, providing a wide range of performance features such as waveform measurements, maths functions, deep memory, high resolution display and triggering on all video waveforms including HDTV. Agilent DSO5054A 4GS/s 500MHz 4-channel digital scope Review by Mauro Grassi T here are so many different digital scopes on the market that many prospective buyers probably think they are all much the same. Nothing could be further from the truth! Each manufacturer has a different philosophy in producing a mix of performance and ease of use, control presentation and a host of operating features. Few digital scopes are truly intuitive 18  Silicon Chip to use, even to people who are very familiar with these instruments. Some have deep multi-level menus and all will have common features, which are sometimes easy to access while others can be quite difficult. Having said that, the digital scope scene does not appear to have changed very much over the last few years, as the principal players have been slow to bring out new models. Well, that has just changed with the release of the 5000-series digital scopes from Agilent Technologies (previously Hewlett-Packard). We had a chance to use the top-ofthe-range 4-channel Agilent DSO5054A for a few days and we came away very impressed. For a start, it has a very simple control layout. Each vertical input channel has its own sensitivity and vertical shift controls and the knobs are colour coded to match the traces siliconchip.com.au Fig 1: the green trace in the top window shows a digital pulse train. The bottom window is the result of zooming in on the un-shaded area in the top display. The top line displays the vertical scales of the four channels, showing that only channel 2 is being used, and the timebase of 200ms/ div is displayed. The top line also says that the un-shaded area in the top window, being expanded below, is 5ms/div, giving a magnification factor of x40. Fig 2: the green trace is a sine wave at around 84Hz. The purple trace is a square wave at around 1.2kHz. The frequency measurements of the waves can be seen midright, while the FFT of the square wave is shown in grey in the bottom part of the display, showing peaks at the odd harmonics. Rectangular mode is selected and the vertical scale (in dB) and the offset in dBV can be selected. The FFT sampling rate stands at 50kS/s. on the screen. This means that you do selectable AC or DC coupling, shown Displaying a signal is easy, as one of not go through the annoying charade of by dedicated LEDs when enabled on the nicer features of this scope is the changing the sensitivity control only to each channel. “Auto-Scale” feature. This is found in find that you have changed and shifted most modern scopes, yet this scope is The Cooks tour the wrong trace! That can be extremely exceptional in this regard. annoying when you have three or more Let’s take a tour of some of the feaSimply connect the probe to your traces on the screen. tures of this scope. The first thing to signal source and press the “AutoThe display looks very bright and notice is the integrat ed help provided Scale” button. Both the triggering sharp. It has 256 intensity levels conby this scope. Pressing and holding mode and the vertical and horizontal trolled by a knob and a high resolution down any button brings up a detailed scales are quickly changed to accomXGA (1024x768 pixels) colour display on-screen message to explain its funcmodate the active waveforms on the that allows fine details to be seen. The tion. That applies to any of the soft screen in an optimal viewing configuintensity of the grid can also be indebuttons as well. ration. Waveforms that are not present pendently controlled. So there is no need to operate “blind” are automatically disabled from being Timebase controls are immediately with this machine. It will tell you what displayed. to the top right of the screen and there to do (well, you do need some clues By the way, Auto-Scale works on all is a button to select main and delayed about operating scopes!) in any of 11 active channels and it neatly separates time-bases. languages. When a knob is turned to the traces on the screen. Any signal Below those are two buttons for its limit, an on-screen bubble pops up with a peak-to-peak amplitude of at measurement: Cursors and “Quick saying so. When a button or knob has least 10mV and a frequency above 50Hz Meas” and below those again a pair of no current function and it is pressed, is automatically displayed. buttons for Save/Recall and printing the scope again tells you. Auto-scale can also be undone at (or dumping to USB the touch of a button flash drive) screen to return to the previgrabs. ous setup! Moreover, Each BNC input the scope does a good Input channels: .................4 has auto-sensing job of selecting auAnalog Bandwidth: ............DC to 500MHz for probes and can tomatic settings and Sampling Rate: ..................4GS/s half channel or 2GS/s for each channel also provide power waveforms can be Memory Depth: .................1Mpts half channel or 500kpts for each channel for active probes. grounded or centred. Vertical Sensitivity: ............2mV/div Individual chanThe former disVertical Resolution: ...........8bits and up to 12bits in high resolution mode nels have selectable plays the waveform LCD display: ......................6.3inch colour TFT XGA, 1024x768 pixels, input impedances with its lowest point 256 levels of intensity control of 50W and 1MW, corresponding to the bandwidth limitbottom edge of the Weight: .............................4.1kg ing to 25MHz and screen, while the cen- Specs at a glance siliconchip.com.au October 2007  19 Fig 3: the green trace shows an AM signal, with a 20MHz carrier frequency. The amplitude and frequency of the signal are shown on the bottom of the display, showing an amplitude of 670mV and a frequency close to the carrier frequency. The carrier frequency was generated by a crystal oscillator on an especially-made board used for demonstrating the scope’s features. tred mode adjusts the waveform to have its middle point in the centre of the screen. The vertical sensitivity can be adjusted in either mode and while the trace is easier to find in the centred mode, this scope allows the vertical scale to be adjusted in the grounded mode and the display is regularly scaled to fit the trace in the best viewing position. This is a very nice feature not readily found in other scopes, where changing the vertical scale often means shifting the trace off the screen! After displaying a trace on the screen, you will probably want to do measurements. So just press the “Quick-Meas” button. You will get a display of the four most recently selected measurements or if none have been selected, you get the signal frequency (provided you have at least one full signal cycle displayed) and the peak-peak voltage for channel 1. Pressing one of the soft buttons (socalled “soft” because they can have many functions) brings up a choice of 23 measurements (duty cycle, rise time, fall time, RMS, standard deviation, max, min etc). You can select the measurement by multiple pressing of the same button or scrolling down through them using the illuminated knob. If that is not sufficient, you can also use cursors to measure points on the waveform. Two cursors on both 20  Silicon Chip Fig 4: the green and purple traces are sine waves, which are out of phase by 180°. The unshaded area in the top window is expanded in more detail in the bottom window. The traces are labeled by user-selectable strings. The bottom line shows the frequency of the green trace and its RMS voltage of 2.201V, its positive duty close to the expected 50% and the phase difference with the purple trace of –177°. vertical and horizontal scales can be selected, shown as dashed orange lines. The cursors can also operate in binary or hexadecimal modes. For example, when sampling a digital signal in binary mode, the cursor can let you know whether the signal is high or low at any point of the waveform. This is displayed as a 4-bit binary string, having one bit for each of the four channels. This can tell you, say, that the waveform is high at 60ns from the trigger point. Running through some of the specs, the DSO5054A has a fast sampling rate up to 4GS/s and has a deep memory of up to 1Mpts (depending on the number of channels in use). This means you can view and store waveforms at high sampling rates for longer. It also means you can zoom in on waveforms and see finer details that you might otherwise miss. This is important for any demanding debugging application. Coupled with its fast refresh rate of 100kHz, the result is a very powerful scope. While other scopes have deep memory modes that can be enabled when needed, this scope has deep memory that is always on, the socalled Mega-Zoom feature. While most scopes will sample at their highest rate at the fastest timebase setting, the sampling rate will drop as the timebase is stretched, simply because the onboard memory is limited. Having a deep memory is therefore essential to sustain high sampling rates for longer periods, allowing more of the waveform to be seen at any one time. The DS5000 series scopes have useful maths functions, including FFT (fast Fourier transform) for spectrum analysis, differentiating and integrating functions, as well as arithmetic operations. This is the first digital scope we have seen with integration and differentiation. Integration is useful if you would like to measure the energy consumption of a circuit, for example. Channels 1 and 2 can be added, multiplied and subtracted and the result displayed as another trace. This can be useful in many situations, not only to compare two waveforms. If you want to know more about a waveform’s frequency components, you can use the FFT function. The FFT can take its input from any of the four channels and even from the result of adding, subtracting and multiplying two of the channels! It can operate in three modes: Rectangular, Hanning and Flat-top. Each is suited to different applications. The Hanning mode has high frequency accuracy and can be used to compare the frequency of two waveforms. The trade-off is less amplitude accuracy. Flat-top mode is useful for high amplitude accuracy of frequency peaks, while Rectangular mode is a good all round mode with good amplitude siliconchip.com.au Fig 5: the yellow trace is mains interference at 50Hz, with an RMS voltage around 400mV and peak-to-peak voltage around 2.2V. The blue background trace is a previously stored version of the same signal but with averaging applied. Stored waveforms can be recalled onto the screen and superimposed on real time signals. and frequency resolution. The FFT is indeed fast and this was the continuing impression we had of this scope. It is truly fast. Pressing the ‘Preset’ button in the FFT menu will cause the settings to change to allow the whole spectrum to be displayed on the screen. This can be considered a kind of “Auto-Scale” feature for the FFT! Standard Connections The DSO5054A has a variety of interfaces. There is the usual GPIB port, an Ethernet port, a USB device port and two USB host ports. The latter are useful for connecting a printer (allowing direct printing of the screen on compatible HP printers) and dumping screen grabs of waveforms onto a USB flash drive. Waveforms can be labeled with an alphanumeric string. There is even a predefined library of labels with common strings like ALE (address latch enable), CLOCK, etc. If you want a larger display, there is an XGA video output port. When connected to a large LCD monitor, the result is a good-looking display that is bright and easy to read. Remote control of the scope is possible through Agilent’s software suite, allowing waveforms to be uploaded to a computer for further analysis. Screen grabs can be saved directly as bit maps, PNG graphics files, or exported in CSV (comma separated siliconchip.com.au Fig 6: the voltage waveform (in purple) across a small motor as it is switched on. Superimposed on this is its FFT (Fourier transform) showing large peaks at some low frequency harmonics, degenerating into more unordered peaks as the frequency increases. The FFT is operating in Rectangular mode and the sampling rate is 50MS/s. values) format for use in a spreadsheet. For more advanced applications, you can program the scope using Agilent’s IO Library suite. Acquisition & triggering Four acquisition modes are available: normal, averaging (up to 65536 sweeps!), peak detect and high resolution. Peak detect mode is useful for debugging applications, where fast glitches cannot be missed. In this mode, the waveform is sampled at the highest rate and maximum and minimum points are stored in memory. This is useful for seeing narrow glitches in the waveform that can easily be missed within a relatively low frequency signal, which most scopes will sample at the less than the maximum sampling rate. This scope has advanced TV triggering modes, from the usual PAL and NTSC, to HDTV1080i/50 and generic modes for composite video signals. As such, it will be appreciated by technicians working with the latest video formats. The Pattern Triggering mode allows each channel to trigger on a low, high or “don’t care” level, or on edge transitions. Each channel can be defined to trigger on any of these. Pulse width triggering allows triggering on a high or low pulse of selectable width. The hold-off period for triggering can be adjusted and this controls the amount of time that the triggering circuit is delayed before it is re-armed. This allows a more stable display of complex waveforms. We should clarify the specifications for this scope. The maximum sampling rate is 4GS/s in half channel mode. This means that only one of channels 1 and 2 can be used and one of channels 3 and 4 can be used. When all channels are used, ie in full channel mode, the maximum sampling rate drops to 2GS/s. A similar caveat applies to the memory depth. What’s the damage? The recommended retail price of the DSO5054A is $14,231 (according to the Agilent website), which is very competitive for an oscilloscope of such specifications. It is supplied with four Agilent 10073C passive probes with automatically detected 10:1 attenuation rated at 400V peak-to-peak CAT II, a carry case and manuals. Agilent’s software suite, including programming libraries and DLLs can be downloaded from the Agilent website. For further information on the Agilent 5000 series scopes, have a look at the Australian Agilent website at www.home.agilent.com/agilent/ product.jspx?cc=AU&lc=eng&ckey= 875171&nid=-35642.0.00&id=875171 or contact the Australian distributors SC Trio Smartcal. October 2007  21