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It’s a computer & digital oscilloscope all in one package! You can control the TDS 7054 with the touch screen, the front panel controls or via the mouse. The scope operates under Windows 98 and any Windows software can be run on it at the same time as the scope is being used. Tektronix TDS7504 Digital Phosphor Oscilloscope While many people tend to be blase about the march of technology, it is difficult not to be impressed by the latest offering from Tektronix, the TDS7000 range. These are Tek’s Digital Phosphor Oscilloscopes, based on a colour LCD display and having very high sampling rates. By LEO SIMPSON Our review machine was the Tektronix TDS7000, a 500MHz, 5 Gigasample/second, 4-channel oscilloscope with an amazing range of facilities. In fact, it is almost possible to ignore the oscilloscope’s performance while you familiarise yourself with the com72  Silicon Chip puter facilities. Did we say computer? Well, yes. This machine is more of a computer than oscilloscope. In fact, the TDS 7000 series can be regarded as a Windows-based computer which happens to have a very high performance digital oscilloscope built into the same box. And rather a big and heavy box it is, measuring 277mm high, 483mm wide and 425mm deep and weighing in at 19kg, which includes the accessory pouch on the top. It is a Pentium Celeron 500MHz computer, with a 6GB hard drive, 128 megabytes of RAM, a 3.5-inch 1.44MB floppy drive and a CD-ROM drive (rear-mounted). It also has approximately 100KB of non-volatile RAM for waveform storage (up to two 50,000 point waveforms can be stored). The TDS 7054 comes loaded with Windows-98 and virtually any Windows based program can be run on the machine. The front panel display is an active-matrix liquid crystal display (LCD), measur­ ing 211mm wide by 158mm high and its display resolution is 640 x 480 pixels. Its contrast Fig.1: this is a typical screen of the TDS 7054 with two traces displayed and running at the default sampling rate, as defined by the timebase setting. Here the timebase is quite slow at 1ms/div and the sampling rate is relatively slow too, at 50kS/sec. This defines the resolution of the waveforms. Fig.3: Again, same waveforms as in Fig.2 but now all the ampli­tude measurement options are shown in the lower half of the screen. Note that some measurement options have been selected for both traces. ratio is 150:1 and the refresh rate is 60Hz. It runs in Windows SVGA highcolor mode (16-bit). What else has it got? A Creative SoundBlaster PCI 64V sound card and a huge array of sockets on the rear panel. These include two PS-2 sockets for a keyboard and mouse, a USB (uni­ versal serial bus) socket for a mouse, two video out sockets (SVGA & VGA), a GPIB (general purpose instrument bus) socket, a PCMCIA card slot, a parallel printer port, an RJ-45 ethernet socket (supports 10base-T and 100base-T) and sound card inputs. The oscilloscope is a 4-channel, 500MHz 5 Gigasample/second digital Fig.2: Here are the same waveforms as in Fig.1 but now the sam­pling rate has been wound up to 5MS/sec and this shows a lot more resolution. Notice the overshoots on the lower trace. Also present on this screen are horizontal cursors and their voltage settings. Note that this shows buttons at the top instead of the Windows menu bar. Fig.4: If you don’t want to go through the process of selecting measurement options for a waveform, you can do it via the “snap-shot” mode, as shown here for channel 2. storage Digital Phosphor Oscilloscope (DPO). DPO is a Tektronix patented system for showing trace intensity modulation similar to that inherent in the CRT phosphor of conventional analog scopes. Let’s make a comment on DPO right at the start. We think it is an awkward name and one which does not really do justice to the scope. Sure, it does show intensity modulation but it is still not the same as an analog scope because the traces still show the quantisation jitter or noise inherent in any digital scope. At the same time, it has all the advantages of a very fast digital scope. Having criticised the DPO name, we must say that the real benefit of this scope is that the sampling rate is not locked to the timebase as it is in most other digital scopes. This normally means that waveforms captured at low timebase speeds are limited to very low sample rates. However, we are getting ahead of mat­ters. Let’s have a look at the control panel. Here again, there are major differences between the Tektro­nix TDS 7000 series and other digital scopes. For a start, each of the four input channels has its own vertical sensitivity and position controls, as well as a button to select an input impedance of November 2000  73 Fig.5: Same waveforms as in Fig.4 but the timebase and vertical settings have been changed. This is the snapshot for channel 1. Note that the timebase is twice as long as Fig.4 and so the sampling rate is halved. 1MΩ or 50Ω, the latter being selected when active probes are in use. Second, the horizontal input also has its own knobs for timebase, delay and resolution. Triggering is controlled by an array of buttons plus the level control. All of these controls are backed up by indicator lights, so that no matter what hap­pens, you should be able to work out the scope settings by look­ing at the indicator lights and the various settings shown on the LCD screen. All of this is very important because all functions are settable via the scope’s touch screen. And when you touch the screen or use the mouse, say to change a trigger setting, not only does it register on the screen but it also shows on the panel lights, where applicable. That is a big advance in scope usability. It means that by looking at the screen readings for sensitivity, etc and the front panel lights, you can always get a picture of what the scope is doing. On-screen help Not only that, the TDS 7000 series has also dispensed with multi-level on-screen menus. Hooray to that because multi-level menus are hard to use, particularly if you don’t use the scope on a regular basis. Even better, you have on-screen help for any function se­lectable on screen, which means virtually everything. Better still, you can read the on-screen help while you use the scope. How? By using an external SVGA monitor (Ah, so that’s what the extra VGA socket is 74  Silicon Chip Fig.6: There are range of options in the display mode, enabling you to select different coloured traces for each channel, tradi­tional green, gray, temperature distribution or spectral distri­bution. for). Well actually, as already noted, there are two video sockets. One is a VGA socket and it is only used for the scope display. The SVGA socket, on the other hand, can be used to display any Windows application you might run, such as Word, Excel, Internet Explorer etc. For example, when I started doing this review I used Word­pad on the second screen, using the keyboard and mouse in the normal way and then, if I wanted to change a setting on the scope, I could move the mouse from the SVGA screen to the scope screen, make the setting on a drop-down menu or button, and then flick back to the word processor to continue writing. Want to write some commentary on the scope screen to an­notate a waveform? Sure, just use the on-screen keyboard direct­ly, or move the cursor with the mouse and then type on the key­board. Want to save a waveform? Easy. Decide whether you want the full screen or just the graticule, hit Control C and then paste it into whatever program you want. Or you can drop it into Wind­ows Paint and save it as bitmap (.bmp) file. That’s how all the waveforms shown here were saved. Back to the scope now. You can operate it like a Windows program, with drop-down menus from the task bar at the top or you can use menu buttons along the top. Either way, you can make all settings via the touch screen or use the mouse, as noted above. Having used both, I found myself preferring the mouse at it seems to be faster and easier, particularly when selecting from the drop-down menus. Measurement options Measurements are easy and highly flexible. Here, when you touch the “Measure”, the scope graticule is vertically compressed so that half the screen now shows measurement options. For exam­ple, for amplitude measurements there are 12 options such as peak-peak, RMS, positive and negative undershoot. You can also select which of the four channels you want to measure and a total of eight different measurements, enable statistics calculations on any of the measurements (mean & standard deviation etc; after all, they do vary all the time) set up reference levels, gating and so on. Fig.3 shows the Measurement screen and you can see that measurements have been selected for both chan­nels. Another screen gives nine time measurement options such as frequency, period and duty cycle, while yet another gives another four measurement options and a third screen gives 12 histogram options. Maybe you don’t want to go through all the business of selecting measurements for each channel. In that case you simply select “snapshot” and it gives a bunch of measurements for Ch1 or any of the other three. Fig.5 shows a snapshot group for Channel 1, while Fig.4 shows a snapshot group for a similar signal but on Channel 2. Fig.7: Quite a few mathematical functions are possible: Shown here are the four predefined expressions but you can also define your own as well as the spectral analyses. We’ve selected Ch1 multiplied by Ch2. The TDS 7000 also has a mathematics (MATH) mode. This ena­bles you to display the result of a mathematics calculation as another trace on the screen. Four predefined expressions are available: Ch1 - Ch2, Ch3 - Ch4, Ch1 x Ch2 and Ch3 x Ch4. You can also do spectral analyses of waveforms in both frequency and time domains. Again, this is where this scope excels because while the FFT functions are locked to the sampling rate, they are not locked to the timebase. So you can do a more detailed analysis than would otherwise be possible. Time did not permit us to delve into these functions at all but clearly there a large number of options available and you can use as many as four different Fig.8: And here is the result of the Ch1 x Ch2 expression select­ed on Fig.7, shown here as the red trace. This can be very useful when monitoring instantaneous power in a circuit. spectral analysers simultaneously. Nor could we really do justice to all the other features of this multifaceted machine. We only had the machine for a few days and in that time you can really only gain a brief acquaintance - you would need weeks to learn and be really adept with all the func­tions and features. However, in the brief time that we had the Tektronix TDS 7054 we continually found ourselves being impressed with its many features and its general ease of use. This is high praise for the designers because it is very difficult to combine very high performance, a vast range of operating features and most of all, ease of use. Still, we’re not sure whether to regard it as high perfor­mance scope with a Windows computer built in or a Windows comput­er which just happens to contain a high performance scope. Tek­ tronix would no doubt prefer to think of it as the former. And whether you are in the market for a costly machine such as this or whether you are just interested in oscilloscopes, we think the TDS 7000 range is the precursor for digital scopes of the future - one day they will all operate under a Windows (or similar) environment. But the TDS 7000 series does it now! For further information on product availability and prices, contact Tek­ tronix on (02) 9888 0100 or see their website at www.tektronix.com SC MORE FROM YOUR EFI CAR! Own an EFI car? Want to get the best from it? 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