With capital equipment budgets being scrutinized relentlessly by upper management to pare down or eliminate altogether any perceived nonessential expenditures, the task of merely justifying—let alone being able to buy—much needed test equipment is becoming an almost insurmountable obstacle for engineering professionals. I'm sure in many cases the engineers really need the new equipment, but all too often management's retort is to “make do with what you already have.” However, when what you already have does not provide the capabilities or functionality you need to efficiently and cost-effectively do your job, then quite possibly EE can give you some help.
Knowing that scopes are used extensively in just about every corner of electronic design, development, test, production, and diagnostics, we set out to profile a number of models from a host of manufacturers that feature some pretty impressive specifications as well as enhanced functionality. And the best part, which should be well-received by your management, is that each of them costs no more than $2,500, and some of them are well under a grand.
Using our comprehensive database of instrumentation vendors, we contacted the companies that offer benchtop, hand-held, and/or PC-based scopes and asked them to complete a lengthy survey of their company's models that meet our price criteria. Armed with their responses, EE's Senior Technical Editor Tom Lecklider prepared a comparison chart that shows the depth and breadth of the kinds of scopes on the marketplace today that won't break the proverbial bank.
As you might expect, both two- and four-channel models abound with bandwidths from as low as 20 MHz for a hand-held unit to 300 MHz for a benchtop instrument. Sample rates congregate around 1 GS/s for the upper-end units. FFT measurements and math functions are available in just about all of the scopes featured in the comparison chart. PC-based scopes can provide a large number of automatic measurements, such as the scope from National Instruments which accommodates 40 on-board and more than 750 when used with LabVIEW. Be sure to check out Tom's article starting on page 26.
Another article you will find useful in this month's issue of EE, especially if you are involved in test system development, is written by Paul Schreier, our LXI ConneXion editor. Timing correlation of instruments located in close proximity is easily accomplished to the nanosecond level using the IEEE 1588 Precision Timing Protocol. But how do you achieve accurate synchronization when the systems are separated by thousands of miles?
You might take a look at using GPS. Installing a GPS receiver at each test site provides precise time synchronization to UTC, a worldwide time reference system. GPS-based systems are accurate for many applications enabling synchronization to around 200 ns among distributed test sites.
A couple of GPS clock sources are profiled at price tags in the $10,000 range along with one that sells for less than $2,000. You'll need a PXI chassis for the cheaper one which boasts ±100-ns timing synchronization. A typical far-field antenna test setup that uses LXI Class B instruments and GPS showcases the advantages of this combined solution.
Be sure to check out these stories. I'm sure you'll find them quite informative and possibly helpful in a current or future test system project.
Paul Milo
Editorial Director
[email protected]