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2016

  Honing your engineering skills and staying alert for serendipity

The signals we deal with continue to become more complex and challenging. So do the standards that govern them and the measurements those standards specify. It’s a trend that shows no sign of slowing, and perhaps it’s some comfort that this trend is a source of intellectual adventure and job security. That’s the positive spin on it anyway!

Even single-domain spectrum measurements such as ACPR can evolve to a sobering complexity. Compare the W-CDMA and LTE-Advanced measurements below.

W-CDMA ACLR ACPR measurement

LTE-A cumulative ACLR CACLR measurement

The W-CDMA ACLR measurement (top) compares an active channel with two adjacent and alternate channels. The cumulative ACLR (CACLR) measurement (bottom) is considerably more complex, combining the power of multiple, non-contiguous carriers in a carrier aggregation configuration.

While tools such as measurement applications in signal analyzers help deal with the complexity of these measurements, they won’t handle all your needs for non-standard signals, troubleshooting, and custom measurements for components and manufacturing tests.

More often than not, finding all the measurement information you’re going to need involves an in-the-moment mix of trusted sources and geeky serendipity. Louis Pasteur’s famous quote comes to mind: “Fortune favors the prepared mind.” In this case, our “preparation” includes intentional and accidental encounters with application notes, books, blogs, symposium presentations, Web searches, and magazine articles.

I’ve been thinking about magazine articles because they cover both ends of the time scale that are important in making good measurements: classic measurement wisdom and techniques for handling the newest signals.

Under the heading “classic wisdom,” I was recently looking for the power-integration equation used for band power in a signal analyzer, vital for measurements such as those above. I found it in one of a series of articles by Bob Nelson at Microwaves & RF. Bob’s articles cover some classic or evergreen topics, and in this case he explains important points about measuring noise or noise-like signals.

By chance, the same day I started drafting this post, I received an email with a link to another of Bob’s articles on an evergreen topic, understanding measurement uncertainties. He not only describes the uncertainties, but gives an example of how to use extensive analyzer specifications to get the best performance in a specific situation. I have looked at this from a different angle myself, here on this blog.

Of course, the “latest and greatest” end of the time scale deserves just as much attention from magazine editors. Articles from experts with access to lots of test equipment provide timely explanations of measurements and usually add important context. Their guidance is even more valuable when the article also contains a list of references or links to related content. Expertly curated pointers are worth a lot, helping me avoid missing something important.

Worrying about missing something important is what keeps me alert to chance encounters with useful information: sometimes I don’t know what I don’t know. I pay special attention to things that would be counter to my assumptions or intuition because they are the source of errors I won’t even be watching for.

In the area of signal analysis, Keysight is starting to collect a foundation of measurement information on one page, starting with the fundamentals of signal analysis. Along with the other sources of information—and some serendipity—it can help us keep up and keep out of trouble.

  Are lifetime and performance ratings wrong, or is it measurement practice?

A guest post to the RF Test Blog from Keysight’s Michael Lux

A while back, Ben discussed the potential for one type of connector damage and supplied a pretty good example:

Millimeter frequency 2.92 mm K connectors with damaged center connector collets

Damage to the collet or female center conductors of two 2.92 mm K connectors has rendered them useless.

Although the long-term performance and durability of these 2.92 mm and other microwave connectors has been verified in controlled conditions with good measurement practice, real-world experience doesn’t always correlate. Keysight’s long experience in calibration and repair offers some insight, and also helps ensure that you get the performance and durability you’ve paid for.

As the amount of work going on at higher frequencies continues to increase—and as inexperienced engineers and technicians are being asked to make measurements—strong foundational skills and good practices are essential for effective high-frequency measurements. Poor practices produce inferior and less-reliable measurements, wasting resources and risking damage to instruments, accessories, and the devices under test.

Details that can be ignored at lower frequencies really begin to matter at microwave, and especially in the millimeter bands. For these more sensitive tasks, investing in some low-cost, online training for your team members can go a long way toward avoiding costly errors. Even a modest amount of training can save substantial amounts of time and resources.

In an effort to solve these problems, Keysight has launched the first in a series of self-paced eLearning courses. Beginning with an RF/µW Fundamentals package, and continuing throughout the next 12 months with additional courses, Keysight will be rolling out an eLearning curriculum and live training sessions focused on areas that will benefit most from a small investment in training.

A good example is proper cable and connector use and care. We’ve found that problems in this area are a major factor in the need for equipment repair and accessory replacement. Believing an ounce of prevention is worth a pound of cure, Keysight has released an online module focused solely on the fundamentals of cable and connector care. For less than the cost of some individual cables or connectors, this course provides “voice of experience” guidance that can reliably change behavior and improve results.

Untrained users can unintentionally misuse or under-utilize new technology, and can take up to five times longer to achieve the same results as a trained user. When you combine these issues with the added cost of unnecessary help desk calls and lost productivity, a modest investment in training is definitely worth a look. For more information about Keysight’s eLearning training courses see RF/µW Measurement Fundamentals Program.

A note from Ben:

From the beginning we intended to include posts from others here, and this is the first. Blogs are a good way to handle news, personal experience, and nuggets of wisdom. However, they aren’t so good at comprehensive coverage or changing behavior, and Michael describes training that can help in this area.