Modern communications systems and their components are not like your fathers Oldsmobile.
Working closely with Agilent Technologies (www.agilent.com) for the last several months on a series of White Papers for this magazine has served as a strong reminder of the place of the test function in this industry. More often than not, talk in the high-frequency industry centers around a technology that has the potential to make a difference. In the semiconductor portion of the industry, for example, this has been such things as power silicon-carbide (SiC) or gallium-nitride (GaN) transistors or microelectromechanical-systems (MEMS) switches. But all of these technology advances are meaningless without some means of characterization and verification—i.e., test equipment.
This issue carries the third in a series of White Papers created by Agilent. Yes, they pitch a product, just as almost every company-sponsored piece of literature does. But they also offer invaluable insights into the test and measurement process, in the case of this issue's piece, into spectrum analysis. Of course, as this piece points out, modern communications systems and their components are not like your father's Oldsmobile. Advances in technology have left their mark on communications systems, notably in the form of the modulation formats that carry voice, data, and video. Once, amplitude modulation (AM) and frequency modulation (FM) were enough to bring that important news program or music show over the radio. Now, it is entire television shows coming over wireless networks to be played back on a cellular phone. This requires more than that kilohertz bandwidth of AM systems, something more like orthogonal-frequency-division-multiplexing (OFDM) or wideband code-division-multiple-access (WCDMA) approaches.
Simple spectrum analysis is no longer enough for evaluating systems and components operating with such complex modulation formats. As the white paper points out, vector signal analysis (VSA) and statistical analysis can shed light on signal anomalies that escape traditional spectrum analysis. Of course, a little bit of test skill goes a long way, and good measurement practices can always help deliver meaningful results. The white paper teaches that, providing a three-step program for analyzing digitally modulated signals.
Take a look at the White Paper tucked into this month's issue. It is part of a tradition in this industry, a tradition of company-sponsored educational programs. That tradition has included transistor application notes from Avantek, the Anzac catalog, and the TechNotes series from Watkins-Johnson Co. (now WJ Communications).
Sure these pieces try to sell a product—what company doesn't try that with their literature? In many ways, however, these are the industry's textbooks. These are the things to be learned by the next generation when this one has moved on. Best save them for a rainy day.