Originally posted Jul 8, 2016
GPS and the skill, creativity and imagination of engineers
When it comes to predicting the future, I’m not sure if RF engineers are any better or worse than others—say economists or the general public. If you limit predictions to the field of electronics and communications, engineers have special insight, but they will still be subject to typical human biases and foibles.
However, when it comes to adapting to the future as it becomes their present, I’d argue that engineers show amazing skill. The problem solving and optimizing that comes instinctively to engineers give them tremendous ability to take advantage of opportunities, both technical and otherwise. Some say skillful problem solving is the defining characteristic of an engineer.
GPS is a good example of both adaptation and problem-solving, and it’s on my mind because of historical and recent developments.
It was originally envisioned as primarily a navigation system, and the scientists and engineers involved did an impressive job of predicting a technological future that could be implemented on a practical basis. Development began in 1973, with the first satellite lunch in 1978, so the current system that includes highly accurate but very inexpensive receivers demonstrates impressive foresight. Indeed, the achievable accuracy is so high in some implementations that it is much better than even the dimensions of receive antennas, and special choke ring antennas are used to take advantage of it.
In some systems, GPS accuracy is better than the dimensions of the receive antenna, and in surveying you’ve probably seen precision radially symmetric antennas such as this ring type. Diagram from the US Patent and Trademark Office, patent #6040805
Over the years, GPS has increasingly been used provide another essential parameter: time. As a matter of fact, the timing information from GPS may now be a more important element of our daily lives than navigation or location information. It’s especially important in keeping cellular systems synchronized, and it’s also used with some wireline networks, the electrical power grid, and even financial banking and trading operations.
As is so often the case, the dependencies and associated risks are exposed when something goes wrong. In January of this year, in the process of decommissioning one GPS satellite, the U.S. Air Force set the clocks wrong on about 15 others. The error was only 13 microseconds, but it caused about 12 hours of system problems and alarms for telecommunications companies. Local oscillators can provide a “holdover time” of about a day in these systems, so a 12-hour disturbance got everyone’s attention.
Outages such as this are a predictable part of our technological future, whether from human error, jamming, hardware failure, or a natural disaster such as the Carrington Event. The fundamental challenge is to find ways to adapt or, better yet, to do the engineering in advance to be able to respond without undue hardship or delay.
RF engineering obviously has a major role to play here, and at least two technologies are currently practical as alternates or supplements to GPS:
- The proposed eLORAN system would replace several earlier LORAN systems that have been shut down in recent years. The required engineering is no barrier, but legislative support is another matter. In addition to serving as a GPS backup, eLORAN offers better signal penetration into buildings, land and water.
- Compact, low-power atomic frequency references can offer independence from GPS, or may provide greatly extended holdover times. Their modest cost should allow wide adoption in communications systems.
As legendary computer scientist Alan Kay once said, “The best way to predict the future is to invent it.” If past is prolog, and I believe it is, I’m confident RF engineers will continue to be among the best at designing for the future, adapting to technology opportunities, and solving the problems that arise along the way.