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Be awed by amazing engineering feats

Posted: 16 Sep 2008 ?? ?Print Version ?Bookmark and Share

Keywords:IC design? engineering? DSL?

Schweber: But sometimes even we, as engineers, accept impressive or unexpected accomplishments without the respect they deserve.

I'm sometimes asked by non-technical friends and family "what are these things they call ICs?" and "how do they work?" I give an explanation with the best way I can, matching it to the questioner's background and aptitude. I end by saying that when you think about it, it's almost sheer magic that we can build these things and make them work, and work repeatedly and reliably.

But sometimes even we, as engineers, accept impressive or unexpected accomplishments without the respect they deserve. This is true even when they overcome long-held beliefs.

Impossible data rates
I have two examples in mind. Consider DSL. We were taught repeatedly that the local loop of the telephone line had a usable 3dB bandwidth from about 300Hz to 3,000Hz. This tight bandwidth was OK because the inherent bandwidth of the loop was low. At the same time, the loop had uneven, unknown and changing spectral response. In addition, the loop was noisy and the voice spectrum contains the most energy and intelligibility. Therefore, everything would be fine. Outside that relatively narrow band, there won't much to work with.

Apparently, the developers of DSL didn't get the word about the narrow bandwidth, noise and overall lousy spectral characteristics. By removing any telco-installed line filters, applying sophisticated A/D signal processing techniques, and adding some advanced data encoding and decoding, the local loop now supports impressive data rates between the end user and the nearby central office. That's quite an accomplishment, and it didn't come easy.

Measuring Coriolus effect
For another example, look at the common mass-flow meter for fluids, based on the Coriolus effect (Note: it is an "effect"; "force" is a misnomer). This is a very tangible physical effect that we see in large-scale, macro-level rotation of air and water currents on Earth, and the apparent curvature of the path of long-range artillery and missiles, to cite some specifics.

Somehow, however, engineers were able to take this macro-effect and harness it on a much smaller scale to build accurate, relatively compact mass-flow meters for fluids and slurries. By passing the fluid through an oscillating U-shaped tube and sensing the tube's twist due to the Coriolus effect, it's possible to make this measurement, albeit with some serious design and technical difficulties.

When I first heard this type of meter described, I thought "They did what? How? Not possible!"

It looks like we should almost never say "never," even to ourselves. And I am thinking about phasers, transporters, tricorders, cloaking devices, and even warp drives.

- Bill Schweber
Site Editor, Planet Analog





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