Electronic Design

Letters

Be Open To New Perspectives
I enjoyed "Sensors To Transform Vehicles Into Electronic Cocoons" \[Jan. 8, p. 74\]. What was Mr. Rabinow's/your test? I think you're right; the key really is free association—that and the ability to not get too focused. An "aha" comes from some unsuspected source. To gain new insight on a challenging aspect of a new invention/creation, I don't hesitate to run the problem past people who have no idea what I'm doing. As I explain it to them, they come up with really bizarre thoughts and ideas, most of which are really worthless. But they open my brain up to new perspectives that I would never have had otherwise. Often, from the expansion of my thinking sphere comes the solution I'm looking for. It works for me, anyway.

Thanks for the article. I tore it out to have my kids read it. By the way, two weeks ago my 14-year old solved a perplexing and long-nagging challenge of how to hold a camera in place while allowing easy removal. He asked me why I didn't affix a magnet to it. I just looked at him. I had puzzled over that for weeks, with brackets and swinging retaining arms. He solved it in seconds. Perfect. Simple. Quick. Inexpensive. I'm not proud; I accept ideas from anybody.
Bill Peterson

We All Pay For Energy Eventually
Yes, there are all sorts of tradeoffs. \["Energy Independence—Without Pollution—Lies At Our Fingertips," Nov. 6, 2000, p. 165.\] I have always thought that we should let capitalism work on the problem. That is, energy should be priced with all of the clean-up costs tacked on upfront. By all, I mean ALL—air, water, greenhouse, medical, "beauty," etc. We all pay for these things after the (energy) fact. The costs are always there, but generally not associated with using the energy. If these costs were upfront, our market system would start to come up with solutions pronto. Plus, our market system would end up trying all sorts of solutions, instead of one size fits all. Unfortunately, I don't think it will ever happen. Geothermal produces the same thermal pollution as fuel burning. It releases central earth's heat into the atmosphere. Excellent point. I had never thought of it in that way. Here in the eastern Sierra area we have some geothermal generators (and some wonderful hot springs).
Hank Garretson

Watch Out For Bad Design Hints
I usually don't comment on articles, but after reading "RF Design Hint Increases Rejection In Telephone Hybrids" \[Nov. 20, 2000, p. 152\], I just couldn't stop myself. This IFD is totally in error and without any basis at all. It suggests adding an attenuator to a bad RL (Return Loss) line to improve the performance of the hybrid.

In short, the X dB pad will improve the line RL by 2X dB, and so will be the apparent im-provement of the hybrid circuit. However, the transmitter power will have to be boosted by X dB in order to transmit the same power to the line. On the other side, the received signal level at the hybrid output will decrease by the same X dB of the attenuator. To sum up: the hybrid Tx-to-Rx rejection was improved by 2X dB; the Tx power increased by X dB; and the Rx power at the output of the hybrid decreased by X dB. So, the Tx-to-Rx signal RATIO at the output of the hybrid stayed at the SAME ratio as without using the attenuator.

Additional problems are the need for a larger Tx line driver, and the lower Rx dynamic range as the Rx signal is now at a lower level and closer to the noise floor of the Rx path amplifiers.
Victor Koren
Senior Analog Designer
Tioga Technologies

Author's response: I completely agree with these explanations. It seemed that the idea was correct at the time, and I didn't check it thoroughly. I have no excuse for how the article was sent for publishing. It's completely my mistake. I apologize and thank Victor for his comments.
Steve Iveges
Telecor Inc.

Safety, But At A Reasonable Cost
I have a few comments on "Electronics Redefines The Auto Of The Future" \[Dec. 4, 2000, p. 54\]. To start, I'm an EE. I have worked in aero and auto, to telecomm. I think you miss the fact that the auto industry has fewer suppliers due to the tremendous legal, financial, and competitive barriers to that market place. The liabilities of using an "unknown" supplier are astronomical, as is the expense of qualifying them.

Next, the equipment in an auto environment is subjected to environments very close to those of military ground equipment. The lead times are years, so the newest and best is simply not likely to be proven yet. These facts make the introduction of electronics expensive, even in the quantities involved.

The other issue you may not recognize is that many owners have already become so \[ticked\] off at all of the junk in a car that costs massive bucks that, wherever possible, we resist the addition of it. Complexity is the inherent enemy of low cost and reliability. I'm all for safety, but at a reasonable cost. The average car price is going up, up, up. Granted, a lot of it is to meet governmental requirements. And, electronics is one of the few things where "more" is getting "cheaper" with time, but only as long as it doesn't interfere with the operation of the car or the expense of repair/ownership when it dies. I don't mean it's okay for it to die after 80K miles. Belts, hoses, tires, etc. all do mechanical duty, so they must be changed, and the cars are designed for that. You can still do that yourself, but an engine computer...no thanks.
Peter

Helicopters To Bring In The Troops
Consider the problem of not going in behind enemy lines, but rapid deployment of troops to locations near the front lines \["Electronic Missile Guidance Changes Tactics And Strategy," Dec. 4, 2000, p. 179\]. How do you quickly move troops and supplies into areas with inadequate airstrips or roads, or roads that have been out of commission? For instance, consider the mountainous terrain in the Balkans, or an island like Granada, which both present their own unique challenges to transportation.

How about the present tracked troop carriers, the Bradley?—Lawrence J. Kamm

Using rockets to slow a large aircraft loaded with munitions and fuel isn't ideal. You're talking about landing into a huge cloud of flame and smoke.

Certainly. Not a trivial bit of engineering, but we have done worse. If it worked, it would put several hundred men anywhere in a very short time.

I think helicopters are the optimum method to insert troops. Companies are now building small commercial helicopters for very reasonable prices using the latest in material technology to make the helicopters carry a reasonable load at fast speeds. With developments like these, the small, lower cost, maneuverable helicopter just might become what the Jeep was for WWII. This brings us back to protecting helicopters with electronic countermeasures, which, in turn, requires the absolute lightest and smallest packaging designs.

Again, certainly.
Tom Campbell
Product Manager
Dow-Key Microwave

Polish Up Your Writing Skills
Applause for "It's High Time We Bring Back The Profession Of Engineering Writing," \[Jan. 8, p. 46\]. The nerve you touch most poignantly is that same one rubbed raw by managers who just don't get it...to whom clarity and precision are off the screen ("what do you mean, communicate?"), making way for quick approximation ("that seems about right...") and a bottom line.

Well, I like bottom lines too. I own this place. But long ago—in fact, in my freshman year of engineering school (right after "schools" were invented)—a thoughtful English teacher stimulated me to write, and almost without warning, this skill has pervaded my whole career. For employers, this had the \[probably\] happy side effect of keeping me from actually designing anything, but it did make their technical and marketing communications sparkle and sell.
Charlie Van Hecke
PIC Wire & Cable

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