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February 1966 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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 Fred Shunaman, Managing
Editor of Radio-Electronics magazine, wrote the editorial column in this 1966 issue
titled, "Electromagnetic Interference... The Future's Greatest Communication
Problem." Boy, was his prediction right on the money. The ambient
electromagnetic energy noise floor in the radio communications realm was many
decibels below what it is today, particularly in urban areas, and Mr. Shunaman
saw it coming; he just couldn't have known how intensely. Rural regions had
practically no noise issues at the time other than interference with AM radios
from dirty motor brushes, sparking transformers, and a few towers for local
television and radio broadcasters. Nowadays, except for a very remote
mountainous and desert areas, there is hardly a spot from where you cannot see a
cellphone or microwave relay tower. Homes and businesses are filled with
cellphones, computers, and "smart" devices spewing ISM band radiation. Wireless
surveillance cameras are everywhere; your car or truck monitor every mile, and
transmitters on your shopping cart tell the store where you are so they can text
you with offers as you pass the shelf (having long ago learned your habits).
Electromagnetic Interference... The Future's Greatest Communication
Problem.
Fred Shunaman, Managing Editor
The United States is the only civilized country that cannot legally restrain
the manufacturer of equipment that will produce electronic interference. Our FCC
can set the amount of radiation a uhf-TV tuner (for example) may produce. But it
cannot prevent a manufacturer from making a TV set that produces more radiation.
(The little notice you see on the back of the receiver is an indication of voluntary
compliance. If a manufacturer does not wish to comply, he can construct a set with
any radiation level he likes.)
But as soon as the set gets into a customer's hands and is put into operation,
the FCC can seize the offending equipment and proceed against the owner, even to
the point of levying fines and imprisonment.
This, of course, is nonsense. The place to stop trouble of this kind is at the
source, not after a layman has bought in good faith what was sold to him as a perfectly
legal piece of equipment. The FCC has requested Congress more than once to pass
laws that would give it the power to stop the trouble at the source. Two bills (Senate
1015 and HR 564) that will give the FCC just that power have been introduced. Their
way through Congress may be long and hard.
These bills would give the FCC authority to "prescribe the permissible degree
of emission of radio-frequency energy of any devices capable of emitting radio frequency
by radiation, conduction, or other means, in a great enough degree to harmfully
interfere with radio communications." Radio and TV sets, electronic garage-door
openers, electronic toys, electronic heaters, diathermy machines and welding equipment
are among the things the FCC says can cause dangerous interference.
And interference can be dangerous. We have heard of devices (including portable
FM receivers and garage-door openers - see p. 58) that interfere with aviation safety
and which might cause a plane to crash. Rexford Daniels, president of Interference
Consultants, Inc., tells of an electroencephalograph that was sending sane people
to institutions because it was picking up signals from a freight elevator in the
hospital and creating spurious brain waves. A story is told of a woman dispatcher
in a taxicab company whose messages interfered with those used to control a guided
missile. Her instructions to a cab driver actuated the destruct circuitry and blew
up the missile.
Electromagnetic radiation can endanger human life and safety by interfering with
communication. It can also be dangerous to human life and health by its direct biological
effects, some understood, others probably yet unknown. We all know that direct exposure
to powerful radar signals can have serious physical effects, possibly extending
even to the second generation. We know less about the more selective effects of
radiation at certain frequencies, although radio waves at 5 mc have been found to
increase the size of tumors, and signals at 700 cycles can anesthetize the brain
(Radio-Electronics, February 1965). The effect of radio broadcast signals on birds
in foggy weather is another thing that is well known, and it has been pointed out
that certain signals in the centimeter range can cause ants to line up with their
antennae all oriented in the same direction.
Another radiation hazard, a little outside the field of radio communications,
was reported recently in New York City. Fourteen children who had been watching
steel girders being tested with high-voltage X-rays were rushed to the hospital
and examined for radiation effects.
The Army took action against a station in Oakland, Calif., because signals from
the station caused sparks in the equipment used to load and unload ammunition. An
even more dramatic case was one in which a Navy plane touched off the whole stock
of flash bulbs in a photographic store near where it was testing its radar.
This interference is curable. In many cases devices that are likely to produce
trouble can be kept out of sensitive areas. In a research laboratory, for example,
incandescent lamps can be used instead of fluorescent ones. Such things as radar
transmitters can be confined to areas where they are not likely to cause trouble.
(Citizens of the Pittsburgh suburb of Oakdale report that an Air Force radar unit
in that thickly settled area produces beeps in radios, TV's, hi-fi equipment, electronic
organs and public-address systems. These cannot be removed by any method of filtering,
apparently.)
The second, possibly most important, remedy is to keep all undesired radio frequency
inside the equipment. Amateurs have learned that it is quite possible to reduce
harmonics of the operating frequency to an imperceptible level, and that direct
radiation from the equipment itself can be cured by good shielding. Shielding has
now become a science. We have louvers, screens and solid sheets especially designed
to control radiation at various frequencies. We even have electromagnetic "weatherstripping"
that will insure that the shielded back of a shielded cabinet, for instance, will
make a perfect electrical connection when screwed on. (This has often not been the
case in many "shielded rooms".)
We are continuing to use more and more power and to extend our signals over a
wider range of frequencies at an increasingly greater rate. It is important not
only that the FCC have the power to deal with all the known bad effects of electromagnetic
radiation, but that we put in a great deal more time and effort searching out still
unknown effects.
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