Electromagnetic Interference
Chuck Doherty
their automotive section this week on the subject of electromagnetic
interference, and how it relates to automotive issues. The article
contained two tales told to the reporter which seemed apocryphal at best.
The first story, as told by an engineer at Underwriters Labs, tells of a CB
radio somehow causing a cement mixer to "activate" [1] and dump its contents
into a handily positioned convertible stopped behind the truck.
The second, from an author who claims to have written three books on the
subject of EMI, tells of "airport navigation systems" at Washington and
Baltimore airports being disrupted each morning, because; "New electronic
[2] Mr. Coffee machines at nearby homes sent out a collective energy pulse
that disrupted the navigation systems." This tale was also given as
happening "in the early 1970's"
I could find mention of neither story on the web, in either bunk status.
Has anyone else encountered these tales?
I sent an email to the features editor of the paper expressing my suspicion
that these stories may not be too well backed, and he agreed that they
sounded quite implausible to him as well, and that he would pass his
concerns along to the wire service (Knight-Ridder) about the degree of fact
checking behind the story.
The Projo website allows only registered members to access article details,
so I have posted the original article in its entirety here:
http://www.zydebabes.com/emi.htm
Chuck Doherty
[1] As far as I know, cement mixers are not "activated" at all; they simply
rotate in one direction while en-route, and reverse the direction to unload.
Depending on the direction, fins welded to the inside of the storage drum
will either direct the slurry back in and around, or out the rear and into a
chute for delivery. It is all quite mechanical, and certainly noting that
would have been under electronic control in the early 1970's as cited in the
story.
[2] The closest feature to anything "electronic" that made its way into a
Mr. Coffee machine in that era was likely a timer. Hardly the stuff of
emi-pulse producing hardware.
Lee Ayrton
On or about Sun, 19 Jan 2003, Chuck Doherty of spamfreechuck@this_address.c...:
> The local newspaper (Providence Journal) published a wire-service story in
> their automotive section this week on the subject of electromagnetic
> interference, and how it relates to automotive issues. The article
> contained two tales told to the reporter which seemed apocryphal at best.
>
> The first story, as told by an engineer at Underwriters Labs, tells of a CB
> radio somehow causing a cement mixer to "activate" [1] and dump its contents
> into a handily positioned convertible stopped behind the truck.
>
> The second, from an author who claims to have written three books on the
> subject of EMI, tells of "airport navigation systems" at Washington and
> Baltimore airports being disrupted each morning, because; "New electronic
> [2] Mr. Coffee machines at nearby homes sent out a collective energy pulse
> that disrupted the navigation systems." This tale was also given as
> happening "in the early 1970's"
>
> I could find mention of neither story on the web, in either bunk status.
>
> Has anyone else encountered these tales?
Good catches, both of them. The "CB causes cement-filled convertible"
story popped up here in December at the hands of D F Manno, who noticed
the same thing in the same article you read. Follow the thread from:
[snip]
> The Projo website allows only registered members to access article details,
> so I have posted the original article in its entirety here:
>
> http://www.zydebabes.com/emi.htm
[snip]
> [1] As far as I know, cement mixers are not "activated" at all; they simply
> rotate in one direction while en-route, and reverse the direction to unload.
> Depending on the direction, fins welded to the inside of the storage drum
> will either direct the slurry back in and around, or out the rear and into a
> chute for delivery. It is all quite mechanical, and certainly noting that
> would have been under electronic control in the early 1970's as cited in the
> story.
That is my understanding as well.
> [2] The closest feature to anything "electronic" that made its way into a
> Mr. Coffee machine in that era was likely a timer. Hardly the stuff of
> emi-pulse producing hardware.
I read this as a novel variant of the "Great Flush" story. The two
flavors of the great flush are the deliberate and the accidental. In the
deliberate, a Clever Youth demonstrates he is smarter than his Elders by
having [SOMENUM] toilets flushed at same time. The resulting pulse
ruptures 1) sewer main or 2) water supply main, demonstrating that the
Elders were mistaken in their assessment of the integrity of the system.
For the accidental, water works employees notice sudden drop in supply
pressure, trace cause back to people using toilets during commerical break
in Milton Berle Show/final game in sporting series. Follow the thread
beginning at:
Your version has the kool nudie tail of modern technology having an
unforseen and automated side effect. Hundreds if not thousands of coffee
makers, all set to turn on at the same time, cause a pulse in the power
grid.
Good work.
--
"In spite of what many of us think, our memories suck." David Martin
gives voice to a basic truth in alt.folklore.urban
Alan J. Wylie
> I read this as a novel variant of the "Great Flush" story. The two
> flavors of the great flush are the deliberate and the accidental.
> In the deliberate, a Clever Youth demonstrates he is smarter than
> his Elders by having [SOMENUM] toilets flushed at same time. The
> resulting pulse ruptures 1) sewer main or 2) water supply main,
> demonstrating that the Elders were mistaken in their assessment of
> the integrity of the system. For the accidental, water works
> employees notice sudden drop in supply pressure, trace cause back to
> people using toilets during commerical break in Milton Berle
> Show/final game in sporting series. Follow the thread beginning at:
> Your version has the kool nudie tail of modern technology having an
> unforseen and automated side effect. Hundreds if not thousands of
> coffee makers, all set to turn on at the same time, cause a pulse in
> the power grid.
There was a real-life variation on this during the UKoGBaNI coal
miners strike (sometime in the 1980's). Arthur Scargill, the miner's
leader, urged all his supporters to flush their toilets at a
pre-announced time.
The idea was that this would cause all the sewage pumping stations in
the country simultaneously to start pumping, causing a surge in
electrical power demand, overloading the National Grid.
--
Alan J. Wylie http://www.glaramara.freeserve.co.uk/
I'm looking for a job. CV at http://www.glaramara.freeserve.co.uk/cv.html
Unix/Linux/C/Internet/embedded and lots more. UK:Bradford/Manchester
Ichimusai
> [2] The closest feature to anything "electronic" that made its way
> into a Mr. Coffee machine in that era was likely a timer. Hardly the
> stuff of emi-pulse producing hardware.
Working as a service tech I and a colleague was once called out by a
lady at the Big Company we served, her terminal hung roughly the same
time every day and would not work until she had restarted it. This was
in the mainframe days and she was using a 19200 bps terminal over a
current loop wire to access it serially.
After some time trying to locate the error, including switching her
terminal for a spare, we both realised that in the next room they had
these big coffee machines you sometimes see in restaurand, the pot
sits on a heating plate and they brew a pot at a time quite rapidly.
When this came on at about 0900 and 1400 the relay in the heater
apparantly produced enough interference to hang her serial
communications.
The solutions was to plug her terminal into a different socket on a
different phase then the coffee machine, and to reroute her current
loop wire a little.
--
Ichimusai "Currently in the loop"
Chuck Doherty
"Ichimusai" <ic...@ichimusai.org> wrote in message
news:u8yxgh...@ichimusai.org...
I can certainly understand how a coffee maker could do this in terms of
causing a spike through the line. After all, there is a fairly big heater
core in there, and most likely a significant reactive component as well,
causing some inductive hijinx when they turned on. There is no question that
situations like the one you encountered are very real, and often hard to
track down. Kudos on finding it.
In the newspaper article however, the blame was being put on the coffee
maker(s) in question being "electronic," and having somehow generated an EMF
signal through the aether (not via the line), and (per the quoted party)
this in turn caused the vaguely-described airport system to shut down. This
would require not only a very unstable system at the airport, but also a
well-tuned coffee machine brewing up emf into a high-gain antenna. That's
what I am raising at least one eyebrow to.
--
Chuck Doherty
email via: my first name -at- my FULL name dot com
BBol924849
>From: "Chuck Doherty" spamfreechuck@this_address.com
>Date: 1/19/03 1:13 PM Pacific
In the early days of computer manufacturing, we were required to put an EMI
shield around the computer transformer, and sometimes around the CRT. Cash
registers, etc., caused interuption of the compputer. We had to run lab tests
to prove their effectiveness. As to the cement truck dumping a load into a
convertible, that one goes back decades, but without the electronic voodoo
stuff.
Alan Follett
<snip>
> There was a real-life variation on this during
> the UKoGBaNI coal miners strike (sometime
> in the 1980's). Arthur Scargill, the miner's
> leader, urged all his supporters to flush their
> toilets at a pre-announced time.
> The idea was that this would cause all the
> sewage pumping stations in the country
> simultaneously to start pumping, causing a
> surge in electrical power demand,
> overloading the National Grid.
With any results, at least in terms of getting cooperation with the
timed-flush request, if not of actually crashing the power grid?
Alan "I hate these cliffhanger endings" Follett
Alan J. Wylie
It was a long time ago, and I can't remember whether there was any significant
announcements of support. I don't think there was any noticable effect on the
power grid. Googling for "dinorwic turbines" explains why this is so.
Alan J. Wylie
> It was a long time ago, and I can't remember whether there was any
> significant announcements of support. I don't think there was any
> noticable effect on the power grid. Googling for "dinorwic turbines"
> explains why this is so.
(I was interrupted by a phone call, and forgot to add this before
posting)
http://groups.google.com/groups?selm=3740D45C.42D6720%40freeuk.com
Charles Wm. Dimmick
> The second, from an author who claims to have written three books on the
> subject of EMI, tells of "airport navigation systems" at Washington and
> Baltimore airports being disrupted each morning, because; "New electronic
> [2] Mr. Coffee machines at nearby homes sent out a collective energy pulse
> that disrupted the navigation systems."
Found your story at:
http://www.auto.com/industry/ul5_20021205.htm
I also found:
" Mr. Coffee was at McDonnell Douglas Helicopter Company where he was
involved in the development of an advanced, integrated helicopter
navigation system. " [Mr. John Coffee, that is]
Charles Wm. Dimmick
--
"And some rin up hill and down dale, knapping the
chucky stanes to pieces wi' hammers, like sae mony
road-makers run daft -- they say it is to see how
the warld was made!"
Charles Wm. Dimmick
> There was a real-life variation on this during the UKoGBaNI coal
> miners strike (sometime in the 1980's). Arthur Scargill, the miner's
> leader, urged all his supporters to flush their toilets at a
> pre-announced time.
>
> The idea was that this would cause all the sewage pumping stations in
> the country simultaneously to start pumping, causing a surge in
> electrical power demand, overloading the National Grid.
With some minor adjustment this might work. However,
what is necessary is for the flushing to be staggered
in such a fashion that all the water demands reach the
pumps at the same time, and since the various WCs are
at various pipe distances from the pumps, the timing
must be arranged so that those furthest away are flushed
first.
Lon Stowell
In the early days of computer manufacturing, the FCC
regulations related to EMI didn't exist and wouldn't
exist for in excess of 25 years... or more.
As for putting shields around the transformer and CRT, those
weren't designed to protect the shielded computer [although
sometimes this was a side benefit] they were designed to
protect other equipment in the area from conducted and
radiated noise. And were necessary mainly due to being
bailing wire for existing subcomponents until builders
convinced their subvendors that yes indeedie, although
FCC [and VDE] law didn't apply to subcomponents, the laws
of economics sure did.
As for a cash register bothering the computer, unless that
was one really oddball cash register with a really really
big internal arc, it wasn't any of the shields that helped,
it was the powerline input filters that helped... although
again the FCC act was to stop the filtered computer from
sending noise out into the powerline, not prevent it
from coming in. Again a good big Trimag often helped
the shieldee.
Joe Yuska
I missed the early posts on this thread, but I saw an interesting
variation on the theme on Boston news tonight. The weather here is due
to be unusually cold in the next few days, so they had a bit on frozen
plumbing, water mains, etc. There was an interview with a water
company official from Saugus, a town that encompasses a long commercial
stripmall farm of Route 1. According to him, there are two contributing
causes to common water main breaks along this strip:
1) increasng depth of frost in cold spells, resulting in more
transmission of traffic vibrations, loading, etc. from the roadway, and
2) Highly increased water pressure in the lines after midnight (loosely)
due to the decreased water demand by the large number of commercial
establishments, particularly restaurants. Supposedly there's an
increase from the ambient diurnal pressure of 70-80 psi to over 100 psi
graveyard shift, enough to stress old mains.
I have nowhere near enough engineering knowledge to judge this, but I
thought it an interesting twist on the old "water hammer" stories of
college dorms.
Joe Yuska
Crashj
> The local newspaper (Providence Journal) published a wire-service story in
> their automotive section this week on the subject of electromagnetic
> interference, and how it relates to automotive issues. The article
> contained two tales told to the reporter which seemed apocryphal at best.
<>
> subject of EMI, tells of "airport navigation systems" at Washington and
> Baltimore airports being disrupted each morning, because; "New electronic
> [2] Mr. Coffee machines at nearby homes sent out a collective energy pulse
> that disrupted the navigation systems." This tale was also given as
> happening "in the early 1970's"
<>
A:disruption in the signal or
B:a power surge that knocked them off line. If it were a power surge
it would knock the entier section off line. Loss of aircraft
navigation systems would be the least of your problems.
There are two possible aircraft navigation systems which might be of
concern:
75.000 MHz is Aircraft Navigation Marker Beacon. This is near
airports on the ILS (Instrument Landing System) approach path.
Three lights are in the cockpit (Purple, Amber, White):
Purple - Outer Marker, Intercept Point, 4 to 7 Miles downrange 400 Hz
Amber - Middle Marker, Cat I Decision Height, 3500 Feet 0300 Hz
White - Inner Marker, Cat II Decision Height, 3000 Feet 3000 Hz
As a plane flies the final approach these lights will illuminate in
turn as the aircraft gets closer to landing.
Vertical Omnirange (VOR) is also used and sometimes the transmitters
are at airports, but this is not really a precision local navigation
type of system. These operate in the range of 108-117.95 MHz .It is
used to go from airport to airport (sort of). The rotary VOR beam
cycles at 30 Hz.
Can anyone demonstrate how a coffee pot would emit a pulse of any
signifigant duration that would disrupt either system for an noticable
amount of time?
A power pulse caused by a suburb of 500 watt pots all going on at a
similar time wouldn't show up at all. Remember, they would not go on
all at once unless they were all set to the same time hack and
everyone wanted their coffee starting at exactly the same time.
Crashj 'who will have some coffee right now' Johnson
Mary Shafer
> The second, from an author who claims to have written three books on the
> subject of EMI, tells of "airport navigation systems" at Washington and
> Baltimore airports being disrupted each morning, because; "New electronic
> [2] Mr. Coffee machines at nearby homes sent out a collective energy pulse
> that disrupted the navigation systems." This tale was also given as
> happening "in the early 1970's"
The E-3 ACIP (Airborne Command and I-something Post) that used to follow
Reagan out to CA, parking at March AFB in Riverside, supposedly had some
sort of electronics that activated automatic garage-door openers along
the approach and take-off paths. This was reported in the Los Angeles
Times and the electronic media. However, I have no idea whether or not
it was ever verified. The USAF denied it, but to paraphrase Mandy
Rice-Davies, "They would, wouldn't they?"
Mary 'Oxford Press shouldn't cal the new edition "The New Edition"'
Lee Ayrton
The classic culprit in this story seems to be Sputnik -- sneaky Rooskies'
orbiting satellite sends signal that happens to activate modern (late
1950s) garage door openers in the middle of the night. To my mild
surprise neither TARFAC nor Snopes have the story. The story is a classic
example of logical -- but wrong -- leaps.
An AFU article from Russell Holsclaw on why the doors malfunctioned
(natural causes, not The Ruskies):
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=RPUD7.531%24be5.79233%40news.uswest.net
From the same thread, the signalcious Ben Zimmer offers a Sputnik
vectoring and an alternate Reagan-era California sighting, this time with
the surface Navy to blame:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&frame=right&th=90b8b9befc8c0b26&seekm=3BDFE8A4.3BE6D2FF%40midway.uchicago.edu#link4
Mary Shafer
> The E-3 ACIP (Airborne Command and I-something Post)
These E-3s might be E-4s. I'm a little uncertain about the
numbering system. They look just like 747s since that's
what they are, so they're easy to recognize whatever the
USAF calls them.
Mary
John Schmitt
Lee Ayrton <lay...@ntplx.net> writes:
>The classic culprit in this story seems to be Sputnik -- sneaky Rooskies'
>orbiting satellite sends signal that happens to activate modern (late
>1950s) garage door openers in the middle of the night. To my mild
>surprise neither TARFAC nor Snopes have the story. The story is a classic
>example of logical -- but wrong -- leaps.
<6o2c28$4gf$1...@mamenchi.zrz.TU-Berlin.DE>#1/1
Gives yet another airing. Quite a number of new technologies have
attracted ULs, perhaps as they are perceived as some sort of
witchcraft.
John "green marker for DVDs, anyone?" Schmitt
As iron rusts when not used and water gets foul from standing or
turns to ice, so the intellect degenerates without exercise.
-- Leonardo da Vinci
Ichimusai
> In the newspaper article however, the blame was being put on the
> coffee maker(s) in question being "electronic," and having somehow
> generated an EMF signal through the aether (not via the line), and
> (per the quoted party) this in turn caused the vaguely-described
> airport system to shut down. This would require not only a very
> unstable system at the airport, but also a well-tuned coffee machine
> brewing up emf into a high-gain antenna. That's what I am raising at
> least one eyebrow to.
Yes, I don't believe that story either. I have been installing
emergency radio coverage at airports and their equipment is very
rugged against radio frequency interference.
--
Ichimusai - Interfered with