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Beth Stackpole
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Blogger
RF disturbances more scary then an nuisance?
Beth Stackpole   11/23/2011 6:42:32 AM
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Good detective work, which unfortunately required a major effort on your part in terms of having to pick up and move. Forget about the inconvenience, the issue you raise about the effect of the RF disturbances on humans is really far more alarming. Glad you were able to clear out of dodge.

Alexander Wolfe
User Rank
Blogger
RFI on the Rise
Alexander Wolfe   11/23/2011 7:59:43 AM
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I would love to see a Sherlock or Monkeys which talks about something that took place in the 21st century. But I digress. My point here is that one can't help but notice that RFI has actually increased in recent years. My beloved Blackberry is among the biggest culprits. Who among us hasn't been on a conference call where asychronous (actually, often persistent) buzzing is disrupting the discussion. "Can everyone check if their Blackberry is near the phone?" is a common question on these calls. I don't know how designers can easily stanch this interference. It's not like you can put a choke on the antenna without killing the signal. Still, it's a serious problem.

Ann R. Thryft
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Blogger
Re: RFI on the Rise
Ann R. Thryft   11/23/2011 11:52:19 AM
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The amount of RFI has definitely increased because there are so many more sources, both in terms of different kinds of wireless transmission technologies on various bands, such as WiFi and 4G networks, and in terms of point sources (millions of cell towers, millions of Blackberries and WiFi-equipped laptops) for each of these transmission technologies. Other, perhaps less obvious sources, include clock radios and halogen lamps.

Rob Spiegel
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Blogger
Re: RFI on the Rise
Rob Spiegel   11/23/2011 2:47:56 PM
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I would imagine there would be some negative impact from all of the RFI. But there doesn't seem to be. Can that just increase year-by-year without it having any impact of humans or devices?

Ratsky
User Rank
Platinum
Re: RF disturbances more scary then an nuisance?
Ratsky   11/23/2011 2:55:52 PM
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I'd like to add some to the discussion on the biological effects of RF.  1.  Way back in the early '70s I worked at Motorola Comm division; next door to my lab was one run by Dr. Quiriano Balzano.  His expertise was (still is, I suppose) exactly that: biological effects of RF radiation.  At the time, he was doing extensive research in a very direct way (very un-PC now!).  He used lab rabbits, exposed to well-controlled RF fields over a wide range of frequencies VHF upwards) for long periods of time.  He found that the most sensitive indication of damage were the rabbits' eyes; they would develop cataracts after a sufficiently long exposure to a sufficiently high field strength.  He then measured the near-field strengths and spectra of the many types of hand-held equipment that Motorola manufactured and sold, and conducted a years-long study using several times the highest levels he measured.  NONE of the test rabbits ever suffered any ill effects; the resulting paper was published, reviewed, etc. and was generally accepted as valid.  No subsequent study has ever been conducted to that same level of detail and thorough ness!

2. There is a very large study group that has been voluntarily exposing themselves to RF field strengrths MUCH MUCH higher for MUCH MUCH longer than, for example cell phones (especially current technologies, which use very low transmitting power even in marginal areas).  I refer to the 1 million+ or so radio amateurs (I am a Life Member of both the ARRL and the IEEE) around the world.  While I am not aware of any organized scientific study of this group, from my personal observation I imagine hams are on average among the HEALTHIEST and longest-lived populations!  I am quite surprised no one has ever thought about doing that study; I suspect that far too many of the possible researchers have axes to grind that might be blunted by its results!

 

TJ McDermott
User Rank
Blogger
Re: RFI on the Rise
TJ McDermott   11/27/2011 8:33:11 AM
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Isn't there a tag or blurb on all electronics, required by the FCC, stating something like "this device causes no radio interference, and will tolerate any interference that in the environment"?

The only instance in recent memory where interference was acted upon was LightSquared's network causing GPS interference.

jmiller
User Rank
Platinum
Re: RF disturbances more scary then an nuisance?
jmiller   11/27/2011 8:40:53 PM
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Did you happen to let any of your neighbors in on the issues with your apartment or was it just every man for himself.

Battar
User Rank
Platinum
Just Bzzt on the stereo?
Battar   11/28/2011 9:44:00 AM
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A long time ago I worked at an intstallation in a Mediterranean port. When a USN sixth fleet carrier was visiting the port, NOONE could watch television or listen to the radio - the inteference from the ship's search radar was just too much. Don't know why they operated the radar in port, but they did.

SSLGuru
User Rank
Iron
Re: Just Bzzt on the stereo?
SSLGuru   11/28/2011 10:32:24 AM
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 I grew up next to a US airbase - in the UK. In the late 70's / early eighties, there was a well known stretch of road adjacent to the air base along which cars had a habit of stalling - dead in their tracks and for no apparent reason. The emergency service crews - AA and the like (UK's equivalent of AAA) - had learnt that the best means fo starting a stalled car in that location was to push the car a few hundred yards down the road. The car would then start with no problems. The problem was sufficiently serious to warrant mention on the local news I recall.

 In that cold war era the authorities denied all knowledge... plus, it only seemed to happen to what were then Japanese imports, so nobody seemed to worry much at the time. (Presumably Japan was using electronic ignition a few years before the homegrown competition).

 I work in solid state lighting. It is amazing just how much equipment is available today with no FCC marks on it. There is bound to be fallout from that as its use spreads. I have one very widely used driver on my desk here today which comlpetely knocks out any fm radios within 20 feet of it. (But who uses those these days I guess??).

 In the 60's and 70's when television was analogue broadcast and the receiving equipment still a work in prgress Joe Public knew all about interference. We can expect the same awareness to arise as the internet of things grows over the next decade and various day to day items stop working for no reason.

We will see jobs, legislation and associated corrective action on multiple fronts as a result.

JC, NYC USA

 

itstechpro
User Rank
Iron
Re: Just Bzzt on the stereo?
itstechpro   11/28/2011 10:46:24 AM
NO RATINGS
In 1976, I was working on a low noise video amplifier for a large area CCD array to be used in astronomical observation. When measuring noise figure and bandwidth, I was plagued by a periodic noise burst that made the measurement impossible.  I checked for sources around the lab and then around the house (lab located in the basement of a hillside home in Fairfax, Marin County, CA.)

Finally, I happend to glance out of the window at the fine view of Mount Tamalpais which we had and recalled the Air Force search radar at its peak.  I could see the radar site (~7 miles away) through binoculars; the rep rate of the interference was what I would have expected from the rotation rate of the antenna.  A small Faraday cage around the measurement setup took care of the radar interference.

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