5 Jan
2016
5 Jan
'16
2:49 a.m.
On Monday 04 January 2016 19:49:44 Jonathan E. Brickman wrote:
On 01/04/2016 01:14 PM, Chris Caudle wrote:
If your microwave interferes with the wifi. there is no way in hell it
will pass an rf leakage test. If the door is sprung a teeny bit, or
isn't closing because of cooked on spilled food, it can leak, a lot.
I am a retired television engineer, and one of the things we have to do
every 5 years is rent a Holiday (sp?) certified broadband leakage
measureing meter and survey all around our transmitters to show the FCC
that its safe for humans to work around. The field strength allowed is
equ to 10 milliwatts per cubic centimeter of flesh for continuous
exposure a 90MHz. That is actually quite strong, but in the range of
wifi or a microwave oven, both of which are adjacent in the 2.4 and 2.5
GHz bands ISTR its dropped to 1 milliwatt per cubic centimeter. Our
elderly GE transmitter on channel 5 passed, no problem.
The engineer at WOAY is where I sent the meter that we have to use, also
had to do his renewal. So when he unpacked it, checked the batteries and
turned it on, then walked into the lunch room for a warmer cup of
coffee, leaving it on the table 10+ feet from the microwave still turned
on. Putting the cup in the oven and setting it for one minute, as soon
as the magnetron reached operating temps, typically not more than 1
second, the alarm on the meter went off. Scrambling back to the table,
it was offscale and didn't come back to zero until the microwave timed
out & shut off. He looked at the door, and one hinge was bent so one
edge had a gap of about 5 sheets of copy paper width. Since it was a
vendors unit, you can guess where the next phone call was to, and he had
a brand new one an hour later, which was invisible to the meter.
Moral is, it doesn't take much to make one leak rf like a fire hose.
That was far enough down in the used calendar pile that we had no wifi,
else I expect we would have been alerted sooner. Now almost everyone is
using it, so we've all a built in to the house alarm when the wifi dies
when the coffee is cold and being warmed up.
I used to have problems with the WiFi to my
wife's laptop slowing
greatly if we were heating anything in the kitchen microwave. I
can't conceive of using something that fragile in a concert
environment.
I'll have to think that there are lots of factors; we used to have an
early 1980's microwave, huge and powerful, about six feet away from
our WAP and there was never a problem. Maybe the laptop's chipset was
sensitive in unusual ways, or something. And I have to agree, 2.4GHz wifi is dangerous right
now...but not
really with directional antennas, banks are still using 2.4GHz for
ATMs across quite a lot of space outdoors, with directionals. And
there's always 5GHz...IR...UV...visible...:-)
The motivation for me is simple. I have worn out too many USB ports
to be happy about it!!! I have thought of trying to throw USB over
three 1/4" phone jack cables (using the _extremely_ __durable
traditional Switchcraft hardware), but have thought that I would
probably run into impedance, isolation, or something else hidden in
USB. I have also spent quite a lot of time looking for adapter combos
which would let me use microUSB for the common detachments, but it
seems that the parts builders just haven't had me in mind.
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>