On Fri 06 Oct 2017 at 01:22:18 (-0400), Gene Heskett wrote: > On Thursday 05 October 2017 22:56:33 David Wright wrote:
> > One advantage of Powerlines is that they aren't bothered by > > microwaves which knock out nearby 2GHz devices. > > As in cooking microwaves? If its leaking that badly, have it serviced by > someone with a leakage measuring apparatus. Or replace it. That level of > leakage is sick bird on this side of the pond. I've checked and > rechecked the $100, 1kw model I got from wallies to take on the road > when I was out doing consultancy things after I retired for a few years, > in my kitchen now and can't find it with that meter. 15+ years old now, > I've had to replace some of the interlock microswitches, but 30 seconds > for a cuppa is still too hot. Sagging doors are the usual suspects. > > Here we have to leak test our broadcast transmitters and be able to > certify they have a leakage field that is less than 5 milliwatts per CC > of human flesh exposed or we cannot renew our license. I think your fears are misplaced and here's why: 5mW/cm² at 5cm is of course the maximum allowed by µwave ovens once they're sold (1mW at the point of sale). Even at 5m, that would still be 0.5µW/cm² given an air path, which is what there is towards both laptop and TV. The FCC maximum power density for general exposure is about the same, so that gives an approximate value for the maximum signal strength at the router and the laptops/rokus when transmitting. But then we have to add in (or rather subtract) the effects of (a) the three walls and two floor trusses along with all their accessories plus the services and ducts contained in them, which lie between said devices and the router, (b) the fact that information has to be extracted from the carrier signal, and (c) the router has to be able to sort out the competing signals it is receiving from all the sources in the kitchen. Another factor that's probably difficult to estimate is how much the computer devices have attenuated their signal strengths (on the basis of reasonable reception) when the µwave suddenly comes on. Do the devices retrain to the new conditions? How long does that take? Is that why the TV sometimes comes back? This last is complicated because the buffering done by a roku varies by channel, programme material, how far into a programme segment since the last commercial, etc etc. Plenty of imponderables. Cheers, David.
