[opendtv] Re: Google's Page: White spaces test was unfair
- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 29 Sep 2008 18:49:13 -0700
Yep, frequency planning and the ability to do signal strength measurements
is a prerequisite to earning a doctor of divinity degree in all states, and
all churches are FCC licensees.
All ministers are engineers, right?
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Manfredi, Albert E
Enviado el: Monday, September 29, 2008 2:39 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Google's Page: White spaces test was unfair
Craig Birkmaier wrote:
> Wireless mikes are used by MANY groups, not just broadcasters. In
> theory you need a license to use them, but in reality most of
> these devices are never registered with the FCC. Among the groups
> using them:
>
> Churches
> Live performance theaters
> Independent producers and videographers
> Trade show hawkers
[ ... ]
> And then there is the other reality - there is a large installed
> base of wireless mikes that use frequencies in the recovered 700
> MHz spectrum. These "licensed" devices will not be able to use
> these frequencies after the analog shut-off. Or more accurately,
> users of these mikes will likely interfere with the new users of
> this spectrum.
Okay, that's fine. What seems to be missing in these discussions, then,
is that the same laws of physics apply in all these cases.
The general problem is, IMO, an insufficient appreciation of the
"inverse square law." Which means, power density drops as the inverse of
the distance from the source. So, if there is a chance that these "white
space devices" will be used in close proximity to a device trying to
pick up a legitimate, non-white-space, much more distant signal, then
there is a potential for problems to occur. The potential exists mostly
with white space devices in consumer hands, specifically those which
auto-detect the "white space."
In chruches, for example, chances are that (a) the pastor has set the
mike's freq correctly, and probably manually, (b) the congregation won't
be using their own white space devices in the church, and (c) no one is
trying to watch TV using and indoor antenna, in this congregation.
If the freq setting mechanism (manual or auto-detection), and the
inverse square law and its consequences, are not taken into account,
then to me any argument in favor seems specious.
Bert
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