On Wed, 07 Apr 2004 17:23:54 GMT, Jim Hampton wrote:

Essentially, it seems there are new interference problems. The police and
fire departments in some areas have been experiencing interference from -
get ready for this - CELL PHONES! Yep, the huge numbers of cell phones and
cell phone towers are beginning to make it difficult for the fire and police
to communicate. Many folks with HTs that have been in reasonably close
proximity to large communications centers (such as the 911 center about two
miles from my house) already know about intermod. Hey, weren't cell phones
supposed to be the new 'emergency' communications?

Let's get this straight. First off, it's not new. It'e been around
for over six years that I know of. The Comm Manager for Washington
County (where I live) was the one who found the cause of the
desensing and blew the whistle to APCO. Then other public safety
victims came out of the woodwork, including several clients of the
company that I consult for.

Secondly, it's not "cell phones". It's Nextel, a hybrid technology
system that emerged from Enhanced Specialized Mobile Repeaters
(ESMRs) which were legalized for-profit entities to sell local
repeater service to small or medium sized businesses on a multi-user
basis. The only relationship that it has to real cell-phones is
that it uses cellular digital technology and is used for "chatting"
rather than dispatching.

What happened was that when the 800 MHz band that was formerly TV
Channels 80-88 was reassigned, part of it went to the (common
carrier) cellphone service and the other part went to the land
mobile services with alternate channels assigned to Industrial and
to Public Safety licensees. The intent was for small businesses to
establish small networks based on high elevation repeater sites
carrying analog dispatch ("push-to-talk") communications, and the
Public Sefety folks to establish trunked local dispatch systems at
low-level sites.

Enter the Merger and Acquisitions Masters. Nextel, guided by a
maverick (who used to be at the FCC and screwed up his projects
there) started buying up those ESMRs and erecting high powered
cellular repeater sites at low elevations, most of which were close
enough to Public Safety trunked system sites to cause front-end
desensing from the full-time and full-channel digital voice systems
that they migrated to.

The sad thing is that the FCC is largely a shill for large business now. It
would't take a ton of effort for some kind of coordination to help avoid
this problem - but, hey, no regulation is better than regulation, right?

APCO and Nextel worked out a solution which would mean moving
licensees out of the interleaved pattern into homogenous blocks
(like in the "good old days"), and worked out a financing plan, and
it's now sitting at the Wireless Bureau "awaiting action" (a euphemism
for gathering dust).



--
73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

On Fri, 09 Apr 2004 00:55:07 GMT, "Phil Kane"
wrote:

snip

Secondly, it's not "cell phones". It's Nextel, a hybrid technology
system that emerged from Enhanced Specialized Mobile Repeaters
(ESMRs) which were legalized for-profit entities to sell local
repeater service to small or medium sized businesses on a multi-user
basis. The only relationship that it has to real cell-phones is
that it uses cellular digital technology and is used for "chatting"
rather than dispatching.

Nextel uses Motorola's iDEN system for their network - a good
technical overview is available he

http://www.geocities.com/45peter/iden.html

snip

73, Leo