"Ari Silversteinn" wrote in message
...
Crossposted to:

rec.radio.amateur.antenna,rec.radio.amateur.misc,r ec,radio.amateur.equipment

Novitiate he

I am learning AM broadcast basics in particular the issues regarding the
geo-targeted broadcasting of alert messages from moving vehicles. Would
most appreciate any assistance.

Due to Katrina/Rita, the company I work for has been given the opportunity
to demonstrate a messaging system that would reach out approximately 1
mile
+/- in transmission deliverance. This would be an "overbroadcast" (my
term)
in that it would override local AM radio broadcasting to reach into cars,
trucks etc. In particular, we are working with a stationary site (a
chemical spill for instance) and an emergency vehicle that would move back
and forth at and through the site, at up to 70 mph, broadcasting an alert,
voice and tone message.

Reading about LPAM, this looks technically possible but one concern I have
is antennae size. A fire truck, for instance, could have an antenna
mounted
on its front, and up to 4 feet over the top of its roof, so we might look
at as much as 20 feet of length. I realize this places us over the 3 meter
max so one of the ???? is whether LFAM is realistic.

Am I way off base here, can any antennae, fractal or other, or any AM
antennae technology, be utilized to design an antenna and propagate this
type of signal?

All comments appreciated.
--
The things that pop into my mind are why AM rather than FM, which tends to
be more local, and do you intend to 'over-broadcast' only the local channels
(how many?) - I assume you intend to make the channel(s) selectable - or the
entire band to ensure you get everyone? Assuming that there is a commercial
AM broadcast station in the vicinity (what, 10 miles? 20 miles?) you are
probably going to be flat out getting a mobile rig to ride over it. How do
you intend to do this?

Cheers.

Ken

On Mon, 3 Oct 2005 11:59:58 +1300, Ken Taylor wrote:

Am I way off base here, can any antennae, fractal or other, or any AM
antennae technology, be utilized to design an antenna and propagate this
type of signal?

All comments appreciated.
--
The things that pop into my mind are why AM rather than FM, which tends to
be more local, and do you intend to 'over-broadcast' only the local channels
(how many?) - I assume you intend to make the channel(s) selectable - or the
entire band to ensure you get everyone?

The issue of selective vs full range broadcasting is a matter that has not
been decided either by client, company or possibility. There are plusses
and minus' to each.

Selective would entail less power but we are being told power of the fire
engine is not an issue.

Assuming that there is a commercial
AM broadcast station in the vicinity (what, 10 miles? 20 miles?) you are
probably going to be flat out getting a mobile rig to ride over it. How do
you intend to do this?

Cheers.

Ken

lol Good question, Ken. Any suggestions?
--
Drop the alphabet for email

there is no requirement that anyone listen to any broadcast radio. with the
rapid growth of satellite radio there are even less people listening to
either am of fm broadcast radio. add those who listen to cd's or dvd's and
you get even less.

There are systems that are used for local road emergency notification, the
560khz one comes to mind, something along those lines would be the best bet,
and add in signs on the backs of vehicles. i guess the real question is,
what are you trying to do by overriding local broadcast stations? and over
what size area?


"Ari Silversteinn" wrote in message
...
On Mon, 3 Oct 2005 11:59:58 +1300, Ken Taylor wrote:

Am I way off base here, can any antennae, fractal or other, or any AM
antennae technology, be utilized to design an antenna and propagate this
type of signal?

All comments appreciated.
--
The things that pop into my mind are why AM rather than FM, which tends
to
be more local, and do you intend to 'over-broadcast' only the local
channels
(how many?) - I assume you intend to make the channel(s) selectable - or
the
entire band to ensure you get everyone?

The issue of selective vs full range broadcasting is a matter that has not
been decided either by client, company or possibility. There are plusses
and minus' to each.

Selective would entail less power but we are being told power of the fire
engine is not an issue.

Assuming that there is a commercial
AM broadcast station in the vicinity (what, 10 miles? 20 miles?) you are
probably going to be flat out getting a mobile rig to ride over it. How
do
you intend to do this?

Cheers.

Ken

lol Good question, Ken. Any suggestions?
--
Drop the alphabet for email

On Mon, 3 Oct 2005 16:20:40 -0000, Dave wrote:

there is no requirement that anyone listen to any broadcast radio. with the
rapid growth of satellite radio there are even less people listening to
either am of fm broadcast radio. add those who listen to cd's or dvd's and
you get even less.

The loss of listenership is not arguable.

There are systems that are used for local road emergency notification, the
560khz one comes to mind, something along those lines would be the best bet,
and add in signs on the backs of vehicles. i guess the real question is,
what are you trying to do by overriding local broadcast stations?

1) to grab those that are listening to AM/FM, it is still a hyooge market,
2) client request, 3) DHS preference 4) the number of people alerted by a
sign/sticker and independent warning channel is much less than both that
and AM/FM, 5) the possibility that once the AM/FM FCC/NAB bond is broken, a
precedent could be set for cell, sat, threading messaging, etc 6) spinoff
tech for local/reg/national emergencies.

and over
what size area?

1 mile radius max from point of incident, less most probably.
--
Drop the alphabet for email