Hi
Some time ago, I4ve used a Honeywell HMC1002 coupled to an instrumentation
amplifier, followed by a AD and processor, to detect traffic entering a
parking lot. It worked nicely, signalling a bus (almost all aluminum and
glass) about 25 meters away, and smaller things nearer. Motorcycles about
1-2 meters.
You dont4t need to drill the road, just attach the box to a pole in the
roadside.
And forget vehicle signatures, if you don4t want to install strong signal
processing and data storage
The part is in DigiKey for about $50 each

Rafael Fraga

----- Original Message -----
From: James Cameron <quozl@US.NETREK.ORG>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, December 15, 2003 9:12 PM
Subject: [OT]: Farm Gate/Grid/Road Monitoring, 6km range, no LOS


> Ideas wanted.  I live on a farm, and would like the approach of vehicles
> announced in two houses.  But I don't want to have false triggers caused
> by thunder, cows, sheep, kangaroos, or insects.
>
> There's three cattle grids involved, where fencing is pierced by the
> road.  A cattle grid, also known as a ramp, is a series of metal bars
> perpendicular to the direction of travel.  There are metal bars up the
> side as well.  Cows and sheep do not pass these, though kangaroos do.
>
> Power is not available at the three grids, and they are not in line of
> sight.  There's an obscuring hill.  The radio propogation using 0.5W
> 477MHz UHF CB for the grids to the two receiving sites are;
>
> Grid 1  6km away        Site 1, okay    Site 2, lousy
> Grid 2  4km away        Site 1, great   Site 2, okay
> Grid 3  3km away        Site 1, great   Site 2, lousy
> Site 1 to Site 2, 4km away, okay.
>
> The roads are gravel, and require frequent maintenance, so that excludes
> inductive loops in the surface.
>
> A future expansion is to add "oncoming traffic in section" signalling,
> because the road is windy and narrow.
>
> Population density is low.  Nearest neighbour is 6km away from Site 2,
> the one after is 10km.
>
> Solution should involve a PIC, of course.  I'd like to have a history or
> log of announcements.
>
> --
> James Cameron    mailto:quozl@us.netrek.org     http://quozl.netrek.org/
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.
>
>

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