On Jun 2, 12:35*am, AndyS wrote:
On Jun 1, 10:21 am, "Clint Alexander" wrote:





I want to make a simple transmitter to use as a locator beacon. But the
source would be in the ground (anywhere between 3 - 10ft). The receiver
would need to locate it, much like a metal detector would except it would be
a small hand-held "wand" with a LCD giving the direction and signal
strength.

I'm not sure of the signaling to use therefore I'm not sure of the antenna
required. But, it would need it to follow part 15 of the FCC
rules/regulations (none hazardous and allows required interference).

I am completely new at this sort of technology. I have created circuits
before using L555 timer, 4046Phase Loop, etc. But I've never went farther
than building simple demonstration circuits. I wondered if there was anyone
on this list that may be able to shed some light on what I would need and/or
how I would use them (a schematical description), or even point me to the
"yellow brick road".

Thanks!
--
//Clint Alexander
Andy writes: * *I messed with a transmitter used to map out caves and

tunnels a while back and think that would fit your bill. *I don't
remember the details
but I think it ran around 100 Khz or so, and the antenna was just a
coil
of wire about a foot in diameter, using magnetic near field coupling.
Power was only a few watts and the range was hundreds of feet.

* *If you google things like "cave mapping" *, " spelunking
transmitters",
and keywords like that, you may have a lead to follow.

* * * * * * Good luck,

* * * * * * *Andy W4OAH- Hide quoted text -

- Show quoted text -

At 457KHz they use ferrite rod antennas

I think if you are building your own system you need a crystal locked
transmitter and a very narrow bandwidth ( DSP filters ? ) receiver in
order to obtain the best range and rejection of unwanted noise and out
of band signals.

Some design notes can be found here.

http://www.ece.uvic.ca/~mblarows/ELE...ort%202-r1.pdf

http://www.backcountryaccess.com/eng...Future_000.pdf

Google or search US patent websites for 457KHZ transmitter antenna.

UKM

UKM