Is this just sensing a switch? If so, how about a grid-dip-oscillator, where
the 'transmitter' is just a tuned LC circuit that can be shorted out by the
switch.

----- Original Message -----
From: Russell McMahon <apptech@CLEAR.NET.NZ>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, June 26, 2000 10:52 AM
Subject: [EE] Lowest possible cost short range RF telemetry solution sought.


> I have an application requiring very short range low speed telemetry.
> Low cost is an overwhelmingly significant factor.
> The application is to transfer an occasional on/off signal over a distance
> of around 1 metre.
> Transmitter and receiver orientation cannot be guaranteed. There may be
> object(s) (possibly a person, metalwork etc) in the direct path although
> there will not be solid metal blockage (OK - I'll tell - it's part of an
an
> exercise machine.).
> For sufficient reasons the client wants a non contact path - wires (or
other
> media) are not acceptable.
> I could roll my own (SAW stabilised oscillator, TRF receiver, ...) and
might
> even get below commercial cost but there must be some cheap short range
> stuff out there. Everything I turn up seems to be slightly longer range
and
> cheaper would always be nice.
> Did I mention low cost :-) ???
>
> I'd be interested in hearing about the lowest cost units that people know
> of.
> Virtually anything that claims to be a telemetry link would work here!
>
> I'll also look at Infra-red and Ultrasonics but RF seems most likely to be
> the answer.
>
>
> TIA
>
>         Russell McMahon