Hi all!

I'd like to build a small, "keychain" RF remote control much like those used
for car alarm control. My "only" other requirement is that the remote should
be bidirectional, ie: able to receive digital data (4 status bits will do)
from the device being controlled.

The usable range for the remote to the device should be some 30m (100ft).
However, I'd like to have an usable range for the device to the remote of
about 1Km (0.6 mile).

Power at the device being controlled is no problem. Likewise, size is not a
problem there.

Conversely, at the remote, size, weight, power consumption and heat
dissipation should be as small as possible (like any decent remote). I am
thinking in 5cm x 2.5cm x 1cm (2 inches x 1 inch x 0.4 inches) to be the
absolute maximum size.

Forget the digital part. I will be using a pair of PIC 16C73 and the
excellent Holtec 3^18 remote control ICs.

I need help with the RF part.

I have been looking at some "ready to use" data RF modules, and while they
are adecuate for the remote to device transmission, none of them comes close
in the device to remote part in terms of usable range (I need 1Km or 0.6
miles). I have already considered devices from:
- Convergent INC - http://www.convergentinc.com/
- RF Monolothics - http://www.rfm.com/
- Radiometrix UK - http://www.radiometrix.co.uk/

Does anyone know of a device suitable for this application?

Thank you for your support!

Regards,
Andres Tarzia
Technology Consultant - SMART S.A.
e-mail: atarzia@smart.com.ar