BACKGROUND

We are interested in finding an electronic distance measurment system
with the characteristics below.  We are also interested in finding
other people or organizations that share our interest in such a
system.

The system must be able to measure the distance between two specific
objects with an accuracy of 0.5 meters over a range of 0m to 50m.  The
system must be attached to one or both of the objects, rather than be
mounted in the environment.  The system must be self contained and not
require a connection (wired or wireless) to anything in the
environment other than, perhaps, a wireless connection between these
two objects.  We are not able to aim the objects at each other to
faciliate the measurement and they might be obscured from each other
by cloth or other material that blocks light and sound.  Because of
this, we expect this system will use radio-frequency energy to
determine the distance.

REQUIRED ANSWER

We'd like a list of such devices that have been built (commerical or
otherwise), as well as people and companies that are interested in
them.  For instance, pointers to university research groups building
devices like this would be of interest.  We'd also be interested in a
list of possible applications of this technology, user-groups for
people using this technology, etc..

EXCLUDED ANSWERS

We are not interested in any system that needs more than a small
battery, needs aiming, or needs one object to be visually visable from
the other object.  We are not interested in any system that requires
structures in the environment, such as base stations, access to wired
electrical power, etc.

I am an electrical engineer who is developing a system that has
similar specifications to the characteristics you stated above.  What
is your interest in such a system? (want to buy one?, want to have one
developed?, developing one yourself? other?) What is your timeframe?
(immediate?, near-term?, future?)