Re: Simple signal transmission using long steel pipe


<paulus9528@xxxxxxxxxxx> wrote in message
news:1144744144.847057.130430@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I am a mechanical/hydraulics engineer with an application which may be
more suited to you guys' expertise. What I want to do is transmit a
signal from a remote (up to 5km) device through a long piece of steel
pipe. The remote device incorporates a sensor which produces a simple
signal (on/off) which I would like to detect remotely. Is this feasible
to transmit a sigal (electrical or sound) without any signal boosters
etc.? If this is in no way feasible I have other solutions but this
would make a real neat, simple and cheap solution. Your advice/help is
much appreciatd.

This is second hand, so I can't provide much info. There was a posting to
this or a related NG way back in response to a similar question. It
mentioned that there is a heating system in Europe that is distributed in
some way throughout a building. It transmits the heat as a hot liquid medium
in pipes, and commands are transmitted acoustically through the liquid.
Useful for old buildings with old systems, where the pipes exist but
installing signal paths separately would be difficult. From a physical point
of view, acoustics should be good at such a task, sound travels well and
rapidly in low-compressibility media such as vapour-free liquids. The
substantial acoustic impedance mismatch between the liquid and the pipe
would minimise loss. Discontinuities such as bends could be another
issue....


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