[lug] Wireless router question (OT)

Stephen Queen svq at peakpeak.com
Fri Nov 5 06:35:38 MST 2004

> This may sound silly but 30m is well within Ethernet specs -- why not
> just run a cable between these three nodes?

As the helicopter lifts off, the system is not moving
forward, so it has no aerodynamic stability. What usually
happens then is that the receiver and transmitter assemblies
start spinning. This twists the cable. This in effect causes
the cable to become a lot less reliable.

> Sounds over-engineered (or is that under-engineered) just from this
> description.  Certainly not as reliable as a simple cable.

Actually, plugging in 3 AP's, 2 of which are setup as
infrastructure clients is simple compared to rigging an
ethernet cable between everything. It has made the system a
lot easier to setup. But as with any engineeering, there are
many trade offs to be considered. The cable we did use had
to be built such that the strength member was slightly
shorter than the cable. That way, as the weight came on to
the cable the signal carrying part of the cable didn't start
bearing the weight of the system. There could not be so much
excess of signal cable that it could snag on the RX and TX
at lift off and set down. Also, the signal carring and
strength member had to be able to move in relation to each
other so as to relieve the stress on the signal part as the
stress shifted. That meant that they could not be tied to
tightly together. Also, as the RX an TX would spin, at
different locations within the cable, the twisting together
of the strength member and signal member would cause the
signal member to pull tighter in that location causing a
great deal of stress on the cable. The life of these cables
was relatively short.

As far as the economics, the AP's are negligible compared to
the cost of helicopter time.


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