On Mon, 28 Oct 2002 [EMAIL PROTECTED] wrote:
> Are we going to have this thing radio controlled or a cable/wire attached to
> it?
>
> >From the CalTech glaciology website...
> "For electromagnetic waves with frequencies from 5 to 300 MHz the loss of
> energy by absorption in ice is sufficiently small that they can penetrate
> large ice masses great distances."
> This means that a radio controlled or transmitting device won't be a
> problem, but are we going to have a camera on this device? That would require
> that we did have a cable running to the surface because TV signals are much
> greater than that correct?
Normal VHF TV signals are located below and above the frequency range
used by FM radio (~92-105 MHz). I believe each channel requires from
6-10 MHz of bandwidth. If one uses MPEG-4 compression (requires probably
a Pentium-III class processor or greater in the Cryobot consuming 20-40W
of power) then one can probably get the bandwidth requirements down to
1-2 MHz or less. So if the ice absorption figures are accurate, then
I don't see the need for any relay stations at all.
> Self navigation would require some good A.I. and computer
> power and we are planning on leaving it down there correct?
I think several robotics labs (MIT, CMU and Los Alamos come to mind)
have developed quite robust self-navigation software for robots.
Of course this would need to be adapted to navigating in ice.
> "Radio waves are reflected by inhomogeneities in the ice and at material
> boundaries, especially at the ice-water and ice-rock interfaces"
> If our little cryobot does maneuver around boulders/asteroids in the ice, the
> radio control could get lost because of their interference.
This only seems to be important if one needs a high bandwidth signal.
Video out could apply enough ECC. Control signals in are very low
bandwidth so this would not seem to be a problem.
It is worth noting that since ice is a solid material, one might
consider ultrasonic signals (at least for the inputs). These might
be able to go up to several MHz without becoming too corrupted by
the inhomogeneities. Given the likely rate of progress of the probe
I can't imagine more than a few kHz of input information being required.
Robert
==
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