Alt-BEAM Archive

Message #07301



To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Tue, 2 Nov 1999 17:15:17 -0800
Subject: [alt-beam] Re: directional antenna?


You can easily experiment with magnetic field induction. In such system, a
low frequency carrier (10-50kHz) can be modulated with data for short
range communication. A number of turns of small gauge wire could be wound
around the circumference of your RJP and the bot uses small coils and a one
transistor amplifier to pick up the signals. Perhaps other bots interfere
with the field and cast magnetic shadows which could be detected? For a
position location system perhaps use one rotating or two fixed small
induction loop antennas wound at right angles to receive the induced signals
from a vertical plane induction loop beacon. It may be interesting to
change the induction loop frequency like a metal detector and maybe
theremin-like music can be generated from the movement of the bot in the
field. The frequencies, principles and complexity are all with the range of
BEAM tech experiments.

Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411

> -----Original Message-----
> From: Senior [SMTP:kyled@cruzers.com]
> Sent: Tuesday, November 02, 1999 2:53 PM
> To: beam@sgiblab.sgi.com
> Subject: Re: directional antenna?
>
> Evan Dudzik wrote:
> >
> > does anyone have any ideas on how to build a
> > unidirectional antenna? this would be great for homing
> > in on RF signals... otherwise, i have another idea.
>
> If there is something that won't let radio waves pass through it you
> could cover all but one part of your antenna with it, effectively
> "aiming" it.
>
> > take three antennas, and place one in the center of
> > the bot... take the next two and place them at the
> > left and right sides of the bot. now, have a beacon
> > set up that transmits signals... it just has to
> > transmit a signal, wait for like a second, and then
> > trasnmit another... the robot will have its central
> > antenna on at all times, waiting for that first
> > signal. when it recieves it, it turns on the other
> > two recieving antennas... when the signal comes, it
> > will reach one antenna BEFORE the other because that
> > antenna is closer. The difference between times would
> > be REALLY short, so the bot would have to have some
> > quick detecting circuitry (TTL... isnt that really
> > fast? fast enough?) this whole thing is kinda how our
> > ears work, sound reaches one side before the other.
> > any ideas on circuitry? or whether this thing would
> > even work? it would be good to help a bot home in on
> > its charging station... or other uses. anyway,
> > thanks.
>
> This is called triangulation because there are three points: Becaon, and
> two on the bot. You only need two on the bot, just have one listening
> and then it turns the other one on or both on all the time or whatever
> you like. It's been done. Steven Bolt did this osrt of thing with sound
> and microphones at:
> http://www.xs4all.nl/~sbolt by the way, anyone heard from him lately?
> or chiu!!!!
>
> So, yes, this is very doable. Search around, maybe you can find a kit or
> schematics.
>
> Kyle



7302 Wed, 3 Nov 1999 09:30:28 +0800 Re: Craig's chloroplast SE
> In a message dated 10/31/99 10:29:00 AM Eastern Standard Time,
cybug@home.net
> writes:
>
> > "OK, from FLED to 1381, that was a step... but from 1381 to
chloroplast,
> > it's a whole new world. I build another little guy last night, and
forget
> > the heat-shrink tubing on motor axles, i put full-on wheels onto the
motors
> > - that engine has some serious torque! From speed NEVER being an
issue,
> to
> > keeping the hysterisis down, because my guy does a 180 on every burst,
it's
> > never been so exciting."
> >
> YEP! Very interesting engine. It is nice to have something with a little
> power to it. I was just wondering, what would happen if you hooked up the
> chloroplasts in a chain, each feeding the next. Would you have a "neuron"
> like deal going that can hold a charge along it's system like memory? This
> just popped into the void between my ears and I haven't thought it
through.
> Anyone have any ideas?
>
> See ya,
> Jim
> http://www.geocities.com/SoHo/Exhibit/8281/beamart.html

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