Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!emory!ogicse!cvedc!mcspdx!adpplz!martin
From: martin@adpplz.UUCP (Martin Golding)
Newsgroups: sci.electronics
Subject: Re: How can you 'track' something back and forth?
Message-ID: <418@adpplz.UUCP>
Date: 30 Jan 91 01:30:08 GMT
References: <304@fxrs.intel.com>
Organization: ADP Dealer Services R&D, Portland, OR
Lines: 41

In <304@fxrs.intel.com> jmasters@fxrs.intel.com (Justin Masters) writes:


>I was wondering how one might go about tracking something back and forth.  I
>intend to use either an IR transmitter or a FM transmitter as a source, but my
>question is how do I track it?

>Some ideas that I had...

>IR.  Utilizing a diamond grid of two receptive elements (recessed, or shielded
>from stray IR energy), I would use some kind logic to simulate the following
>way a human centers his eyes on a light.  He sees some light from the right
>side, and turns his head towards it, until the amount of light being received
>in both eyes is equal (looking straight at it), and then stopping your head.

>FM.  Somehow receive a pulsed signal on an FM signal to two different points,
>and combining the signal to each other to see which pulse 'arrived' first.


>How would you go about doing a comparison to see which receptor/receiver had
>received its signal first or was closer to the point desired?

>What kind of motor do you try to use (12v or less) to turn towards the
>originating signal, and how do you control it?  How do you keep from
>having constant 'over-compensation'?  In otherwords, how would you keep the
>motor from going back and forth in slight increments while trying to center on
>a stationary point?

I'm entirely unqualified to be reading this stuff, never mind replying to
it.
However,

Have you considered sound? High frequencies are reasonably directional
and hard to reflect. Then you could use tuned tubes at angles and check
volume, or measure phase differences, which at a few tens of khz would
be practically hours between pulses. Polaroid has an experimenters kit
for their ranging system, which of course is probably completely irrelevant.

Hey, whaddaya want, I' software, ok?

Martin Golding