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Subject: 
Re: FW: simple but functional radar
Newsgroups: 
lugnet.robotics
Date: 
Wed, 13 Jan 1999 21:21:00 GMT
Original-From: 
Peter Hesketh <pbh@phesk.demon.co.uk+StopSpammers+>
Viewed: 
1054 times
  
In article <369D0A38.8BEA4429@opendisc.com>, Joe Greene
<lugnet.robotics@lugnet.com> writes
Ok concept..don't know if the RCX can handle this but could the RCX issue a
coded ping, and wait for it to bounce, using the time delay to calculate the
distance to the nearest object? or is th  RCX clock to slow for this??

By several orders of magnitude.  The shortest possible ping is about 41
milliseconds long, and a reflection from a surface 2 feet away would
only take 4 nanoseconds to go there and back.  As 41 milliseconds is
41,000,000 nanoseconds, this means that that the echo from the start of
the ping will get back to the receiver only a ten-millionth of the way
through the ping.

It's not so much that the RCX is too slow, but that the speed of light
is too darn fast!  That's why many people use sonar instead.
--
Regards - Peter Hesketh, Mynyddbach, Mon.
Forty reasons why a dog is better than a woman: number 18
"Dogs never need to examine the relationship."
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics



Message is in Reply To:
  Re: FW: simple but functional radar
 
Ok concept..don't know if the RCX can handle this but could the RCX issue a coded ping, and wait for it to bounce, using the time delay to calculate the distance to the nearest object? or is th RCX clock to slow for this?? (...) Joe Greene Technical (...) (25 years ago, 13-Jan-99, to lugnet.robotics)

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