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[DPRG]Wall-E -> 1GHZ computers laser rangefinding

Subject: [DPRG]Wall-E -> 1GHZ computers laser rangefinding
From: John Swindle swindle at compuserve.com
Date: Sun Jul 27 13:42:45 CDT 2008

Folks:

I disagree with one of the comments about using IR instead of 
visible light, supposedly because there is too much visible light 
noise in the environment. A similar reasoning error is made when 
thinking about using 40KHz for sonar, thinking that there's less 
sound noise around that frequency. Just because we can't hear or 
see something says nothing about how much noise there is at those 
frequencies. Indeed, there's lots of IR noise. Everything is 
somewhat hot. And for sonar, the harmonics of our machines and 
our squeaky sneakers are well above our range of hearing. The key 
to rejecting noise is the modulation.

Back to my passive sonar stuff now. (I'm using audible sound so 
that I can debug it with my ears instead of always depending on 
the microphones and calculations.)

John Swindle

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