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DPRG: IR too sensitive.

Subject: DPRG: IR too sensitive.
From: Gary Croll gary.croll at ucr.edu
Date: Tue Mar 9 04:14:35 CST 1999

I've found it's a lot easier to reduce the drive to the LED rather than try
to de-sensitize the receiver. Also, look at the beam angle of the LED's
you're using. The more diffused the beam, the shorter the range. Using a
file on the lens of the LED really diffuses it if that's what you're after.

You may also be getting leakage into the IR module. Placement of the LED
with respect to the module is very important in eliminating this. I use the
Radio Shack LED bezel mounts for my LED's. Center to center distance is 1/2
inch between module and LED with the receiver module face 1/8 inch back
>from the LED.

I recently got some high output LED's with a 6 degree beam angle I'm trying
out. I'm hoping to improve on my unit's range which currently is only
reliable out to 40".

At 10:25 AM 3/9/99 -0600, you wrote:
>Have any of you had the sharp IR detectors that were way too sensitive?
>I see things from 7-9" on each.  I have scotch taped the detector with I
>lost count how many layers of tape.  I have the oscillator as far out of
>tune as the detector will still detect, and still I have too much range.
>What I am trying to achieve is a 3-4" detect so I can navigate between
>objects.  The 7-9" on each side plus the with of the robot at 10" is too
>wide for the required corridor.  
>I tried red cellophane, but that didn't seem to block any IR at all.  Does
>anyone have any ideas?
>What else can I do?
>Matt Minnis
>Preferred Resources          (314) 567-7600 phone
>701 Emerson rd.              (314) 993-6699 fax
>Suite 475
>St. Louis, MO
Gary Croll (KE6GHS)
University of Ca.
B-221 Sproul Hall
voice (909) 787-3041
fax (909) 787-7282
video (909) 787-8813


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