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Subject: 
Re: IR Demodulator Range Finder Hack
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Mon, 17 Nov 1997 17:21:57 GMT
Original-From: 
Graeme Dunbar <G.R.A.DUNBAR@EEE.RGU.ACsaynotospam.UK>
Viewed: 
2819 times
  
On 17 Nov 97 at 11:08, John Hatton wrote:

> A few months ago I found information on how to modify the Sharp IR
> Demodulator to produce an analogue voltage relating to the strength
> of IR received. The problem is that I have lost the information and
> can't remember where I saw it. Has anybody else seen this
> information and remember where it was or have sufficient information
> to perform the modification ?.
> 
> Thanks in advance for any help.
> 
> John Hatton
> johnha@icsplc.co.uk

I would be interested to hear about this too please.  We are running
a Group Design Exercise (our own version of a Lego robot
competition).  Designing the staff entry (to check the idea was
feasible in the short time alloctated to the exercise) I noticed that
using a Sharp IS1U60 to locate a beacon, the duration of the
output pulse seemed to depend on the signal strength.  I assume that
with a stronger signal it takes longer for the capacitor/resistor
preceding the comparator to discharge.

My final design used two detectors pointing forward and a baffle to
cast a shadow if the beacon shone from the side. This gives a
simple left-forward-right signal.  However if I had more time I would
see if it was possible to make use of the variation in pulse width.
I think it might be possible to overlap the fields of view of the two
detectors and use the difference in pulse widths to give a
proportional feedback signal.  Has anyone tried this?

        Regards,
            Graeme

------------------------------------------------------------
Graeme Dunbar
School of Electronic and Electrical Engineering
The Robert Gordon University
Schoolhill, Aberdeen AB10 1FR, Scotland, U.K.
Tel. +44 1224 262415
Fax  +44 1224 262444
email  g.r.a.dunbar@rgu.ac.uk
------------------------------------------------------------



Message is in Reply To:
  IR Demodulator Range Finder Hack
 
A few months ago I found information on how to modify the Sharp IR Demodulator to produce an analogue voltage relating to the strength of IR received. The problem is that I have lost the information and can't remember where I saw it. Has anybody (...) (29 years ago, 17-Nov-97, to lugnet.robotics.handyboard)

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