>Can also be used as a basic, very basic two-channel, logic analyser
Interesting. How is your setup for this?

/Ake

-----Ursprungligt meddelande-----
Fr=E5n: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]F=F6r Jinx
Skickat: den 9 juni 2004 01:56
Till: PICLIST@MITVMA.MIT.EDU
=C4mne: Re: [PIC:] My second project: IR LED Distance Sensor


> > Are you able to 'scope the o/p of the receiver to ascertain exactly
> > what that "noise" is ?

> Unfortunately not yet as a scope for me is still in the wish-for phase

For that kind of signal you should be able to use a PC's sound card
and a sound capture/processor utility (eg Goldwave - free, very good,
hardly disabled at all, used it for years). Can also be used as a basic,
very basic two-channel, logic analyser

http://www.hitsquad.com/smm/programs/GoldWave/

or www.goldwave.com of course

I've tried others (eg CoolEdit), prefer GW (OK GW, where's my $$$ ;0)

> > If not, and you can't find an obvious local culprit, perhaps data
log
> > the ADC at a higher rate than 1/4s to look for a pattern (or not)

> Actually I moved it down to 1/4 second for the same reason.  I at
first
> had it running as fast as possible and was seeing the "noise", so I
> slowed it down dramatically to see if the fluctuations were still
there.
>  And yes they were.

> But I think I found a suitable answer.  If you look just at the three
DIFF
> above, you'll see that if you take only the last byte of the hex
number,
> the numbers look as expected:  02, 02, 01.

> So I did that and all the "noise" disappeared magically.

But are you sure you aren't sticking your head in the sand ? If there
really is a physical noise problem, a s/w workaround won't make it
go away. Apologies if that sounds preachy

> > A quick experiment would be to put the whole thing in a box and
> > make sure that with no light whatsoever the o/p is low and stable

> You know I was thinking something along that line.  I was thinking
> that if it was in a black box that it might be able to measure
distance
> quite accurately. But I couldn't think of a good reason to measure a
>  distance to something in a dark place.  (-:

Make you a wiz at Murder In The Dark ?

What I was getting at was that by putting the circuit in a lightless box
you have a controlled environment which you can use to judge/verify
the sensor's performance

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu