> on the subject of IR I have this idea for a project and I wonder if
> anyone can help...
> I need to detect a certain frequency which is very strait forward (
> using a PLL) but at the same time measure the amplitude of that
> frequency. basic what I want to achieve is detect the object
> transmitting and By the amplitude of the frequency transmitted see if
> it is at a certain distance from the receiver.
> those anyone as any thoughts?

This means you won't be able to use the very handy integrated IR receivers
that are tuned to specific carrier frequencies.  That's a lot of analog
electronics to duplicate.  Creating a peak detector will either fall out
of your AGC circuit, or it will be easy to add compared to all the other
stuff you need to receive IR well.

There are many other factors that effect received light level other than
distance.  In addition, it may not be so easy to get a linear, or even
known, response from the receiver.  All you normally count on is that it's
monotonic with some minimum sensitivity over the range of interest.
Otherwise yes, all else being equal, the light level will be inversely
proportional to the square of the distance.

All in all, I think trying to get meaninful information from light level
is a bad idea.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics