Re: Thursday, Jan 27

[Tim Vanderhoek <vanderh@ecf.utoronto.ca>]

On Wed, Jan 26, 2000 at 10:35:36PM -0500, Joyce Poon wrote:
> 
> at high freq -- ie if we modulate at 800Hz, our filter will pick up
> anything over 800Hz, including the enemy signal possibly).  I could build
> a bandpass filter but that gets complicated....

Something about a competition to use the highest IR frequency scares
me.

If you're right and most other groups are using frequencies that are an
order of _magnitude_ higher than 800Hz, then you would not need to
construct a very good bandpass filter for it to be effective!  If most
people are >>800Hz, then I think this is the way to go.  That's a pretty
easy filter to build (just short-out the high-frequencies through a
cap).

If, however, people are scattered across the range from 800Hz to
10KHz, then the above won't work as well.

Have you considered the chips mentioned on page 141 of the design
manual?  I don't know how easy they are to use.

_However_, until we actually get these things together, we don't
really know too much.  We may find that 800Hz is too susceptible to
noise, for that matter...

It may be better not to worry about details (such as the specific
frequency used) until after a basic sensor circuit is working.


-- 
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