Hi Fr. Tom,

I thought it would be helpful if I explained it in more detail, considering
the responses I got (they were good, but this isn't exactly a
communications system ;-)

Yes, what you describe is exactly what I plan on doing. I was planning on
using cardboard, painted black, as the barrier. You did remind me, though,
to test this for IR opacity.

I derived a formula for the range of angles for which each sensor will be
illuminated for given barrier dimensions and used it to tweak the spacing
for the right null zone width (some null zone is probably necessary to
prevent the thing from going nuts when it is close to being pointed
correctly).

Thanks,

Sean


At 08:42 AM 6/7/00 -0400, you wrote:
>Sean,
>Now that we know more details we can be more helpful
>in our responses. :)
>
>Since you are using four phototransistors  and they will be
>very close to one another, you want to maximize the
>signal differential. This can be attained by making sure
>that each of them sees a different view. You would want the
>detectors to be aiming ever so slightly AWAY from the
>center, -OR- make sure that there is some optical separation
>based on the presence of an optical barrier between
>each of the sensors.
>
>This helps enhance the difference signal significantly.
>It does not in any way *boost* the received signal,
>but it does help make the four received signals more
>differential, so to speak. The barrier must be IR opaque
>and just high enough to cast a shadow when illuminated
>off-axis. You can use the rocket itself as the barrier.
>If possible, mount the four sensors in the nose cone,
>separated as far apart as you can. In this case the
>nose cone itself becomes the optical barrier.
>
>Fr. Tom McGahee
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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