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Re: TV aerial rotator question

On Fri, 4 Jan 2002, Phil wrote:

> I have discovered a TV aerial rotator in a mail-order catalogue. It is
> described as a model AR300XC and uses a three wire cable to connect to the
> controller....  My question is, do these rotators have a feed-back pot?
> A three wire cable  makes me think that this is unlikely.

No, they use an identical motor in the controller on the pointer to move
the pointer the "same" as the one on the roof.  Assumption is that they
go at the same speed.

This is the basis of the APRStk automatic satellite tracking, doppler
tuning and TV rotator control software.  It uses 2 bits on your parallel
port to control the rotator through a simple $20 interface.  THus you get
full LEO satellite tracking for the $65 cost of the TV rotator and the
interface compared to almost $900 for  the typical AZ/EL mount and PC card

See http://www.ew.usna.edu/~bruninga/rotator.html

No, it will not give 1 degree resolution, but it will keep a small beam
within say 5 or 10 degrees of a LEO pass.  And that is much more than
adequate for a small beam (which is all that is needed for the LEO's
anyway)... And EL rotation is also not needed for 98% of all satellite
access times.   See table on web page.

de WB4APR, Bob

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