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Re: New Az/El rotor from Yeasu

Dave Cawley wrote:
> From: Dave Cawley
> Cambridge  England
> Timestep@dial.pipex.com
> Tel.  +44 1440 820040
> Fax. +44 1440 820281
> Yes the G-5400 rotator is now gone.  The new G-5500 has the stop at North
> instead of south.  But the cleaver thing is, that it doesn't just stop at
> North it keeps on going (overlapping) by an additional 90 degrees, in other
> words 450 instead of 360 degrees, smart indeed !
> The Timestep AutoTrack  II plugs straight into either the 5400-5600-5500 and
> has software compensation for user induced bad mechanical alignment.
> We have the new 5500 in stock here in England.
> Regards
> Dave G4IUG
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

In order to take advantage of this additional 360-450 degree rotation in
automated setups, the rotor drivers used must be programmed to determine
which direction the rotor should turn to reach the desired bearing and. 
For example if the desired bearing is 25 degrees and the rotor is currently
aimed at 140 degrees, it seems like it would be better to turn counter
clockwise to 25 degrees.  Likewise if the current bearing is 270 degrees it
might want to turn clockwise to 385 degrees.  

However, each of these decisions must also be weighted by the consideration
of the likely direction the rotors will be turning after this original
bearing.  In the above example, if the rotor turns clockwise from 270 to
385 degrees and then the subsequent tracking movement is counter clockwise
from 385 to 140 degrees, then it would be better to have originally turned
counter clockwise from 270 to 25 and then tracked from 25 to 140 without
meeting the rotor stop.  In the former case the rotors would have turned
115 degrees clockwise 270-385), then clockwise another 65 degrees (385-450)
to the rotor stop.  From there it would have to turn counter clockwise
about 355 degrees (450-95).  The 355 instead of 360 because the satellite
has moved some while the rotor was turning.  This is a total of 535 degrees
of turning up to this point.  In the second case the rotors would turn
counter clockwise 245 degrees (270-25) and then track clockwise 70 degrees
(25-95), a total of only 315 degrees to get to this same point in the

That extra 90 degrees of rotation may be nice for manual operations, but
for automatic tracking, there will have to be a good deal more decision
making programmed into the rotor drivers to take advantage of this extra
rotation.  In addition, the drivers will have to recognize when it has this
new rotator to control and when it has the standard 360 degree turning
rotor.  This means all the tracking programs will have to be programmed to
tell the driver which it is controlling.

All this is to say, unless the drivers and tracking programs are updated to
handle the above considerations, you are going to continue to have 0-360
rotation with the new rotators operating under computer control.

73, Roy

Internet: w0sl@amsat.org
Home Page: http://home.swbell.net/rdwelch
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org