DC servo with optical encoders. The motors are "pulsed" with DC square waves
of varying duration in order to offer different speeds. The optical encoders
are good resolution - .26 arcsec for the little NexStars, .20 arcsec for the
N5/8. The limiting factors in accuracy are:
- Open loop tracking - after pointing at the scope an object ("goto"),
NexStars start off with a predetermined tracking speed in each axis and they
never check position again until you perform another "goto".
- The software is only using 16bit resolution for coordinates, this results in
unnecessary rounding to the nearest .26 or .20 arcsec.
- Large amount of backlash in gear chain. Makes precise guiding extremely
difficult, if not impossible.
Mike Swanson
Leftfieldstar@aol.com wrote:
> What kind of motor drive is employed in these current models? Are they
> brushless dc servo with optical encoders or are they stepper motors? Thank
> you, Dominic DiLeo.
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