Software Bisque Paramount ME - Periodic Error Correction (PEC); Recording the Periodic Error

Paramount ME User’s Guide
65
PEC cutoff speed: 0
Maximum voltage: 15
Maximum gain: 150
Periodic Error Correction (PEC)
Important
Note
The average periodic error for the Paramount ME is just over three
arcseconds peak to peak. Measuring this small error using
conventional periodic error measurement techniques offered by
TheSky6 can be difficult, since the magnitude of error from seeing
normally exceeds the periodic error of the worm.
Software Bisque offers a powerful periodic error analysis program
called PrecisionPEC. PrecisionPEC is a Windows-based application
that allows you to analyze and quantify the Paramount ME’s periodic
error using tracking data that is acquired over multiple periods of the
worm. PrecisionPEC knows the fundamental harmonics of the
mount, and uses them to analyze the tracking data and determine
the optimal periodic error curve.
Once the optimal periodic curve is applied, the typical errors caused
by periodic error after applying a PrecisionPEC-generated periodic
error curve are about one arcsecond peak to peak.
PrecisionPEC-derived periodic error correction curves essentially
make periodic error negligible. Note that PrecisionPEC is sold
separately from Software Bisque. Visit
HTUhttp://www.bisque.com/PrecisionPECUTH for details about this product.
As such, PrecisionPEC makes TheSky6’s Paramount ME-related
periodic error correction algorithms (essentially) obsolete. Software
Bisque strongly encourages Paramount ME owners to use
PrecisionPEC to determine periodic error rather than TheSky6’s PEC
fitting features described below.
The Paramount ME’s worm/gear drive train has very small periodic error (seven
arcseconds peak to peak or less) and the error is very smooth. The MKS 4000 has
advanced periodic error correction (PEC) capability. The majority of periodic error comes
from the worm gear and the associated pulley system driving the worm gear.
Great pains must be taken in manufacturing and assembly to reduce the magnitude of the
periodic error in any system. Additionally, the worm and gear should be smooth – a
necessary requirement for any periodic error compensation function to work effectively.
Recording the Periodic Error
Recording the Paramount ME’s periodic error involves guiding on a star using a CCD
camera or manually making guiding adjustments for one revolution of the worm.