I've looked around at the MAPUG archives and Doc G's site and have a few questions about the details

of PEC (RA) training.

I recall some time ago that maybe there's a bug in the PEC s/w so that one should not wait for the
counter to drop down to 0 before training begins. I believe the change in operation is that one
should start operating the arrow controls immediately and follow it through zero and up to 240 (or
where ever the s/w signals an end). Is that correct? Apparently older version of the s/w use the
range from 0 to 240, and newer ones from 0 to 200. Is that correct?

As for the operation of the PEC (RA) method, it looks like the following:

1. training goes over a 8 minute period
2. the software breaks up the 8 minute (480 second) period into 240 (or 200)
intervals (I'll use 200 in what follows)
3. Each of the 200 intervals represents 2.4 seconds

( Continuing. Here's where I'm a little in doubt, so chime in if you want.)

4. 108 RA motor pulses are produced in a non-PEC trained operation to
drive the RA motor westward to keep up with the westward moving sky
(Now I'm on really weak ground)
5. When the PEC is trained, each operation of the eastward arrow requires the motor to stop, so
effecitvely a pulse count is removed from the interval (bin). The implication that the RA
motor only needs to stop is that the scope only needs to let the sky drift for the object
to
return to center. ---- Note that each pulse lasts 2.4/108 seconds
6. When the PEC is trained, each operation of the westward arrow produces a (additional) pulse,
so a pulse is added to the interval (bin counter). (We are trying to keep up with a westward

drifting sky by driving the motor westward.)
7. I think (!guess?) that when the s/w is about to execute the pulse commands for an interval it

looks at the count for the next interval and tries to apply the number of necessary pulses
evenly. Normally it would see 108, but suppose the count was 54, then it would pulse, stop,

pulse, stop ... through the 2.4 second interval.

The process outlined in steps 5 & 6 theoretically should produce 108*200 or 21600 pulses if all 200
bins are summed, since there must be an equal number of east and west pulses (actually none in the
eastward direction) if the object is to remain in the center of the (calibrated) eyepiece.

Well, that's a bit of guess work on items 5-7, so chime in if you have other info to offer.

--
"We have nothing to sphere, but spheres themselves."
-- Ms. Maxwell, My HS 3-D Geometry Teacher

Wayne T. Watson
Web Page: http://www.sirius.com/~mtn_view (Updated 6/21/2000)
Imaginarium Science Museum:
http://www.sirius.com/~mtn_view/imaginarium.html

View index by [date] [author] [subject]
Previous message: [M]: RE: Latitude, longitude..., Don Tabbutt
Next message: Re: [M]: RS232 Problem, Bob Denny
Next message in thread: Re: [M]: PEC Training Details?, Ralph P. Pass III