Factory PEC curve, how is it generated?


skester@...
 

Thank you Roland and Christopher.  Encoder measurement is the obvious choice in hindsight.


Roland Christen
 

A precision encoder is attached to the RA axis and the resultant PE error is measured using software similar to PEMPro. We do about 5 cycles for each mount (takes about 1/2 hour for that measurement). The curve is calculated and downloaded into the CP and the error is measured again with PEM turned ON. The resultant curve is evaluated and if it's good, the mount goes thru the final testing stages.

Rolando



-----Original Message-----
From: skester@...
To: main@ap-gto.groups.io
Sent: Wed, Feb 10, 2021 12:49 pm
Subject: [ap-gto] Factory PEC curve, how is it generated?

This question is simply to satisfy my curiosity.  To create the factory installed PEC curve I assume each mount must be tested and track a star like source moving at sidereal rate for several worm gear cycles.  Doing this on a real star under the night sky would seem out of the question as it would require many clear nights and much time/effort to do for each mount produced.  That would seem to leave an artificial star that moves at a simulated sidereal rate on a test bench?  Or is there another method I haven't thought of, perhaps using encoders?

Thanks,
Scott
 

--
Roland Christen
Astro-Physics


Christopher Erickson
 

My guess is a custom bench top jig with an absolute encoder.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Feb 10, 2021, 8:49 AM <skester@...> wrote:
This question is simply to satisfy my curiosity.  To create the factory installed PEC curve I assume each mount must be tested and track a star like source moving at sidereal rate for several worm gear cycles.  Doing this on a real star under the night sky would seem out of the question as it would require many clear nights and much time/effort to do for each mount produced.  That would seem to leave an artificial star that moves at a simulated sidereal rate on a test bench?  Or is there another method I haven't thought of, perhaps using encoders?

Thanks,
Scott
 


skester@...
 

This question is simply to satisfy my curiosity.  To create the factory installed PEC curve I assume each mount must be tested and track a star like source moving at sidereal rate for several worm gear cycles.  Doing this on a real star under the night sky would seem out of the question as it would require many clear nights and much time/effort to do for each mount produced.  That would seem to leave an artificial star that moves at a simulated sidereal rate on a test bench?  Or is there another method I haven't thought of, perhaps using encoders?

Thanks,
Scott