My memory is not what it used to be but..... You're right about Dec (Dec usually doesn't move anyway) but I
distinctly remember (memory corrupted?) they said there have been instances where pec and predictive result in
worse behavior. So caveat emptor : let the user beware. So, if anyone has questions, I urge them to read up on
predictive. Users can decide to enable both or only one.
As Brian said PEC and autoguiding work well with most mounts, including Losmandy's.
That said, there are drawbacks to the predictive algorithm. That is it can take multiple worm cycles to get accurately calculated phase/amplitude. At first they tried to make that algorithm work with no knowledge of frequency/periods. I could have told them that was going to take lots of tracking time to calculate. I think they figured out later that it was better to let the user provide frequency hints. :-) Even then phase has to be established and that may take a while.
Also, guider pulses are not always very accurate so it might not be possible to get a good calculation of amplitude. So, IMO it only adds functionality to PEC for frequencies that can't be corrected by PEC because those frequencies don't repeat in the same phase every worm cycle.
-Ray Gralak
Author of PEMPro V3:
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of crocco1250 via Groups.Io
Sent: Thursday, January 30, 2020 6:00 PM
To: [email protected]
Subject: Re: [Losmandy_users_io] Is PEC maintained regardless of shut down process?
Brian
My memory is not what it used to be but..... You're right about Dec (Dec usually doesn't move anyway) but I
distinctly remember (memory corrupted?) they said there have been instances where pec and predictive result in
worse behavior. So caveat emptor : let the user beware. So, if anyone has questions, I urge them to read up on
predictive. Users can decide to enable both or only one.
Chuck
________________________________
On Thursday, January 30, 2020 Brian Valente <[email protected]> wrote:
Chuck that's not quite correct, in fact PHD recommends in most cases the in-mount PEC is complementary to PHD
guiding
PHD has predictive PEC, which watches the worm period and models periodic error behavior. if you enable mount-
based PEC, it will simply model less error (usually the harmonics of the primary are what's left)
You may have been thinking of DEC backlash compensation? which you don't want enabled in the mount? it does
indeed fight with PHD's auto backlash compensation, and PHd's is much better at doing it. regardless, you'd want to
pick one or the other there not
On Thu, Jan 30, 2020 at 5:44 PM crocco1250 via Groups.Io <crocco1250@...> wrote:
Anthony
My reading of the phd2 manual says you can use pec but they don't recommend it. Apparently, phd2 has
an active corrective function (whose name escapes me at this second) that is similar to pec. They state plhd2 can
fight their active predictive algorythm. Phd2 wants you to run their automated system and claim its superior to peck.
Chuck
________________________________
On Thursday, January 30, 2020 Anthony Q <[email protected]> wrote:
I was thinking that number in PHD2 would be lower with PEC, assuming other issues being equal, (I think
mine is mirror shift.)
I think I am hoping to shortcut measuring PE, with no luck. (Using PHD2 functions.)
I just need to run PEMPro again, but I'd rather take pictures.
With the Moon getting bright again, I'll take advantage to run PEMPro...
Thanks for the info everyone!
--
Brian
Brian Valente
portfolio brianvalentephotography.com <>
