Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

PHD2 Predictive PEC

  • Please log in to reply
40 replies to this topic

#26 anismo

anismo

    Fly Me to the Moon

  • *****
  • Posts: 5932
  • Joined: 30 Jan 2014
  • Loc: Austin, TX, USA

Posted 08 September 2017 - 09:03 AM

I turned on Predictive PEC out of curiosity this week. I already had pretty good guiding (typically less than 0.4 arcsec) but with this enabled, it felt like I was getting very smooth corrections instead of occasional sharp ones.. or may be it is just the seeing (which has been very very steady this summer in Austin)



#27 RedLionNJ

RedLionNJ

    Soyuz

  • *****
  • Posts: 3545
  • Joined: 29 Dec 2009
  • Loc: Red Lion, NJ, USA

Posted 08 September 2017 - 10:01 AM

I think that if people expect improvement with this approach - which I also did long ago - they should think through what is going on.

 

If you think the mount doesn't respond quickly enough - try using a high power eyepiece or video view and watch a star as you give it perhaps a 1/10 second guide pulse in RA.  Unless your mount is really having trouble - you should see the star shift very quickly and then immediately stop - which means small corrections every second should be no problem for it to handle.  There is no backlash or gearing issue involved as long as the gears are engaged and the pulse is less than sidereal rate - e.g. 0.5x.

 

This is an excellent and frequently-ignored point. I think a paragraph like this should be displayed every time something like PHD or MetaGuide fires up.  People simply expect the impossible from these programs when the root cause lays in the mount. Only once the mount is well-balanced and responsive can you expect auto-guiding to work its own magic.



#28 syyntax

syyntax

    Mariner 2

  • -----
  • Posts: 256
  • Joined: 27 Jul 2016
  • Loc: Acworth, GA

Posted 10 October 2017 - 10:57 PM

I've noticed that PHD2 v2.6.4 was released on Sept 25th.. It's headlining the "New Predictive PEC Guide algorithm for RA"

 

Has anyone tried this out yet, with this new release? any thoughts?

 

As soon as I get clear skies, I'll definitely be trying it out.. I have some specific interests in how it might handle some of my issues in RA.. (rough gears, non typical, short term PE issues)...

 

I've noticed that it says that we should be enabling our PEC recording in the mount, while employing the new PPEC guiding algorithm..

 

https://openphdguidi..._algorithms.htm (bottom 1/3 of the document).

 

I would enjoy hearing about experiences/issues with this new option!


  • xiando likes this

#29 xiando

xiando

    Fly Me to the Moon

  • *****
  • Posts: 6374
  • Joined: 27 May 2015
  • Loc: Cloudy NEOhio

Posted 11 October 2017 - 12:34 AM

I plan(ned) on trying it out the next time we have sky However, the puzzler for me is that I've already downloaded and installed 2.6.4 but there is no PPEC tab or any settings as far as I can tell. The linked doc and the original advert blurb imply there are manually adjustable controls (presumably for short, medium, and long cycle noise), including: predictive gain, period length, and min-move, but I don't see any.

 

Is this meant to be a "blind" backgrounded enhancement?



#30 KenS

KenS

    Viking 1

  • *****
  • Posts: 905
  • Joined: 10 Jan 2015
  • Loc: Melbourne, Australia

Posted 11 October 2017 - 04:24 AM

Its one of the algorithms on the Algorithms tab

PPEC.png


  • xiando likes this

#31 xiando

xiando

    Fly Me to the Moon

  • *****
  • Posts: 6374
  • Joined: 27 May 2015
  • Loc: Cloudy NEOhio

Posted 11 October 2017 - 07:06 AM

Oh!...Or maybe better said "Doh!"

 

I didn't realize I'd need to use the dropdown to show it. Thanks for righting my sail, Ken. waytogo.gif



#32 George P Dunham

George P Dunham

    Viking 1

  • -----
  • Posts: 675
  • Joined: 24 Jun 2012
  • Loc: Crawford,CO USA

Posted 11 October 2017 - 06:47 PM

Is there a consensus about the Predictive PEC and MX+ mounts?



#33 scopenitout

scopenitout

    Surveyor 1

  • -----
  • topic starter
  • Posts: 1718
  • Joined: 24 Aug 2013
  • Loc: Mt. Belzoni

Posted 11 October 2017 - 07:22 PM

I gave it a run for 10 nights with the Paramount MyT. With native PEC off the mount PE is around 3 arc-sec. PPEC didn't make any meaningful improvement with native PEC on or off. Maybe PPEC will be more useful to mounts with less mechanical precision.

#34 Woodbridge_Dave

Woodbridge_Dave

    Explorer 1

  • -----
  • Posts: 72
  • Joined: 23 Jun 2009

Posted 12 October 2017 - 08:19 AM

The idea of pre-emptively attacking movement is good, but in practice I have yet to see any benefit from PPEC.  My RMS is no different with or without PPEC, and its not because I have a pristine mount.  I have an average mount (AZEQ6) with typical amounts of periodic error which is not improved by PPEC.  



#35 akulapanam

akulapanam

    Mercury-Atlas

  • *****
  • Posts: 2531
  • Joined: 26 Aug 2012

Posted 12 October 2017 - 11:07 PM

What they need to add is a standard deviation filter to ignore sharp movements by poor seeing

Edited by akulapanam, 12 October 2017 - 11:07 PM.

  • elmiko likes this

#36 ChristopherL

ChristopherL

    Mariner 2

  • -----
  • Posts: 264
  • Joined: 20 Sep 2016
  • Loc: UK

Posted 19 January 2018 - 04:01 AM

I've noticed that it says that we should be enabling our PEC recording in the mount, while employing the new PPEC guiding algorithm..

 

https://openphdguidi..._algorithms.htm (bottom 1/3 of the document).

 

Can anyone clarify? I ran PPEC for about 30 mins last night on my AVX and it did not improve my guiding. On the plus side it did not make it any worse! AVX's PEC was turned off.

Attached Thumbnails

  • true_rms_PPEC.png


#37 xiando

xiando

    Fly Me to the Moon

  • *****
  • Posts: 6374
  • Joined: 27 May 2015
  • Loc: Cloudy NEOhio

Posted 22 January 2018 - 01:54 PM

Personally, I had little luck with the "new" predictive mode guiding and dropped back to standard. I spent a couple of nights working with it, but it's performance was poorer than "normal" guiding ~2-3arc sec vs ~1 for regular)  Admittedly, it's highly possible I was being impatient due to the scarcity of suitable nights in cloudy Cleveland for imaging, and I expect that once I try it again without that hurried approach I should be able to gain better clarity on how to make it productive. In principle, it should provide tighter control than the method I'm presently using.

 

On a vaguely related note, it'd be a wondrous thing to have so many good nights for imaging that dropping a few to "housekeeping experiments" didn't always seem like "wasting time" (yes I realize it's not technically "wasting time")... After all, my goal is to take images and massage them best I can into works of "art", not to spend the few nights available to me for this hobby's pursuit chasing the parallel hobbies of "telescope tuning" and/or "astronomical gear purchasing".



#38 FiremanDan

FiremanDan

    Aurora

  • *****
  • Posts: 4735
  • Joined: 11 Apr 2014
  • Loc: Virginia

Posted 22 January 2018 - 08:04 PM

With my CGE Pro, I found a small improvement. I am not 100% sure that it was the new settings or seeing. But it seemed over several nights to improve the RMS a little. With my Mach1GTO I left the predictive PEC on, while the ASCOM driver had the mount's PEC off. I have since inquired about best practices on the Yahoo Group and found most people suggest keeping PEC on. I will probably keep predictive PEC on initially and hope that they work well together. I would say it doesn't seem any worse than the normal settings, so count me as a fan of it!



#39 Charlie B

Charlie B

    Apollo

  • -----
  • Posts: 1436
  • Joined: 22 Mar 2008
  • Loc: Sterling, Virginia

Posted 22 January 2018 - 08:19 PM

 

I've noticed that it says that we should be enabling our PEC recording in the mount, while employing the new PPEC guiding algorithm..

 

https://openphdguidi..._algorithms.htm (bottom 1/3 of the document).

 

Can anyone clarify? I ran PPEC for about 30 mins last night on my AVX and it did not improve my guiding. On the plus side it did not make it any worse! AVX's PEC was turned off.

 

I believe the instructions said that PEC should be enabled on the mount.

 

Regards,

 

Charlie B



#40 mikefulb

mikefulb

    Surveyor 1

  • *****
  • Posts: 1658
  • Joined: 17 Apr 2006

Posted 22 January 2018 - 08:21 PM

Witth my ES G11 PMC-Eight I have measured about +/- 8 arcsecond PE and found enabling PPEC seemed to give better RA RMS - it wasn't a big difference but I seem to consistently get lower number with it on vs when I turn it off.



#41 Charlie B

Charlie B

    Apollo

  • -----
  • Posts: 1436
  • Joined: 22 Mar 2008
  • Loc: Sterling, Virginia

Posted 22 January 2018 - 08:22 PM

 

 

I've noticed that it says that we should be enabling our PEC recording in the mount, while employing the new PPEC guiding algorithm..

 

https://openphdguidi..._algorithms.htm (bottom 1/3 of the document).

 

Can anyone clarify? I ran PPEC for about 30 mins last night on my AVX and it did not improve my guiding. On the plus side it did not make it any worse! AVX's PEC was turned off.

 

I believe the instructions said that PEC should be enabled on the mount.

 

Regards,

 

Charlie B

 

"If you’re following best practices, you will have programmed periodic error correction in your mount (assuming that feature is available to you).  Doing this reduces the amount of work that needs to be done by PHD2, and the PEC correction in the mount is normally saved permanently."




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics