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Feeding back PHD2 logs into EQMOD to see mount issues

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#1 miwitte

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Posted 19 November 2019 - 01:05 PM

This was something i was pondering a while back after going to my Edge. Since we can take the unguided output of phd2 and run it through PECPrep and then use that as a PEC curve, I  was wondering if anyone has seen feeding back PHD2 logs without guiding to see what the mount was actually doing. sometimes I get these transitions when Dec or RA will go crazy for a little while then settle down. If you could place the mount where it was having issues, turn off guiding and feed the logs into EQMOD it could potentially show what the mount was doing. So you could see backlash, cable snags whatever. I think the issue would be to know exactly where the mount was so this might only apply for mounts with encoders. 

 

Just curious if anyone's tried this Ive been down for a while but trying to get back in the game and planning on getting my guiding going with new 290 camera and OAG. I want to baseline my guiding then install my Rowan zero backlash RA kit.



#2 Tapio

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Posted 19 November 2019 - 01:11 PM

I don't think you can "feed the logs into Eqmod".
And frankly I don't understand how it would help.

#3 scadvice

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Posted 19 November 2019 - 02:54 PM

Post this on here for a good answer to your questions. I talked to Andy Galasso and Bruce Waddington at the  AIC conference this last weekend and they were very helpful.

 

https://groups.googl...pen-phd-guiding

 

Be sure to read "How to ask for help"



#4 miwitte

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Posted 19 November 2019 - 05:04 PM

Actually you can take your PHD logs and use PEC Prep or another tool to create a PEC curve and feed that into EQMOD to null out the error from the gears. So theoretically you should be able to input a guiding session and see what the mount is doing at least in RA. Just curious if anyone has tried something like that as it should be the same as a PEC curve.

 

Just a weird idea....



#5 KenS

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Posted 20 November 2019 - 01:51 AM

You can analyse the guide log with PHD log viewer or PEMPro log viewer to see what your mount is doing. Both can add the guide pulses back to the cure so you can estimate the raw behavior of the mount (assuming no backlash).

Both can also perform frequency analysis on the RA axis.



#6 Patrick Chevalley

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Posted 20 November 2019 - 10:40 AM

Install  the PHD2 Log Viewer from : https://openphdguidi...hd2-log-viewer/

And read : https://openphdguidi..._Guide_Logs.pdf

 

To get the PE curve, right click and select "Analyze selected, raw RA".



#7 miwitte

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Posted 20 November 2019 - 02:45 PM

patrick fantastic software i use it exclusively during sessions so thanks for the great software!

 

My though was more of getting the mount into the position where the "craziness" occurred and play it back and potentially would show if there is a cable issue, backlash etc. Ill be sitting watching the run and doing processing on older data and suddenly guiding will go crazy, you go outside and everything looks fine its really hard to track that type of intermittent stuff down. i thought possibly playing back the pulses might point toward something as intermittent is really hard to track down.



#8 lakeorion

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Posted 21 November 2019 - 11:36 AM

I wish there were a way to pause the log during all of SGP's 'interference' in guiding.  Autofocus (with guiding paused because of OAG) settling shouldn't be counted in my RMS, or dithers.  But they are and now I have no idea how good I'm actually guiding.




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