Re: PXP Model


Ross Salinger
 

Well, is there any way to see the modeled parameters along with an explanation of what each one means? I know that there is an overall “quality score” but I’d be interested in seeing what kind of sag, collimation, etc errors the model if predicting as well. I think that if I have MDL running with its log on and SiTech has its log on, then any delta between the two logs will tell the tale. I don’t care if it’s PXP or something “else” in SiTEch that’s making the jumps happen. Heck it could even be a bug in MDL in the way it interacts with SiTech. (I may run a test with PHD to check into that.)

 

I recall that you and Bob were NOT guiding at the time. We spent the night tracking down a bit of jitter in the images that turned out to be poor focus, if memory serves. I’m wondering if the combination of absolute encoders, PXP tracking adjustments and MDL guiding  might occasionally result in a bad net tracking change between guide images. It’s the only thing I can think of to explain jumps that happen without a transient (wind, cloud, gamma ray, etc.) affecting things after getting excellent guiding for 10-15 minutes – much longer than the worm period.

 

Rgrds-Ross

 

From: SiTechservo@... [mailto:SiTechservo@...]
Sent: Sunday, October 15, 2017 11:34 PM
To: SiTechservo@...
Subject: RE: [SiTechservo] Re: PXP Model

 

 

Hi Ross,

Yes sort of, in Change Config/Logging check the box for tracking information.  That will record all the tracking commands, but not identify PXP corrections alone.  It will show any spikes.

But remember, Bob and I ran the mount for several hours and never saw any spikes in RA nor DEC.

 

Don W

 

---In SiTechservo@..., <rgsalinger@...> wrote :

Is there any way to see what adjustments are being made as the mount is tracking? For the past 5 months every time I use SiTEch and PXP I get really good guiding for a while and then I get jumps. Since the jumping happens in DEC, where the mount really ought to be still, I am wondering if the model software may be making tiny moves and then the mount absolute encoders, try to correct it forming a feedback loop for a few seconds.  I’m going to turn off the model completely in a test to see if that makes guiding better or worse sometime this week. I know that there is a “freeze DEC” option as well. I just wanted to be certain that I wasn’t completely off base with the idea that a DEC jump could be associated with mount modeling.

 

Rgrds-Ross

From: SiTechservo@... [mailto:SiTechservo@...]
Sent: Sunday, October 15, 2017 5:34 PM
To: SiTechservo@...
Subject: [SiTechservo] Re: PXP Model

 

 

Hi Ross,

Yes it does two ways.  First the basic PXP corrections are applied to the RA and Dec to correct for the various errors that the PXP model detects when you build the model.  Then second, as you track, those errors change as you move to different Alt-Az positions, so over time there will be additional corrections.

Don W



---In SiTechservo@..., <rgsalinger@...> wrote :

Does the PXP model in my system alter the RA and / DEC when the scope is tracking? I understand that it works when the scope is slewing to give me excellent pointing but I'm wondering if it also move the mount a bit when the mount is tracking.

 

Rgrds-Ross

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