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Absolute encoders + guiding, no problems?

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#1 orion69

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Posted 15 February 2014 - 08:01 PM

Let's say I have ASA DDM60 mount (or any other with absolute encoders) but also using guiding with OAG (very long subs, some flexure...). Will there be some conflict between encoders and guiding commands? Since guiding software is probably important, let's say I'm using Maxim DL.

Also question for mount without encoders, what about Paramount MX with PEC and guiding, any conflict there?

Thx

#2 Raginar

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Posted 15 February 2014 - 08:17 PM

No. The encoders are seperate from the guiding inputs. Think of the encoders as basically a super-advanced form of PEC based no kidding on the motion of the worm. You'd still need to guide for things like atmospherics or flexure. Things that the encoders can't see.

There used to be a misnomer that you shouldn't use guiding and PEC together. It's not really applicable these days. At least that's my understanding.


#3 orion69

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Posted 15 February 2014 - 08:25 PM

I know they are separate, that could be a problem.
Imagine this situation: you have a good model (>100 stars) and first 15-20 min everything is ok, guiding more or less not necessary. But then after 20 min there is some flexure or model is simply not good enough and tracking error is becoming significant. But encoders doesn't know that there is a problem and interpret guiding commands as tracking error, thus effectively being in conflict with guiding.
Possible?

#4 Raginar

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Posted 15 February 2014 - 08:38 PM

The encoders have no idea that there is tracking error. They are mutually exclusive from the guide commands. So, in your example, for the first 20 minutes when guiding isn't required, your guider is literally doing nothing whereas the encoders work to remove the mechanical errors in your system. Once you run into issues with seeing via flexure or whatnot, guiding will remove them while the encoders continue to remove the PE from the mechanical side of the house.

You're over-thinking it.

#5 orion69

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Posted 15 February 2014 - 08:40 PM

You're over-thinking it.


Well, for 9000 Euros I have to be sure.

#6 Raginar

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Posted 15 February 2014 - 08:47 PM

For 9000 Euros I'd talk directly to the manufacturer :) and verify at someone's observatory to make sure I liked it.

#7 EFT

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Posted 15 February 2014 - 09:28 PM

Absolutely no problem at all. If a mount with absolute encoders were unable to ever be guided it would be hobbled. There are times and targets, regardless of how good a mount tracks because of its machining and encoders, that it is still beneficial to guide. All of the mounts currently sporting absolute encoders can also be guided and there is no conflict. You have at least 2 manufacturers over in Europe that you can confirm that with and a couple in the US.

#8 Per Frejvall

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Posted 16 February 2014 - 01:13 AM

Correct. Guiding moves the mount, encoders adjust. No conflict.

/per

#9 orion69

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Posted 17 February 2014 - 07:27 AM

Thanks all!

#10 Raginar

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Posted 17 February 2014 - 02:01 PM

No worries :)






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