EQ6-R EQMOD PPEC

[MikeeJC]

I've always used EQMOD's AutoPec when guiding but now wanting to use PPEC instead (although not sure if it's a major advantage or not).

I've created a PEC curve over 9 cycles and know to go into the developer area of EQMOD and record this to the mount.  My question is, I've heard this can be done during the day but how does the mount know when to sync with the curve?  Does the mount have to be in exactly the same position as when recording the curve?  As I have to set up each night I've already taken the scope off and moved the tripod into the shed.  Is it now too late to load the curve and send it to the mount or can I just make sure it's in the home position before sending it?

Thanks
Mike

[ONIKKINEN]

I think the mount is aware of the RA worm gear position, there is a small notch in a washer attached to the end of the worm gear, which is read by a sensor when the notch rotates over it. I have not used EQMODs PPEC, but from a mechanical point of view i think this is how the mount knows what part of the cycle the gear is in. So as long as you dont go and rotate this system manually somehow (impossible without dismantling the mount) it should be ok. Could be wrong though, someone who uses PPEC might have more info on that.

There is another option to periodic error correction, and one that will require no extra work or recording of the error. That would be the Predictive PEC algorithm in PHD2. This will record the periodic error as you guide, and gets increasingly more accurate the more you run the mount. This data is gathered directly from guiding performance, so i think has a chance to be more accurate, and i can confirm it works really well with my AZ-EQ6 that has a very aggressive peak twice per worm cycle. It does take a while to get accurate, about a few cycles worth of guiding per night. But chances are your early night data is not perfect anyway due to the scope still cooling down (if you set up fresh with the scope indoors before use), so there are no practical losses per night when using this. Not sure if the prediction data stays between nights when using the same calibration, as i recalibrate each night.

[Aramcheck]

Astrobloke shows how to record the PPEC on his youtube video: https://youtu.be/PfvWhx7ozi0?si=7EEuao1nvAxTY1Ni&t=942 

I've only tried it couple of times & didn't see any noticeable benefit, but that could be down to other factors in my mount...

Cheers
Ivor

 

[MikeeJC]

2 hours ago, ONIKKINEN said:

I think the mount is aware of the RA worm gear position, there is a small notch in a washer attached to the end of the worm gear, which is read by a sensor when the notch rotates over it. I have not used EQMODs PPEC, but from a mechanical point of view i think this is how the mount knows what part of the cycle the gear is in. So as long as you dont go and rotate this system manually somehow (impossible without dismantling the mount) it should be ok. Could be wrong though, someone who uses PPEC might have more info on that.

There is another option to periodic error correction, and one that will require no extra work or recording of the error. That would be the Predictive PEC algorithm in PHD2. This will record the periodic error as you guide, and gets increasingly more accurate the more you run the mount. This data is gathered directly from guiding performance, so i think has a chance to be more accurate, and i can confirm it works really well with my AZ-EQ6 that has a very aggressive peak twice per worm cycle. It does take a while to get accurate, about a few cycles worth of guiding per night. But chances are your early night data is not perfect anyway due to the scope still cooling down (if you set up fresh with the scope indoors before use), so there are no practical losses per night when using this. Not sure if the prediction data stays between nights when using the same calibration, as i recalibrate each night.

Thanks.

Haven't tried PHD2's predictive PEC algorithm as yet, maybe worth a try.

[MikeeJC]

1 hour ago, Aramcheck said:

Astrobloke shows how to record the PPEC on his youtube video: https://youtu.be/PfvWhx7ozi0?si=7EEuao1nvAxTY1Ni&t=942 

I've only tried it couple of times & didn't see any noticeable benefit, but that could be down to other factors in my mount...

Cheers
Ivor

 

Thanks Ivor

I've watched Astrobloke's video and a couple of others but although they say the PEC can be written to the mount during the day, there's no mention of what happens if the mount has been moved and put away i.e. clutches released etc.

 

[Budgie1]

35 minutes ago, MikeeJC said:

there's no mention of what happens if the mount has been moved and put away i.e. clutches released etc.

I think it assumes you start & finish a session in a known position, like the Home or Park positions.

I mark my mount with a Sharpie on the RA & DEC, so I can release the clutches for balancing etc, then put the axis back to where I parked it. Never had any dramas and it also means if you do need to reset the position (a cable got caught or something) then you just tell the mount to go to the Home Position and reset the axis with the clutches released.  

Like Ivor, I tried using the EQMOD PPEC on my HEQ5 but it actually seemed to make the guiding worse when it was switched on, so I don't use it now. 

[MikeeJC]

23 hours ago, Budgie1 said:

I think it assumes you start & finish a session in a known position, like the Home or Park positions.

I mark my mount with a Sharpie on the RA & DEC, so I can release the clutches for balancing etc, then put the axis back to where I parked it. Never had any dramas and it also means if you do need to reset the position (a cable got caught or something) then you just tell the mount to go to the Home Position and reset the axis with the clutches released.  

Like Ivor, I tried using the EQMOD PPEC on my HEQ5 but it actually seemed to make the guiding worse when it was switched on, so I don't use it now. 

Thanks Martin

I suppose the only way is to send the curve to the mount and see what happens... or run another session (if I get a long enough stretch of clear sky) and then send it to the mount straight after.