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peter_4059
07-10-2017, 08:40 AM
Just wondering if anyone has programmed their EQ8 PEC curve and then used that with eqmod driving the mount?

AndrewJ
07-10-2017, 11:08 AM
Gday Peter

I havent done it with an EQ8 but have with my AZEQ5
Doesnt appear to hurt anything, but if you plan to guide using pulseguides vs ST4, you may need to turn PPEC OFF when doing the calibration stage, then turn PPEC back ON, as pulseguides can get chopped short if PPPEC is running.
After training the PPEC, you can also play it back and record position over time to see what the stored model looks like.

Andrew

peter_4059
07-10-2017, 11:45 AM
Hi Andrew, thanks for the information. How did you record the PEC data into the mount? Did you do it with the hand controller connected or via eqmod?

Peter

AndrewJ
07-10-2017, 12:06 PM
Gday Peter
I actually used Metaguide
Basically, i started EQMod and bring up the dialog with the new buttons for PEC.
Then i connect with Metaguide ( or PHD2 )
Ensure PPEC is OFF
Set up the guide app and calibrate
Let it run without guide commands for a worm turn or 2 to get a PEC off unguided baseline.
Start Guiding as per normal, and when steady, use the new button in EQMod to start PPEC training.
The power switch on the mount starts double flashing.
When the PEC sensor detects, the mount starts logging the errors.
When its finished a full turn of the worm, just stop the PPEC train using the button.
Then turn PPEC ON and turn OFF guider commands to the mount.
Plot the result to see how well it works

Andrew

peter_4059
07-10-2017, 12:13 PM
Thanks Andrew. I wasn't sure if the new eqmod buttons were actually allowing me to record the mount pec curve or just enable/disable it but it sounds like it is all there ready to go in eqmod. Does the mount give any feedback when the pec training is complete?

Regarding the guider calibration issue, is that just a matter of clearing the relevant check box in eqmod while the guider is calibrating and then checking it again when calibration is complete?

Peter

AndrewJ
07-10-2017, 01:54 PM
Gday Peter

There are 2 buttons, one for PPEC ON/OFF and one for PPEC train.
Also Encoders ON/Off ( set them to OFF )
When PPEC is ON and playing back, the power led flashes in triple blinks
During training it is double blinks
When done, ( IIRC ) the blinking stops
( its in the manual )
There is a way to interrogate the mount for actual status, so you can see remotely when training is done, but not sure if EQMod utilises it yet.

Andrew

peter_4059
07-10-2017, 02:01 PM
Thanks Andrew . I had a look at the manual, it says it beeps when training is complete. Not sure if this works with no hand controller connected.

Why do you switch the encoders off?

AndrewJ
07-10-2017, 05:09 PM
Gday Peter

Cos they are cheap and not very accurate.
They are excellent for manual declutching and rubbernecking ( ie freedom find ), but if you want accuracy and stability, you need to turn them off as they can arbitrarily reset your microstep count ( ie real position ), even if it hasnt actually changed.
Also, any damage/grot on them can reset your true position with bad results.

Andrew

peter_4059
07-01-2018, 10:59 AM
I finally got around to programming the EQ8 PEC last night. Followed Andrew's instructions above and it all went smoothly. I checked the unguided PEC before and after with pempro. Pempro reports 6.7 as peak to peak without PEC and 4.0 as peak to peak with PEC enabled.

It certainly made the guiding work well!

AndrewJ
07-01-2018, 11:12 AM
Gday Peter
The plots you show are PEMPros "manipulated" data.
Do you have the raw log files for unguided PEC off and unguided PEC ON??
If you post them, i have an app that can overlay them in one plot
to see what the differences are.
Andrew

peter_4059
07-01-2018, 11:17 AM
Hi Andrew,

Are these the logs you refer to? 726 is pre PEC and 740 is post.

Peter

AndrewJ
07-01-2018, 01:09 PM
Gday Peter

Yep, perfect.
I have attached both plots overlaid.
There was some RA drift so i normalised the data, but nothing else.
From the raw data with PPEC OFF, you can see that each cycle of the worm has very different PE. Its nice and smooth, but varies quite a lot in amplitude between cycles. This makes creating a usable/repeatable PPEC plot quite difficult. Also, i note a clear fundamantal at 18.
I know the EQ8 uses a belt drive on the RA but dont know the exact toothcount of the pulleys, but from photos i have seen, it looks close to 18
If so, the Hi Freq ripple in your data is probably due to this belt tension being a bit loose. ( I had the same problem with my AZEQ5, which had a shocking ripple in it. )

Andrew

PS on another cruddy night, it may pay to do several more ultra long duration PPEC OFF unguided plots, just to see how irregular the playback is over different sections of the wormwheel

peter_4059
07-01-2018, 02:14 PM
Hi Andrew,

I had a look at the RA belt drive. Mine seems firm enough so it must be something else causing the ripple at 18.

AndrewJ
07-01-2018, 03:14 PM
Gday Peter
Can you mark the teeth with a texta on the outside and hence count the number????
My belt also appeared tight but until i tightened it more, i had shocking ripples in my playback

Andrew