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PEC training confusion


Anthonyexmouth

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1 minute ago, Anthonyexmouth said:

Is that likely to be caused by my blundering around with the worm gear tension? or maybe tight belts?

I don't think tight belts will cause this - I have mine really tight. When I first did my mod, I thought I had them tight, but it turned out that I need them like really, really tight - so now they are as tight as they can be - motor can't move any further.

But worm gear tension can be issue, and also I would look into end float. The graph shown in EQMod window represents one revolution of worm gear - that means big gear that belt is put on and one that you adjust end floats for (from the link I posted). Above graph shows two tight spots - exactly half way around - I would say that end float is to blame.

Did you check all your gears by hand? By actually turning gears with your fingers you can sense a lot of issues with it - just do it slowly and feel their motion under your fingers.

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1 minute ago, vlaiv said:

I don't think tight belts will cause this - I have mine really tight. When I first did my mod, I thought I had them tight, but it turned out that I need them like really, really tight - so now they are as tight as they can be - motor can't move any further.

But worm gear tension can be issue, and also I would look into end float. The graph shown in EQMod window represents one revolution of worm gear - that means big gear that belt is put on and one that you adjust end floats for (from the link I posted). Above graph shows two tight spots - exactly half way around - I would say that end float is to blame.

Did you check all your gears by hand? By actually turning gears with your fingers you can sense a lot of issues with it - just do it slowly and feel their motion under your fingers.

Yeah, i ran it a few times with my hand with the belt off while adjusting the tension. Luckily global warming gave us one of the hottest feb days today, hopefully another one tomorrow so i can sit in the garden at my pier and try again. 

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On 22/02/2019 at 08:17, Demonperformer said:

Sorry, realise yours is permanent and wasn't trying to hijack the thread (much!), but the process obviously takes a significant amount of time and was wondering if it was still a worthwhile option when all the gear is put back together each session in not necessarily exactly the same relative positions. If PEC is working out of step it would be likely to cause more problems than it solves?

There's a relatively new feature in PHD2 - you need the latest version - called 'predictive PEC' or PPEC. It 'learns' your system's behaviour over the first few cycles and then applies it, and  it constantly refines its model of the PEC. It does appear to work and I use it all the time now.

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20 minutes ago, Stub Mandrel said:

There's a relatively new feature in PHD2 - you need the latest version - called 'predictive PEC' or PPEC. It 'learns' your system's behaviour over the first few cycles and then applies it, and  it constantly refines its model of the PEC. It does appear to work and I use it all the time now.

Does that augment Sidereal+PEC in EQMOD or do you turn it off there? 

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7 hours ago, Stub Mandrel said:

There's a relatively new feature in PHD2 - you need the latest version - called 'predictive PEC' or PPEC. It 'learns' your system's behaviour over the first few cycles and then applies it, and  it constantly refines its model of the PEC. It does appear to work and I use it all the time now.

That is definitely worth investigating. Will go looking ...

Thanks.

Edited by Demonperformer
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  • 3 years later...
On 19/02/2019 at 20:18, vlaiv said:

Here is how I do it:

Disable any PEC if you already have it loaded in EQMod (there are controls for PEC in one of the tabs).

Fire up PHD2 and do calibration near equator. Disable guide output for PHD2 and start "guiding" session (mount won't be guided at this point because you disabled guide command output). Make sure you have logging enabled in PHD2. Do about 1 hour and 30 minutes of recording. HEQ5 has worm period of 638s and you want as much full periods as you can. If you want for example 8 full periods, that is going to be 1:25 or something like that. Make sure you record for at least 1 minute past complete cycle just to make sure you got it. While you are "guiding" at some point - press PEC timestamp button in EQMod.

Once you are finished, just stop guiding and close PHD2. Next start PECPrep on same computer, load phd2 log and analyze PE curve. Choose only harmonics of Worm period in main window - generate PEC curve and save it.

Load it into EQMod and make sure you have PEC gain set to 1.

From that point on, it should be always loaded when you start EQMod - and default tracking rate should be Sidereal+PEC.

That is it.

does this work on Heq5 pro ? i was told you could not store the pec curve only on heq6 ....if you forget to park the mount i believe you loose the pec .

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11 hours ago, ninjageezer said:

does this work on Heq5 pro ? i was told you could not store the pec curve only on heq6 ....if you forget to park the mount i believe you loose the pec .

It works with HEQ5 if you have EQMod. It performs and stores pec curve for you.

Because of this and lack of encoders - you must park HEQ5 after each session before you shut down EQMod. If you don't park - you won't loose PEC curve but it will go out of sync (be unusable and will do more damage to mount performance than turning it off) and in principle - you can sync it back (there is option for that) - but in practice that never seems to work well as it requires too much eyeballing precision.

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11 minutes ago, vlaiv said:

Because of this and lack of encoders

I thought encoders have nothing to do with PPEC storage. 
Please correct me if I’m wrong but the EQ6-R Pro has no encoders and stores the PPEC curve. I believe it is able to reproduce the curve regardless if it was previously parked.

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2 minutes ago, barbulo said:

I thought encoders have nothing to do with PPEC storage. 
Please correct me if I’m wrong but the EQ6-R Pro has no encoders and stores the PPEC curve. I believe it is able to reproduce the curve regardless if it was previously parked.

Mounts with stepper motors know their position by counting steps.

If  this information can be recorded between power cycles, then in principle there is no need for parking. There are two places you can record this information - hand controller or mount itself.

Parking just ensures that you start each session from 0 position and that there is no need for remembering actual position where mount was turned off.

In any case EQMod does not have this capability and if mount does not remember this in firmware (not hand controller but on mount itself) - then you will loose sync.

Encoders nicely solve all of this as you don't need to remember anything - you always know where you are pointing, but yes, you are right - it can be implemented without encoders as long as it "stays with the mount" and is not implemented in external device (here hand controller is also external device as you can use mount without it and swap between mounts).

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