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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

iOptron PEC update to drivers

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Very curious to see your first results.
Is it advisable to use PEC and guiding together or will they get in each others way?
3 years 1 month ago #67640

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Theory around this from cloudy nights / stargazer's lounge forum and what i have done some research on.
Happy to be corrected on these, please jump in!

A note about the mount and guiding:
The GEM45 has 216 teeth and a cycle of 400 seconds, with a tooth to tooth period of 1.85 seconds.
My thoughts are an exposure times of up to 1.85 seconds, which will allow at least a pulse per tooth.
Seeing conditions will dictate the exposure times as well, to avoid chasing seeing.
(Although some debate about this, so best to experiment.)

Types of Errors:
1.) PEC -> Error in the alignment of the drive (on RA only.)
This creates some positive and then some negative guide pulses on regular schedule based on drive cycle.
GEM 45 / CEM 40 is 400s on RA, which can be eliminated through predictive pulses stored on a chip on the drive.
(These are the pulses we want to eliminate, when we are recording.)

2.) Polar / Level misalignment will create pulses in a single direction, on both RA and DEC.
This creates some positive OR negative pulses in a single direction, based on the amount of misalignment.
(If you have a permanent setup, it can be wise to slightly polar misalign on RA, to reduce backlash, then these + PEC can be recorded onto the chip.
If like me your setup is mobile, then it is best to avoid this while recording for good clean recording.
Drift aligning on on RA near the meridian will get this close to perfect.)

3.) Balance / Backlash, this may create pulses after a pulse to correct overstatement.
When a mount counterweight is light, the unbalanced is in the opposite sidereal direction of RA, which means that it is putting positive pressure on the worm gear that is lifting the scope.
However after a meridian flip, it will be lying on the leading edge on the tooth, which puts a negative pressure on the worm gear as it is lowing the scope.
Backlash is when the weight of the mount needs to move from a one side of the tooth to the other, to get it to move the mount.
(These types of pulses cannot be corrected, with PEC and should be corrected by balancing mount correctly.)
(Guiding will still help with this)

4.) Wind, vibrations, other random noise / jitter, etc
These pulses are random noise and can only be corrected with a guide star.

5.) Seeing conditions should be eliminated by setting your guiding exposure times, as high as possible for your mount.

Recording Assumptions:
Based on the above assumptions, the following procedure will be performed as part of the recording procedure.
1.) Setup mount on a solid concrete patio, to avoid vibrations.
2.) Get mount as level as possible, and polar align with iPolar.
3.) Slew to a near equator (opposite of polaris) and on the right of the meridian. (I am in the Northern Hemisphere.)
It means that my mount will be lifting the scope on each tooth with a lite counterweight, to reduce any backlash.
4.) Guide on 1.85s exposure and drift align near meridian to make sure that my RA is really good.
This should ensure that i can get a great RA drift alignment but with very little DEC interference.
5.) Turn on GPA guiding and guide for 4 worm cycles to train GPA predictive on PEC, (400s *4)
6.) Adjust the GPA prediction gain to 100% and control gain to 0% and commence recording.

Remarks
I will post the before guide graph and the after guide graphs on here.
The idea here is to make sure that i only get the predictive pulses, recorded into the CHIP.
This way in the future PEC is eliminated immediately, and GPA can focus on polar drift / level / balance issues.
Christopher | Sussex England | n2042.blogspot.com
iOptron GEM45 | Altair Mobile Pier | TSPhoton 154 @ F3.7
ASI 294MM Pro | ASI EFW | ASI EAF | ASI 120MM
Mini PC | Quad 4GB 64GB 5G | Juice USB Harness
Last edit: 3 years 1 month ago by christopher.
3 years 1 month ago #67642

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Great work! Unfortunately I had no available time to test it. Did you make any progress with predictive guiding recording?

Also, I noticed into you that you set back baudrate to 115200, since the v3 driver default to 9600. Was it necessary for proper connection? If so, we have to advice Jasem that defaulting to v3 driver in indi 1.8.9 broke GEM45 communication.
3 years 3 weeks ago #68047

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Okay super frustrated, since i updated my firmware and moved to the V3 driver, my mount is doing something super weird.
I cannot slew to a target in Kstars, because it keeps slewing in the opposite direction.
I thought it was because of something i broke in the code. So i have done a purge and reinstall from scratch on the stable drivers - same issue. I formatted the machine and reinstalled everything from scratch and it still does it. why?

I found this thread of others that have the same issue.
www.indilib.org/forum/general/8852-locat....html?start=24#68128
Edit: Spent this afternoon working out the issue, see above thread for solution.

Now i have to wait some days for the stars to appear again.
Also updated my fork to include the correct buadrate and to be able to findhome for GEM45.
Christopher | Sussex England | n2042.blogspot.com
iOptron GEM45 | Altair Mobile Pier | TSPhoton 154 @ F3.7
ASI 294MM Pro | ASI EFW | ASI EAF | ASI 120MM
Mini PC | Quad 4GB 64GB 5G | Juice USB Harness
Last edit: 3 years 3 weeks ago by christopher.
3 years 3 weeks ago #68130

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Nice work on including PEC.
The CEM25p has PEC capabilities, I'm going to have a peek at what you've done and see if it can added to the ieq driver.
3 years 2 weeks ago #68521

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Hey Gonzo,

i originally wrote the code in iEQ driver. the issue i had was with the check data status.
the cem25 firmware will not support the capability to report data status.

I have reverted the code back into the iEQ driver in my fork.
github/seventi71/indi
Happy for you to add improvements :)

If you are on the latest firmware and the report data status does not work, you will get errors, let me know.

Over the weekend i can update the getDataStatus function to use a timer, instead of a checking completion.
The Gem28 has a worm period of 600secs, as this is the longest period, i will set it in the header file.
If your mount is say 500sec, it will automatically stop recording in the mount, even though the driver will still say recording until timer ends.
We could put a table in the header with the timings of the different mounts, not sure if worth it vs a fixed amount.
All the new mounts will work on v3 firmware, so should be able to use the new driver.

Regards
Chris
Christopher | Sussex England | n2042.blogspot.com
iOptron GEM45 | Altair Mobile Pier | TSPhoton 154 @ F3.7
ASI 294MM Pro | ASI EFW | ASI EAF | ASI 120MM
Mini PC | Quad 4GB 64GB 5G | Juice USB Harness
Last edit: 3 years 2 weeks ago by christopher.
3 years 2 weeks ago #68543

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thanks, I will git clone your repo and test your driver on my CEM25p which has the latest firmware (I believe).
The following user(s) said Thank You: christopher
3 years 2 weeks ago #68547

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Testing it...

First thing I noticed is that the park function is broken, you can issue a park and the mount will slew to the park position but never actually finish.
2021-03-12T10:12:43: [INFO] Parking is in progress...
2021-03-12T10:12:43: [INFO] Slewing to RA: 22:05:37 - DEC: 90:00:00

While on the normal driver:
2021-03-12T10:10:21: [INFO] Mount is parked.
2021-03-12T10:10:20: [INFO] Manual parking complete. Shut the mount down.
2021-03-12T10:10:06: [INFO] Parking is in progress...

and the second thing is I see the following error:
2021-03-12T10:12:27: [ERROR] Serial read error: Timeout error.

and I cannot test the PEC right now as it needs guiding, but I think I can test that with the sims later on today
3 years 2 weeks ago #68548

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I don't know if it helps but I had the same parking issue on my GEM45. I reset the park position using the hand controller (goto home, set park to current) and after that the park in Indi worked again as expected (it completed).
3 years 2 weeks ago #68552

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@Gonso, if you turn tracking on, then you can record ... the current recording check only checks tracking.
It does not know if you are actually guiding... this is something we could integrate in the future if needed.
It is there to stop you from recording by accident and wiping data, while not guiding.

I think the parking issue seems to be something else that has creeped in from other source.
My parking does something similar. I find that if I turn on tracking and then turn it off then parking completes.

I will test this hypothesis, by turning off all the PEC code by commenting it out and see if it still happens.
All the PEC code is enclosed in comments that start with "v3.0" and end with "end mod".

Edit:
I just removed all the PEC code in iOptronV3 and did a rebuild and the parking issue still exists.

 
Christopher | Sussex England | n2042.blogspot.com
iOptron GEM45 | Altair Mobile Pier | TSPhoton 154 @ F3.7
ASI 294MM Pro | ASI EFW | ASI EAF | ASI 120MM
Mini PC | Quad 4GB 64GB 5G | Juice USB Harness
Last edit: 3 years 2 weeks ago by christopher.
3 years 2 weeks ago #68556

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my CEM25p has the latest firmware, using the driver from Indi 1.8.9 it parks perfectly fine, however with your added PEC it never compelte the park. I'll compare the two drivers at some point later
3 years 2 weeks ago #68557

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Thanks i suspect that if you solve the parking issue for iEq, you will solve it for the iOptron V3 as well.

I have updated the ieq driver to be a timer, which records for 600 sec, it is set in the header file. name is Wormdrive = 600; 
I think your worm drive is 500 odd seconds. (Best way to tell is to guide using GPG and get it to estimate it or search the web?)

To record, you need to unpark and start tracking.
Push record and leave it tracking for full duration.

If you cancel tracking, by slewing / parking etc it will cancel the record.
If you push the record button again, it will cancel the recording.
Data status button just says not supported.
Christopher | Sussex England | n2042.blogspot.com
iOptron GEM45 | Altair Mobile Pier | TSPhoton 154 @ F3.7
ASI 294MM Pro | ASI EFW | ASI EAF | ASI 120MM
Mini PC | Quad 4GB 64GB 5G | Juice USB Harness
The following user(s) said Thank You: Gonzothegreat
Last edit: 3 years 2 weeks ago by christopher.
3 years 2 weeks ago #68559

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