|
Hi all,
?
I retrofitted my classic 18¡¯¡¯ Obsession with a ServoCAT in 2020.? I do seem to have a problem with the guiding (but I¡¯m not 100% sure). ?When I go to an object using my Nexus DSC Pro, I can
see that the ServoCat is doing a great job and the numbers on the ServoCAT go down to 0.0, 0.0.? However, the object does not stay at 0.0, 0.0, but start to drift (a bit).? The numbers on the Nexus will typically go to 0.10 ¨C 0.20.? Occasionally the numbers
do get better, as the number jumps to 0.05, 0.05 again.? Typically, the jumps are in the range of 0.10.?
?
Should the numbers just stay at 0.0, 0.0?? What is the possible cause for this?
?
- Is it because the telescope is not totally level in the garden (in the grass)?
- Is there a setting on the Nexus or the ServoCAT I need to change?
- Did I make a mistake while installing the ServoCAT
- Or is this normal and expected behavior?
?
Thanks a lot for looking into my question,
?
Wim
|
Wim,
Don¡¯t know if this is the problem, but it might be something to check out: ?Here¡¯s a theory: What if the clutch on the azimuth motor is not totally disengaged? Then, when servocat gets the mount to the appropriate azimuth position, the motor stops. Then, since the azimuth motor is no longer working, gravity will become a force that will want to move the Mount¡only is the clutch is total disengaged (i. e. The clutch is holding tight)¡ just a thought.
On Mon, Jun 10, 2024 at 6:04?AM Wim De clutc Meester via <deepskywim= [email protected]> wrote:
Hi all,
?
I retrofitted my classic 18¡¯¡¯ Obsession with a ServoCAT in 2020.? I do seem to have a problem with the guiding (but I¡¯m not 100% sure).? When I go to an object using my Nexus DSC Pro, I can
see that the ServoCat is doing a great job and the numbers on the ServoCAT go down to 0.0, 0.0.? However, the object does not stay at 0.0, 0.0, but start to drift (a bit).? The numbers on the Nexus will typically go to 0.10 ¨C 0.20.? Occasionally the numbers
do get better, as the number jumps to 0.05, 0.05 again.? Typically, the jumps are in the range of 0.10.?
?
Should the numbers just stay at 0.0, 0.0?? What is the possible cause for this?
?
- Is it because the telescope is not totally level in the garden (in the grass)?
- Is there a setting on the Nexus or the ServoCAT I need to change?
- Did I make a mistake while installing the ServoCAT
- Or is this normal and expected behavior?
?
Thanks a lot for looking into my question,
?
Wim
|
Thanks for the suggestion Mike, but I don't think this is the problem.? The telescope does not move at all, but I can check this again this evening!
|
Wim,
Good morning sir. I hope you are doing well.?
So ... first and foremost I'd check the ratios. If you have not fine tuned them you should be able to get slightly better tracking by doing the "Simple Track Improvement" routine found in a doc of that name on the CD. Try that first.?
Then do the "Backlash Compensation" doc routine.?
These two need to be done before we can go further.?
And as a side note it is unlikely it is a loose disengagement lever.?
Gary
|
Thanks Gary,
I will try these.? I will look for the CD this evening and read about the Simple Track Improvement and Backlash Compensation routines.? Do I need a special cable to execute these routines?
Cheers,
Wim
|
Wim,
No - they're pretty basic yet work well.
g.
------ Original Message ------
Date 6/10/2024 8:59:07 AM
Subject Re: [ServoCAT] Guiding problems
Thanks Gary,
I will try these.? I will look for the CD this evening and read about the Simple Track Improvement and Backlash Compensation routines.? Do I need a special cable to execute these routines?
Cheers,
Wim
|
I looked into the documentation, so I will first need to use the ServoCAT Utility () to download the current configuration values from the ServoCAT, do the test, and upload the new gear ratios to the ServoCAT using the official ServoCAT (ServoCAT-Sky) software.?
If I understand correctly, I can do this during the day.?
For the backlash compensation, I will need a clear night.
Is this all correct?
Cheers,
Wim?
|
Yes - you can do the track improvement during the day however be careful to do an accurate daytime alignment using a planetarium program and the encoder counts. You can also go as far as 179¡ã away for the best results. Just don't go more than that (stay at say 170 or below, and at 100 at least).?
Gary?
------ Original Message ------
Date 6/10/2024 10:28:00 AM
Subject Re: [ServoCAT] Guiding problems
I looked into the documentation, so I will first need to use the ServoCAT Utility () to download the current configuration values from the ServoCAT, do the test, and upload the new gear ratios to the ServoCAT using the official ServoCAT (ServoCAT-Sky) software.?
If I understand correctly, I can do this during the day.?
For the backlash compensation, I will need a clear night.
Is this all correct?
Cheers,
Wim?
|
Thanks,
Isn't the backlash compensation also possible during the day?? I guess I can check the encoder values and just get the time it takes before the values start to change.
Something came up this evening, so no tests today.? I can already install the software :P
Cheers,
Wim
|
The backlash has to be under the sky as you need to see an object in the eyepiece to determine when motion starts.?
------ Original Message ------
Date 6/10/2024 3:32:36 PM
Subject Re: [ServoCAT] Guiding problems
Thanks,
Isn't the backlash compensation also possible during the day?? I guess I can check the encoder values and just get the time it takes before the values start to change.
Something came up this evening, so no tests today.? I can already install the software :P
Cheers,
Wim
|
I tried to connect to the ServoCAT with the ServoCAT Utility (SCU.exe), but I fail to do so... I get the following output.?  I can connect with the ServoCAT-Sky tool using COM port 1.? Is there something I need to do to use SCU.exe?? I tried with Windows 11 and Windows 10 (both running in a Virtual Machine, because I'm using a Mac).? If needed, I can try to bring a Windows laptop from work, but I don't think that this is the problem.?? Or should I just start with the delivered 18'' Obsession configuration file that was delivered on the CD-ROM (in the file Obs_Retro.DAT) and update the ratios from there? Cheers, Wim
|
My guess is you are not ON com 1.?
Open Device Manager (do a search in the white box on the task bar) ---- is there a listing for "PORTS"??
If not is the cable plugged in (from the ServoCAT)??
If not plug it in - now is there something there for PORTS??
If so, open it up (the arrow for PORTS) and look at the entry. One of them, if more than one, should say "USB Serial Port" and have a com number listed. Use that value.?
NOTE: you can "prove" that the ServoCAT is on that port by seeing it listed like above (with the cable plugged in) ... and then seeing that listing disappear when you unplug the cable.?
g.
------ Original Message ------
Date 6/11/2024 3:32:22 PM
Subject Re: [ServoCAT] Guiding problems
I tried to connect to the ServoCAT with the ServoCAT Utility (SCU.exe), but I fail to do so... I get the following output.?
I can connect with the ServoCAT-Sky tool using COM port 1.? Is there something I need to do to use SCU.exe?? I tried with Windows 11 and Windows 10 (both running in a Virtual Machine, because I'm using a Mac).? If needed, I can try to bring a Windows laptop from work, but I don't think that this is the problem.??
Or should I just start with the delivered 18'' Obsession configuration file that was delivered on the CD-ROM (in the file Obs_Retro.DAT) and update the ratios from there?
Cheers,
Wim
|
I could test with a real Windows laptop today, and I can use SCU.exe and the ServoCAT-Sky programs.? So, the problem was in the Virtual Machine.? Will try the track improvement and backlash compensation as soon as possible.?
I'll let you know the results!
Cheers,
Wim
|
I could do the procedures from the track improvement procedure yesterday.? In Azimuth, I had to do some adjustments (as the first stop was at 8.1).? After uploading the new value for the ratio, the result after a goto was within 1 degree.? In Altitude, I only had to do a small adjustment.??
Now I'm waiting for nice weather, but the weather predictions do not show any possibility to check the results in the first ten day.
Cheers,
Wim
|
Super! Was that on a 100 degree move?
There's enough variability in the results that a 1% error is more than acceptable. Considering that for example this does not take into account a) the speed that it is slewing, b) the direction it is slewing and c) sidereal movement during the move. I suspect since this is the case that one could do the test both moving away CW as well as CCW and average the results. Or, ideally, you could do the test for an AZ check/improvement by finding an object near this point: AZ = LAT-90; ALT = 90-LAT. At this point the AZ tracking is (near) zero. Likewise for ALT you could do this at AZ = 180¡ã where the ALT tracking will be zero.?
Gary?
|
Hi Gary,
That was on a 170 degree move.? I guess the tracking will already be much better now.? I used 90 - LAT for the azimuth and 15 degrees for altitude, as explained the in PDF file on the CD.?
I'm looking forward for a clear night!
Cheers,
Wim
|
Hi Gary,
We had a clear night last night, so I could finally test the changes I had made.? I can confirm that everything seems to run much better than before.? Thanks for the advice!
Cheers,
Wim
|
Super - glad to hear it!?
Gary Myers StellarCAT
------ Original Message ------
Date 6/24/2024 4:37:45 AM
Subject Re: [ServoCAT] Guiding problems
Hi Gary,
We had a clear night last night, so I could finally test the changes I had made.? I can confirm that everything seems to run much better than before.? Thanks for the advice!
Cheers,
Wim
|
Hi Gary
you indicate ¡°Or, ideally, you could do the test for an AZ check/improvement by finding an object near this point: AZ = LAT-90; ALT = 90-LAT. At this point the AZ tracking is (near) zero¡±
To understand properly what you say :
For my 45degree latitude in France this means do the test for Az finding an object near AZ=45-90= -45degree so at northwest ( Alt=90-45=45degree)
what Is special about this northwest zone for Az tracking ?
Thanks for feedback?
Raphael
|
Raphael,
The 'special' aspect of this point in space is that it is where the AZ tracking is zero. So any testing done around this point will reflect changes in the ALT only. It is the AZ equivalent of moving the scope to directly south where the ALT tracking is zero. In either care the value decreases going one direction until it hits zero and then as it goes through that 'point' it reverses slowly increasing. So for directly south the ALT will slowly decrease as it is going UP .... until it hits zero at the meridian. Then it starts to go DWN on the other side. Likewise the AZ is going CW but decreasing rate as you approach this spot from the eastern side... then goes CCW as you go pass it towards the north.?
There's probably a name for it. I found this out through testing.?
g.
------ Original Message ------
Date 6/29/2024 2:30:27 AM
Subject Re: [ServoCAT] Guiding problems
Hi Gary
you indicate ¡°Or, ideally, you could do the test for an AZ check/improvement by finding an object near this point: AZ = LAT-90; ALT = 90-LAT. At this point the AZ tracking is (near) zero¡±
To understand properly what you say :
For my 45degree latitude in France this means do the test for Az finding an object near AZ=45-90= -45degree so at northwest ( Alt=90-45=45degree)
what Is special about this northwest zone for Az tracking ?
Thanks for feedback?
Raphael
|
Wim De Meester