Date   

Re: #question What determines azimuth in SiTechExe? #question

Mark Copper
 
Edited

That is, indeed, the behavior I expected, but it does not seem to be what I'm observing.

For example, I synced to Segin (epsilon cass) a few minutes ago. At my latitude, azimuth should be about 331 degrees and altitude about 26 degrees. However, under numbers, the az is about 2:30:00 or ~38 degrees; alt is about 8:10:00. Scope az and alt under "controller stuff" is indeed close to the "numbers" numbers.
----------------------------------------
Yikes! My clocks were out of sync. And having corrected them I got a proper updating of alt and az upon syncing on a star. I got a hint when my planetarium software said a star was up but SiTechExe warned it was below the horizon!


#question: How to resume tracking in DragNTrack mode?

Mark Copper
 

I put the controller in DragNTrack mode. I pointed towards celestial north pole, powered up, held ESC button on handpad until controller LED flashed. Then I navigated away from north and could hear the motors working. Pressing RTN on handpad stops the motors and the controller LED's begin a slow flash.

However, according to the operations manual, pressing RTN again should toggle tracking back on. But it does not do so for my scope. Am I missing something?

Thanks.


Re: Stars drift with high resolution encoders

<Joerg>
 

Thanks!

When the weather is better I will make a video and a tracking log. Sadly the forecast says rain for many days. :-(

Joerg


Re: Slewing in Reverse

Andrew Brockett
 

Apologies for the delay. Not too many clear skies this August!
 
Thanks Don. Checked Lats & Longs in Sitech, SGP & TSX. All the same. I'm in the UK.

Excellent pointer Dan. The Single Phot Init from the Run script is excellent. However, could do with a bit of help to refine. In Change Config under the camera Stuff tab, I have SGP ticked for the Camera Control Software and Plate Solve 2 for the Plate Solver. I have done this because I have Plate Solve 2 already set up in my SGP. So my first question is, is the Plate Solver 2 called up by the Script through SGP or is it independent i.e. within the Sitech software. The other question is if I want to run my plate solving through a blind solver can I do that via the box in the Camera Stuff tab where it says Astrometry.net Solve Field Command. What is the syntax of this box, is it the folder location of my Astrometry.net files? The manual doesn't appear to give guidance on this one.

Regards, Andrew


Re: Questions on Mathis MI750 controller and mount

jimsgtastro
 

Thank you, Dan.  I'll check the version and try slowing the slew.

Jim

On Tue, Aug 24, 2021 at 4:18 PM Dan Gray <grayarea@...> wrote:
Hi Jim,
Try lowering the slew speed.  If it can't keep up (due to lack of gear mesh or lube), it could very well be jerky.
Normally those mounts came with a servoII, you can look at the firmware version, if it's about 87 or so, it's a servoII.  It should be upgraded to the latest servoII firmware on our website.
Dan


On Tue, Aug 24, 2021 at 2:25 PM jimsgtastro <JimSarge@...> wrote:
There have been several mentions of the Sitech controlled Mathis mounts.  I've sent these questions to Mathis, but I'm not sure anyone is home.  I don't know of anywhere else to discuss this mount/controller combo than this forum.

I'm helping to get a MI-750 with 20" Planewave CD running again.  it has the SiTech controller and the driver says it's version STI 1.4.3. It has the high resolution encoders fitted and appears to be operating properly with the encoders set to Cascade mode.
 
Is this a SiTech Servo II controller?  Can I load it with Servo II firmware?
 
The mount moves under the hand controller, under the STI driver and under the SiTech 095U driver, however both RA and DEC moves are sluggish and not smooth - there's a certain amount of roughness in the slews.
 
We don't know how old the lube on the gears is.  I can certainly clean and re-lube the gears.  Have others needed to do this?
 
The power supply that was set up on this mount may not be adequate - it's just a little 12V, 5A typical small brick.  Is there a recommended input voltage or power supply specifications?
 
Thank you for any comments/ suggestions you may have.

Jim Seargeant


Re: Questions on Mathis MI750 controller and mount

Dan Gray
 

Hi Jim,
Try lowering the slew speed.  If it can't keep up (due to lack of gear mesh or lube), it could very well be jerky.
Normally those mounts came with a servoII, you can look at the firmware version, if it's about 87 or so, it's a servoII.  It should be upgraded to the latest servoII firmware on our website.
Dan


On Tue, Aug 24, 2021 at 2:25 PM jimsgtastro <JimSarge@...> wrote:
There have been several mentions of the Sitech controlled Mathis mounts.  I've sent these questions to Mathis, but I'm not sure anyone is home.  I don't know of anywhere else to discuss this mount/controller combo than this forum.

I'm helping to get a MI-750 with 20" Planewave CD running again.  it has the SiTech controller and the driver says it's version STI 1.4.3. It has the high resolution encoders fitted and appears to be operating properly with the encoders set to Cascade mode.
 
Is this a SiTech Servo II controller?  Can I load it with Servo II firmware?
 
The mount moves under the hand controller, under the STI driver and under the SiTech 095U driver, however both RA and DEC moves are sluggish and not smooth - there's a certain amount of roughness in the slews.
 
We don't know how old the lube on the gears is.  I can certainly clean and re-lube the gears.  Have others needed to do this?
 
The power supply that was set up on this mount may not be adequate - it's just a little 12V, 5A typical small brick.  Is there a recommended input voltage or power supply specifications?
 
Thank you for any comments/ suggestions you may have.

Jim Seargeant


Re: Stars drift with high resolution encoders

Dan Gray
 

Joerg,
A tracking log will be a good tool.  You'll be able to see if it's servo position error for sure.
Do you have a video camera, or a fast cmos camera?  It would be really simple to make a video over time.  I would suggest the southern meridian for checking the azimuth, and east or west when checking the altitude.
Now you can see if it's interpolation error or not.

Dan


On Tue, Aug 24, 2021 at 2:14 PM Don W <westergren@...> wrote:
Hi Jesse,

Yes, that is an excellent point.  Use the Tracking log to see the numbers showing the motion of scope while tracking a target.
Don W


Re: #question What determines azimuth in SiTechExe? #question

Dan Gray
 

Hi Mark,
v3.9 is a servoI firmware version I think.  I think you are using a fairly recent version because of one of your prior posts.
In the numbers tab, the alt and az are the actual altitude and azimuth of your telescope non-dependent on the mount type.  SInce you're using an alt/az, it should be pretty close, but based on your pointing model, etc.
in the COntroller Stuff, it's "R/A OR Azimuth", or "Dec OR Altutude".  I've been changing this nomenclature to Primary axis and Secondary axis.  Again, in your case it should be pretty close.
But it sounds like if the azimuth is reading wrong, you need to go to SkyView, and sync on a known object (after pointing to it). Then it will read properly.

Dan





On Mon, Aug 23, 2021 at 5:02 PM Mark Copper <mlcopper@...> wrote:
In my version of SiTechExe (v3.9) "azimuth" is given both in the numbers tab and in the controller information window. However, it doesn't seem to be user configurable, either directly or by syncing to a star whose azimuth is known to the program.

Well, I could physically rotate the base of my alt/az scope. Should I?

Thanks.


Questions on Mathis MI750 controller and mount

jimsgtastro
 

There have been several mentions of the Sitech controlled Mathis mounts.  I've sent these questions to Mathis, but I'm not sure anyone is home.  I don't know of anywhere else to discuss this mount/controller combo than this forum.

I'm helping to get a MI-750 with 20" Planewave CD running again.  it has the SiTech controller and the driver says it's version STI 1.4.3. It has the high resolution encoders fitted and appears to be operating properly with the encoders set to Cascade mode.
 
Is this a SiTech Servo II controller?  Can I load it with Servo II firmware?
 
The mount moves under the hand controller, under the STI driver and under the SiTech 095U driver, however both RA and DEC moves are sluggish and not smooth - there's a certain amount of roughness in the slews.
 
We don't know how old the lube on the gears is.  I can certainly clean and re-lube the gears.  Have others needed to do this?
 
The power supply that was set up on this mount may not be adequate - it's just a little 12V, 5A typical small brick.  Is there a recommended input voltage or power supply specifications?
 
Thank you for any comments/ suggestions you may have.

Jim Seargeant


Re: Stars drift with high resolution encoders

Don W
 

Hi Jesse,

Yes, that is an excellent point.  Use the Tracking log to see the numbers showing the motion of scope while tracking a target.
Don W


Re: Stars drift with high resolution encoders

jmgoldba
 

On Tue, Aug 10, 2021 at 12:31 PM, wrote:
an issue with small star drift around the right star position.
Assuming the issue ultimately isn't encoder resolution (or interpolation) have you collected log files that give you more visibility of what the exact "drift around" issue is? Don will recall an issue we had with occasional jumps coming from our DEC axis encoders and the log files were helpful. -Jesse


Re: Stars drift with high resolution encoders

<Joerg>
 

Jesse,

I tried a new PXP model but no difference to the old one.

Joerg


#question What determines azimuth in SiTechExe? #question

Mark Copper
 

In my version of SiTechExe (v3.9) "azimuth" is given both in the numbers tab and in the controller information window. However, it doesn't seem to be user configurable, either directly or by syncing to a star whose azimuth is known to the program.

Well, I could physically rotate the base of my alt/az scope. Should I?

Thanks.


Re: what you can and can't do with SiTechExe under Linux

Mark Copper
 

Hi Dan,

Thanks for thinking about this off-the-beaten-path project.

Choosing "offset init" rather than "cal star init" has no benefit, even when calibration points have been cleared. Also there is no benefit setting PID to (15000,1000,12000). That is, oscillation triggers when the scope is moved after initiation.

The oscillation remains remarkably consistent: "error" in the numbers tab climbing to ~12' in azimuth and snapping back to 0. Plus there is that odd virtual handpad behavior in azimuth: the scope only rotates clockwise when SiTechExe is started -- that is, even when the left buttons are pressed, the scope only rotates right -- and then if the oscillation is triggered, the scope only rotates counterclockwise, even if the right button is pressed. Finally, there was that strange "awakening" where, for a short time, the virtual handpad worked properly and oscillation was not triggered.

I don't need great tracking. Say, less than 2 arcminutes error in 2 or 3 minutes for right now. I do need precision pointing, bringing faint objects to the center of field of view -- I had planned to achieve that with successive approximations using plate solving. It seemed that simple offset init didn't quite get me the tracking I needed but that 3 cal stars did. Perhaps it would be enough to repeat the offset init when the scope is close to its target?

Mark


Re: Stars drift with high resolution encoders

<Joerg>
 

Dan,

 

The diameter of azimuth disk is 1174.72mm, altitude is 1268.21mm.

At round about D disk =1200mm, 1arcsec conforms to 2.9µm on tape. 1 sec tracking at sidereal rate conforms to 0.0436mm on the tape.

The magnetic tape has a pole length of 1mm and the read head is MK1-2k-R.

That should give a maximal resolution of 0.5µm.

 

Joerg


Re: servoII controller

Dan Gray
 

I just sent out a post, I'm going to duplicate it here.

You need to make the motor directions strictly the following.
1. Point the counterweight to the west side.  I call this "Looking West".  Don't run SiTechExe, it fusses with the motor directions when crossing the pole.  So if you were running SiTechExe, reboot the controller to clear out any inversions SiTechExe may have made (note ServoConfig does not do this).
2. Press the up button.  The scope should move to the north.
3. Press the right button, the scope should move to the west.

So, Don is correct, SiTechExe switches directions whenever SiTechExe thinks the declination is crossing the north pole (if you live north of the equator).
If you're "looking east", (counterweight to the west) (or if it's initialized wrong and SiTechExe "Thinks" it's "looking East",  the push buttons for the declination are backwards.
Dan



On Sun, Aug 22, 2021 at 3:25 PM Don W <westergren@...> wrote:
Hi Nigel,

Where in the sky is you scope pointed?  If it is pointed below the pole the Dec motion is reversed.  Try pointing the scope straight up at the zenith to check the motion.  If that motion is reversed, then reverse the switches in Servo Config.
Don W


Re: Stars drift with high resolution encoders

jmgoldba
 

On Tue, Aug 10, 2021 at 12:31 PM, wrote:
The issue in "precise mode" or "cascade mode" can be switched off if "Track Only Sidereal (No PXP)" in Mount Parms has been activated.
How old is your PXP model? - Jesse


Re: what you can and can't do with SiTechExe under Linux

Dan Gray
 

Don't use "Cal Star Init" unless you're going to make a model.
Right click on the very large PointXP button, and clear out all of your  calibration points.
You should only use the Simple OFFSET init unless you're going to make a complete telescope model with points all over the sky.

I recommend going down to 1000 on the integral, and maybe up to 12000 on the derivative.  What's your proportional?  I recommend about 15000, but all this can depend on the resolution of the motor encoder itself.

Dan




On Sun, Aug 22, 2021 at 3:53 PM Mark Copper <mlcopper@...> wrote:
Back to square one, strangely and unfortunately. Everything had seemed OK so I swung for the fences with Kstars but no joy.

Basically what happened this afternoon:
1. Turn controller on.
2. Launch SiTechExe (mono -v SiTechExe.exe)
3. Launch indiserver SiTech
4. Connect to SiTech from KStars
5. Connect to SiTech from INDI control panel
6. Select sidereal tracking in INDI control panel
7. Position telescope manually, enter Algorab coordinates, and sync in INDI control panel
8. Choose Cal Star Init from SiTech window. Tracking begins.
9. Enter coordinates for Spica and set goto in INDI control panel. Oscillation begins.
   Oscillation cycle ~5 seconds. Primary axis error oscillates 0-13 arcminutes. SiTechExe window alternates between "tracking" and "slewing". RA varies ~35". Dec varies ~3'.

Next, I abandoned KStars, and powered the controller off. Then tried the same procedure entirely within SiTechExe:
1. Switched on controller
2. Launched SiTechExe.exe
3. Entered Algorab coordinates in the SiTechExe "goto/sync" window and synced. Chose "cal star init" from panel. Tracking started.
4. Entered Spica coordinates in the "goto/sync" window and clicked "goto".

The first time I did this, the controller died after a jerk. I tried once again, and this time the scope did slew to Spica location, but then fell into the same oscillation as I had experienced previously with Kstars.

This all happened with integral set to 2500 and derivative set to 8000.

Is there a goblin in there somewhere?

Mark


Re: Mount not initialized

Dan Gray
 

HI Yoro,
You need to make the motor directions strictly the following.

1. Point the counterweight to the west side.  I call this "Looking West".  Don't run SiTechExe, it fusses with the motor directions when crossing the pole.  So if you were running SiTechExe, reboot the controller to clear out any inversions SiTechExe may have made (note ServoConfig does not do this).
2. Press the up button.  The scope should move to the north.
3. Press the right button, the scope should move to the west.

Make sure that the scope is initialized and accurate before performing a "Set Park".

Dan




On Mon, Aug 23, 2021 at 9:44 AM Don W <westergren@...> wrote:
Hi Yoro,
Your description of the Park position indicates that position is an ambiguous position.  You are pointing the scope at the north horizon, what is missing is whether it is looking east or looking west.  If the mount guesses wrong, it will go the wrong way.  I don't know where your "Home" is.  If you move (set) the park position to be 1 degree above the horizon then the ambiguity is not there.  Then the mount will know the "side of pier".
Don W


Re: Stars drift with high resolution encoders

Dan Gray
 

Can you tell me the diameter of the disk for the magnetic tape?  In the spec sheet, it gives about +-0.004 mm per meter for magnetization accuracy + interpolation error .
If we know the diameter, we can figure out the arc seconds error.
We can also find the period of the interpolation if we know which readhead you have. The pole spacing is 1, 2, or 5 mm.
Dan


On Mon, Aug 23, 2021 at 3:52 AM <Joerg> <joeps@...> wrote:

Hi Dan,

 

The encoders have been discontinued but I found a link to the user manual.

http://www.enkodery.pl/download/instrukcja_obslugi_gc-mk.pdf

 

I have a pole length of 1mm and the highest resolution read head.

 

Now I made some additional tests. In all modes with activated scope encoders the drift is visible, also with tick management.

There is no large difference whether only one Az or Alt encoder have been activated or both at the same time.

When one or both scope encoder enabled the star follows a circular trail of about 3 times the star diameter. The time for a complete circle is several seconds.

What I don’t understand is the circular trail when only one encoder is enabled.

In my opinion in that case should be the trail a line if magnetization accuracy and interpolation error are blame for that.

 

Joerg

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