Date   

Re: A question for Don

Dan Gray
 

The absolute encoder checkbox should not be used unless both encoders are absolute.  The only effect on the system is when you start SiTechExe, it reads the encoders and saved offsets and starts up initialized, no need to unpark or sync on a star or something.
Dan


On Mon, Apr 26, 2021 at 8:01 PM Russell R via groups.io <rem.64=yahoo.com@groups.io> wrote:
Hi Dan H,

From what I see, if you shoot from the hip, I definitely don't want to get in a gun battle with you! 

Regarding the absolute check box, I'm not sure, maybe Don knows.  If it was me, I would tick the box and see what happens. I live on the edge.
 
I keep looking at that Dec clamp....... I'm assuming it is to stop the Dec axis from freewheeling?   It would be good if you could put that Renishaw in that spot and somehow make a brake on that stacked harmonic drive.
Now look at who's shooting from the hip. ;-)

I always wondered if split rings have a problem with eccentricity on the ring, is that an issue?

Well done and thanks for sharing those photos!!

Russell R.


Re: saving the tracking change to the controller

Dan Gray
 

Hi Gary and Don,
The equatorial rate is designed only for stand alone operation, no computer..
When you have a rate here, and checkbox the Equatorial, the Servo Controller starts up tracking at the rate you specify.
If you run SiTechExe, the equatorial rate has absolutely zero effect on the tracking, as soon as SiTechExe sends a motion command, the equatorial rate is stopped.
The rate now comes from motion commands from SiTechExe.
Dan


On Wed, Apr 28, 2021 at 3:54 PM Gary Hug <garyhug@...> wrote:
Thanks for the information Don.

I'll work on that a bit more when skies clear.

cheers
Gary

On 4/27/2021 8:28 AM, Don W wrote:
> Hi Gary,
> In ServoConfig when changing the Equatorial Rate, you then must both "Send
> Configuration to Controller" and "Save Controller Configuration to Flash ROM".
>
> When you run SiTechexe and watch the value for RA, it won't change the RA value
> shown at the bottom of the SiTech window nor in the SkyView display.  The only
> way to check if the rate has actually changed is to track a star in the sky.
>
> However there is another way to modify the tracking rate (separate from
> ServoConfig), in SiTechexe you can use Offset Tracking Rates in the Features
> Tab.  This will definitely change your tracking rates, but it can not be saved
> for another session.
>
> Don W
>






Re: Quite A Learning Curve

CandCShaw
 

Enjoy Rusty!!!!

Chuck


On Apr 29, 2021, at 9:29 AM, Rusty Fletcher <rusty@...> wrote:



[Edited Message Follows]

Thank you for your reply Paul,

Good Idea! After I get the the new servo motors mounted, electronics installed, and all the software running on one computer, I will star test everything and check the Task Manager performance tab. The upgrade may take a month or more. I haven't started yet. When I'm doing an upgrade like this I like to take my time and work carefully. Right now I am thoroughly studying everything so I understand how the new servo system will work. I appreciate you guys advice.

Thank you,
Rusty


Re: Quite A Learning Curve

Rusty Fletcher
 
Edited

Thank you for your reply Paul,

Good Idea! After I get the the new servo motors mounted, electronics installed, and all the software running on one computer, I will star test everything and check the Task Manager performance tab. The upgrade may take a month or more. I haven't started yet. When I'm doing an upgrade like this I like to take my time and work carefully. Right now I am thoroughly studying everything so I understand how the new servo system will work. I appreciate you guys advice.

Thank you,
Rusty


Re: Quite A Learning Curve

paul K
 

The concept of multi threaded application software and computer processors running at many millions of instructions per second means that for all intents and purposes, the processes in the machine (cameras, mounts, guide camera, etc) run concurrently, with no interference between them. Your guide cam and main cam can download simultaneously with no delay /lag to other processes. The computer processor(s) switches between the processes to ensure they are serviced effectivley.

'Simultaneous' is not entirely technically true and depends on many things, but the huge processor and bus (internal data transfer ) speeds mean the tasks you need to perform in terms of astronomy gear (mount, camera, guide camera, rotator, dome and shutter robotics, add anything you like to this list) means that your computer's capablity is barely taxed. The amount of downtime the processor has is huge (even when it is simultaneously downloading a hi res image and a guide cam image) - you can see this for yourself on a Windows computer by running Task Manager and looking at the performance tab.

USB connectors can be daisy chained if you don't have enough on the laptop, just buy as many usb hubs as you need. I use two four port hubs to connect eight items of gear to my old (2001 vintage) Dell with 4 GB RAM.

Going back to your dual core laptop. My Toshiba dual core with 4 GB of RAM ran Sitech, PHD2 guiding, image capture software, my dome control robotics, and played youtube videos simultaneously.

you won't have any computer capacity problems with a single computer running all your gear.

good luck with it.
Paul


Re: Quite A Learning Curve

Rusty Fletcher
 

Hello Don,

I have been trying for over a week to fully understand this? You said " Pulseguide measures the error and sends a required correction in terms of arc-sec to the controller (inside the PC)". My question is: How does Pulseguide measure the error? Doesn't the guiding camera (not the main imaging camera) have to take an image (1 or 2 sec exposure), download that image to the computer, then PHD analyze the amount of error correction that needs to be done, and then send a correction to the SiTech controller? It seems to me if I have only one computer constantly downloading small images (I use a Meade Deep Sky II camera for auto-guiding on a second guide-scope) every 3 or 4 seconds, and (that same computer) downloading high resolution color images from my ZWO ASI533 camera through a USB 3.0 cable every 20 to 40 seconds, and that same computer running planetarium software (The Sky 6.0), things are going to start lagging and running slow. And, sometimes there will be delays between the computer trying to download auto-guiding images and trying to download the main images at the same time, which will cause lots of tracking problems. For ALT/AZ auto-guiding I like for my guiding corrections to occur in less that 5 second intervals. That is when I get the best images. I usually take about 200 or more images of one deep space object and stack them. Attached is an image I did recently.


Re: saving the tracking change to the controller

Gary Hug
 

Thanks for the information Don.

I'll work on that a bit more when skies clear.

cheers
Gary

On 4/27/2021 8:28 AM, Don W wrote:
Hi Gary,
In ServoConfig when changing the Equatorial Rate, you then must both "Send Configuration to Controller" and "Save Controller Configuration to Flash ROM".
When you run SiTechexe and watch the value for RA, it won't change the RA value shown at the bottom of the SiTech window nor in the SkyView display.  The only way to check if the rate has actually changed is to track a star in the sky.
However there is another way to modify the tracking rate (separate from ServoConfig), in SiTechexe you can use Offset Tracking Rates in the Features Tab.  This will definitely change your tracking rates, but it can not be saved for another session.
Don W


Re: saving the tracking change to the controller

Don W
 

Hi Gary,
In ServoConfig when changing the Equatorial Rate, you then must both "Send Configuration to Controller" and "Save Controller Configuration to Flash ROM".

When you run SiTechexe and watch the value for RA, it won't change the RA value shown at the bottom of the SiTech window nor in the SkyView display.  The only way to check if the rate has actually changed is to track a star in the sky.

However there is another way to modify the tracking rate (separate from ServoConfig), in SiTechexe you can use Offset Tracking Rates in the Features Tab.  This will definitely change your tracking rates, but it can not be saved for another session.

Don W


Re: saving the tracking change to the controller

Gary Hug
 

Actually I'm not sure if the controller recognizes the tracking rate change but it is not changing the rate in the SiTech.exe program.

On 4/27/2021 1:56 AM, Gary Hug wrote:
Ive got another very basic question that I probably should already know the answer.
While I can change the tracking rate in the Servo config program and could see the motor change the rate, I tried to save that configuration to the servo controller II but the tracking rate didn't change when using the Servo Controller II.  Do I need to use (reset the SiTech Technology Controller)?
I tried to save the configuration in the controller by using (send the configuration to controller) but that didn't seem to change the tracking rate through the controller.  I also tried (save controller configuration to Flash ROM) but no joy there either.
sorry for all the silly questions but I haven't had to change much in the last decade and I have a 40mb hard drive in a 40 terabyte world.
thanks
Gary


Re: A question for Don

Dan Hummel
 

As for the DEC clamp, it's essential for dismantling this scope. To counterbalance all the gear we have strapped to the secondary cage we have over 70 pounds of steel bolted to the base of the mirror bucket. This scope didn't lend itself well to modifications. Once the secondary and trusses are removed, the tub is extremely bottom heavy. To lift the mirror assembly out of the bucket requires either a super human effort to lift it straight up or tilt the bucket as close to horizontal as possible. The feeler stock has no chance in supporting that much force. Without that clamp we would need a mobile crane.

And yes, how accurately can you bend a steel pipe. And will it stay bent that way. We depend heavenly on mount modeling and hope we don't run over a mosquito . To do it again we would salvage the optics, scrap the drive and start from scratch.



saving the tracking change to the controller

Gary Hug
 

Ive got another very basic question that I probably should already know the answer.

While I can change the tracking rate in the Servo config program and could see the motor change the rate, I tried to save that configuration to the servo controller II but the tracking rate didn't change when using the Servo Controller II. Do I need to use (reset the SiTech Technology Controller)?

I tried to save the configuration in the controller by using (send the configuration to controller) but that didn't seem to change the tracking rate through the controller. I also tried (save controller configuration to Flash ROM) but no joy there either.

sorry for all the silly questions but I haven't had to change much in the last decade and I have a 40mb hard drive in a 40 terabyte world.

thanks
Gary


Re: changing the tracking rate

Gary Hug
 

Yeah I knew that; but just think of doubling that!!
(:>)
G

On 4/26/2021 7:37 PM, Don W wrote:
Hi Gary,
Good luck adjusting your tracking rate.  But I am an unpaid "volunteer".
Don W


Re: A question for Don

Russell R
 

Hi Dan H,

From what I see, if you shoot from the hip, I definitely don't want to get in a gun battle with you! 

Regarding the absolute check box, I'm not sure, maybe Don knows.  If it was me, I would tick the box and see what happens. I live on the edge.
 
I keep looking at that Dec clamp....... I'm assuming it is to stop the Dec axis from freewheeling?   It would be good if you could put that Renishaw in that spot and somehow make a brake on that stacked harmonic drive.
Now look at who's shooting from the hip. ;-)

I always wondered if split rings have a problem with eccentricity on the ring, is that an issue?

Well done and thanks for sharing those photos!!

Russell R.


Re: changing the tracking rate

Don W
 

Hi Gary,
Good luck adjusting your tracking rate.  But I am an unpaid "volunteer".
Don W


Re: changing the tracking rate

Gary Hug
 

Yes, Thank you for the info. I did indeed have some numbers in local search box that I've now set to zero. I'm now able to change the tracking rate. As a test I took the tracking speed from 83500000 to 10000000 and the timing belt speed is greatly reduced. So while I'm not sure yet what numbers I'll end up with, I'm confident I can get there..

Thanks again guys,
I think Dan should double your salary (:>)

cheers
Gary

On 4/26/2021 11:13 AM, Don W wrote:
Hi Gary,
In servoConfig.exe you can adjust the tracking rate, and you can set an adjustment rate that you can use with the HandPad.  I am copying the paragraphs from the Setup Manual here:
*Setting Up the Equatorial Mode*
*Using the ServoConfig software, click on “Edit Parameters”, then “Auto Tracking”.Click on the Equatorial mode radio button.Set up the Equatorial rate.If you know the number of effective encoder ticks for one revolution of the Right Ascension axis, enter that number in the green text box to the right.After pressing the Enter key, the proper Equatorial rate will be calculated and will appear in the “equatorial rate” text box. (The number you entered in the green box will also change to accommodate the math the controller uses internally.Not to worry, if you entered the correct ticks/rev, the slight change the controller needs will not mess things up for you!) If you do not know the exact number to enter and want to experiment, a larger number will make the system track faster.*
**
*You can adjust the tracking rate up and down by pressing a certain sequence on the handpad (described in the next section).The amount it is adjusted per handpad press is in the text box labeled “Equatorial Up/Down Adjust”.
*
**
*To raise the tracking speed, press the top left key, and while holding it down (think of it as an ALT key) press the up direction.*
**
*To lower the tracking speed, press the top left key, and while holding it down (think of it as an ALT key) press the down direction.*
**
*The up/down speed adjustment will not work if you have set up the local search feature (version 1.7 or later of the firmware).To enable the UP/Down adjustments, you will have to enter a value of zero in the local search distance and speed parameters.*
I don't know how many times you can adjust the speed.  But you can increase or decrease the setting.  I think the value in the green box for R/A Total Motor Encoder Ticks is independent of the setting elsewhere for ticks/rev.
Just to be sure, are you positive that your tick/rev are 83.5 million?  That is very high, and being high makes the mount track faster.  Please recheck your ticks calculation.
Don W


Re: Meridian Flip Settings Explained

MartinC
 

Hi Don,
Many thanks for your kind words. I'm sure Dan is always busy. I'm just pleased the problem has been recognised which is great. I'm very confident Dan will resolve. I'm no programmer. I just write code for my own amusement. I can imagine it could be a tricky one.

180° is certainly not where I'll be going. It was just to demonstrate how the problem can be 'exposed' for want of a better word.

I'll wait to hear back from you.

Best wishes
Martin


Re: Meridian Flip Settings Explained

Don W
 

Hi Martin,

I suspect the "Bug" has been there a long time, but few (or no one) has ever run into it before.  You did a great job documenting the problem.

I expect Dan to check this out and reply - probably with a new version that fixes it.  However Dan also travels a lot and might not be able to work on it for a while.  He or I will let you know.

The setting for Track Past the meridian limit can not be logical over 90°.  If the meridian limit is zero Over the pole and 178 to 180° under the pole the track past hits the horizon at 90°.  You don't want to look at China (below the horizon).  So a setting of 180° is absurd. - with unknown consequences.

All the limits are measured from the Zenith.  The under pole limits assume that the angle is the anti-zenith for the pole, so the meridian under the pole is at 180°.

Don W


Re: Meridian Flip Settings Explained

MartinC
 

Hi Don,

Many thanks for your reply, much appreciated. Yes, I concur 100%. Those settings do perform as you state.
But of course, the false\unwanted mirror slew (potential bug) is still present.

With the same settings you've just given me you can prove this to by just opening SkyView alone.
  • To generate a mirror slew, first slew to any object East of the -178° "Meridian West Under Pole" limit and North of the blue Track Past threshold.
  • Now re-select the same objetct or any other object within approximately 30 arc sec radius of it (maybe more - I've not determined the exact amount yet).
  • Now click on the GoTo button and you will see the mirror slew take place.
  • Now re-slew back to the same target in the North East.
  • Now change the Track Past threshold to something less than 90 but somewhere north of the target.
  • Now re-select that same target & click on the GoTo button again.
  • This time you will see that the mount does not move. To be precise it performs a small 'jiggle' & then settles without any slew.
So with these settings this anomaly\potential bug only occurs for targets between the eastern track past threshold and the "Meridian West Under Pole" limit.
I strongly suggest that the small window of approx 30" (or so) is typical of a small slew called for by a plate solver; and hence, why plate solving exposes the problem.

  • Now return the Track Past threshold to it's default value of 2°.
  • Now re-test but this time first slew to a target in the small 2° degree gap between the blue TrackPast threshold & the "Meridian West Under Pole" limit.
  • The same mirror slew takes place.

To me it suggests this behaviour has been present for a while or maybe its always been there? And I've just stumbled across it due to my new mount configuration.

As you correctly state Don, the 90° gives me what I need. I need to consider circumpolar objects, especially in the winter months with the longer nights so I may need to go further than 90°?

But!! The problem is that as the TrackPast threshold increases so does the problem area. If you make the TrackPast 180° you will experience mirror slews from any point in the East. Over the pole as well.

My 'Catch 22' scenario is that I need to push the TrackPast threshold out to at least 90° but in so doing I exclude a large number of targets on the rise in the East; which is nice part of sky for me to begin imaging (weights down of course).

I'm not sure what you mean about handpad motion? But yes SGP triggers false slews, so does Voyager, so does APT & I've just tried slewing from Cartes Du Ciel with targets 32 arc sec apart & that also produces false\mirror slews.

I've attached a labelled screen shot of a test example.

It will certainly be very interesting to see what comes out of Dans findings.

Best regards
Martin


Re: changing the tracking rate

Gary Hug
 

Yeah, I think your right, Joshua.

I'm beginning to suspect the motor or controller is dropping ticks. The other motor I had seemed to suddenly became faulty and that's why I changed it out but maybe it wasn't the motor. Maybe the controller needs tested out. I've had that Servo II controller in use for over a decade. Or more likely I've got my tracking rate messed up while my slew rates are relatively accurate. Don suggested checking my tracking rate adjustment,

"The up/down speed adjustment will not work if you have set up the local search feature (version 1.7 or later of the firmware). To enable the UP/Down adjustments, you will have to enter a value of zero in the local search distance and speed parameters."

I had some numbers in the ('local search' dialog box) so maybe by setting this number to zero will allow and up down tracking adjustment. I'll try it next time the wind is less than 20-40 MPH and its not raining. (Or what we call Full Moon (:>) )

Thanks for the suggestions guys,

cheers
Gary

On 4/26/2021 3:18 PM, Joshua Hufford wrote:
Gary, trying to correct for slewing errors by changing the tick count seems like an exercise in frustration to me.
There is a tool in ServoConfig to determine the amount of ticks. If you can't get an exact figure using math this "should" get you close. If your slews are accurate but your tracking speed is off or the other way around, I'd look for the problem elsewhere, not by changing the tick count.
My $.02
Josh
On Mon, Apr 26, 2021 at 3:06 PM Gary Hug <garyhug@mercurywireless.net <mailto:garyhug@mercurywireless.net>> wrote:
What I meant to say was I was adjusting the ticks/360 degree rate according to
the accuracy of the slews.  As example if I plate solved some position in the
east sky and slewed 120 degrees to the west but ended up at only moving 105
degrees to the west (that west position again being plate solved also) Then I
know to increase the number of ticks needed by approximately 10%.  Now if there
are motor issues or ticks missing or slipping somewhere this won't work of
course.
So I do need to do as you and Don suggest just to make sure the count is close
to the predicted through the gear train.
I have a unique mount that uses basically a pinch roller for the drive
mechanism
or as I like to call it a 'high pressure friction drive'.  The drive roller
is a
1" slightly tapered shaft pressed against the outer surface of the  48"
diameter
3/8" steel disk.  So I start with a 48-1 ratio x a 30-1 gear reducer x 1.5 to 1
timing pulley arraignment x 2000 x 19.1 = 82,512,000 ticks per 360 degree.
My previous motor had a 10-1 gear ratio, but I changed the timing gear from 2-1
to a now 1.5-1.  The scope is approx 1200 lbs including the mount, so the high
gearing ratio gives me a greatly relaxed need for torque at the expense of
speed
reduction.  I can turn the pulley next to the motor by one finger in both
directions so the torque required by the motor is minimal.
cheers
Gary
On 4/26/2021 6:44 AM, Russell R via groups.io <http://groups.io> wrote:
> Gary,
>
> My guess would be tick count is off.   Just has a reminder, that encoder
is read
> in quadrature, 500 X 4 X 19.1 X gearing ratio.
> How do you increase or decrease ticks by slewing?  Maybe I don't understand.
>
> Russell R.
>


Re: changing the tracking rate

Joshua Hufford
 

Gary, trying to correct for slewing errors by changing the tick count seems like an exercise in frustration to me. 

There is a tool in ServoConfig to determine the amount of ticks. If you can't get an exact figure using math this "should" get you close. If your slews are accurate but your tracking speed is off or the other way around, I'd look for the problem elsewhere, not by changing the tick count. 

My $.02

Josh

On Mon, Apr 26, 2021 at 3:06 PM Gary Hug <garyhug@...> wrote:
What I meant to say was I was adjusting the ticks/360 degree rate according to
the accuracy of the slews.  As example if I plate solved some position in the
east sky and slewed 120 degrees to the west but ended up at only moving 105
degrees to the west (that west position again being plate solved also) Then I
know to increase the number of ticks needed by approximately 10%.  Now if there
are motor issues or ticks missing or slipping somewhere this won't work of course.

So I do need to do as you and Don suggest just to make sure the count is close
to the predicted through the gear train.

I have a unique mount that uses basically a pinch roller for the drive mechanism
or as I like to call it a 'high pressure friction drive'.  The drive roller is a
1" slightly tapered shaft pressed against the outer surface of the  48" diameter
3/8" steel disk.  So I start with a 48-1 ratio x a 30-1 gear reducer x 1.5 to 1
timing pulley arraignment x 2000 x 19.1 = 82,512,000 ticks per 360 degree.
My previous motor had a 10-1 gear ratio, but I changed the timing gear from 2-1
to a now 1.5-1.  The scope is approx 1200 lbs including the mount, so the high
gearing ratio gives me a greatly relaxed need for torque at the expense of speed
reduction.  I can turn the pulley next to the motor by one finger in both
directions so the torque required by the motor is minimal.

cheers
Gary

On 4/26/2021 6:44 AM, Russell R via groups.io wrote:
> Gary,
>
> My guess would be tick count is off.   Just has a reminder, that encoder is read
> in quadrature, 500 X 4 X 19.1 X gearing ratio.
> How do you increase or decrease ticks by slewing?  Maybe I don't understand.
>
> Russell R.
>





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