Date   

Re: Bad DEC backlash in Mach1GTOs?

Roland Christen
 

You can try backlash comp, but remember, it is so small that you run the risk of overcompensating and the result will be a back and forth oscillation.

Rolando



-----Original Message-----
From: privatekey42@... [ap-gto]
To: ap-gto
Sent: Fri, Jun 22, 2018 12:23 pm
Subject: RE: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Thanks for your comments Roland. Much appreciated. Nice idea re the guide software re dithering …. hopefully PHD will take it up.

Re the unavoidable small amount of backlash in the system - is it worth then enabling backlash compensation in PHD2? It's noted on the CN forum that even users without obvious issues still can see the effects of this small backlash in taking a few pulses to start moving in the other direction. Backlash compensation may help to get that down to just one or two pulses.

Again. Thanks for your advice.

Paul



Re: Bad DEC backlash in Mach1GTOs?

Eric Dreher
 

Wade, that sounds suspiciously like Metaguide.  :)

Eric


Re: Bad DEC backlash in Mach1GTOs?

Mlooker
 

PHD has a lot of features to help mounts that have a lot of backlash, but in the case of the Mach1, you will have to turn off any and all backlash settings. Because if you don't, I guarantee you will get oscillations on the Dec axis. It will bobble back and forth and never settle down.

Start with a real good calibration run. Make sure that you follow the PHD instructions to the letter when calibrating. Next, turn aggressiveness down all the way and slowly bring it up and watch your guider graph. Somewhere between 50% and 70% aggressiveness the guiding in Dec should settle down and become smooth and accurate. Do the same on RA.

Rolando


On 6/22/2018 3:22 PM, privatekey42@... [ap-gto] wrote:
 
Thanks for your comments Roland. Much appreciated. Nice idea re the guide software re dithering …. hopefully PHD will take it up.

Re the unavoidable small amount of backlash in the system - is it worth then enabling backlash compensation in PHD2? It's noted on the CN forum that even users without obvious issues still can see the effects of this small backlash in taking a few pulses to start moving in the other direction. Backlash compensation may help to get that down to just one or two pulses.

Again. Thanks for your advice.

Paul


Re: Bad DEC backlash in Mach1GTOs?

Paul
 

Thanks for your comments Roland. Much appreciated. Nice idea re the guide software re dithering …. hopefully PHD will take it up.

Re the unavoidable small amount of backlash in the system - is it worth then enabling backlash compensation in PHD2? It's noted on the CN forum that even users without obvious issues still can see the effects of this small backlash in taking a few pulses to start moving in the other direction. Backlash compensation may help to get that down to just one or two pulses.

Again. Thanks for your advice.

Paul


Re: Bad DEC backlash in Mach1GTOs?

W Hilmo
 

I think that it would also be interesting if you could configure the guide software to take many exposures and average the location of the centroid before making an adjustment. For example, it seems like it would be beneficial in the normal guiding case to take 10 or 15 (or more) one second exposures, and then average them to determine whether (and how much of ) a correction is needed. In this way, you could average out the seeing for a long period of time without risking saturation of the guide star. Naturally, you would want a different behavior during recovery from a dither, as you note below.



-Wade



From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Friday, June 22, 2018 12:48 PM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?





Yes, you may quote me, although I'm sure there will be dissenting opinions.



I want to add another comment to the long guide exposure versus short exposure debate. Long exposure was thought to be more accurate because you are averaging the seeing noise and thus acting only on the actual tracking error. That works in some cases, but today we like to take lots of shorter exposures, dither them so that we can stack and cancel background noise. The problem is that dithering requires several exposures to bring the star back to the center. If your exposure is long, it may take a long time if your guide exposure is on the order of 5 to 10 seconds.



It would be interesting if the guide software could increase the exposure rate to once a second until the star reaches the center and then automatically slow down to a longer guide exposure. This could also be incorporated during guiding, if the star exceeds the Min Move setting bring it back quickly with a series of short exposures until the star is back to center, then resume the longer exposure series.



Rolando







-----Original Message-----
From: stelios_t@yahoo.com [ap-gto] <ap-gto@yahoogroups.com>
To: ap-gto <ap-gto@yahoogroups.com>
Sent: Fri, Jun 22, 2018 7:02 am
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Thank you! Is it OK if I quote from this on CN?





[Non-text portions of this message have been removed]


Re: PHD2 Dec Axis Issue?

dvuolhhr6nx4a532a3phnju3zs6lzvlgxdl2wzaf@...
 

Hi,

I think my only issue was that because I was dithering a lot with short exposures (and extreme dither) PHD2 and the mount were kinda working against each other resulting in the higher RMS values. Without dithering the mounts tracks/guides beautifully. So more user operator error :)


Re: Bad DEC backlash in Mach1GTOs?

Roland Christen
 

Yes, you may quote me, although I'm sure there will be dissenting opinions.

I want to add another comment to the long guide exposure versus short exposure debate. Long exposure was thought to be more accurate because you are averaging the seeing noise and thus acting only on the actual tracking error. That works in some cases, but today we like to take lots of shorter exposures, dither them so that we can stack and cancel background noise. The problem is that dithering requires several exposures to bring the star back to the center. If your exposure is long, it may take a long time if your guide exposure is on the order of 5 to 10 seconds.

It would be interesting if the guide software could increase the exposure rate to once a second until the star reaches the center and then automatically slow down to a longer guide exposure. This could also be incorporated during guiding, if the star exceeds the Min Move setting bring it back quickly with a series of short exposures until the star is back to center, then resume the longer exposure series.

Rolando



-----Original Message-----
From: stelios_t@... [ap-gto]
To: ap-gto
Sent: Fri, Jun 22, 2018 7:02 am
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Thank you! Is it OK if I quote from this on CN? 


Re: Bad DEC backlash in Mach1GTOs?

Ray Gralak
 

Thank you! Is it OK if I quote from this on CN?
You didn't say *who* you wanted to quote. :-)

Some don't use the yahoo web site so they can't tell to which post you are referring.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Friday, June 22, 2018 10:02 AM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Thank you! Is it OK if I quote from this on CN?


Re: What happened to my virtual port???

Ray Gralak
 

Hi Dan,

It would only matter if you are using SGPro for plate solving with APPM/APCC Pro.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Friday, June 22, 2018 11:36 AM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: What happened to my virtual port???




Ray,
I am a long time user of APCC, the Pro addition. I am new to SGPro. Everything works fine but I have noted that
when used with SGPro to connect to my 1100GTO, the virtual port connection of APCC is not used ( active).
Does this matter?

Dan


Re: Bad DEC backlash in Mach1GTOs?

Karen Christen
 

Stelios – I’m not entirely sure who you’re asking, but if you’re asking if you may quote from Roland’s response, then yes, be our guest.

Karen

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Friday, June 22, 2018 12:02 PM
To: ap-gto@...
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?

 

 

Thank you! Is it OK if I quote from this on CN? 


Re: What happened to my virtual port???

Dan Richey <drichey@...>
 

Ray,
I am a long time user of APCC, the Pro addition. I am new to SGPro. Everything works fine but I have noted that when used with SGPro to connect to my 1100GTO, the virtual port connection of APCC is not used ( active). Does this matter?

Dan


Re: PHD2 Dec Axis Issue?

Diego Gomez
 

Hi Tony,

Regarding the issue you were facing, I wondered if it was addressed. If yes, could you please let us know what you did?

Thanks,
Diego


Re: Bad DEC backlash in Mach1GTOs?

Stelios
 

Thank you! Is it OK if I quote from this on CN? 


Re: What happened to my virtual port???

Ray Gralak
 

-- Error! Virtual port COM11 (the same port I've always used
since day 1, automatically) must be created! (words to that effect).
Have you connected any other devices (e.g. a USB/serial converter) recently to the computer that might have created a virtual COM port? It could be that another device has commandeered COM11.

If you go into Windows Device Manager and look under "Ports (COM & LPT)" it should show what device driver owns COM11.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Friday, June 22, 2018 2:48 AM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] What happened to my virtual port???



Yesterday, I repeated a routine that I've done a hundred times:




Start APCC.


Click "Connect" (auto-initializes mount).

Click "Connect" on AP-V2 button in APCC...

-- Error! Virtual port COM11 (the same port I've always used since day 1, automatically) must be created! (words
to that effect).




OK, I figured something happened to zap the virtual port. I went to create virtual ports, and all from COM10
through forever were available, EXCEPT--you guessed it--COM11.




So I figured some glitch in memory, shut down laptop, rebooted. Same issue!




I was able to recover by creating COM12, and setting the AP-V2 driver to use COM12. Everything worked fine for
the rest of the night, but I still don't understand what could possibly have happened to make COM11 disappear.

Also, in the Device Manager, it *does* show COM11 under Ports (COM/LPT ). But for some reason AP-V2 can't
use it.

I'd love to know what happened and if it's indicative of some other underlying issue. Also how to fix it (reinstall
everything?)


Re: Bad DEC backlash in Mach1GTOs?

Bill Long
 

Okay thanks. I didn't think it would matter.


From: ap-gto@... on behalf of 'Ray Gralak (Groups)' groups3@... [ap-gto]
Sent: Friday, June 22, 2018 5:17:49 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
 
 

Hi Bill,

> Should I be worried that I had the HA filter on? I guess it would help cut down on noise?

As Roland stated, a filter has no effect on the PE measurement.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

> -----Original Message-----
> From: ap-gto@... [mailto:ap-gto@...]
> Sent: Thursday, June 21, 2018 7:29 PM
> To: ap-gto@...
> Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
>
>
>
> Related to mount performance but sort of a side tangent since you responded.
>
>
>
>
> I took some PEMPro data the other day, because I think that my previous run was not valid. I took all of the data,
> then realized I had my HA filter in front of the camera. The data looked great (under 7" of P-P error, 0.46"
> corrected) and seems to be working even better than my last run.
>
>
>
>
> Should I be worried that I had the HA filter on? I guess it would help cut down on noise?
>
>
>
> ________________________________
>
> From: ap-gto@... on behalf of 'Ray Gralak (Groups)'
> groups3@... [ap-gto]
> Sent: Thursday, June 21, 2018 7:25 PM
> To: ap-gto@...
> Subject: RE: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
>
>
>
> > I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
> > switch to using Ethernet for mount control versus USB though to see if that helps.
>
> It could be. About a year ago I found a couple of Dec related bugs in the PHD2 code. I would have assumed that
> the PHD2 developers
> found and fixed the issues by now, but maybe not.
>
> Someone mentioned guiding oscillations on CN. One of the software errors I found is that sometimes PHD2
> miscalculates backlash and
> that can cause an oscillating pattern because PHD2 overcompensates some moves.
>
> But I have to say that some of the comments on CN seem skewed, like from ahelms. If you are on this forum,
> ahelms, send me a private
> email with a copy of that white paper you sent AP. I would like to take a look at your analysis.
>
> -Ray Gralak
> Author of APCC (Astro-Physics Command Center): http://www.astro-
> physics.com/index.htm?products/accessories/software/apcc/apcc
> Author of PEMPro V3: https://www.ccdware.com
> Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver
>
> > -----Original Message-----
> > From: ap-gto@... [mailto:ap-gto@...]
> > Sent: Thursday, June 21, 2018 5:54 PM
> > To: ap-gto@...
> > Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
> >
> >
> >
> > I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
> > switch to using Ethernet for mount control versus USB though to see if that helps.
> >
> >
> >
> > ________________________________
> >
> > From: ap-gto@... <ap-gto@...> on behalf of stelios_t@... [ap-gto] > > gto@...>
> > Sent: Thursday, June 21, 2018 5:20 PM
> > To: ap-gto@...
> > Subject: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
> >
> >
> >
> > Not so fast.
> >
> > First of all, the people responding on CN (with an opinion) almost invariably have a Mach1 or other AP mount.
> >
> > Second, the issue so far appears to *possibly* be linked to recent mount versions. In one mount shown it
> > appears clearly, and in the other (mine) it's more sporadic, but I wouldn't say nonexistent. I never remeshed
> > anything, my mount is a bit over a year old.
> >
> >
> >
> > The issue being discussed is that there seems to be a lag when PhD2 issues a DEC adjustment command to
> the
> > mount. The mount appears to not respond--then after several "pulses" it finally responds and over-corrects (the
> > extent may be a setting issue), leading to something like the "bobble" Rolando once talked about. The lag in
> > response does appear back-lash-y. (I have Backlash compensation *off* in PhD2).
> >
> > In my case, guiding overall is more than satisfactory, especially since I have not (yet) implemented Rolando's
> > advice to adjust MinMo to seeing. I am not complaining or about to return my mount! But this issue does require
> > some investigation, IMO.
> >
> > And it is silly to dismiss PhD2 (not that AP does so, I know they are getting progressively more involved with it)
> > which is used by the vast majority of imagers *today*. To attract additional business from new imagers, any
> > mount manufacturer should expect these people will be using PhD2 and SGP and Pixinsight in the vast
> majority.
> >
> >
> > ---In ap-gto@..., wrote :
> >
> >
> > I had a Mach1 before replacing it with A-P1100 and never had issues as described at CN. I blame on user error
> > and possibly used incorrect or bad settings/configuration in PHD2. Also the user may have incorrectly re-
> meshed
> > the gears.
> >
> >
> > Peter
> >
> >
> >
> > ---In ap-gto@..., wrote :
> >
> >
> > Hi guys,
> > There is a thread going on at cloudnights:
> >
> >
> > Getting started with the AP Mach 1 - Page 3 - Mounts - Cloudy Nights
> >
> > > 07-getting-started-with-the-ap-mach-1%2Fpage-
> >
> 3&data=02%7C01%7C%7C893600c21b4f4537b5bc08d5d7d5fc3a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7
> >
> C1%7C0%7C636652236414578860&sdata=6q3hBmmdeW%2FKzeDkjTaO1mh%2BFvZjwb0fQIwv3FM3ZR4%3D
> > &reserved=0>
> >
> >
> >
> >
> > that says that there is a problem with DEC backlash in Mach1GTOs.
> >
> > Do people see this problem in general with Mach1GTOs?
> >
> >
> > cytan
> >
> > P.S. I may have "hijacked" the AP keyboard discussion in my first post. Apologies!
> >
> >
> >
> >
> >
>
>
>
>


Re: Bad DEC backlash in Mach1GTOs?

Ray Gralak
 

Hi Bill,

Should I be worried that I had the HA filter on? I guess it would help cut down on noise?
As Roland stated, a filter has no effect on the PE measurement.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Thursday, June 21, 2018 7:29 PM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Related to mount performance but sort of a side tangent since you responded.




I took some PEMPro data the other day, because I think that my previous run was not valid. I took all of the data,
then realized I had my HA filter in front of the camera. The data looked great (under 7" of P-P error, 0.46"
corrected) and seems to be working even better than my last run.




Should I be worried that I had the HA filter on? I guess it would help cut down on noise?



________________________________

From: ap-gto@yahoogroups.com <ap-gto@yahoogroups.com> on behalf of 'Ray Gralak (Groups)'
groups3@gralak.com [ap-gto] <ap-gto@yahoogroups.com>
Sent: Thursday, June 21, 2018 7:25 PM
To: ap-gto@yahoogroups.com
Subject: RE: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
switch to using Ethernet for mount control versus USB though to see if that helps.
It could be. About a year ago I found a couple of Dec related bugs in the PHD2 code. I would have assumed that
the PHD2 developers
found and fixed the issues by now, but maybe not.

Someone mentioned guiding oscillations on CN. One of the software errors I found is that sometimes PHD2
miscalculates backlash and
that can cause an oscillating pattern because PHD2 overcompensates some moves.

But I have to say that some of the comments on CN seem skewed, like from ahelms. If you are on this forum,
ahelms, send me a private
email with a copy of that white paper you sent AP. I would like to take a look at your analysis.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-
physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Thursday, June 21, 2018 5:54 PM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
switch to using Ethernet for mount control versus USB though to see if that helps.



________________________________

From: ap-gto@yahoogroups.com <ap-gto@yahoogroups.com> on behalf of stelios_t@yahoo.com [ap-gto] <ap-
gto@yahoogroups.com>
Sent: Thursday, June 21, 2018 5:20 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Not so fast.

First of all, the people responding on CN (with an opinion) almost invariably have a Mach1 or other AP mount.

Second, the issue so far appears to *possibly* be linked to recent mount versions. In one mount shown it
appears clearly, and in the other (mine) it's more sporadic, but I wouldn't say nonexistent. I never remeshed
anything, my mount is a bit over a year old.



The issue being discussed is that there seems to be a lag when PhD2 issues a DEC adjustment command to
the
mount. The mount appears to not respond--then after several "pulses" it finally responds and over-corrects (the
extent may be a setting issue), leading to something like the "bobble" Rolando once talked about. The lag in
response does appear back-lash-y. (I have Backlash compensation *off* in PhD2).

In my case, guiding overall is more than satisfactory, especially since I have not (yet) implemented Rolando's
advice to adjust MinMo to seeing. I am not complaining or about to return my mount! But this issue does require
some investigation, IMO.

And it is silly to dismiss PhD2 (not that AP does so, I know they are getting progressively more involved with it)
which is used by the vast majority of imagers *today*. To attract additional business from new imagers, any
mount manufacturer should expect these people will be using PhD2 and SGP and Pixinsight in the vast
majority.


---In ap-gto@yahoogroups.com, <pnagy@...> wrote :


I had a Mach1 before replacing it with A-P1100 and never had issues as described at CN. I blame on user error
and possibly used incorrect or bad settings/configuration in PHD2. Also the user may have incorrectly re-
meshed
the gears.


Peter



---In ap-gto@yahoogroups.com, <cytan299@...> wrote :


Hi guys,
There is a thread going on at cloudnights:


Getting started with the AP Mach 1 - Page 3 - Mounts - Cloudy Nights
<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.cloudynights.com%2Ftopic%2F6212
07-getting-started-with-the-ap-mach-1%2Fpage-
3&data=02%7C01%7C%7C893600c21b4f4537b5bc08d5d7d5fc3a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7
C1%7C0%7C636652236414578860&sdata=6q3hBmmdeW%2FKzeDkjTaO1mh%2BFvZjwb0fQIwv3FM3ZR4%3D
&reserved=0>




that says that there is a problem with DEC backlash in Mach1GTOs.

Do people see this problem in general with Mach1GTOs?


cytan

P.S. I may have "hijacked" the AP keyboard discussion in my first post. Apologies!







What happened to my virtual port???

Stelios
 

Yesterday, I repeated a routine that I've done a hundred times:


Start APCC.


Click "Connect" (auto-initializes mount).

Click "Connect" on AP-V2 button in APCC...

-- Error! Virtual port COM11 (the same port I've always used since day 1, automatically) must be created! (words to that effect).


OK, I figured something happened to zap the virtual port. I went to create virtual ports, and all from COM10 through forever were available, EXCEPT--you guessed it--COM11.


So I figured some glitch in memory, shut down laptop, rebooted. Same issue!


I was able to recover by creating COM12, and setting the AP-V2 driver to use COM12. Everything worked fine for the rest of the night, but I still don't understand what could possibly have happened to make COM11 disappear.

Also, in the Device Manager, it *does* show COM11 under Ports (COM/LPT). But for some reason AP-V2 can't use it.

I'd love to know what happened and if it's indicative of some other underlying issue. Also how to fix it (reinstall everything?)


Re: Bad DEC backlash in Mach1GTOs?

Roland Christen
 

Filters should not have any effect on PemPro.

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] To: ap-gto
Sent: Thu, Jun 21, 2018 4:28 pm
Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Related to mount performance but sort of a side tangent since you responded.

I took some PEMPro data the other day, because I think that my previous run was not valid. I took all of the data, then realized I had my HA filter in front of the camera. The data looked great (under 7" of P-P error, 0.46" corrected) and seems to be working even better than my last run.

Should I be worried that I had the HA filter on? I guess it would help cut down on noise?



From: ap-gto@... gto@...> on behalf of 'Ray Gralak (Groups)' groups3@... [ap-gto] gto@...>
Sent: Thursday, June 21, 2018 7:25 PM
To: ap-gto@...
Subject: RE: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
 
 
> I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
> switch to using Ethernet for mount control versus USB though to see if that helps.

It could be. About a year ago I found a couple of Dec related bugs in the PHD2 code. I would have assumed that the PHD2 developers
found and fixed the issues by now, but maybe not.

Someone mentioned guiding oscillations on CN. One of the software errors I found is that sometimes PHD2 miscalculates backlash and
that can cause an oscillating pattern because PHD2 overcompensates some moves.

But I have to say that some of the comments on CN seem skewed, like from ahelms. If you are on this forum, ahelms, send me a private
email with a copy of that white paper you sent AP. I would like to take a look at your analysis.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

> -----Original Message-----
> From: ap-gto@... [mailto:ap-gto@...]
> Sent: Thursday, June 21, 2018 5:54 PM
> To: ap-gto@...
> Subject: Re: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
>
>
>
> I am not so sure its not PHD2. I have seen the same thing occurring recently on my 1100 with DEC. I plan to
> switch to using Ethernet for mount control versus USB though to see if that helps.
>
>
>
> ________________________________
>
> From: ap-gto@... gto@...> on behalf of stelios_t@... [ap-gto] > gto@...>
> Sent: Thursday, June 21, 2018 5:20 PM
> To: ap-gto@...
> Subject: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?
>
>
>
> Not so fast.
>
> First of all, the people responding on CN (with an opinion) almost invariably have a Mach1 or other AP mount.
>
> Second, the issue so far appears to *possibly* be linked to recent mount versions. In one mount shown it
> appears clearly, and in the other (mine) it's more sporadic, but I wouldn't say nonexistent. I never remeshed
> anything, my mount is a bit over a year old.
>
>
>
> The issue being discussed is that there seems to be a lag when PhD2 issues a DEC adjustment command to the
> mount. The mount appears to not respond--then after several "pulses" it finally responds and over-corrects (the
> extent may be a setting issue), leading to something like the "bobble" Rolando once talked about. The lag in
> response does appear back-lash-y. (I have Backlash compensation *off* in PhD2).
>
> In my case, guiding overall is more than satisfactory, especially since I have not (yet) implemented Rolando's
> advice to adjust MinMo to seeing. I am not complaining or about to return my mount! But this issue does require
> some investigation, IMO.
>
> And it is silly to dismiss PhD2 (not that AP does so, I know they are getting progressively more involved with it)
> which is used by the vast majority of imagers *today*. To attract additional business from new imagers, any
> mount manufacturer should expect these people will be using PhD2 and SGP and Pixinsight in the vast majority.
>
>
> ---In ap-gto@..., wrote :
>
>
> I had a Mach1 before replacing it with A-P1100 and never had issues as described at CN. I blame on user error
> and possibly used incorrect or bad settings/configuration in PHD2. Also the user may have incorrectly re-meshed
> the gears.
>
>
> Peter
>
>
>
> ---In ap-gto@..., wrote :
>
>
> Hi guys,
> There is a thread going on at cloudnights:
>
>
> Getting started with the AP Mach 1 - Page 3 - Mounts - Cloudy Nights
> <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.cloudynights.com%2Ftopic%2F6212
> 07-getting-started-with-the-ap-mach-1%2Fpage-
> 3&data=02%7C01%7C%7C893600c21b4f4537b5bc08d5d7d5fc3a%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7
> C1%7C0%7C636652236414578860&sdata=6q3hBmmdeW%2FKzeDkjTaO1mh%2BFvZjwb0fQIwv3FM3ZR4%3D
> &reserved=0>
>
>
>
>
> that says that there is a problem with DEC backlash in Mach1GTOs.
>
> Do people see this problem in general with Mach1GTOs?
>
>
> cytan
>
> P.S. I may have "hijacked" the AP keyboard discussion in my first post. Apologies!
>
>
>
>
>




Re: Bad DEC backlash in Mach1GTOs?

Roland Christen
 


The issue being discussed is that there seems to be a lag when PhD2 issues a DEC adjustment command to the mount. The mount appears to not respond--then after several "pulses" it finally responds and over-corrects (the extent may be a setting issue), leading to something like the "bobble" Rolando once talked about. The lag in response does appear back-lash-y
There is delay in reversing Dec. Although the motor reverses instantly, the geartrain has a small delay of about 1/3 to 1/2 second. The delay is a combination of geartrain backlash and worm tooth loading. Although the worms are spring loaded, there is a pressure that builds up on the driven side of the worm which is released when the worm is reversed. This is one part of the reversal that cannot be adjusted out, it is a normal consequence of worm gears and will always be present no matter how they are driven (spur gear, belt drive or other). It is known as hysteresis and it basically is a non-linear (low gain) portion of the servo loop.

The spur reduction gears have a tiny bit of clearance in order for them to respond smoothly. Yes, they can be adjusted to have almost no backlash delay, but it is not wise to do so (ESPECIALLY for RA). The tighter you adjust them in Dec, at some point they will simply not respond well because of the increased friction.

The best way to guide Dec is to use a fast 1 to 2 second guide exposures which will quickly nudge the mount back toward zero during a reversal. Set the MinMove to approximately the peak seeing level. You can judge this level by simply recording the Dec axis star motion with guiding turned off. If the star is moving around at the rate of +- 1 arc second, then set the Min Move to 1 arc second. Setting it lower will cause the software to chase the guide star after the fact and result in way too many reversals. Theoretically the Dec axis drifts slowly in one direction, with +- seeing noise superimposed. A good guiding algorithm ignores the noise and simply moves the Dec axis always in one direction toward the zero line. A proper Min Move goes a long way toward ignoring the seeing noise.

Rolando


-----Original Message-----
From: stelios_t@... [ap-gto]
To: ap-gto Sent: Thu, Jun 21, 2018 2:20 pm
Subject: [ap-gto] Re: Bad DEC backlash in Mach1GTOs?



Not so fast.

First of all, the people responding on CN (with an opinion) almost invariably have a Mach1 or other AP mount. 

Second, the issue so far appears to *possibly* be linked to recent mount versions. In one mount shown it appears clearly, and in the other (mine) it's more sporadic, but I wouldn't say nonexistent. I never remeshed anything, my mount is a bit over a year old. 

The issue being discussed is that there seems to be a lag when PhD2 issues a DEC adjustment command to the mount. The mount appears to not respond--then after several "pulses" it finally responds and over-corrects (the extent may be a setting issue), leading to something like the "bobble" Rolando once talked about. The lag in response does appear back-lash-y. (I have Backlash compensation *off* in PhD2).

In my case, guiding overall is more than satisfactory, especially since I have not (yet) implemented Rolando's advice to adjust MinMo to seeing. I am not complaining or about to return my mount! But this issue does require some investigation, IMO. 

And it is silly to dismiss PhD2 (not that AP does so, I know they are getting progressively more involved with it) which is used by the vast majority of imagers *today*. To attract additional business from new imagers, any mount manufacturer should expect these people will be using PhD2 and SGP and Pixinsight in the vast majority.


---In ap-gto@..., wrote :

I had a Mach1 before replacing it with A-P1100 and never had issues as described at CN. I blame on user error and possibly used incorrect or bad settings/configuration in PHD2. Also the user may have incorrectly re-meshed the gears.

Peter


---In ap-gto@..., wrote :

Hi guys,
   There is a thread going on at cloudnights:


that says that there is a problem with DEC backlash in Mach1GTOs.

Do people see this problem in general with Mach1GTOs?

cytan

P.S. I may have "hijacked" the AP keyboard discussion in my first post. Apologies!




Re: Mach1 Control Options

Roland Christen
 

I would go with Ethernet. It is the most reliable of the three.

Rolando



-----Original Message-----
From: darrellx@... [ap-gto]
To: ap-gto
Sent: Thu, Jun 21, 2018 1:13 pm
Subject: [ap-gto] Mach1 Control Options



Hi All

I have just received notification that my Mach1 is on its way to me.  I even have a Tracking Number. Great news.  I am getting excited.

Since I placed the order early this year I have downloaded all the documentation I can find and I have read it all.  My Observatory and Piers are ready. Most of my software is loaded and configured on my new laptop (Windows 10).  The exception is APCC.  I am still deciding if I will purchase it or not. Maybe use SN7.  I can hardly wait.

But I do have one issue that I am having a bit of trouble resolving - not a big one but I am hoping for a bit of input from those who already have a Mach1.

How to control the mount.

When I setup my Piers, one at home and one in my dark site observatory, I also ran USB and Cat 6 (ethernet) cables.  At the Observatory, the distance from Laptop to Mount will be less than 2 meters (6fee t).  When at home, the distance is less than 5 meters (15feet).  When at either site I will not be setting up each night to break it down in the morning.  I expect that the equipment will remain setup for a month or two at a time.

So I have three choices - USB, Ethernet, Wireless.

I am wondering what is the most common or preferred or recommended method for controlling the Mount.  I was leaning towards USB, but have since changed my mind to Wireless.  Does it make that much of a difference between these options?

Thanks
Darrell