About APCC and ISS tracking and PC Time


drgert1
 

Hello All,

There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.

The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)

My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.

Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)

Of course a great shout-out to Ray for the excellent work.

Cheers,
Gert


W Hilmo
 

Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.

 

The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
Sent: Wednesday, April 7, 2021 2:02 PM
To: main@ap-gto.groups.io
Subject: [ap-gto] About APCC and ISS tracking and PC Time

 

Hello All,

There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.

The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)

My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.

Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)

Of course a great shout-out to Ray for the excellent work.

Cheers,
Gert


Dale Ghent
 

Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale

On Apr 7, 2021, at 21:08, W Hilmo <y.groups@hilmo.net> wrote:

Your computer should be able to sync time with NIST, as long as you have an internet connection. APCC can then update the mount’s time with the computer’s time. This doesn’t require a new feature.



The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver. I do a fair amount of imaging from sites with no internet. Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.



From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
Sent: Wednesday, April 7, 2021 2:02 PM
To: main@ap-gto.groups.io
Subject: [ap-gto] About APCC and ISS tracking and PC Time



Hello All,

There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.

The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)

My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.

Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)

Of course a great shout-out to Ray for the excellent work.

Cheers,
Gert



Christopher Erickson
 

Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

I hope this helps.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   


On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:

Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>







Dale Ghent
 

Yep. 

The hows and whys are covered by the NMEATime author here:


On Apr 7, 2021, at 10:13 PM, Christopher Erickson <christopher.k.erickson@...> wrote:


Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

I hope this helps.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:

Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>







Woody Schlom
 

Christopher,

 

Thanks for that insight on GPS clock accuracy.  I realized it took several minutes for greatest geographical accuracy (often called 3D by GPS makers), but didn’t realize that the clock accuracy could take as long as 20 minutes.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Christopher Erickson
Sent: Wednesday, April 7, 2021 7:13 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

 

Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

 

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

 

I hope this helps.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:


Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>






Dale Ghent
 

In reality the minimum possible time for a GPS cold start is 12.5 minutes, but this is under optimal conditions where the receiver has a full view of the sky down to the horizon. Without that full view and with some sat signals being blocked or reflected by structures or other objects, accumulating the constellation almanac will take longer.  This period of time is referred to as Time To First Fix.

On Apr 7, 2021, at 10:43 PM, Woody Schlom <woody_is@...> wrote:



Christopher,

 

Thanks for that insight on GPS clock accuracy.  I realized it took several minutes for greatest geographical accuracy (often called 3D by GPS makers), but didn’t realize that the clock accuracy could take as long as 20 minutes.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Christopher Erickson
Sent: Wednesday, April 7, 2021 7:13 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

 

Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

 

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

 

I hope this helps.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:


Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>






W Hilmo
 

This is great information!

 

I have been using a free tool called GPSTime (https://www.coaa.co.uk/gpstime.htm), and it works ok.  I took a look at NMEATime and it looks to be far superior.  Since it installs as a service, I just need to make sure that my cheap GPS dongle is plugged in, and it takes care of the rest.

 

In my opinion, it’s well worth the cost, so I went ahead and purchased it.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Dale Ghent
Sent: Wednesday, April 7, 2021 7:33 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

 

Yep. 

 

The hows and whys are covered by the NMEATime author here:

 



On Apr 7, 2021, at 10:13 PM, Christopher Erickson <christopher.k.erickson@...> wrote:



Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

 

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

 

I hope this helps.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:


Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>






Christopher Erickson
 

I think that having a GPS hooked up to the scope PC and running for at least 20 minutes before using it to tune the PC internal clock will be critical for both satellite tracking as well as for occultation captures.

"My advice is always free and worth every penny!"

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


On Thu, Apr 8, 2021 at 7:52 AM W Hilmo <y.groups@...> wrote:

This is great information!

 

I have been using a free tool called GPSTime (https://www.coaa.co.uk/gpstime.htm), and it works ok.  I took a look at NMEATime and it looks to be far superior.  Since it installs as a service, I just need to make sure that my cheap GPS dongle is plugged in, and it takes care of the rest.

 

In my opinion, it’s well worth the cost, so I went ahead and purchased it.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Dale Ghent
Sent: Wednesday, April 7, 2021 7:33 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

 

Yep. 

 

The hows and whys are covered by the NMEATime author here:

 



On Apr 7, 2021, at 10:13 PM, Christopher Erickson <christopher.k.erickson@...> wrote:



Only FWIW, SharpCap can access the GPS chip in my QHY174M-GPS cams and sync the PC clock to them.

 

I always run GPS's for at least 20 minutes on-sky before I attempt to sync a PC to them before I capture an occultation. I have seen GPS time being up to 20 seconds off from a GPS until they get a full ephemeris update from the satellites.

 

I hope this helps.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Wed, Apr 7, 2021, 3:50 PM Dale Ghent <daleg@...> wrote:


Ugh. Windows' built-in time client has been a pain to deal with and performed sadly only until recently, and even still it requires some tweaks in order to keep host clock drift reasonably in check. One of the time server vendors I've used in the past has a decent series of KB articles regarding this:

https://kb.meinbergglobal.com/kb/time_sync/timekeeping_on_windows/accurate_time_in_windows

As for using a GPS to sync the signal timecode to the host, I do this now using a $15 USB GPS dongle from Amazon and the NMEATime2 app from VisualGPS: http://visualgps.net/#nmeatime2-content

NMEATime2 does it right, including calibrating for the delay between the signal being emitted, received, and working its way through the OS to the app. This delay calibration is key for any app that's used to keep time with any signal source and why you can't just read the GPS sentences as they come off the serial port and write that time to the OS clock. It's pretty good for $20 and change, and a total solution for under $40 if you include the cost of any USB GPS dongle.

/dale


> On Apr 7, 2021, at 21:08, W Hilmo <y.groups@...> wrote:
>
> Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.
>
>
>
> The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.
>
>
>
> From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of drgert1 via groups.io
> Sent: Wednesday, April 7, 2021 2:02 PM
> To: main@ap-gto.groups.io
> Subject: [ap-gto] About APCC and ISS tracking and PC Time
>
>
>
> Hello All,
>
> There was a nice ISS pass yesterday. I tried to follow it with APCC horizon utility.
> I see the PC time as the most tricky parameter. In my case the mount was trailing the ISS by a bit.
> Obviously my PC time wasn't spot-on. Now for folks like me who are getting forgetful maybe it's an opportunity for Ray to put some automated NIST time sync into APCC just as a helpful measure. Maybe with a little popup 'OK' button.
>
> The tracking feature is just great. I like the way it is organized sending the custom tracking speeds to the mount (which you can see in the driver UI)
>
> My one improvement request would be to have the hand controller buttons 'N E S W' able to overlay the motion of the tracking. When I pushed the buttons during the ISS flyover the mount moved but 'something was fighting' the motion and pushed the ISS back to the edge of the field of view.
>
> Maybe even have an option for a USB joystick to control the mount motion. (This would be even a cool thing outside off ISS tracking) :-)
>
> Of course a great shout-out to Ray for the excellent work.
>
> Cheers,
> Gert
>
>
>






drgert1
 

Hello All,

Thanks for the great discussion. I just tested a GPS dongle vs the Windows 10 time (just after having told Windows to sync with the network time reference). The time is off by 1hr and 2sec. Now, which one is right for ISS tracking? Very interesting!



Cheers,
Gert


Dale Ghent
 

I'm not sure which app it is that you're using, but it's probably not adjusting its display of time for DST given that it's 1 hour behind your clock display and your location is observing DST. Seems odd to me that it wouldn't do this, but perhaps it uses its own timezone conversion based on the coordinates and this tz data might not have any notion of DST or purposefully avoids adjusting for it.

If you want your computer clock to be tied to the GPS-derived time, you should use an app like the aforementioned NMEATime2 instead of eyeballing it. Give sufficient time for the GPS lock to happen and the computer clock to the slewed to the GPS time before connecting to the mount with the A-P driver, which should have the "Sync PC time to mount" option set. I believe this is done only on initial connection to the mount when location and time are initialized.

Actually, this is a good question for Ray: Is the clock sync done only on initialization or is it also done periodically for the duration of the connection? I've never been clear on this and have always assumed it was a one-time deal when the driver first initializes the mount.

/dale

On Apr 9, 2021, at 01:30, drgert1 via groups.io <drgert1=yahoo.com@groups.io> wrote:

Hello All,

Thanks for the great discussion. I just tested a GPS dongle vs the Windows 10 time (just after having told Windows to sync with the network time reference). The time is off by 1hr and 2sec. Now, which one is right for ISS tracking? Very interesting!

<GPS_vs_Win10.jpg>

Cheers,
Gert


drgert1
 

@Dale & All,

The app came for free with the GPS dongle. Not very sophisticated. Thus probably missing out on DST. I asked NMEATime2 about preferences of COM over USB vs BT. BT seems to be deprecated. More interesting the 2sec gap between Win10 clock and GPS. I had used the sync with network in the MSFT clock settings popup just 5min prior. Alas I probably hadn't let the GPS soak for  long enough. Will try again.

Ping for Ray : Any ideas about hand controller / joystick override for the ISS tracking ?

Cheers,
Gert


ap@CaptivePhotons.com
 

Are any of these using the 1 PPS feature of GPS for better accuracy than the serial data stream?   

 

I’m not sure there is a practical difference but they all seemed to not have it, not sure if that’s a windows/USB thing, or just that they are a bit behind, or if there’s something expensive about it so it doesn’t show up in these products?

 

I went to buy one and felt like I was getting a CFL light bulb instead of LED – not awful, just not current.

 

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of drgert1 via groups.io
Sent: Friday, April 9, 2021 4:31 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

 

@Dale & All,

The app came for free with the GPS dongle. Not very sophisticated. Thus probably missing out on DST. I asked NMEATime2 about preferences of COM over USB vs BT. BT seems to be deprecated. More interesting the 2sec gap between Win10 clock and GPS. I had used the sync with network in the MSFT clock settings popup just 5min prior. Alas I probably hadn't let the GPS soak for  long enough. Will try again.

Ping for Ray : Any ideas about hand controller / joystick override for the ISS tracking ?

Cheers,
Gert


Bob
 

On Thu, Apr 8, 2021 at 09:09 AM, W Hilmo wrote:

Your computer should be able to sync time with NIST, as long as you have an internet connection.  APCC can then update the mount’s time with the computer’s time.  This doesn’t require a new feature.

 

The new feature that I would like to see is for APCC to have an option to update the computer time from a GPS receiver.  I do a fair amount of imaging from sites with no internet.  Right now, I have a 3rd party piece of software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right from APCC.

 
I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I couldn't find it. Now I know why.

Any idea if/when this feature will be introduced?


Ray Gralak
 

Hi Bob,

I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with
APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I
couldn't find it. Now I know why.

Any idea if/when this feature will be introduced?
It probably will not be a feature of APCC because to set the time on the computer APCC would have to be run "as administrator". That is something we probably would not want to do because then the ASCOM driver would not be able to automatically start APCC.

If you have a network connection, you could use Dimension 4. Also, some inexpensive or free utilities supposedly can update the system time with some GPS devices. One I have run across is called "VisualGPS", but I don't know if it will work with the device you have.

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Bob
Sent: Sunday, May 23, 2021 11:44 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] About APCC and ISS tracking and PC Time

On Thu, Apr 8, 2021 at 09:09 AM, W Hilmo wrote:


Your computer should be able to sync time with NIST, as long as you have an internet connection. APCC
can then update the mount’s time with the computer’s time. This doesn’t require a new feature.



The new feature that I would like to see is for APCC to have an option to update the computer time from a
GPS receiver. I do a fair amount of imaging from sites with no internet. Right now, I have a 3rd party piece of
software that I use to sync the computer clock from the GPS, but it would be nice to have an option to do this right
from APCC.



I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with
APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I
couldn't find it. Now I know why.

Any idea if/when this feature will be introduced?


Dale Ghent
 

On May 24, 2021, at 02:43, Bob <astro@dinoworld.com.au> wrote:

I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I couldn't find it. Now I know why.

Any idea if/when this feature will be introduced?
Time syncing is complex enough of a topic that it's best to let dedicated apps which handle the intricacies involved do the driving on this. There are entire professions and academic pursuits based around just this topic, after all, so it's just not something you snap your fingers and see appear in code no matter how "easy" it might appear to the uninitiated.

On Windows:

For NTP, there is the Dimension4. This implements a more aggressive NTP client than the standard one that's built-in to Windows.

For GPS devices that emit standard NMEA time sentences over a serial (COM) port, there is NMEATime2 ($20) or the older, free version, NMEATime.

If you are operating on Linux or other type of *NIX OS, then there are many to accommodate all sorts of time sources.


ap@CaptivePhotons.com
 

Dale Ghent said:

For NTP, there is the Dimension4. This implements a more aggressive NTP client than the standard one that's built-in to Windows.

For GPS devices that emit standard NMEA time sentences over a serial (COM) port, there is NMEATime2 ($20) or the older, free version, NMEATime.

If you are operating on Linux or other type of *NIX OS, then there are many to accommodate all sorts of time sources.
One thing to realize is that NMEA time is inherently inaccurate, exacerbated by USB serial delays. Most GPS chips also emit a PPS or 1PPS (1 pulse per second) electrical signal that is very precise, and can be used to synchronize the information from NMEA. Essentially the later says "the time is X" and the PPS signal says "right now".

Windows cannot easily do this, and none of the GPS' that attach via USB can do this.

It is unclear that driving a mount, even as fast as ISS, require this. VisualGPS / NMEATime2 (Dale's example but good one) has a lot of math added to try to pull out all the accuracy possible from UPS GPS without PPS. It's a good windows tool to get what is likely "good enough".

It is relatively cheap however to get more accuracy: A raspberry Pi with off the shelf code and a tiny bit of soldering will let you build a very accurate time server for around $45 ($10 GPS, $35 rPi 3B). The rPi will run GPSD to process the time signals, and coordinates with PPS on a GPIO pin. Built in CHRONYC (which is NTP in disguise) will provide a time signal other systems can coordinate with. I did one recently with:

https://www.amazon.com/gp/product/B07P8YMVNT

Note that while it has USB, you have to solder to the other pins to get the PPS signal. Interestingly this device is sensitive enough a get a decent signal inside a dozen feet from a window. The rPi can power it. Add a $5 12v to 5v step down and you can power the rPi from your 12v mount supply and strap the combination to your tripod. (Try to keep the GPS device, at least the antenna, a bit away from any wifi emitters as they can conflict -- that's generally a true statement not specific to this).

Then on Windows run the Meinberg NTP server and connect to the rPi (preferably over ethernet for low delay) and it will drive the Windows clock. It is unclear exactly how accurate this combination is, but certainly sub millisecond and probably a few dozen microseconds. Add internet time servers to the Meinberg list and it will fall back to them when the rPi is not available.

Again, it's not clear that NMEA derived time is inadequate, in fact some back of the envelop math makes me think it is quite good enough. But if you are a tad obsessive about getting accurate time on windows, this is a cheap alternative, and easier than trying to "fix" windows directly to use a GPS properly.

Linwood


 

>>> For GPS devices that emit standard NMEA time sentences over a serial (COM) port, there is NMEATime2 ($20) or the older, free version, NMEATime.

just for the heck of it, i purchase NMEATime2 and an inexpensive GPS receiver (something like a $30 garmin from Amazon)

it's easy to set up and use and seems to provide exceedingly accurate (and continuous) time updates to my windows setup.

i just placed the GPS puck on top of the telescope (i have my computer mounted to a top plate on the OTA)


Surprised at how easy it was to install and use 



On Mon, May 24, 2021 at 6:12 AM Dale Ghent <daleg@...> wrote:

> On May 24, 2021, at 02:43, Bob <astro@...> wrote:

> I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I couldn't find it. Now I know why.
>
> Any idea if/when this feature will be introduced?

Time syncing is complex enough of a topic that it's best to let dedicated apps which handle the intricacies involved do the driving on this. There are entire professions and academic pursuits based around just this topic, after all, so it's just not something you snap your fingers and see appear in code no matter how "easy" it might appear to the uninitiated.

On Windows:

For NTP, there is the Dimension4. This implements a more aggressive NTP client than the standard one that's built-in to Windows.

For GPS devices that emit standard NMEA time sentences over a serial (COM) port, there is NMEATime2 ($20) or the older, free version, NMEATime.

If you are operating on Linux or other type of *NIX OS, then there are many to accommodate all sorts of time sources.






--
Brian 



Brian Valente


Bob
 

On Mon, May 24, 2021 at 08:32 PM, Ray Gralak wrote:
Hi Bob,

I'm really quite surprised that APCC cannot utilise gps time directly. I bought a $10 usb gps and it works well with
APCC. When I went looking for the setting in APCC that would allow me to utilise the gps time instead of PC time, I
couldn't find it. Now I know why.

Any idea if/when this feature will be introduced?
It probably will not be a feature of APCC because to set the time on the computer APCC would have to be run "as administrator". That is something we probably would not want to do because then the ASCOM driver would not be able to automatically start APCC.

If you have a network connection, you could use Dimension 4. Also, some inexpensive or free utilities supposedly can update the system time with some GPS devices. One I have run across is called "VisualGPS", but I don't know if it will work with the device you have.

-Ray
Thanks Ray.  Although, APCC could still use the GPS time without updating the computer time perhaps, which would get around the admin issue? I guess this could be problematic for other software though. I guess I will go with some third party software then.


Dale Ghent
 

On May 25, 2021, at 05:31, Bob <astro@dinoworld.com.au> wrote:

Thanks Ray. Although, APCC could still use the GPS time without updating the computer time perhaps, which would get around the admin issue? I guess this could be problematic for other software though. I guess I will go with some third party software then.
The same clock discipline considerations that exist when syncing time to the PC clock would also exist when syncing to the mount. The PC clock and mount's own clock should also be in sync for reasons including proper precession calculations anyway, so it's best for the mount to be programmed with the PC's time, and the PC's clock to in turn be properly synchronized with a time source.

Time sources and synchronization on the PC is going to be far more flexible and readily doable in a correct way anyhow. NTP infrastructure takes care of these details in whole, with time sources being other NTP servers on the internet to local NTP infrastructure that's uses local time sources, such as a GPS receiver, rubidium clocks, or even NIST's WWV and WWVH shortwave radio. Absent NTP but with a GPS receiver on Windows, you can use NMEATime2. As far as the GPS function in APCC goes, it's useful for your lat/long. Time is going to be a more advanced concern.

As an aside, here's a little neat thing about time sync services, at least here in the US: The US Naval Observatory and NIST still operate telephone lines for their time services. You can call them at any time to hear an audible 1 PPS tick with time announcements every minute. It's pretty moot in the age of mobile phones that have clocks that are synced to the telephone switch's own atomic clock, but If anyone feels like hearing the voices of broadcasters Fred Covington (USNO) or John Doyle (WWV) crooning out the time at 2am, one can still do so.