Re: About APCC and ISS tracking and PC Time


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
>
>
>





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