I would like to ask a question about updating date and time on my Raspberry Pi 4. I have been using the Astroberry suite quite successfully and I must say I really like it, especially for its ease of use, since I am far from a Linux expert.

I know the Raspberry doesn't have its own way of updating time and date at startup but I don't want to hook it up to the home network every time I go out imaging - in fact, I use it as a hotspot, so that I can VNC into it immediately at startup, from my laptop.

The way I have been updating GPS coordinates, date and time, so far, has been with the GPSNMEA driver in EKOS. On my Android phone I have NetGPS, set to port 50000, same in GPSNMEA. I connect my phone to the Raspberry hotspot via WI-FI and then I launch EKOS.

The driver updates the location and time correctly, and feeds it to KStars and all my slews are usually correct.

However, last night, I tried to slew to the Moon and some planets, and I saw that the telescope was way off, even if I plate solved a few points and built a good model of the sky. Then I noticed that inside GPSNMEA the time was correct, but not the date. It should have been October, 5th, instead it was still October, 4th - which was the last time I hook up the Raspberry to the network, via ethernet, to update some things.

Now, I don't remember if this was a one time thing, since I usually just do DSO imaging and after the first plate solve, all the following GO-TOs are pretty much spot on.

So, if possible, I would like to know the following three things:

1) - is there a reliable way of updating date, time and GPS coordinates using GPSNMEA and a phone app, so that everything goes correctly?

2) - I would like to know if I can do this manually from the terminal with the sudo command, so that I can somehow force it in case things don't work with 1)

3) - since I image almost always from the same location, can I write its coordinates somewhere in some config file so that if I don't launch GPSNMEA and just update time and date with 2), once I open KStars/EKOS, they read those as the default coordinates?

Thanks for the help!

Matteo

Matteo

I had this problem a few weeks ago. I ended up not using my GPS!!! Ther are mainly 2 reasons, 1) the GPPS may not lock quickly as the cell phone (which uses tower trangulation when GPS is not locked) in my case it took hours as my location is not open entirely to the sky, and 2) it is messy with kstars, sometimes my mount just slew below the horizon as the GPS trying to take over!!!

Not the response you are hoping for, but this is my experience with GPS modules with KStars. There is another thread about using GPS with mount and unify the time as UTC, but still, there is a problem with DST...

Thank you for the reply, Mohamed. You are having different problems than me, but what you are saying is even one more reason to have a "back up plan" to be able to set things manually, if automation fails. The last thing you want is being somewhere, maybe under dark skies, with no internet connection, and not be able to image because there's no way of fixing the date, time and local coordinates.

So, let's hope someone with more knowledge sees this thread and tells us if there's a solution!

I think there are two issues: the system time and the time and location in KStars.
Regarding the system time I use a DS3231 Real Time Clock, which continues increasing the system time while the RPi is switched off.
Regarding the time and location in KStars, I use either a NMEA driver or the mount GPS and specify "mount updates KStars" in the latter case.

HTH, Wouter

Hi Wouter,

I'm not familiar with the DS3231 solution. Can you please through some light on it?
I found the module and ordered one to try.

My understanding is you don't use an external GPS module, you depend on your smartphone GPS?

Yes, the NMEA driver in Ekos can be used with a smartphone. I have an iPhone and use the GPS2Ip app. There is a similar one for Android which you can find when you search this forum.


Wouter