Re: Setting up auto time with draws gps #ntp #chrony #gps #clock #battery


Budd Churchward
 

Sorry for not making myself clear. The clock problem was something I saw while using the UDRC-II which has no GPS. The Rpi does a real lousy job of keeping time all by itself. One of the best things about the new DRAWS is that we now have a solution. The GPS and the RTC with back up battery are a welcome addition to the digital controller. It looks like we need to give the board a chance to see the satellites and set up the RTC. Then we can tuck DRAWS into our Go-Kit and it will be ready when we need it. The back up battery is an important part of this plan.

73 Budd WB7FHC

-----Original Message-----
From: Basil Gunn
Sent: Wednesday, December 26, 2018 10:30 PM
To: udrc@nw-digital-radio.groups.io
Subject: Re: [udrc] Setting up auto time with draws gps


Budd Churchward <budd@...> writes:

My experience with NTP service is that you need to keep it active. If
you let it set the clock on the Rpi and then keep running without the
internet connection the time on the clock gets pretty far off quite
quickly. Like one day later it is way off.
It's a little confusing because the DRAWS image uses chronyd for the NTP
service and NOT ntpd.
So there are 3 situations:

No gps antenna
No Internet connection
No gps antenna or Internet connection

I have a script that dumps the world for chrony here:
n7nix/gps/verify_time.sh

It's also good to see how many satellites the gps is picking up with:
gpsmon

Usually if your clock is off by a lot & you are connected to the
Internet you can kick it in the butt as root with:

chronyc makestep

/Basil

Budd WB7FHC

From: John D Hays - K7VE
Sent: Wednesday, December 26, 2018 5:34 PM
To: udrc@nw-digital-radio.groups.io
Subject: Re: [udrc] Setting up auto time with draws gps

As has been discussed previously. NTP services like chrony slowly adjust the system clock based on information obtained from both ntp servers and refclocks (like the GPS and PPS).

Basil has created a script that verifies time at ~/n7nix/gps/verify_time.sh

The command line to do a quick update of the clock is: sudo chronyc makestep


You can verify your clocks with: chronyc sources -v


The battery backed RTC in the GPS must be set by the GPS once it has acquired the time reference from the satellites.

In my opinion, NTP time synchronization works best if the computer is not powered down and the Raspberry Pi is well suited to continuous operation at low power consumption. With the computer running continuously the chrony daemon can keep the system clock well synchronized whether using the GPS/PPS and/or network connections. (It ignores sources that are not reporting or are way out of sync.)



On Wed, Dec 26, 2018, 16:16 Art - KC7SDA <@nouse4anick wrote:

i think you have to have the battery installed for the rtc.... it takes a bit to get the signal and then set the clock.

I'm assuming you did the chrony and gps install as described in the wiki?

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