USB DCF77 on Turris Omnia

would something like that (Expert mouseCLOCK USB II DCF77 USB, 0107, GUDE)
help, to have a more accurate time on the Omnia Turris Router?
So “my” Router/firewall would also be a Stratum 2 (or 1) on my LAN!

have a nice day
vinc

Why would you do that when you can sync your system time via NTP?

  • Afaik, DCF77 is less precise than NTP.
  • To have a real stratum 1, you’d need a GPS receiver which you could connect to your omnia.
  • If that’s so important, I would say, that you can configure your omnia as startum 1 for clients in your network even when you are taking time from external source (correct me anyone if I’m wrong here)

[quote=“lampler, post:3, topic:1153, full:true”]you can configure your omnia as startum 1 for clients in your network even when you are taking time from external source (correct me anyone if I’m wrong here)
[/quote]
you definitely can do it with chrony.

DCF77 can be really high precision. This depends on the used modulation of the signal (amplitude modulation or phase modulation) and the propagation delay. NTP driver ids are PCF, DCF, NEOL for example.

You may use any external or internal receiver with time as long as it provides a high precision second mark. USB does not count as high precision. GPIO and hard serial do in most cases but for GPS you generally need a PPS signal. Some receivers can output this but not all.

For precision there is something else to consider: how precise is precise? Stratum 2/3 pool servers provide my chrony with a time exact to a few milliseconds. For non-scientific uses this is enough. A cheap USB based clock won’t be better than this because USB by itself can not be more precise than one millisecond.

Does anybody know if there would be any possibility to use LTE card embedded GPS functionality for time sync? That would be great if yes.

LTE is USB so there’s little sense using it - better to rely on internet ntp pool accessible through that LTE.

Aha understood. Thank you for clarification.

I don’t see why it should make little sense to use LTE’s GPS via USB (but I’m not so good with Linux to understand :frowning: :slight_smile: )

IMHO using the GPS, USB DCF77 or other time sync other than NTP could be usable if the device (Omnia) don’t have access to internet (or limited, or not stable etc) but still can provide services for devices in local network.

I know that ntp doesn’t need many data but with GPS on LTE you don’t need any data at all for time sync for example

chrony is usually doing well when dealing with intermittent internet connection. It may apply clock drift delta and continue correcting RTC even after it lost the reference server. So yes, I can see the point in USB-based gps only for completely offline deployment - bet then why would you need then firewall and LTE? If for OOB - same OOB can be used for time sync.