I am in Australia and the accuracy of the NITZ service can be slow by up to 15 SECONDS. I have no idea why it is so bad. You can try this for yourself. Just get a GSM modem connected to your laptop, set it up to accept NITZ updates and print the results on the serial port, and take a drive around your neighbourhood. As you go between towers you will get new NITZ updates, and you can log the accuracy.
Try not to get arrested as a terrorist :) There is a simplified NTP service that only receives a small packet, I think I saw an example for Arduino. Tom Harris <celephi...@gmail.com> On 12 November 2014 09:34, Tony <tn...@toneh.demon.co.uk> wrote: > On 11/11/2014 21:52, Tom Harris wrote: > >> How are you getting time from the GSM network? If you are using the NITZ >> (look it up) service then you can use an unactivated SIM for free, but the >> accuracy is woeful, it can be seconds out. >> > I'm not at the moment; mobile phones do set their clocks from the network > but I've no idea how accurately it can be done - which is why I was asking. > >> Else you will have to have a live SIM and use NTP to a server. If you make >> any progress please post to the list. I have not heard of being able to >> access the clock in the tower over the network. >> >> The beauty of phone network is that it works in buildings, where GPS does >> not reach. >> >> Tom Harris <celephi...@gmail.com> >> > > I would have a live SIM as the modem would be used periodically (but not > necessarily frequently - perhaps every 24 hours or more) to send data. I > would not want to use an NTP service as I would only have a > micro-controller with limited memory. > > > Tony H > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.