The oscillator used in the hackaday project actually gets its precision from receiving a GPS signal! So if you can't receive GPS, their project won't work.
If you can normally receive GPS, then your purposes may be served by simply using a standard (probably USB) GPS receiver plugged into the Pi. That can be configured to keep the on board RTC accurate to within limits. If you just use the time stamp sent by the GPS, that will keep the RTC accurate to within a second or two. Some GPS have a PPS (pulse per second) output which the GPS driver can use to achieve sub-second synchronisation accuracy. If your main objective is to ensure that the RTC doesn't drift over the longer term, this will work fine.
If you can't receive GPS, then you're looking at using something which has a temperature stabilised oscillator, and maybe uses other tricks as well, to output a stable frequency - expensive!
There are other solutions; for example the various time/date broadcasts on 60kHz or 70kHz in many countries. But computer-interfaceable modules for these may well cost more than a GPS! Or you can find some other accurate radio signal, and translate it to the required frequency.
And if you fit a backup battery to the Pi, it will retain the time during a power down (which I don't think is the case with the hackaday project).
If you can normally receive GPS, then your purposes may be served by simply using a standard (probably USB) GPS receiver plugged into the Pi. That can be configured to keep the on board RTC accurate to within limits. If you just use the time stamp sent by the GPS, that will keep the RTC accurate to within a second or two. Some GPS have a PPS (pulse per second) output which the GPS driver can use to achieve sub-second synchronisation accuracy. If your main objective is to ensure that the RTC doesn't drift over the longer term, this will work fine.
If you can't receive GPS, then you're looking at using something which has a temperature stabilised oscillator, and maybe uses other tricks as well, to output a stable frequency - expensive!
There are other solutions; for example the various time/date broadcasts on 60kHz or 70kHz in many countries. But computer-interfaceable modules for these may well cost more than a GPS! Or you can find some other accurate radio signal, and translate it to the required frequency.
And if you fit a backup battery to the Pi, it will retain the time during a power down (which I don't think is the case with the hackaday project).
Statistics: Posted by stevend — Sat Jun 29, 2024 11:27 am