5 ms·

It's called GPS :-) You can use a GPS as a time source for an NTP server (on your airwalled network).

• rlpb 6y ago
  Unfortunately the GPS signal is generally too weak to be used indoors - especially in a larger building like a hospital.
  • stragies 6y ago
    Do you need to be more than 1km underground, or away from outside walls? Just put the GPS-receiver on the far end of an RS485 serial connection. First google hit: https://www.worldtimesolutions.com/products/gps_rs485_time_source.html https://www.worldtimesolutions.com/products/gps_rs485_time_s...
    • duskwuff 6y ago
      That'd depend on the hospital building out an RS485 infrastructure to support the device, though, which is a nontrivial ask. Piggybacking off of a cell network is honestly probably the right solution. It doesn't have quite as high resolution as GPS, but that's hardly necessary for the sort of timestamps we're discussing -- even a resolution of a minute or two would be a huge improvement on "hope the tech who installed the equipment set the time correctly".
    • rlpb 6y ago
      Remember that anything that is harder than setting the date and time is unlikely to be done in practice, since we're looking for something easier than that. Routing cabling out of a room seems unlikely.
  • walshemj 6y ago
    You put your ntp stratum one where it can receive the signal