Meteorological data is time stamped so that it can be readily incorporated and compared with other data sets. In order for this to be done properly the clocks in all loggers must be synchronized.
Most loggers use quartz crystals for their real-time clocks. This is a very accurate approach; for example, a quartz wristwatch will drift about a half second per day when worn. However, this type of clock is susceptible to changes in temperature. A quartz clock running outside in the elements is more likely to drift on the order of 6 seconds per day. In order to compensate for this internet time servers are used.
Symphonie-series data loggers use the iPack's internet connection to access internet time servers. These servers are running on computers worldwide, often hosted by government agencies and universities. They in turn are synchronizing with other time servers and ultimately one of the atomic clocks around the world.
iPackGPS units use the RFC 1305 (NTP) protocol for synchronizing their clocks. All older iPacks use the RFC 868 (Time) protocol. These two types are inherently different, but some internet time servers support both types.
Be sure to include a proper time server in your iPack's configuration file (ipk or lgr) to keep your logger's clock and your valuable data properly time stamped.