The driver is quite chatty on stdout if ntpd is run with debugging. A manual will be required though. Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. 1 Assume GPS receiver is on a mobile platform if set. The driver has been developed under FreeBSD, and may still be pretty FreeBSD centric.
Patches are most welcome.
Performance Really good. The limiting factor will be the timebase of the computer and the precision with which you can timestamp the rising flank of the PPS signal.