ntp-refclock 1:4.2.0a+stable-8.1ubuntu6.3 (amd64 binary) in ubuntu dapper

 NTP, the Network Time Protocol, is used to keep computer clocks accurate
 over the Internet, or by following an accurate hardware receiver which
 interprets GPS, DCF-77, NIST or similar time signals.
 .
 This version of the ntp daemon can understand a variety of time signal
 receivers. If you do not have a radio clock, use the ntp-simple package
 instead, as it consumes far less memory.
 .
 If you're serious about building a high-quality stratum 1 timekeeper, please
 take a look at Ulrich Windl's PPSkit patchset for the Linux kernel, available
 from the kernel.org mirror network in pub/linux/daemons/ntp.