[ Thanks to LinuxDevices.com for this link.
]
http://www.linuxdevices.com/news/NS7834875345.html “EndRun
Technologies, a Santa Rosa, Calif. startup, says they have lowered
the cost of delivering precision time to networks and embedded
systems. The company’s Præcis family of time and frequency
products accomplish this by extracting time information that is
accurate to within 10 microseconds from signals transmitted by CDMA
cellular wireless network base stations. In effect, the CDMA base
stations serve as GPS “repeaters”. EndRun Technologies supports
the Præcis family with open source Linux drivers, employing
the Network Time Protocol (NTP) time transfer standard.”
“Like cellular telephones (and unlike alternative technology
precision time instruments), the Præcis products operate
reliably inside buildings. By contast, traditional GPS timing
systems generally need outdoor, roof-mounted antennas.”
“Systems connected to the Internet can generally obtain time
information from remote time servers. Although there are
substantial latencies in transfering data between points on the
Internet, the NTP protocol provides a means to remove propagation
delays. However, the best accuracy that can be obtained in this
manner is on the order of 100 microseconds. Using a locally
connected device such as the Præcis can thus improve time
accuracy by an order of magnitude.”