Low-cost precision time source supports Linux systems
May 4, 2000 — by LinuxDevices Staff — from the LinuxDevices Archive — viewsEndRun 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 accomplishes 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.
EndRun Technologies' new precision timing products will be available in three versions:
- Præcis Ct — operates as a low cost timing source for the synchronization of network servers. It offers drop-in compatibility with Unix/Linux and Windows NT servers, using existing public domain NTP software/drivers.
- Præcis Cf — provides both a 1 Pulse Per Second and a precision 10 MHz standard frequency for users requiring an accurate, low cost, convenient time and frequency source.
- Præcis Ce — intended for OEM customers requiring a small circuit board (2.5 x 5 in.) for embedded time and frequency applications.
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