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White Papers

Introduction of NTP (PDF)
Description: The need for synchronized time is critical for today’s network environments. Using NTP is an excellent way to keep a large number of network nodes in close synchronization. NTP requires a minimum of network overhead and can also maintain a high level of synchronization accuracy and security. In addition, an effectively designed NTP infrastructure is relatively easy to implement, making NTP ideal for both small and large enterprise networks.

 

Precision Time Protocol (PTP/IEEE-1588) (PDF)
Description: The Precision Time Protocol, as defined in the IEEE-1588 standard, provides a method to precisely synchronize computers over a Local Area Network (LAN). PTP is capable of synchronizing multiple clocks to better than 100 nanoseconds on a network specifically designed for IEEE-1588. A Network Time Server with PTP is typically referred to as an “IEEE-1588 Grandmaster” or “PTP Grandmaster”. This paper describes basic principles of PTP, information on using dual Grandmasters, and the requirements of the network to achieve sub-100 nanosecond time synchronization.

 

About Peering and Stratum 2 (PDF)

Description: NTP Servers are primarily designed for Stratum 1 operation, but also support Stratum 2. The best use for a Stratum 1 time server is as an INDEPENDENT source of reliable & accurate time. NTP products can be configured for peering but we don’t recommend it for Stratum 1 Time Servers. This paper explains why. It also explains the difference between Stratum 2 mode and peering, and a couple of recommended network configurations that ensure the best time.

 

Best Practices to Secure Your Time Server (PDF)

Description: These are the steps we recommend to further secure a NTP Time Server on a private network, behind a firewall. For installations on a public network there should be additional safeguards such as changing User Accounts. These additional safeguards are not described in this paper.

 

Frequency Distribution for Satellite Earth Stations (PDF)

Description: Large earth stations host communication systems that provide mission-critical, high-bandwidth services to multiple customers. Within these earth stations are many frequency-based devices with independent local oscillators that generate and convert carrier frequencies, and modulate and demodulate data. Locking these oscillators to a common, stable and low-noise frequency reference distribution system is fundamental to minimizing frequency issues and supporting higher data rates. This application note focuses on the important role and benefits of a frequency reference distribution system, design considerations, and best practices to deploy a system that meets large earth station reliability and quality-of-service requirements.

 

GPS Frequency Reference for Satellite Earth Stations (PDF)

Description: The satellite communications infrastructure provides critical services for government and civil applications at increasing carrier frequencies and data rates. Within the ground and space-borne systems are devices that generate microwave level frequencies that form uplinks and downlinks.