NTP server is a network device that provides network servers and other network infrastructure with a precise reference. NTP server gets the correct time from an external source, such as time and radio frequency or GPS. This article describes the external time references that are available to synchronize NTP servers and discusses the merits of each.
There are a number of time and frequency are available in various locations. The WWVB signal is a reference to US-based DCF-77 in Germany and MSF in the United Kingdom. This time the transmission of radio frequencies and to ensure a stable and accurate time. Furthermore, an indoor pool located radio antenna can be used to receive these signals - lowering installation costs. However, radio signals can be influenced by local topography - such as hills and valleys. There is no guarantee of receiving radio signals, even if within the range of signal transmission.
The MSF radio signal transmission in the United Kingdom by the National Physics Laboratory recently moved from Rugby in the East Midlands for Anthorn in Cumbria. Since the passage has been widely recognized that the signal reception in southern England has suffered - even if it is in the range of materials for signal reception.
The local environment can also affect radio signals. Radio antennas placed in metal cages or metal clad buildings can experience poor signal reception. Moreover, the antenna is located in a basement or underground may fail.
Uses the global positioning system GPS navigation around the world. Each GPS satellite has a very high precision on-board atomic clock synchronization - a point of ideal reference for NTP server synchronization.
The GPS is a constellation of 24 satellites in orbit around each time streaming and positioning information. This information can be received anywhere on the face of the planet, with an antenna can be supplied with the line of sight of satellites.
GPS has a number of benefits based on the time and frequency radio transmissions. First, the GPS can be received all over the world and is not limited by transmission power and reach of radio signal. Secondly, the GPS signal is much clearer than the solutions. Thirdly, the GPS timing information can be received from someone who can provide an antenna with a good view of the sky. However, GPS antennas must not be the line of sight with GPS satellites. Therefore, the ideal place for a GPS antenna is located on a roof with a full 360 degrees of the sky. Moreover, if the buildings or trees obscure the horizon in any case, it may compromise the integrity of receipt. Roof-mounted antennas can significantly increase the cost of installing an NTP server.
To summarize, the radio and GPS based time and frequency references for NTP server systems for both advantages and disadvantages. However, the accuracy of GPS and hospitality assured, but with the roof-mounted antennas, make the choice of reference for NTP server systems.
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