TrueTime IRIG NTS-100, Руководство пользователя

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1/20/97
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3.
SECTION III
OPERATION
3.1 INTRODUCTION
3.1.1 The NTS-100 Module provides extremely accurate time over an Ethernet connection
when synchronized via one of four input options:
3.1.2 The first option is a 1 Pulse Per Second input. In this configuration, the date and time of
day to the nearest second must be set via the RS232 interface. The time is then
incremented on each rising edge of the input 1PPS. The operator must also provide
information about upcoming leap second events via the RS232 interface.
3.1.3 The second option is to synchronize the NTS-100 module to an IRIG B source. In this
configuration, the user must provide the correct date as well as information about coming
leap second events via the RS232 interface.
3.1.4 The third option is to synchronize via an internal dial-up modem to the Automated
Computer Time Service operated by the National Institute of Standards and Technology
(NIST). Between calls to this time service, the NTS-100 will “flywheel” on its internal
oscillator. The user may set the desired accuracy and the NTS-100 will set the interval
between calls required to maintain the desired accuracy. This option requires no
operator input to maintain accurate UTC time and automatically handles leap second
events.
3.1.5 The final, and most accurate option is to synchronize the NTS-100 module to the USNO
by use of the NAVSTAR Global Positioning System (GPS). This option requires no
operator input to maintain accurate UTC time and automatically handles leap second
events.
3.2 BASIC OPERATION
3.2.1 This Section provides a complete description of the basic operation of the NTS-100. The
Synchronization Option specific operation details are contained in Section 5.
3.3 NETWORK INTERFACE
3.3.1 TrueTime’s NTS-100 module supports RFC-868, RFC-1119, RFC-1305 and RFC-1361.
An NTP or SNTP client daemon compatible with the user’s computer platform is
required for accurate network synchronization. The daemon must be told the NTS-100
IP address.
3.4 START-UP
3.4.1 On power up, the NTS-100 module will check its EEPROM for valid configuration data. If
configuration data is valid and present, then the NTS-100 will attempt to synchronize its
internal time to the synchronization source, if that source is IRIG-B, GPS or ACTS. If the
source is 1PPS, then the NTS-100 will wait for the operator to initiate the synchronization
procedure.
3.4.2 Once the NTS-100 has synchronized itself to the source, then it will be ready to respond
to any requests that it receives over the network from supported protocols. During