Meinberg LANTIME, Руководство по эксплуатации

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NTP-Timeserver LANTIME/SHS
Secure Hybrid System with Strongly Verificated Reference Time
Meinberg LANTIME devices are Stratum-1 time servers which provide a high-
accuracy reference time to TCP/IP networks via the Network Time Protocol (NTP).
The main difference between the LANTIME models is the primary time source from
which a device derives its reference time. Primary time source options include
external radio clocks, built-in DCF77, GPS, or IRIG receivers, and even a hybrid
combination of a DCF77 and a GPS receiver.
The LANTIME/SHS/BGT (Secure Hybrid System, 19" modular case) has a built-in
hybrid radio clock which derives its reference time from both the satellite based
Global Positioning System (GPS) and long wave receiver PZF5xx. During normal
operation the hybrid radio clock passes the highly accurate reference time on to the
built-in NTP time server which makes the reference time available to the network.
In order to prevent the NTP server from spreading a faulty reference time in the
network, the hybrid receiver includes two independent standard radio clocks. Both the
satellite receiver GPS167 and the long wave receiver PZF5xx have their own signals
and high quality crystal oscillators which let the radio clocks provide accurate time
even if their primary time transmitters cannot be received for a few days.
The two radio clocks derive their time telegrams and high accuracy pulse-per-second
(PPS) signals from two independent primary time sources. The time telegrams and the
PPS signals output by the clocks are compared against each other. If either the
difference between the time telegrams or the difference between the PPS signals
exceeds a configurable limit of some milliseconds, or if one of the receivers stops
generating a time telegram, then the hybrid radio clock stops passing any timing
information to the NTP server. So the NTP server can only spread a very strongly
verificated reference time.
The radio clock modules are assembled in a 19" modular case (3UE) which also
includes a single board computer, and a power supply unit. Configurable settings can
be modified via menus on the 4 line LC display and the four buttons in the front
panel. A failure output can be used to generate an alarm signal if any malfunction is
detected.
The single board computer runs a Linux system which is loaded from flash disk into
RAM at power-up. Aside from NTP, the Linux operating system supports additional
network protocols like HTTP(S), SSH, FTP, or telnet, which allows remote
configuration or monitoring across the network, e.g. using a common web browser.
Remote access from the network can also be disabled for security reasons.
Changes in the radio clocks' receiver status, errors conditions, and other events
generate error messages which can be logged on either the local Linux system, or on
another SYSLOG server in the network. Additionally, those messages can be sent to a
management console by SNMP traps or automatic e-mails.
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