GlobalTime NTP Products
User manual of GTT-030
3
Global Positioning Satellite (GPS) signals act as the reference source of
GTT-030 network time server.
The time reference contained in the GPS satellite signals synchronizes with the universal time
coordinated (UTC). The long-term frequency stability has achieved the10-13 level of magnitude of
cesium atomic clock, which is equivalent to be only 1 second slower during 30 years. To adjust local time
with this reference signal can eliminate the accumulation of deviation resulted from the low accuracy of
local clock time and also can greatly improve the timing precision of the server. GTT-030 network time
server use a professional 12-channel GPS receiver. It can receive and lock the satellite signal fast and
reliably.
NTP protocol (Network Time Protocol) is a common international network timing protocol. Its principle is
through the client to launch a time polling to the server after an interval of time. According to a certain
filtering algorithm it can calculate the time deviation between the server and the client as well as the
propagation delay caused by network transmission. Then according to these two parameters to adjust
the client's local time and make it consistent with the server. Compared to other time calibration
prorocols, NTP protocol can
eliminate the impact caused by network transmission delay, so it can
provide high-precision timing services. Detailed description can be referred to the latest protocol
standards documents RFC1305 and RFC2030. GTT-030 network time server can be compatible with
NTP v2 / v3 / v4 in various versions.
1.4
The device description
Figure 1-1
The front panel description
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The front panel is as shown above. The interface functions are as follows:
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monitoring: local monitoring serial port, DB9 public outlet, RS232 electrical level
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Network: 10/100M Base-T adaptive network port, RJ45 connector
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2 Indicator lights: one indicates the power while the other indicates the status, both of them
indicate the device working state
Figure 1-2 The back panel description
