Huahuan Electronics HX.PTP-GM02, User Manual

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Beijing Huahuan Electronics Co., Ltd
on the GeckoSynco side is a 6-pin RJ12 rather than usual RJ45. Connector on the
othere end of the cable needs to match the specification of the matching input port
on the Ethernet switch.
It should be noted here that the use of 1PPS+ToD signal as time reference
has one precaution to be considered. Different from bidirectional PTP protocol
exchanges between the T-GM and the switch, which automatically calculates the
cable delay, the 1PPS+ToD is single directional, and thus the cable delay cannot
be automatically adapted. When phase error needs to be within a few
nonoseconds, installation engnieer needs to know the cable delay and compensate
through the management interface provided by the GeckoSynco software. The
1PPS signal in a CAT5 cable is delayed about 5.02ns/meter. The web interface for
entering cable delay is described in section 6.1.7. The GeckoSynco can actually
measure the delay during installation by putting a loopback socket at the other end
of the cable, without carefully measuring the cable length.
2.3. GeckoSynco as NTP Server
Most networked computers get their time from NTP servers. There are many
NTP servers on the internet. For example, the IP address for one of the United
States NIST (National Institute of Standards and Technology) NTP servers is
129.6.15.28.
However, not every computer network is connected to the internet. For
example, many private LANs are physically separated from the outside world for
security concerns. Computers in these isolated networks still need to keep correct
time. A common solution is to setup a local NTP server within the network.
The GeckoSynco can be used as the local NTP server in such networks.
GeckoSynco synchronizes to the TAI/UTC international standard time through
GNSS satellites, with sub-microsecond accuracy. The built-in NTP service makes
it an ideal stratum-1 NTP server. Without congestions and the resulting packet
HX.PTP-GM02 IEEE-1588 Grandmaster Clock V1.0 7