PoE to power Vortex26 August 2013
The new Vortex V-400NP range of time displays has PoE (Power-over-Ethernet) capability, so that they need only a network connection to a PoE switch from where they derive their power.
“This provides huge flexibility in installation and reduces the cost of providing accurate timekeeping as the overhead of installing a mains connection can often be more than the cost of the display itself, “ said Vortex Director, Ian Prowse. “Sadly, the PoE specification has a power limitation which means that for the time being at least, only clocks with [up to] 100mm digits can be powered over the network though alternative solutions are available where mains power is difficult to implement.”
When using NTP as a time reference, network delays are important and the V-400N and V-400NP series have algorithms that automatically correct for network latency. Depending on the application, it can also be important also to ensure that the NTP time reference (which can be a public server on the internet) is as closely referenced to GPS as possible; Stratum-0 comes from a master clock directly referenced to GPS and within 10ms of GPS time whereas a Stratum-1 server which is locked to a Stratum-0 reference can be up to 10 times less accurate (within about 100ms of GPS) and that is before any network jitter and delay is accounted for.