Power‐over‐Ethernet (PoE) extends versatility for system designers and companies. No longer does one have to locate access points within the typical six foot electrical cord reach of an AC outlet or look for convenient locations to install new outlets at points where it is suitable to run conduit and mount outlet boxes.
A PoE clock system only requires technicians to run one Ethernet cable—CAT5 or CAT6—to the access point for supplying both power and NTP time synchronization. With PoE, power‐sourcing equipment detects the presence of an appropriate “power device” (e.g. PoE Hub) and injects the applicable current into the data cable. An access point can operate solely from the power it receives through the data cable. PoE is known by IEEE802.3af international standard.
PoE OFFERS THE FOLLOWING BENEFITS
Cost Savings
PoE significantly reduces the need for electricians to install conduits, electrical wiring, and outlets throughout a facility. Consider an installation of 50 or more clocks. This requires a lot of conduits, outlet boxes, electrical wiring, and the time of qualified electrician(s). The low cost of deploying PoE compared to traditional electrical circuits leads to worthwhile returns on investment.
Flexible Access Point Locations
With PoE, a customer has greater freedom to choose clock installation sites. You don’t need to depend on only locations within short distances from AC outlets. This makes it easy to relocate access points in the future if the need to expand the system arises.
Higher Reliability
Systems with fewer wires tend to be more reliable. With LANs not using PoE, an electrician may unplug an access point to use its AC outlet to power their equipment. Electricians rewiring electrical circuits could inadvertently cut power to an access point. PoE eliminates the possibility of situations that disrupt the operation of the network.
Enhanced Operational Support
Many PoE devices, including Masterclock NTP clocks, implement SNMP (simple network management protocol), which enables support staff to remotely manage the electrical power supplied to the access points. Support staffs can disable a PoE‐enabled access point by shutting off its access point after detecting a malfunction or tampering. The temporary disabling of the access point can protect against intruders continuing unauthorized access to the device(s). Other SNMP‐based features enable the monitoring of the condition and consumption of power, which enhance the ability to ensure smooth and efficient network operation.
Easier International Development
For manufacturers, PoE offers the benefit of the vendor not needing to provide different power cords for various countries. This not only helps keep the cost of access points down—it is one less piece of equipment that installers need to worry about.
The IEEE has standardized the use of 48 VDC as the injected PoE voltage. The use of this higher voltage reduces the current flowing through the CAT5 / CAT6 cable and therefore increases the CAT5 / CAT6 cable length limitations. All Masterclock, Inc. equipment labeled PoE compatible or compliant will accept and operate from the 48 VDC that is supplied over the CAT5 / CAT6 cable.
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Presentation by John Clark, CEO & Dr. Demetrios Matsakis, Chief ScientistTime Behind and Beyond the Clock
