The Central Co-Ordinator (CCO) on the Powerline chip syncs to the AC cycle, which is at 50 Hz (or 60Hz). This is only used as a timing marker so that all units are synchronised. The chip will happily sync at 50Hz or 60Hz (it supports 10 above and 10 below) and it can also sync using its own internal clock. The Powerline standard is designed to work across DC and Coax as long as there is a carrier signal but the internal clock can suffer from clock drift which is why running over power is better. The area known to cause problems is when the carrier drifts (for example 50->52->54->52) in which case the chip will use its internal clock
© 2016 Power Ethernet Limited. All rights reserved.