{HEAD ~ The time synchronization schemes} based on a Global Positioning System and a wide area communication network can be combined to synchronize the stationary clocks of phasor measurement units of {TAIL ~ a wide area monitoring system} to a central server clock at a Network Control Center of the system 
{ HEAD ~ The time synchronization schemes } based on a Global Positioning System and a wide area communication network can be combined to synchronize the stationary clocks of phasor measurement units of { TAIL ~ a wide area monitoring system } to a central server clock at a Network Control Center of the system
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH