Evaluation of the potential for power line carrier (PLC) to interfere with use of the Nationwide Differential GPS network

Power line carrier (PLC) is an important technique used extensively on electric power lines for communication and telemetry. PLC uses signals in the 40-490 kHz range that couple to and propagate over power line conductors. Applications of PLC include protective relaying, telemetering, voice communications, supervisory control, etc. The new Nationwide Differential Global Positioning System (NDGPS) network uses the 283.5-325 kHz band to broadcast GPS correction messages throughout the world, and some PLC transmitters may operate in this band. Limited work has been done to either measure or model the electromagnetic fields associated with PLC operation and some of these studies demonstrate the potential for PLC fields close to power lines to degrade navigation signal receiver performance. This paper presents PLC field strength measurements, describes NDGPS signal structure, and recommends frequency separation as the best approach to mitigation for potential PLC interference to NDGPS receivers operated near to power lines.