Broadband over power lines

Over the past few years advances in signal processing technology have enabled the advent of modem chips that are able to overcome the transmission difficulties associated with sending communications signals over electrical power lines. In the United States, this capability has been termed “Broadband over Power Lines” or BPL. There are two predominant types of BPL communications configurations: Access BPL and In-Home BPL. Access BPL is comprised of injectors (used to inject High Frequency (HF) signals onto medium or low voltage power lines), extractors (used to retrieve these signals) and repeaters (used to regenerate signals to prevent attenuation losses). In addition to taking advantage of the power line infrastructure, In-Home BPL modems utilize the existing house wiring to provision a Local Area Network (LAN) that can be used throughout the home. One of the largest commercial markets for BPL is the ability to provide Internet Services by means of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocols, which can support voice, data, and video services. Another significant benefit from BPL is the ability to employ “intelligent” power line networks that make use of Supervisory Control and Data Acquisition (SCADA) devices, dynamic provisioning, and other forms of modernized electrical power networks. A SCADA system can save time and money by reducing the need for service personnel to physically visit each site for inspection, data collection, and routine logging or even to make adjustments. The benefits also include the ability for real-time monitoring, system modifications, troubleshooting, increased equipment life, and automatic report generating. The Federal Communications Commission (FCC) monitors approximately 59,000 frequencies for military, National Security & Emergency Preparedness (NS/EP), and other purposes. A key concern associated with the BPL is that coupling of HF signals onto unshielded wiring, such as that used for outdoor power lines, may generate interference signals that could impact licensed services such as amateur radio, or “hams”. Public safety agencies including fire, police, the Red Cross and other agencies also depend on the use of the special propagation properties found only in the HF radio spectrum. This Technical Information Bulletin (TIB) examines the architecture and considers possible benefits and concerns of BPL technology with respect to the National Communications System (NCS) and the communication requirements for NS/EP.