Motorola BPL Technology Reduces Interference to HF Spectrum Users
The news article
released last week that they were encouraged by new Motorola BPL (Broadband over Power Line) technology that reduces interference to users of the HF and low VHF spectrum. According to the article, the Motorola Powerline LV system avoids using medium-voltage power lines and introduces the broadband signals only on the low-voltage side of the power transformer, greatly reducing the potential for interference. "We know that medium-voltage (MV) power lines are no place for broadband energy, since there is overwhelming technical evidence that radio interference from BPL is unavoidable if MV lines are used. By confining their Access BPL system to LV lines and by adding hardware notch filters for additional protection to amateur radio frequency allocations, Motorola has addressed our interference concerns, " said ARRL CEO David Sumner.
You may be wondering how the broadband signal is distributed over a wide area if it is not introduced until the low-voltage side of the transformer and does not travel on the medium voltage lines. The ARRL article does not answer this question, but the Motorola news release, Motorola's Commercial Broadband Over Powerline Solution Debuts at Telecom 2005 - Company Introduces First Powerline LV Utility Customer
explains how distribution to the low-voltage lines is done through Motorola's license-free 5 GHz Canopy Broadband Internet Platform
The first customer is Broad River Electric in upstate South Carolina. It has 25,000 rural utility customers and receives networking communications and project management support from New Horizon Electric Cooperatives. "As an electric cooperative in an area with very limited broadband service options, we were actively seeking ways to bring high-speed Internet to our customers. Powerline LV presented a cost-effective approach to serving customer needs within a rural, underserved market, while also satisfying Broad River's need for managing core business applications on an IP system. As a result, we see return on investment potential in both areas, " said Michael Varner, vice president for information services at New Horizon.
Given the BPL interference problems noted in previous editions of RF Report, this low-voltage system combined with a wireless backbone distribution network looks like it could be easier and perhaps less expensive to build out and operate than the medium-voltage systems currently being tested.