My radio interests have included bouncing radio signals off of meteor trails, off of the moon, very long distance communications in the VHF-microwave bands and wireless networks. In the late 1980's, I designed and built 2 Mbps, 10 GHz and 500 kbps, 900 MHz digital ham radios which were used to create a wide area amateur radio TCP/IP network in Northern California.

I should probably add that for most of my amateur radio career, until about 10 years ago, I was a member of the ARRL but that presently I am not. While a member, I had several technical articles published in ARRL magazines, compendiums and The Radio Handbook, which is also published by them.

Like many of Computing Unplugged's readers, I'm something of a gadget geek and have collected my share of cameras, telescopes, GPS receivers and the like. I got a Palm VII PDA when they first came out and have recently acquired another Palm OS device, the Treo 700p.

David: You wrote some open letters on BPL and some of the issues involved. Can you summarize those letters for our readers?

Glenn: The letters were written to describe the characteristics and differences of Corridor's technology, which was in danger of being lumped together with conventional BPL technology operating in the 4-80 MHz region.

One letter detailed the complete absence of any interference between Corridor's 216 Mbps demonstration system and the amateur radio service. Another letter was sent to the FCC to request that BPL rules and regulations, which were intended to apply to HF-BPL technology, were not inadvertently applied to Corridor's BPL technology as well.

The FCC, who originally coined the Broadband-over-Powerline (BPL) acronym, concurred that Corridor's technology was completely different and should not be included in the rule making and limited the new rules to systems operating below 80 MHz.

David: At Corridor, you work with Microwave BPL. What's the difference between that and the Access BPL that we've been discussing?

Glenn: The main difference between Corridor's technology, E-Line, and conventional BPL is information capacity. While both approaches use the existing power line as a pipe, E-Line uses only one conductor of the line in a newly invented way that allows energy transport of an extremely broad frequency range while losing relatively little along the way.

Conventional BPL is limited to a narrow frequency range, HF, because the physics of two-wire transmission lines prevents propagation once the frequency of transport gets too high compared to the spacing of the wires. When this occurs, the wires behave more as antennas than as transmission lines.

As you can see in my sidebar article "Understanding the information rate of BPL and other last-mile pipes" (elsewhere in this issue, at http://www.computingunplugged.com/issues/issue200608/00001828001.html), even common telephone lines used for DSL can have more capacity because they are quite close together. Because E-Line operates on a new and completely different principle, it does not suffer from this limitation. The sidebar article shows a comparison when up to 7 GHz of bandwidth is allowed. As you can see, The information capacity of E-Line is second only to optical fiber and can be more than 1000 times that of HF-BPL.