Even the ARRL would agree that setting limits that reduce the probability of interference to 0% would be unreasonable.

The key here is creating a framework that allows BPL operators to run their networks with reasonable power levels (that guarantee high performance and a very low number of interference cases), but having mechanisms to solve the small number of interference cases that may appear.

So, the question is (and here is where the different camps disagree) is whether the allowed power level should be 100 (interference in 5% of cases), 50 (1% of cases) or 10 (0.1% of cases). The position of the BPL industry is the power levels should be set in a way in which the probability of interference is reasonably low, while allowing the BPL system to operate with reasonably high performance.

We also agree that, once a system is installed and operating under FCC limits, if the BPL system causes interference to a licensed radio user, the BPL operator needs to immediately reconfigure the system to solve the interference. This is a mandate from FCC and we think that's perfectly reasonable.

DS2 [the company Chano works for, and a key manufacturer of BPL chips] sees this situation as an opportunity to provide differentiation in our products (and here comes the marketing pitch): we think that it's key that our chips provide the tools that allow equipment manufacturer to:

• Transmit using FCC-compliant power levels.
• Adapt power levels dynamically.
• Easily notch out frequencies that cause interference to licensed users, with on-the-fly reconfigurability
• Get protection in their investment in case future FCC rulings introduce changes in power levels or prohibited frequencies.

In 2003 (three years ago), DS2 introduced its second Generation powerline chipset, which was the first in the industry to provide speeds up to 200 Mbps, and 40dB programmable notches. These chips have been designed to allow BPL vendors to design equipment that meets FCC requirements, to adequately protect ham radio bands and to provide additional mitigation mechanism in case any isolated interference case is detected in a BPL network. The ARRL lab tested this technology in April this year and issued a favorable review.

David: Detractors claim that the radio frequency band used by BPL is quite subject to interference by simple consumer devices like baby monitors. I would think that a broadband service that can be easily cut off is a bad thing. So, is the claim true from your perspective? How reliable is BPL service and what is the risk of the service stopping?

Chano: In this area, BPL technology has improvemented dramatically in recent years. As BPL technology providers gain more experience from real life installations, we have added better and more robust algorithms to deal with the typical noise sources found in the BPL frequency band.

If a BPL network is well designed, the probability of a service cut-off due to one of those sources is negligible.

Again, it's important to differentiate between first generation and second generation products, as second generation products provide huge improvements in reliability.