April 13, 2007

Clearing the Air on 'White Spaces,' Part II

By Mike Robuck

In last Monday's newsletter, we ran a correction of sorts on the FCC's review to allow companies the use of "white spaces" to beam Internet access through. Dave Large, who wrote the NCTA's appendix that was submitted to the FCC, wanted to clarify the following sentence that ran in the original story April 2: "If the cable plant is tight, there should be no problem; but if there's a leak, then there's ingress and interference."

Cisco Systems engineer and CT columnist Ron Hranac penned this response to further clarify the issue for us:

"Dave Large makes a critically important point about the potential for direct pickup interference from signals in the so-called white spaces.

"I'd add that cable network leakage/ingress could cause problems, since signals from 'white space' transmitters might find their way into the cable plant and interfere with signals carried on the system. Granted, the plant should in theory have no leakage or ingress, but as we know, the real world is often quite different. Any over-the-air signal - regardless of the source - has the potential to interfere with signals carried in a cable network if that network isn't kept tight from a leakage/ingress perspective.

"And to reinforce Dave's point, direct pickup interference is not something that cable operators can control. Leakage/ingress is something that cable operators can control."

We thank both Large and Hranac for writing, and, as always, we defer to their expertise. In case you missed the previous two installments, the first article is here, and Large's response can be found here.

- Mike Robuck