Clearing the Air on White Spaces Article

By Mike Robuck

Due to an error in production, last week's newsletter story on the FCC examining the potential of allowing companies the use of "white spaces" to beam Internet access through should not have contained the following sentence: "If the cable plant is tight, there should be no problem; but if there's a leak, then there's ingress and interference."

Dave Large, who wrote the NCTA's appendix that was submitted to the FCC, provided a detailed explanation via email in regards to the potential for direct pickup interference:

"Direct pickup has nothing to do with the cable plant, but rather with the shielding effectiveness of the television receiver. The FCC's Part 15 rules regarding 'cable-ready' television receivers address receiver shielding. What I found in my analysis was that, even if the receiver met the FCC requirements, the radiation from a nearby unlicensed transmitter would be adequate to cause interference by leaking into the input circuits of the television's tuner.

"Furthermore, tests run by C.T. Jones for CableLabs a few years ago showed that most receivers did not meet the FCC shielding requirements, especially at VHF channels. The result is that an unlicensed device in one apartment can well interfere with reception in an adjoining apartment (as well as with reception in the same apartment). Furthermore, since cable operators typically use every channel to feed "cable-ready" receivers (where no converter is required), there is no way for the unlicensed device to avoid channels in use."

CT Reports regrets the error, and thanks Dave Large for clearing it up.

- Mike Robuck