Calvary Chapel of Costa Mesa, Calif., is asking the FCC to change its rules governing contour protection for short-spaced FMs. It wants the commission to eliminate a technical anomaly when computing interference contours for non-73.215 facilities operating with excessive height above average terrain for their given class.
Calvary, an association of Christian churches, is licensee of short-spaced FM KWVE(FM) in San Clemente, Calif.
The group is talking about so-called “buried” FM antennas. It says the current version of Section 73.215 rules that is used to protect short-spaced FMs allow the required “maximum class” facility to have its antenna buried underground — “sometimes by as much as several hundred feet,” writes the group.
“When this happens, assumptions underlying the standard propagation curves are no longer valid, and the accuracy of their predictions breaks down.” It proposes adding a more real-world methodology to the rules.
The anomaly, says Calvary Chapel artificially and unnecessarily restricts the ability of many stations from maximizing their short-spaced facilities because of the requirement to avoid “receiving” Class C interference “that is physically impossible to materialize in the real world.”
“The contour protection rules should not utilize an interference contour from an assumed buried FM antenna that would never be constructed and would not appreciably radiate if it were,” states consulting engineers Jack Mullaney and Alan Gearing for Calvary Chapel. The requested rule modification does not change the way any “protected” contours are computed and therefore, will not increase the likelihood that objectionable interference will be caused to any FM station, according to the engineers.
The newsletter CGC Communicator, which first reported the story, says the net result of eliminating the imaginary underground antennas would improve short-spacing options “without disturbing the status quo.”