The National Association of Broadcasters is asking the Federal Communications Commission to “promptly reject” a petition filed by low-power activist group Prometheus Radio Project asking the agency’s to take a second look at its recent decision to change the rules dictating how FM translators are sited.

Prometheus last week filed a petition for reconsideration asking the FCC to reverse its recent decision to eliminate distance limitations for translators rebroadcasting AM stations. The group is pushing regulators to revert to previous translator siting rules as well as launch a new rulemaking that would protect LPFMs from being “chained to their current location” as the gaps around them are filled by FM translators.

The Commission unanimously voted in February to slightly relax the existing tower siting rules that have been seen as too restrictive by many owners. They’ve required an AM station to place a rebroadcasting FM translator either within its daytime service contour or within a 25-mile radius of its transmitter, whichever distance was less.

The new rules allow the rebroadcasting FM translator to be located anywhere within the AM station’s daytime service contour or anywhere within a 25-mile radius of the transmitter, even if the contour extends farther than 25 miles from the transmitter. The change is essentially designed to give owners more flexibility where a fill-in translator can be located. The rule change also opened the door for some AM owners to move a translator up to 250 miles as long as the signal made its first jump during last year’s two filing windows.

According to Prometheus’ calculations, at least 1,644 AM stations stand to benefit from the revised rules. In a petition to the FCC the group says abolishing the previous 40-mile standard “vastly increases” the geographic area in which AM stations may place FM translators, including what it says is a tower site that’s “far beyond” the AM station’s core service area.

Prometheus predicts devastating results for low-power stations. “Countless incumbent LPFM stations that are outside the core service area of AM stations will now be severely limited when seeking to relocate within their communities of service because new and relocated FM translators will inevitably box in or short-space them,” the group says in its petition. Prometheus also argued the Commission falsely equated the public interest value of “market-driven commercial AM stations” with “intensely local” noncommercial low-power FM outlets.

Prometheus has also raised the question of whether the updated rule violates the Local Community Radio Act. Signed into law by President Obama in Jan. 2011, the law sets the rules for siting low-power stations, including certain minimum distance spacing requirements that need to be met.

But the NAB says it was only after “careful consideration” that the FCC made the right decision when it adopted the changes that engineers say will provide AM stations with more flexibility when locating FM translators. The old rules were “too confining and unnecessary” according to the trade group. The NAB also argues that Prometheus’ claim that the move will “box in” LPFMs that may need to relocate in the future is “purely speculative” and reveals the group has “a misunderstanding” about how the Commission’s LPFM contour protection rules function.

The NAB is also taking issue with Prometheus’ claim that a delay in adopting the new rules would serve the public interest, saying that’s based on a “galling” argument that LPFMs better serve listeners than AM broadcasters simply because they’re noncommercial outlets. “Prometheus disregards the community-oriented news, public affairs and entertainment programming that AM radio stations broadcast to their local communities,” NAB says, adding, “AM radio broadcasters are proud of their service, but unlike Prometheus, do not need to malign LPFM stations to boost our value.”

The two organizations have been at odds for several weeks over the FCC decision. Ahead of the FCC’s April 10 launch date, Prometheus had asked the Commission to issue an emergency stay to the changes. But the NAB urged the FCC to go forward with its new rules, arguing the changes dovetail with AM revitalization efforts. The NAB received an unexpected boost when LPFM advocate REC Networks weighed in telling the FCC it should move forward, noting the decision will be especially beneficial to Class C and Class D stations in rural areas. “LPFMs must share with FM translators and each must share fairly,” REC Networks founder Michelle Bradley told the FCC. But she said the face-off between translators and low-power FMs illustrates the need for the FCC to update its predicted interference guidelines to specifically account for LPFMs.

The FCC’s efforts to light up additional low-power FMs have picked up steam over the past few years. The result is the agency reports the number of translators jumped 13% compared to a year ago with a record 7,453 translators licensed as of March 31.