Nuts and Bolts of 99-25
MM 99-25 essentially took the best qualities of the two petitions filed to re-create LPFM, modified them slightly, and asked for a lot more public input. If the service was legalized as written, it would have created three classes of stations. Power levels would be set at 10, 100 and 1000 watts respectively, allowing the most powerful to cover a service area more than 17 miles wide. The least powerful was projected to cover three to four miles with its signal.
It encouraged potential LPFM licensees to live within the communities their stations would serve, but didn't put a maximum cap on the number of stations one person or corporation could own. It also asked for more comment on several issues, like whether LPFM programming should require local origination; whether or not the stations could sell commercials; and if electronic filing would help get more people to apply for licenses.
But MM 99-25's most controversial suggestion involved relaxing the current FM interference standards. By loosening these up, more LPFM stations could be fit on the spectrum. Here's a simple example of how the change would work:
Under current rules, FM stations must not only make sure not to cause interference with those stations that share its own frequency (or channel), but also with those three channels away on either side. This is called first, second and third-adjacency interference protection.
Under the FCC's proposal, LPFM stations would've only had to worry about interfering with those stations on the neighboring (first adjacent) channels. It was an important proposed change in policy because it would allow LPFM stations on the air where second and third-adjacent channel restrictions would otherwise prohibit them.
This fueled the major bone of contention surrounding the LPFM debate - the potential for interference between stations. The NAB and its member stations claimed that relaxing the protection standards would lead to chaos on the FM band, making their stations unlistenable to many. But proponents of LPFM argued that because full-power stations operate at such higher wattages than LPFM stations, there'd be no real problems.
FM radio receivers are built in such a way that if two competing signals are received, the radio will automatically lock onto the stronger of the two. With full power FM stations operating at thousands of watts and LPFM stations operating at powers as low as 100 watts or less, it was tough to take the NAB's major argument seriously.
Nonetheless, the broadcast industry spent a lot of money to produce a "technical study" claiming that most FM radios would have problems with new LPFM stations. However, at least two other studies were conducted that came to the opposite conclusion. One of them was done by the FCC itself, who said, "all the receivers in the sample, except for two, appear to meet or exceed the...second adjacent channel protection criterion and to exceed the...third adjacent channel protection criterion by a substantial margin."