The only potential negative impacts that we would see to LPFM stations from new FM translators in this filing window would be for LPFM stations operating on 88.1 through 92.3. LPFM stations operating on 92.5~107.9 would experience no impacts. There are very few LPFM stations operating in the 88.1~91.9 reserved band.
It is important to remember that this upcoming window will only allow new translators on 88.1 through 91.9 (Channels 201~220). This window does not allow for new translators on the non-reserved band channels from 92.1 through 107.9 (Channels 221~300).
FM translators will be required to protect LPFM stations. This means that the interfering contour (40 dBu for co-channel and 54 dBu for first-adjacent channel) cannot overlap the 60 dBu contour of an LPFM station. FM translator applications are not required to protect LPFM stations operating on second-adjacent channels.
Like LPFM, FM translators are also secondary status. There is no situation where an LPFM station can be displaced by rule as a result of a new translator unlike displacement as a result by a new or modified full-service station, pursuant to ยง73.809 of the rules.
For LPFM stations operating on 88.1 to 91.9
FM translators are allowed to use directional antenna patterns and sometimes those patterns can be "creative" to "surround" an LPFM station on more than one side of the LPFM's protected contour (picture Pac Man eating a dot). We must also consider "Michi's Rule #19" that states that "broadcast contours can be deceiving". Real world conditions, such as terrain could potentially cause interference to LPFM stations even though the contours do not overlap. If predicted or actual interference occurs, LPFM stations do have recourse under Sections 74.1203 and 74.1204(f) of the FCC Rules. See our guidance on Translator to LPFM interference handling for more details.
New FM translators operating on second adjacent channels may add new second-adjacent channel short-spacing. If this type of short-spacing happens, the LPFM station will be able to continue to operate at their current location. If in the future, the LPFM station needs to move closer (based on distance rounded to the nearest kilometer) to the short-spaced translator, then a new second-adjacent channel waiver will be required. Note though, that the closer you move a station towards a second-adjacent channel short-spaced station, the easier it is to demonstrate a lack of interference.
For LPFM stations operating on 92.1
See our advice above for stations operating on 88.1~91.9 as it may be possible that a translator on 91.9 could cause potential first-adjacent channel interference to an LPFM on 92.1. First adjacent interference is not as pronounced as interference that happens on co-channel (the same channel) so the chances of real world interference in this scenario are far reduced.
New FM translators operating on 91.7 may add new second-adjacent channel short-spacing. If this type of short-spacing happens, the LPFM station will be able to continue to operate at their current location. If in the future, the LPFM station needs to move closer (based on distance rounded to the nearest kilometer) to the short-spaced translator, then a new second-adjacent channel waiver will be required. Note though, that the closer you move a station towards a second-adjacent channel short-spaced station, the easier it is to demonstrate a lack of interference.
For LPFM stations operating on 92.3
New FM translators operating on 91.9 may add new second-adjacent channel short-spacing. If this type of short-spacing happens, the LPFM station will be able to continue to operate at their current location. If in the future, the LPFM station needs to move closer (based on distance rounded to the nearest kilometer) to the short-spaced translator, then a new second-adjacent channel waiver will be required. Note though, that the closer you move a station towards a second-adjacent channel short-spaced station, the easier it is to demonstrate a lack of interference.
