LPFM stations operating on 88.1~92.3 (Channels 201~222)

Updated July 13, 2023 (includes rule changes that will not be adopted until after the July 20, 2023 FCC Open Meeting)

The first 4 MHz of the FM broadcast band from 88 to 92 MHz (88.1~91.9 MHz / Channels 201~220) is known as the "reserved band".  This spectrum was set aside and reserved only for noncommercial educational (NCE) broadcast stations.  The reserved band includes several unique characteristics that are not applicable in the "non-reserved band" from 92 to 108 MHz.  

The frequencies 92.1 (Channel 221) and 92.3 (Channel 222) are not in the reserved band however LPFM stations on these channels will be affected by spectrum activity that may take place in the reserved band.

How full-power reserved band full-service FM stations are allocated

There are some very unique differences on how full-service FM stations operating on reserved band channels are allocated compared to their non-reserved band counterparts. 

While non-reserved band full-service FM stations are determined based on a table of allotments which require rulemaking proceedings to add new allotments, there is no table of allotments for the reserved band.  New stations are only added during designated filing windows (the last one being in 2021).  Instead of a rulemaking process, the FCC uses a "fair distribution" process and then if necessary, a point system in order to settle mutually exclusive (competing) applications filed during that window.  

In the non-reserved band, full-service FM stations follow a distance separation chart similar to LPFM (§73.207).  Full-service FM proposals that are "short spaced" may request an alternate arrangement (§73.215) where they can meet a shorter minimum distance and then for the short-spaced stations, use a contour study to show that there is a lack of contour overlap of one station's interfering contour with the other station's protected service contour and vice versa. The full-service FM station may use a directional antenna.  In addition, the other station must be protected as if they are operating at maximum facilities for their service class, unless that other station was authorized using the contour method. 

In the reserved band, there are no distance separation tables except when needing to protect full-service FM stations in the non-reserved band.  To protect other full-service FM stations in the reserved band, only a contour study  to show that there is a lack of contour overlap of one station's interfering contour with the other station's protected service contour and vice versa (§73.509).  Directional antennas are more common in the reserved-band than in the non-reserved band. Class B and B1 stations in the reserved band use the 60 dBu protected contour instead of the 57 or 54 dBu contours used in the non-reserved band. Existing full-service FM stations in the reserved band are permitted to overlap their protected service contour with the interfering contour of another reserved band full-service FM station upon a showing that the population in the area of overlap is minimal and that the change is being done in order to increase the overall population served by the station.  This is also known as a "Raleigh Waiver".

Minor modifications for reserved band full-service FM stations are handled in a manner similar to full-service FM stations in the non-reserved band.  Full-service FM stations may change to any location where, using the rules in effect for that service, creates a situation where the old and new facilities cannot operate.  Full-service FM stations in the reserved band can also change to any other channel within the reserved band.  Full-service FM stations in the reserved band must place a 60 dBu contour over at least 50% of the community of license (this is different than in the non-reserved band).  If the minor modification requires a change in the community of license, the applicant must demonstrate why the community of license change will result in a "preferred arrangement of allotments".  The proposed community of license change goes to public notice (through the Federal Register) and there is a 30-day period for comments prior to being granted.   

What this means for LPFM stations is that there are many more opportunities for reserved-band channel stations to make minor modifications that may cause incoming interference, require displacement of the LPFM station or further restrict where an LPFM station can move. 

How LPFM stations in the reserved band protect other FM facilities

LPFM stations must protect full-service FM, FM translator, other LPFM and foreign stations in the reserved band in the same manner as they protect these facilities in the non-reserved band, by station class or translator service contour size, without regard to reduced power or antenna directionality. 

In addition, a small number of full-service and Class D (secondary) FM stations in the reserved band that were originally authorized prior to 1962 operate with facilities that exceed their service class designation.  LPFM stations must protect these reserved-band stations using the service class that is appropriate for the station's actual facilities (this can include protections at classes C1, C0 or C in areas where Class B stations are used and the "C" service classes are not normally available).  

Channel 6 TV stations and FM broadcasting on 87.7

Television Channel 6 operates in the spectrum between 82~88 MHz, just below the FM broadcast band.  LPFM has some very unique service rules for protecting broadcast facilities in the Channel 6 spectrum.

Full-service Channel 6 TV stations

There are currently 9 (soon to be 8) full-service TV stations operating on RF Channel 6 across the country. These stations are in Philadelphia, PA;  Altoona, PA; Hayes Center, NE; Pelham, GA; Wrens GA; Cambridge, OH; Ensign, KS; Tuscaloosa, AL; and Butte, MT.  The Channel 6 station in Butte, MT has been authorized a change to a different channel but must still be protected until a license application is filed by the TV station (KTVM-TV) to complete the channel change.  

Low Power TV stations

On Channel 6, there are 77 secondary facilities.  These facilities include Digital Low Power TV (LPTV) stations, Digital TV translators and Digital Class A TV stations.  

Sound broadcasting on 87.7 MHz ("FM6", "Franken-FM")

Of the LPTV stations mentioned, there are currently 14 of those facilities operating in a hybrid system that splits the channel through providing video services over a reduced bandwidth and operating an analog FM radio channel at 87.75 MHz, receivable on most radios at 87.7 FM.  13 of those stations have been operating in this manner under Special Temporary Authority, however, the FCC has allowed these 13 stations as well as one additional Channel 6 LPTV station to operate in this manner permanently.  The FCC will not authorize any LPTV stations, other than those 14 to operate in this manner.  These FM6 facilities must be protected by LPFM stations as if they are Low Power TV stations.

LPFM stations protecting Channel 6 TV facilities

When proposing facilities, LPFM stations in the reserved-band must be aware of Channel 6 TV facilities (both full-service and low power) and must meet specific distance separation requirements to those facilities based on TV station type (§73.825).  The distance required will depend on which FM channel the LPFM station is proposing operations on (distances in kilometers):

Waiver of the §73.825 distance separation requirements

In the event that an LPFM proposal in the reserved band does not meet the minimum distance separation requirements shown above, there are two options available to waive this requirement:

Consent of the TV Channel 6 station

If the LPFM applicant is able to reach out to the short-spaced Channel 6 TV station licensee(s) and is able to get a letter of consent by all of the affected TV stations to operate within the short-spaced distance, the distance separation requirements will be waived. The letter of consent must be included in the application.

Contour protection method

Because not all TV stations (especially at the low power levels) are not created equal, REC negotiated a policy with the FCC to permit LPFM stations to use the same engineering method shown in §74.1205 of the rules for FM translators to demonstrate a lack of interference.  If this contour protection method is proposed, the LPFM applicant must send notification to the affected TV station(s) to advise that the application has been filed.  While all of television has transitioned to digital or FM6 hybrid digital, the FCC still treats TV facilities as analog for the purpose of protection by FM stations. 

Using the contour protection method, a TV facility is protected out to its 47 dBu service contour (using F[50,50] curves).  In the analog days, this was known as the "Grade B" contour. The TV facility's effective radiated power, antenna height and directional pattern can be taken into consdieration when determining the 47 dBu service contour.  

For the proposed LPFM facility, we use an interfering contour (using the F[50,10] curves) based on the LPFM station's effective radiated power, antenna height and a directional pattern, if used.

In order to obtain the waiver, the 47 dBu service contour of the TV facility cannot overlap interfering contour of the LPFM station using the appropriate field strength shown based on the LPFM station's proposed operating channel.  

LPFM directional antennas: LPFM stations may utilize a directional antenna in order to protect a Channel 6 TV facility using this method however, any use of a directional antenna for this purpose will require a proof of performance and other "non-exempted" directional requirements for LPFM.  We discuss this more on our page about Directional Antennas for LPFM.

The bottom line on the reserved band

With the changes in the rules that took place in 2019 as well as the slow exodus of full-service TV stations going away from Channel 6 and the certainties put into place by the FCC in the "Franken FM" decision, there will be a greater availability of reserved band channels for LPFM, even in more urban areas that were otherwise off limits in the past.  We always question caution and due dilligence when proposing a reserved band channel because of the increased engineering flexibility that full-power FM stations have in this band and the higher likelihood that a reserved band channel is being used as a translator input that must be protected by LPFM.  Because of the many uncertainties, proposals in the reserved band need to be extensively pre-analyzed by someone experienced with all broadcast services to make sure that your LPFM proposal will be a good fit for the band.