Class C4 Fact Sheet: What LPFMs need to know..

SSR Communications had filed a Petition for Rulemaking to the Federal Communications Commission to do two things:

  • Establish a new Class C4 FM class of service, and
  • Make changes to §73.215 of the Rules regarding "short spaced" full-service FM stations.

In this fact sheet we will touch on the Class C4 proposal.

See our separate fact sheet on the proposed §73.215 changes.

First, let's talk about "zones"

In the full-service FM world, the FCC divides the country into "zones".  Zone I includes the areas of WI, IN, MI, IL, OH, WV, PA, NY, VT, NH, ME, MA, RI, CT, NJ, MD, DE and VA shown on the map below. 

Map of FM Zone I - See 47 C.F.R. §73.205(a) for a description of the boundary.

There is also a Zone I-A which includes most of California (south of 40 degrees north) as well as all of Puerto Rico and the Virgin Islands.

FM classes A, B1 and B are available in Zones I and I-A.

Zone II includes all areas of the country not in Zone I including Alaska, Hawaii and the Pacific territories.   FM classes A, C3, C2, C1, C0 and C are available in Zone II.

C4 is proposed only for Zone II

The proposed Class C4 service will only be available in the Zone II areas.  In other words, it will not be available in the area shown on the map above nor will it be available in California (south of 40 degrees), nor in Puerto Rico or the Virgin Islands.

What is Class C4?

Class C4 is a new full-service FM class that will be placed between classes A and C3.  Class C4's maximum facility will be 12 kilowatts at 100 meters height above average terrain (HAAT) and produces a service contour of 33 kilometers.  In comparison, Class A is 6 kilowatts at 100 meters HAAT and produces a service contour of 28 kilometers and the next class up, C3 is 25 kilowatts at 100 meters HAAT and produces a service contour of 39 kilometers.

How would a Class A station qualify for Class C4?

In order to meet the qualifications for Class C4, they would have to meet the higher distance separation requirements.  If a Class A station does not meet the distance separation at their current site and height, they may be able to make a minor change to effectuate the upgrade by moving to a different location or different channel.  They can also invoke a rule, §73.215 (which we will talk about in another fact sheet) where they can use a combination of a shorter distance separation requirement, a directional antenna and contour overlap.  In commercial full-service rules, a "minor change" involves any change where the current facility and the proposed facility are mutually exclusive.  However, in the full-service world, there are community of license coverage requirements and if a station wants to change their city of license, it will add further complications, especially if they are moving towards an urbanized area.  We will not get into too many details here but there are limits on what the full service station will do?

How many stations will be able to upgrade to Class C4?

In an analysis conducted in March, 2018, REC estimates that at their current sites, 202 Class A FM facilities in Zone II would be able to upgrade to Class C4 using the regular (§73.207) FM distance separation rules.  An additional 1,029 facilities do not meet minimum separations using the §73.207 rules but depending on their specific situation may be able to upgrade using the §73.215 rule.  There are a lot of complexities around §73.215 which could include the use of directional antennas which would create a huge expense for many stations. It's also important to realize that full-service commercial FM stations have some very strict rules related to directional antennas and they are not as flexible as directional antennas used by translators (in commercial rules, the pattern of a directional antenna can not change more than 2 dB every 10 degrees and in the reserved band, a directional antenna can not cause a null greater than 15 dB less than the farthest lobe.)

Is this Class C4 upgrade just to satisfy NAB, iHeart Media and Cumulus as a way to "destroy LPFM"?

Actually, the other part of this proposal (that involves changes to §73.215) is currently opposed by iHeart Media and the NAB.  Of the facilities we have identified as upgradable under §73.207 or the current §73.215 rule:

  • iHeart Media: 2.8%
  • Educational Media Foundation (K-Love, Air1): 1.7%
  • Cumulus: 1.6%

In fact, 80% of the potentially eligible Class A stations are owned by entities that have only one potentially eligible Class A station.  Therefore, C4 is more likely to benefit a small single station or small group owner than it will be for the big boys.

Class C4 impacts to LPFM

In June, 2018, REC did a snapshot study of LPFM stations compared to Class A stations that can potentially upgrade either under §73.207 or the current §73.215 rule.  Of the LPFM stations:

  • 8 are currently §73.807 short-spaced on co- or first-adjacent channels due to full-service application activity subsequent to the LPFM authorization.
  • 97 are legally spaced to potential Class-A stations on co-channel or first-adjacent channel but are within the radius described §73.807 as not being "fully spaced" thus meaning they may be experiencing interference due to a possible contour overlap.
  • If every eligible Class-A station was to upgrade, 52 LPFM stations that are currently "fully-spaced" will now be within the radius where they may receive possible interference.  They still meet the §73.807 minimums.
  • If every eligible Class-A station was to upgrade, 26 LPFM stations would become second-adjacent channel short-spaced.  This only means that if the LPFM station was to move to a location on the same channel closer to the Class-C4 station, then a second-adjacent channel waiver request will be required.  Remember, on second-adjacent, the closer you are to the short-spaced station, the better.
  • 22 LPFM stations are currently §73.807(a) short-spaced to eligible Class-A stations on second-adjacent channels.

Can a Class C4 force a LPFM station off the air?

First, let's review what it takes for an LPFM station to be displaced by a full-service station.  LPFM has a great rule called §73.809.  Under this rule, the only ways that an LPFM station can be displaced by a subsequently authorized full-service facility is if the full-service application or change results in the 70 dBu city grade contour of the new facility overlapping with the interfering contour of the LPFM station on co- or first-adjacent channel.  The full-service station must initiate the request to displace the LPFM.  REC is currently aware of a few LPFM stations that are city grade overlapped but are still functioning.  For non-commercial stations below 92 (reserved band), there will be interference if there is overlap of the interfering contour of the LPFM and the community of license for the NCE station.  Therefore, from a legal standpoint, it's very hard to knock an LPFM off the air.

Won't an upgrading Class A station increase noise floor and make the channel unusable?

In this example, we have a hypothetical LPFM station on flat earth with a perfect 5.6 km service contour (in green). A Class A station is located 89 kilometers away. This is legal spacing under §73.807 but it less than the 92 km that the FCC advises the LPFM station may receive interference.  This LPFM station may already be experiencing some interference to the east.    The interfering contour of the station as a Class A is shown in red.  The interfering contour of the full-power station upgraded to C4 is shown in blue.  

There are several factors that goes into that but it is possible.  Keep in mind, when LPFM was created, it was given this 20 kilometer "buffer zone" around the standard service contour for each full-service station class.  This buffer zone was created so full-power stations could move locations without impacting the LPFM station (or so they said back in 1999).  If we didn't have this buffer zone, LPFM stations could come as close as 49 kilometers to a Class A station on co-channel.  With that said, it is still possible that there will be an increase in the noise floor that could cause interference in areas that are currently not receiving interference.

Can an upgrading Class A station cause a "box-in" situation like what is happening with translators?

First of all, a "box-in" normally means a situation where an FM translator moves closer to an LPFM station and even though the translator can still legally put their facility there based on contours, it creates a distance spacing situation where the LPFM can only move in directions away from the short-spaced translator.  

This is a situation where we may have gotten through to the FCC staff based on the way the Notice of Inquiry was written.  In Section 3(b)(1) of the Local Community Radio Act (LCRA), it states that the FCC shall not amend its rules to reduce the minimum co-channel, first-adjacent and second-adjacent channel separation requirements in effect on the date of enactment of the [LCRA] Act betweeen LPFM and full-service FM stations (emphasis added). The LCRA was signed by President Obama and enacted on January 4, 2011. In comments and in face-to-face presentations with Audio Division staff, REC had proposed that because of the 20 km buffer zone that is already over-protecting Class A stations and due to the fact that the Class C4 service was not codified in the rules on the date when the LCRA was enacted, the FCC is not statutorly obligated to provide any specififc protection to Class C4 as long as protection is provided (since there was no Class C4 on the books in 2011 for the FCC to reference to).  Therefore, REC had proposed that for co-channel and first-adjacent channel, Class C4 should have the same minimum distance separation requirements that Class A does.  This will mean that if a Class A station upgrades at their current location, it will not create a "box-in" situation.  If a Class A station moves closer to the LPFM to make the upgrade, then any "box-in" situation would be no different than if the Class A station was not upgrading. 

It's important to realize that we will have to increase the second-adjacent channel minimum distance separation by 5 km (to 34 km) because the Class C4 service contour is 5km larger and how second-adjacent channel spacing is calculated, the increase is necessary.

Class C4 impact on a future LP-250 service

In 2014 in our comments on the C4 proposal, REC showed how even if both LP-250 and Class C4 were created (and the FCC accepts our request fo C4 to have the same minimum required distance as A), the flat-earth interfering contour of the upgraded LP-250 and the flat-earth protected contour of Class C4 will not overlap and remain well clear of each other due to the 20 km Class-A buffer zone. 

On co-channel and first-adjacent channels, Class C4 will not impede the upgrade of any LPFM station to LP-250.  There will only be an impediment on second adjacent channels where the area is currently not short spaced under Class A but would be short spaced under Class C4.

Class C4 impacts to FM Translators

Unlike LPFM which has a very nice interference/displacement rule in §73.809, FM translators are subject to §74.1203(a) which states that a translator will not be allowed to continue to operate if it causes any actual interference to the transmission of any authorized broadcast station.  This is the price that translators are having to pay to have contour protections to full-service stations and being able to come up on a full-service station's service contour.  This means that if a Class A station upgrades, it is much more likely that it will cause a displacement to a translator than it would than a displacement to an LPFM station.  

How does the LCRA play into Class C4?

First and foremost, Class C4, like Class A is a primary service and is considered "full-service" in respect to the language in the LCRA.  As already mentioned, the FCC has the flexibility under Section 3 to create a specific minimum distance separation but is obligated to provide some form of protection under Section 2 (it only makes sense).  As a result, REC is proposing that the FCC use the same distances for Class C4 as Class A for co-channel and first-adjacent chanels. 

We do note that it is very likely that the comments that will come from some with cross-service (AM) translators will advocate that their specific translators be protected from upgraded and new Class C4 stations thus suggesting a "primary" or "protected" status for specific types of translators.  Any atttempt to change the status of specific types of FM translators (or all FM translators) would be direct contravention of Section 5(3) of the LCRA (the "equal in status" clause).   The FCC has already suggested in the Notice of Inquiry that they may be reluctant to adopt any proposal that would have a significantly negative impact on FM translators and LPFM stations. 

Unlike where it comes to the licensing of new translators, there is nothing in the LCRA that would put the authorization of new or upgraded Class C4 full-service primary stations under any kind of "community need" statute.  We note that "community need" for a full-service FM station has already been determined in accordance with §307(b) of the Communications Act.  (The FCC shall make distribution of licenses among the several states and communities to provide a fair, efficent and equitable distribution of radio service.)


This fact sheet only covers one of the two major aspsects of the Notice of Inquiry.  REC will be publishing a fact sheet on the other aspect of the inquiry (the proposed changes to §73.215).  

REC recognizes that there could be some LPFM stations that would be impacted in some way by the Class C4 upgrades using the existing §73.207 and §73.215 rules. REC's constituency includes a spectrum of stations wider than LPFM.  We do have concerns regarding rural stations and like how LP-250 would benefit LPFM stations, C4 will do the same for some Class A stations.   

We don't see this as a plot by NAB, NPR, iHeart, Cumulus or EMF to "destroy" LPFM.  These are mainly mom and pop, minority and small group owners needing better building penetration.  Not everyone can upgrade, not everyone will upgrade.  However, we can only implement this service if it is not detremental to LPFM and translators.  REC feels that it will threaten the translators more than LPFM and we have our buffer zones to thank for that.