REC reminds FM translator applicants and LPFM permittees on protections towards unbuilt LPFM stations

REC puts out this reminder to engineers and other parties who are involved with the modification of FM translators to assure that the "note" to §74.1204(a)(4).  The note reads:

LP100 stations, to the purposes of determining overlap pursuant to this paragraph, LPFM applications and permits that have not yet been licensed must be considered as operating with the maximum permitted facilities. All LPFM TIS stations must be protected on the basis of a nondirectional antenna.

While §74.1204 does not define a "maximum permitted facility", the same language is used in §73.215(a) (4)  to refer to the maximum facilities for full power FM stations in Puerto Rico and the Virgin Islands which then refers to §73.211(b)(3) which defines the maximum ERP and HAAT for stations in Puerto Rico and the Virgin Islands.  

With that said, it can be interpreted that the maximum permitted facility for an LPFM station is 0.1 kilowatts effective radiated power (ERP) at 30 meters height above average terrain (HAAT). 

What this means is that LPFM stations that have not been granted their license to cover for a particular facility (even if it still a pending application filed before the FM translator modification application was filed) needs to be protected at its current location at a full 100 watts with the tower height adjusted up so it is at the 30 meter level, even if the actual antenna height proposed or authorized is much lower. 

For example, let's say the LPFM station has been authorized a radiation center at 20 meters above ground level and their calculated HAAT is 12 meters, the contour for the LPFM construction permit needs to be calculated at 38 meters above ground level.  (30 - 12 = 18, 18 + 20 = 38).  

Based on the surrounding terrain, such a recalculation may have a minimal impact however for some "foothill" locations, it could substantially increase the size of the protected contour towards the valley.  

Here's an extreme example of how a "foothill effect" LPFM station that is still under construction has a larger protected service contour.  This example is a hypothetical LPFM station in the foothills of the San Fernando Valley.  The CP is granted for 20 meters above ground level (AGL).  The HAAT was calculated at -56 (minus 56).  Since the maximum permitted facility is 30 meters HAAT, this means that the antenna height can be increased by 84 meters to reach 30 meters HAAT.  

In the contour map above, the red curve is the proposed and authorized protected contour based on -56 meters HAAT while the blue curve is the same location and power but at 30 meters HAAT.  The blue curve is the maximum permitted facility subject to protection under the Note to §74.1204(a)(4) while the permit has not been covered. 

This map is calculated based on 360 radials.  When we calculate the size of the contour, whether it is using 36 or 360 radials, we measure the HAAT from the site along the radial and then use the field strength curves to determine the contour size.  If the HAAT calculated along a particular radial is less than 30 meters, it is rounded up to 30 meters.  This explains why short curves to the north and west.  In this case, this is the San Fernando Valley in California and Oat Mountain is to the north and the Santa Susana Mountains are to the west.  

To sum it up, LPFM stations are protected by FM translators as follows:

2013-era LPFM station that either has not been granted or has had their original construction permit granted but a license to cover has not yet been granted. Your proposed or authorized facility is protected to the maximum permitted facility as demonstrated above.
LPFM station that has been granted, the license to cover has been granted. Your facility is protected only to your actual operating facility even if your actual HAAT is under 30 meters.
LPFM station that has been granted, has a granted license to cover but also has a modification to change channel or move to a different location Your current facility is protected only to your actual operating facility even if your actual HAAT is under 30 meters however, the proposed facility is protected to the maximum permitted facility as demonstrated above.

From prior testing, Commstudy 2 does not automatically support the maximum permitted facility (it uses the data from the FCC database).  We are not sure how other software (V-Soft, FM Commander, etc.) handles this.  

REC has already filed an Informal Objection against an FM translator that is proposing to place their translator along the service contours of 5 unbuilt LPFM stations.  Among other issues, we raise the maximum permitted facility rule to demonstrate that the proposed translator is overlapping the LPFM stations.  

LPFM stations at HAATs above 30 meters are already at maximum permitted facilities however we do advise all LPFM stations running reduced power above 30 meters HAAT to check their HAAT using both the FCC 30-second terrain data and GLOBE terrain data.  If the GLOBE terrain data shows that the HAAT is lower, it may be possible to get a slight power increase using GLOBE terrain data.  A 318 filing would be required.  REC can assist with those filings at reasonable rates.  

Please note that REC does not provide any legal (attorney) services and our bandwidth for filing informal objections in proceedings are limited to those that we feel that advocacy is necessary to benefit or protect the LPFM service as a whole.  REC may be able to review your situation to determine if overlap is taking place, please contact us if you suspect overlap. 

Finally, for LPFM stations, we do note that while LPFM stations are not specifically called out, we sttrongly suggest that LPFM stations review §74.1203 of the rules which addresses actual interfenrece by translators to other authorized broadcast stations.   

We do note that REC is also working with AM stations to modify translators.  REC will adhere to the maximum permitted facility rule for unbuilt LPFM faciltiies.