myLPFM v.3.5 - powered by REC

The Encorachment Report is a powerful tool in myLPFM that looks at all other broadcast facilities including applications to determine if any of those facilities could result in interference towards an LPFM station.

The Encroachment Report is accessed by clicking on the skull icon on the Left Menu.

Loading stations

When the Encroachment Report is first ran, myLPFM will need to conduct contour studies on all nearby facilities. Therefore, there may be a wait while the system gathers the information needed. Please wait for the process to complete. On subsequent accesses, the facilities previously studied will be cached and there will not be wait. If there has been any recent application activity, the system will conduct contour studies on those new records and adds them to the report.

Reading the report

The Encroachment Report divides up the nearby facilities by channel adjacency, so there will be different sections for:

Co-channel - (same channel/frequency)
First-adjacent channel - (+/- 1 channel or 0.2 MHz)
Second-adjacent channel - (+/- 2 channels or 0.4 MHz)
Third-adjacent channel - (+/- 3 channels or 0.6 MHz)
Intermediate frequency (IF) - (+/- 53 and 54 channels or 10.6 and 10.8 MHz)

Note: Even though second-adjacent, third-adjacent or IF channels will not really cause any interference to the LPFM station, subsequent applications filed on second-adjacent channels may impact an LPFM station's ability to modify their facility to a different location in the future. Third-adjacent and IF channel short spacing will only become an issue if the short-spaced facilities are located in Canada or Mexico.

Station information

For each facility, the Encroachment Report will include the station's call sign, frequency, channel, station class, type of service, community of license, application type, status and date and ownership information. For FM translators, the LPFM protection level is shown:

Lower Tier - FM translators with a service contour of less than 7.3 km
Mid Tier - FM translators with a service contour of between 7.3 and 13.3 km
Upper Tier - FM translators with a service contour exceeding 13.3 km

Distance column

In the Distance column, the report shows the measured distance from the LPFM station to that station, the bearing (direction) from the LPFM to the other station as well as the interfering contour of the other station at the LPFM site.

Minimum column

In this column, you will see the § 73.807 minimum distance separation required between the LPFM station and the class of the other station. On co-channel and first-adjacent channel, the next row will have the § 73.807 recommended minimum distance for no interference. In the third row on all records, an indicator of whether the facility is:

Clear - Meets both § 73.807 required minimum distance and recommended distance for interference free
Inside - Meets the § 73.807 required minimum distance but is less than the recommended distance for being interference free
Short - Does not meet the § 73.807 minimum distance separation. In these cases, the LPFM station can still move away from that facility but not closer.

At Contour (Service) column

(Co-channel and first-adjacent channel records only.)

On the first row for each facility record, this shows the distance from the LPFM station to the LPFM's 60 dBu service contour along the bearing from the LPFM towards the other facility. The second row shows the interfering contour of the other facility as it arrives at the service contour of the LPFM station and the third row gives a status of that calculation:

Clear - The standard interfering contour of the other station does not reach the service contour of the LPFM. There is no overlap.
Overlap - The standard interfering contour of the other station does reach to a location inside the service contour of the LPFM. There is incoming overlap and a potential for interference.
Inside - The location of the other station is inside of the service contour of the LPFM station. This would be very severe interference if the encroaching station is not an FM booster operated by the LPFM station or another LPFM station that is in a time share agreement with your LPFM station. As a contour cannot be properly measured, you will see a field strength result of 9999.0 dBu. This is normal in this case.

At Contour (Interfering) column

(Co-channel and first-adjacent channel records only.)

This column is used to determine if the LPFM station is subject to potential displacement pursuant to § 73.809 of the Rules. Data in this column will only appear for full-service FM stations and will not appear for FM translators, boosters or other LPFM stations. The first row indicates the distance from the LPFM station to the LPFM station's interfering contour along the bearing towards the full service FM station. The second row indicates the field strength of the LPFM station's interfering contour at the full service FM station's 60 dBu service contour. The third row indicates the LPFM station's potential displacement status:

Clear - The LPFM station interfering contour does not reach the full service station's 60 dBu service contour therefore there is no risk of § 73.809 displacement.
Check COL - The LPFM station interfering contour appears to be overlapping the full service station's 60 dBu service contour. § 73.809 displacement will only occur if the LPFM interfering contour reaches the boundary of the full service station's community of license and may be subject to displacement if the full service FM station makes a complaint.
Displacement - The LPFM station interfering contour appears to be overlapping the full service station's 70 dBu community coverage contour. In this case, there would be § 73.809 and the LPFM station would be subject to displacement in the event that the full service FM station makes a complaint.

NOTE: Full-service stations operating on Channels 201~220 (88.1~91.9) are only required to place a 60 dBu service contour over at least 50% of their community of license. REC has interpreted § 73.809 that in these cases, the portions of the community of license that is outside of a 60 dBu contour is still subject to protection from LPFM stations and could result in displacement despite receiving a Clear result on the Encroachment Report. The Encroachment Report does not support boundaries for communities of license. Therefore, any new encroachments on 88.1~91.9 should be also checked externally to assure that there is no displacement risk.

Also, it is important to remember in all cases where there is a situation that may lead to a § 73.809 displacement, this displacement is not automatic. It is up to the primary FM station to follow procedures to start an interference complaint against the secondary LPFM station. The intention of this information in the Encroachment Report is to allow LPFM stations to proactively think about next steps. Chances are that if there is a potential for § 73.809 displacement, there's also a good chance the LPFM station will receive significant interference where, even absent a formal complaint from the full-service station, may have a significant impact on the reception of the LPFM station.

Second Adjacent column

On second-adjacent channel stations that are short-spaced to the LPFM, this column will display the service contour of the short-spaced second adjacent station at the LPFM site. The next row indicates the distance from the LPFM station to the 'overlap zone'. The overlap zone is the area where there can be no occupied structures or 4-lane signed highways where second adjacent channel interference can occur. The overlap zone size can be reduced or eliminated at ground level through the use of certain antenna designs.

Left column color code

The color code on the left of each station in the report serves as a quick reference to the facilities encroachment and potential displacement status in respect to the LPFM station

Green	There does not appear to be any encroachments or displacement risk with this station.
Yellow	There appears to be an encroachment that will cause incoming interference to the LPFM station, but no risk of § 73.809 displacement.
Red	There appears to be an encroachment that will cause incoming interference to the LPFM station and a potential risk of § 73.809 displacement.

Finally: Contours can be deceiving

The 'quick and dirty' way of predicting a station's coverage and interference potential is through the use of the field strength contours. Contours are determined based solely on a station's power (ERP) in a particular direction and the height above average terrain (HAAT) in that direction. HAAT only looks at the elevations between 2 and 10 miles from the station and any terrain within 2 miles or more than 10 miles away are not taken into consideration when predicting coverage in this manner. There are much more accurate ways of measuring a station's coverage and interference potential such as through the use of terrain-based propagation models like Longley/Rice. However, from a regulatory perspective, it will be the contours that will prevail (Longley/Rice has been accepted in some exceptional situations, but rarely in order to demonstrate protection). Therefore, it is possible for a station to place a 60 dBu field strength in an area that is outside of the station's designated 60 dBu contour.

Likewise, the Encroachment Report depends solely on contours to make its determination. LPFM stations should use the data returned in this Encorachment Report solely as a guide to engage industry professionals in order to determine a more accurate prediction of any listing shown in this report, including the 'green' results. The Encorachment Report should not be depended on solely as a conclusion on an LPFM station's potential interference or displacement situation but instead, should be considered a starting point.