Reduced Interference Report

Feature avaialble for REC Clients with a $350 minimum spend.

FCC Rules regarding LPFM channel changes

§ 73.870(a) of the FCC Rules allows an LPFM station to change to an available channel if that channel is considered 'adjacent'. For the purposes of this rule, 'adjacent' is considered first, second or third adjacent as well as the intermediate frequencies (+/- 53 or 54 channels. For example, an LPFM station on 93.1 can change, assuming that the new channel meets the § 73.807 distance separation requirements to 92.5, 92.7, 92.9, 93.3, 93.5, 93.7, 103.7 or 103.9 MHz.

The rule also permits, upon a showing of reduced interference, a change to any channel.

Accessing the Reduced Interference Check

The Reduced Interference Check can be used by first going to either Channel Change or Move Station to perform a channel search. For each potentially available channel that is not considered 'adjacent', there will be an option Check Reduced Intf.

Clicking this option will result in a report that shows on the current channel from the current location, interference details from other stations on the same and first adjacent channels. It will also show the interference details for the requested channel and its first adjacent channels at the location being evaluated.

Evaluating the report

For details on the information displayed in these reports, see the help page for Encroachment Reports.

When evaluating whether the new channel would result in reduced interference, the most common method used by the FCC is the field strength of the interfering F(50, 10) contour of the interfering station in respect to the LPFM station. This analysis looks at the field strength of the interfering contour at the location that is at the edge of the LPFM station's service contour in the direction of the interfering station. If the field strength (dBu) of the interfering station(s) on the analyzed channel are lower than those on the existing channel, then there is a good possibility that a non-adjacent channel change for reduced interference can be justified.

The report will also look at the outward interfering contour from the LPFM station towards other stations. If it can be shown that the interfering contour substantially reaches the other station's service contour to the point where the other station can request displacement of the LPFM station under § 73.809 of the rules, then the LPFM station may have justification for a non-adjacent channel change.

This report will also show a brief summary of the analysis displayed and will make a suggestion whether a non-adjacent channel change could be justified.

This report does not replace the services of a professional

LPFM stations should use this tool as a first guide to eliminate obviously ineligible alternate channels, but in the long run, needs to work with a professional, such as REC Networks in order to perform a full analysis and submit to the FCC, such analysis including contour maps that justifies the request.