Source: https://recnet.com/73807
Timestamp: 2019-04-20 22:35:21+00:00

Document:
§73.807 is definitely the "big one" of the LPFM rules. This rule specifies how an LPFM station must be spaced from other radio stations including those in Canada and Mexico in order to operate.
Co-channel means another station operating on the same channel.
First-adjacent channel means that the other station is one "dial click" away either up or down. This is also known as 200 kilohertz (kHz) or 0.2 megahertz (MHz). For example: If the proposed LPFM station is on 94.3, the first-adjacent channels are 94.1 and 94.5.
Second-adjacent channels are two "dial clicks" away either up or down or 400 kHz or 0.4 MHz. If the proposed LPFM station is on 94.3, the second-adjacent channels are 93.9 and 94.7.
Third-adjacent channels are three "dial clicks" away either up or down or 600 kHz or 0.6 MHz. If the proposed LPFM station is on 94.3, the third-adjacent channels are 93.7 and 94.9.
"Intermediate Frequency", sometimes referred to as just "I.F." are 53 or 54 clicks away up or down, 10.6 and 10.8 MHz. Inside every radio receiver, there's also a "transmitter", well sort of. FM radios include a local oscillator that operates at 10.7 MHz. The FCC and other nations have recognized that two stations that are about 10.7 MHz apart from each other have a potential to interfere when one station is stronger than the other because of the oscillator. Originally, LPFM was subject to the IF protection rules to other full-service and FM translator stations. IF rules never applied to FM translators or Class D FM stations operating 99 watts ERP or less. In 2012, the FCC removed the requirement that LPFM stations, including those operating a full 100 watts to protect the IF channels of domestic FM stations of any time. IF protections still apply to protecting Canadian and Mexican stations in accordance with international agreements.
When the FCC first created LPFM, they decided to go with distance separation tables instead of using a more complex method that is used for FM translators and full-service non-commercial educational (NCE) stations. The thought process was to make LPFM a simple service that "does not require a consulting engineer to fill out the application" (keep in mind, that was 1999). The likely other reason was that the new LPFM stations would be the first new stations to be electronically filed in the FCC's Consolidated Data Base System (CDBS) and they probably wanted the applications to be simple. The distances are based on the standard distances for each service class. For LPFM protecting other stations, the distance is based on the standard distance to the LPFM station's interfering contour (bigger for co-channel and gets smaller for first and second) plus the standard distance to the existing station's protected service contour. For protection to full-service stations in the USA, an additional 20 kilometer "buffer zone" is added for co- and first-adjacent channels. The original thought process behind that was to allow full-service stations to be able to "move" without impacting the LPFM stations. This thought process would later to prove to not be that effective. However, the buffer zone does reduce the number of cases where an LPFM station's interfering contour does cross into another station's protected contour.
When LPFM was first created, the FCC determined that LPFM stations should only be required to protect other stations on co-channel, first-adjacent and second-adjacent channels, but not third-adjacent channels. This move was very controversial at the time and was met with great resistance, mainly from the National Association of Broadcasters (NAB) and National Public Radio (NPR). As part of the campaign against the new LPFM stations that were about to be licensed, the NAB produced a compact disc and sent it to members of Congress with simulations of how third-adjacent channel interference by LPFM stations was going to sound when listening to other stations. Congress bought it and in 2001, they passed the Radio Broadcast Protection Act (RBPA) which stated in part, that LPFM stations must also protect other stations on third-adjacent channels. They also forced the FCC to use distance separation rules to protect all other stations as opposed to a more flexible "contour overlap" system that is used by FM translators. The law was changed half-way into the first LPFM window. The RBPA specifically invalidated all applications where the third adjacent channel spacing could not be met (the FCC did provide a remedial window for applicants to change channels or locations to comply with the new law, those that could not change, were dismissed).
Part of the RBPA ordered the FCC to conduct a study on third-adjacent channel interference. In what would be called the MITRE study (the study was conducted by the MITRE Corporation and Comsearch), experimental LPFM stations were placed on the air. These stations were situated in areas that would be short-spaced on third adjacent channels. The MITRE Study had determined that there was very little impact to third-adjacent channel stations by LPFM operations. Based on that information as well as public comments, the FCC made their report to Congress with details from the MITRE Study. Several attempts were made to pass the Local Community Radio Act (LCRA) over various years. In 2010, the LCRA was passed by voice vote in both houses and was signed by Presdent Obama in early 2011. Under portions of the LCRA, the third-adajcent channel restriction was removed for protecting domestic stations, LPFM had the ability to short space on second-adjacent channels upon a showing that there would be no interference to any radio service (the FCC would later interpret "any radio service" to mean any radio service on a second-adjacent channel). The LCRA also had provisions that protected radio reading services for the blind and visually impaired as well as provisions that assured that both LPFM and FM translators would remain secondary and that licenses would be distributed based on community need.
Can the FCC grant a waiver of the Local Community Radio Act?
Two LPFM stations are spaced precisely 24 km apart, is interference between the stations still possible?
My proposed LPFM station is spaced 69 km from a Class-A FM station on co-channel. The Class-A station has filed an objection showing overlap. I'm in the foothills. Is my application doomed?
I am already granted with a second adjacent waiver but now I need to make a change on Form 318 for the same channel. Since I have already received a second-adjacent channel waiver for a particular station, do I have to submit a new waiver request?
Can the FCC waive minimum distance spacing requirements for a full-power station on the same channel or first adjacent channel?
What is a contour and what is the difference between a "50,50" and a "50,10" contour?
Are full power stations running hybrid HD Radio (IBOC) afforded any additional protections above and beyond the current analog protections?
Minimum separation requirements for LPFM stations are listed in the following paragraphs. Except as noted below, an LPFM station will not be authorized unless the co-channel, and first- and second-adjacent channel separations are met. An LPFM station need not satisfy the third-adjacent channel separations listed in paragraphs (a) through (c) in order to be authorized. The third-adjacent channel separations are included for use in determining for purposes of Section 73.810 which third-adjacent channel interference regime applies to an LPFM station.
Minimum distances for co-channel and first-adjacent channel are separated into two columns. The left-hand column lists the required minimum separation to protect other stations and the right-hand column lists (for informational purposes only) the minimum distance necessary for the LPFM station to receive no interference from other stations assumed to be operating at the maximum permitted facilities for the station class. For second-adjacent channel, the required minimum distance separation is sufficient to avoid interference received from other stations.
(a)(1) An LPFM station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, applications for new and existing FM stations filed prior to the release of the public notice announcing an LPFM window period, authorized LPFM stations, LPFM station applications that were timely-filed within a previous window, and vacant FM allotments. LPFM modification applications must either meet the distance separations in the following table or, if short-spaced, not lessen the spacing to subsequently authorized stations.
(a)(2) LPFM stations must satisfy the second-adjacent channel minimum distance separation requirements of paragraph (a)(1) of this section with respect to any third-adjacent channel FM station that, as of September 20, 2000, broadcasts a radio reading service via a subcarrier frequency.
Note to paragraphs (a) and (b): Minimum distance separations towards “grandfathered” superpowered Reserved Band stations are as specified.
Full service FM stations operating within the reserved band (Channels 201-220) with facilities in excess of those permitted in § 73.211(b)(1) or § 73.211(b)(3) shall be protected by LPFM stations in accordance with the minimum distance separations for the nearest class as determined under § 73.211. For example, a Class B1 station operating with facilities that result in a 60 dBu contour that exceeds 39 kilometers but is less than 52 kilometers would be protected by the Class B minimum distance separations. Class D stations with 60 dBu contours that exceed 5 kilometers will be protected by the Class A minimum distance separations. Class B stations with 60 dBu contours that exceed 52 kilometers will be protected as Class C1 or Class C stations depending upon the distance to the 60 dBu contour. No stations will be protected beyond Class C separations.
(c)(1) In addition to meeting the separations specified in paragraphs (a) and (b), LPFM applications must meet the minimum separation requirements in the following table with respect to authorized FM translator stations, cutoff FM translator applications, and FM translator applications filed prior to the release of the Public Notice announcing the LPFM window period.
(d) Existing LPFM stations which do not meet the separations in paragraphs (a) through (c) of this section may be relocated provided that the separation to any short-spaced station is not reduced.
(e)(1) Waiver of the second-adjacent channel separations. The Commission will entertain requests to waive the second-adjacent channel separations in paragraphs (a) through (c) of this section on a case-by-case basis. In each case, the LPFM station must establish, using methods of predicting interference taking into account all relevant factors, including terrain-sensitive propagation models, that its proposed operations will not result in interference to any authorized radio service. The LPFM station may do so by demonstrating that no actual interference will occur due to intervening terrain or lack of population. The LPFM station may use an undesired/desired signal strength ratio methodology to define areas of potential interference.
(A) Upon receipt of a complaint of interference from an LPFM station operating pursuant to a waiver granted under paragraph (e)(1) of this section, the Commission shall notify the identified LPFM station by telephone or other electronic communication within one business day.
(B) An LPFM station that receives a waiver under paragraph (e)(1) of this section shall suspend operation immediately upon notification by the Commission that it is causing interference to the reception of an existing or modified full-service FM station without regard to the location of the station receiving interference. The LPFM station shall not resume operation until such interference has been eliminated or it can demonstrate to the Commission that the interference was not due to emissions from the LPFM station. Short test transmissions may be made during the period of suspended operation to check the efficacy of remedial measures.
(f) Commercial and noncommercial educational stations authorized under subparts B and C of this part, as well as new or modified commercial FM allotments, are not required to adhere to the separations specified in this rule section, even where new or increased interference would be created.
(g) International considerations within the border zones.
(3) The Commission will notify the International Telecommunications Union (ITU) of any LPFM authorizations in the US Virgin Islands. Any authorization issued for a US Virgin Islands LPFM station will include a condition that permits the Commission to modify, suspend or terminate without right to a hearing if found by the Commission to be necessary to conform to any international regulations or agreements.
(4) The Commission will initiate international coordination of a LPFM proposal even where the above Canadian and Mexican spacing tables are met, if it appears that such coordination is necessary to maintain compliance with international agreements.
When the FCC created LPFM, the decision was made early on to use distance separation as opposed to using contours. Much of the reason for this could be attributed to statements made FCC Chairman (at the time) William Kennard who had a desire to keep LPFM so simple, "you would not have to hire a consulting engineer." This was also at a time when the FCC was converting from the old BAPS engineering database to the then-modern CDBS database. I really don't think staff was ready to "test" the directional antenna functionality to the extent that a LPFM filing window could bring. The FCC claimed in the Report and Order that using contours would be burdensome on the applicants. The spacing was also written with a 20 kilometer buffer zone around the standard service contours of the full-service station classes. This was intended to allow full-service FM stations to move by not putting much of a burden on the LPFM station.
You may also notice a "full-spaced" value for each full-service and FM translator class. This was a part of the "keep it simple" policy for LPFM at the time. These "fully-spaced" values are not binding but are provided only as a convenience.
When LPFM was originally created, there was both a 100-watt and a 10-watt service. The FCC would open a window for 100-watt stations and would delay the 10-watt service for a future time. At the time, the LP-10 rules were written so they would not be protected by LP-100 stations nor were they protected by transalators. The wording of the Local Community Radio Act would have required LP-10 stations to be protected by translators. The FCC never authorized any LP-10 stations and the service was eliminated in the November, 2012 Order.
The Radio Broadcast Protection Act would put the requirement of prescribe protections using distance separation from LPFM to all radio services on co-, first-, second and third-adjacent channels into statute in 2001. When the Local Community Radio Act of 2010 was enacted in January 2011, there was a language change that was not really noticed until later in time. Under the LCRA, Section 2 requires the FCC to "prescribe protections" on co-channel, first and second adjacent channels. Section 2 did not elaborate what kind of protections, as opposed to the original RBPA language. Section 3 of the LCRA does state that the FCC cannot reduce the minimum separation requirements between LPFM stations and full-service FM stations that we codified as of the day that the LCRA was enacted (January, 2011). This means that if the FCC wanted to, they could allow contours instead of distance separation to protect translators and other LPFM stations. In previous orders, the FCC has concluded that there is nothing in the LCRA that specifies power levels. Therefore, an argument can be made that the LP-10 minimum distance separation tables can be used as they were codified when the LCRA was enacted. By using these charts instead of the LP-100 charts, it would open up more opportunities and still leave a buffer zone to most full-service stations.
The FCC would eventually allow a form of contour protection, specifically in the form of the second adjacent channel waiver where it can be shown that the interfering contour of the LPFM does not overlap the protected service contour of the second-adjacent channel short-spaced station.
73.807 Interference protection to full service FM stations.
(a) An LP100 station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, timely filed applications for new and existing FM stations, authorized LP100 stations, LP100 station applications that were timelyfiled within a previous window, and vacant FM allotments. LP100 stations are not required to protect LP10 stations.
(b) An LP10 station will not be authorized unless the minimum distance separations are met with respect to authorized FM stations, timely-filed applications for new and existing FM stations, vacant FM allotments, or LPFM stations.
Minimum distance separations towards ‘‘grandfathered’’ superpowered Reserved Band stations, are as specified. Full service FM stations operating within the reserved band (Channels 201–220) with facilities in excess of those permitted in § 73.211(b)(1) or § 73.211(b)(3) shall be protected by LPFM stations in accordance with the minimum distance separations for the nearest class as determined under § 73.211. For example, a Class B1 station operating with facilities that result in a 60 dBu contour that exceeds 39 kilometers but is less than 52 kilometers would be protected by the Class B minimum distance separations. Class D stations with 60 dBu contours that exceed 5 kilometers will be protected by the Class A minimum distance separations. Class B stations with 60 dBu contours that exceed 52 kilometers will be protected as Class C1 or Class C stations depending upon the distance to the 60 dBu contour. No stations will be protected beyond Class C separations.
(e) Existing Class LP100 and LP10 stations which do not meet the separations in paragraphs (a) through (e) of this section may be relocated provided that the separation to any short-spaced station is not reduced.
(5) The Commission will notify the International Telecommunications Union (ITU) of any LPFM authorizations in the US Virgin Islands. Any authorization issued for a US Virgin Islands LPFM station will include a condition that permits the Commission to modify, suspend or terminate without right to a hearing if found by the Commission to be necessary to conform to any international regulations or agreements.
(6) The Commission may, at its option, initiate international coordination of a LPFM proposal even where the above Canadian and Mexican spacing tables are met, if it appears that such coordination is necessary to maintain compliance with international agreements.
(a)(1) An LP100 station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, timely filed applications for new and existing FM stationsfiled prior to the release of the public notice announcing an LPFM window period for LP100 stations, authorized LP100 stations, LP100 station applications that were timely-filed within a previous window, and vacant FM allotments. LP100 stations are not required to protect LP10 stations. LPFM modification applications must either meet the distance separations in the following table or, if short-spaced, not lessen the spacing to subsequently authorized stations.
(b)(1) An LP10 station will not be authorized unless the minimum distance separations in the following table are met with respect to authorized FM stations, timely-filed applications for new and existing FM stations filed prior to the release of the public notice announcing an LPFM window period for LP10 stations, vacant FM allotments, or LPFM stations.
Minimum distance separations towards ‘‘grandfathered’’ superpowered Reserved Band stations, are as specified.
Full service FM stations operating within the reserved band (Channels 201–220) with facilities in excess of those permitted in § 73.211(b)(1) or § 73.211(b)(3) shall be protected by LPFM stations in accordance with the minimum distance separations for the nearest class as determined under § 73.211. For example, a Class B1 station operating with facilities that result in a 60 dBu contour that exceeds 39 kilometers but is less than 52 kilometers would be protected by the Class B minimum distance separations. Class D stations with 60 dBu contours that exceed 5 kilometers will be protected by the Class A minimum distance separations. Class B stations with 60 dBu contours that exceed 52 kilometers will be protected as Class C1 or Class C stations depending upon the distance to the 60 dBu contour. No stations will be protected beyond Class C separations.
(6) The Commission may, at its option, will initiate international coordination of a LPFM proposal even where the above Canadian and Mexican spacing tables are met, if it appears that such coordination is necessary to maintain compliance with international agreements.
(a)(1) An LP100 station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, applications for new and existing FM stations filed prior to the release of the public notice announcing an LPFM window period for LP100 stations, authorized LP100 stations, LP100 station applications that were timely-filed within a previous window, and vacant FM allotments. LP100 stations are not required to protect LP10 stations. LPFM modification applications must either meet the distance separations in the following table or, if short-spaced, not lessen the spacing to subsequently authorized stations.
(b)(1) An LP10 station will not be authorized unless the minimum distance separations in the following table are met with respect to authorized FM stations, applications for new and existing FM stations filed prior to the release of the public notice announcing an LPFM window period for LP10 stations, vacant FM allotments, or LPFM stations.
(6) The Commission will initiate international coordination of a LPFM proposal even where the above Canadian and Mexican spacing tables are met, if it appears that such coordination is necessary to maintain compliance with international agreements.
Minimum separation requirements for LP100 and LP10 stations, as defined in §§ 73.811 and 73.853 are listed in the following paragraphs. An LPFM station will not be authorized unless these the co-channel, first- and second-adjacent and IF channel separations are met. An LPFM station need not satisfy the third-adjacent channel separations listed in paragraphs (a) through (d) in order to be authorized. Minimum distances for co-channel and first-adjacent channel are separated into two columns. The left-hand column lists the required minimum separation to protect other stations and the right-hand column lists (for informational purposes only) the minimum distance necessary for the LPFM station to receive no interference from other stations assumed to be operating at the maximum permitted facilities for the station class. For second-adjacent channels and IF channels, the required minimum distance separation is sufficient to avoid interference received from other stations.
(a)(1) An LP100 station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, applications that were timely-filed within a previous window, and vacant FM allotments. LP100 stations are not required to protect LP10 stations. LPFM modification applications must either meet the distance separations in the following table or, if short-spaced, not lessen the spacing to subsequently authorized stations.
Minimum separation requirements for LP100 and LP10 LPFM stations, as defined in §§ 73.811 and 73.853 are listed in the following paragraphs. An Except as noted below, an LPFM station will not be authorized unless the co-channel, first- and second-adjacent and IF channel separations are met. An LPFM station need not satisfy the third-adjacent channel separations listed in paragraphs (a) through (d) (c) in order to be authorized. Minimum distances for co-channel and first-adjacent channel are separated into two columns. The left-hand column lists the required minimum separation to protect other stations and the right-hand column lists (for informational purposes only) the minimum distance necessary for the LPFM station to receive no interference from other stations assumed to be operating at the maximum permitted facilities for the station class. For second-adjacent channels and IF channels channel, the required minimum distance separation is sufficient to avoid interference received from other stations.
(a)(1) An LP100 LPFM station will not be authorized initially unless the minimum distance separations in the following table are met with respect to authorized FM stations, applications for new and existing FM stations filed prior to the release of the public notice announcing an LPFM window period, authorized LPFM stations, LPFM station applications that were timely-filed within a previous window, and vacant FM allotments. LP100 stations are not required to protect LP10 stations. LPFM modification applications must either meet the distance separations in the following table or, if short-spaced, not lessen the spacing to subsequently authorized stations.
(e) (d) Existing Class LP100 and LP10 LPFM stations which do not meet the separations in paragraphs (a) through (e) (c) of this section may be relocated provided that the separation to any short-spaced station is not reduced.
(i) Upon receipt of a complaint of interference from an LPFM station operating pursuant to a waiver granted under paragraph (e)(1) of this section, the Commission shall notify the identified LPFM station by telephone or other electronic communication within one business day.
(ii) An LPFM station that receives a waiver under paragraph (e)(1) of this section shall suspend operation immediately upon notification by the Commission that it is causing interference to the reception of an existing or modified full-service FM station without regard to the location of the station receiving interference. The LPFM station shall not resume operation until such interference has been eliminated or it can demonstrate to the Commission that the interference was not due to emissions from the LPFM station. Short test transmissions may be made during the period of suspended operation to check the efficacy of remedial measures.
(5) (3) The Commission will notify the International Telecommunications Union (ITU) of any LPFM authorizations in the US Virgin Islands. Any authorization issued for a US Virgin Islands LPFM station will include a condition that permits the Commission to modify, suspend or terminate without right to a hearing if found by the Commission to be necessary to conform to any international regulations or agreements.
(6) (4) The Commission will initiate international coordination of a LPFM proposal even where the above Canadian and Mexican spacing tables are met, if it appears that such coordination is necessary to maintain compliance with international agreements.

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