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LPFM Notice of Proposed Rulemaking: Difference between revisions
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=== LP-10 | === Microradio (LP-10) === | ||
The FCC proposed a third class of LPFM station that would be intended for an individual or a group of people with limited means to construct a station and reach listeners within the confines of a very localized setting. This service would operate between 1 and 10 watts ERP with a maximum antenna height of 30 meters HAAT. This would create a 60 dBu service contour between 1.8 and 3.2 kilometers (1 to 2 miles). This type of facility is similar to what was proposed in RM-9208 but on any FM channel instead of a dedicated channel as originally proposed. The FCC sees microstations to be used for limited coverage at schools, small neighborhoods, subdivisions and town centers. The FCC did seek comment to whether such facilities could satisfy some of the demand expressed for inexpensive community radio services, particularly in places where LP100 cannot work because of interference to financial constraints. The FCC estimates that the costs would be low, potentially in the hundreds of dollars for some facilities. The FCC questions whether this service should be restricted to noncommercial applicants, commercial applicants or both. | |||
Under the FCC's proposal, the Microradio class would be technically tertiary as it would not be protected by FM translators, FM boosters or LP-100 stations. They further state that because of the low powers, that second or third-adjacent as well as intermediate frequency interference would not be a serious threat but they are concerned if many stations are operating in the same general area. The FCC requested comments on how these stations would affect full-power stations would impact their current operations or transition to digital. | |||
{| class="wikitable" | |||
|+Potential minimum distance separations of Microradio (LP-10) stations to domestic FM facilities | |||
!Station Class | |||
!Co-Channel minimum distance | |||
!First-Adjacent channel minimum distance | |||
!Second-adjacent channel minimum distance reserved band | |||
!Second and third-adjacent channel minimum distance commercial band | |||
!Intermediate Frequency | |||
|- | |||
|A | |||
|34 | |||
|31 | |||
|29 | |||
|28 | |||
|5 | |||
|- | |||
|C3 | |||
|45 | |||
|42 | |||
|40 | |||
|39 | |||
|7 | |||
|- | |||
|B1 | |||
|51 | |||
|48 | |||
|46 | |||
|45 | |||
|7 | |||
|- | |||
|C2 | |||
|58 | |||
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|10 | |||
|- | |||
|B | |||
|73 | |||
|69 | |||
|67 | |||
|65 | |||
|10 | |||
|- | |||
|C1 | |||
|78 | |||
|75 | |||
|73 | |||
|72 | |||
|18 | |||
|- | |||
|C | |||
|97 | |||
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|92 | |||
|26 | |||
|- | |||
|D | |||
|11 | |||
|8 | |||
|6 | |||
|6 | |||
|2 | |||
|- | |||
|Microradio | |||
|7 | |||
|4 | |||
| -- | |||
| -- | |||
| -- | |||
|} | |||
=== Transmitter certification === | === Transmitter certification === | ||
In the discussion on the Microradio class, the FCC stated that there should be a requirement that transmitters should be FCC certified. This is out of concern of the statements made in comments by many that wanted to see "kit" type transmitters used. They state that the uncertified transmitters may not meet out-of-channel emission limits and other standards related to interference protections on adjacent channels citing the numerous occasions that uncertified transmitters caused dangerous interference on aviation frequencies. | |||
== Interference protection == | == Interference protection == | ||
=== Use of distance separation === | === Use of distance separation === | ||
In the NPRM, the FCC supports the use of distance separation citing that they expect a very large number of applications. The expeditious authorization of such service requires a simple, yet effective means of controlling interference among stations. Separate distance separation tables would be necessary for LPFM proposals within 320 kilometers of Canada and Mexico pursuant to the appropriate international agreements. Distance separation would also permit for quick automated "self check" tools for frequency availability before an applicant files its application. | |||
By dismissing the use of contour overlap, the FCC stated it could impose additional processing burdens on the staff and could delay the authorization of LPFM and could place a heavy burden on small LPFM applicants. | |||
For secondary applications, the FCC also inquires whether there should be a limit on the amount of interference that an LPFM station would receive. Other approaches could include reduced distance separations and the use of contours similar to those used by commercial stations under §73.215 or more elaborate terrain models, such as Longley-Rice. | |||
Types of interference protection standards | |||
=== Third-adjacent channel protection === | There was no issues from commenters about LPFM stations needing to protect co-channel and first-adjacent channels. Supporting comments generally opposed any second or third-adjacent channel protection requirements. Opposing commenters, such as the National Association of Broadcasters, National Public Radio and the New Jersey Broadcasters Association stated that these provisions need to be retained in order to prevent interference and/or protect future digital radio services. | ||
Because the requirement for second and third adjacent channels would substantially limit availability, the FCC is inclined to authorize LPFM without second and third adjacent channel protection standards. | |||
==== Third-adjacent channel protection ==== | |||
The FCC believes that there is a strong case for not requiring third-adjacent channel protections. Authorizing LPFM without a third-adjacent channel requirement would entail, at worst, little risk of interference to existing radio service. Areas of interference would be very small and would occur only within the immediate vicinity of the LPFM station. An LP-1000 station at maximum facilities is predicted to create interference to a distance of 1.4 kilometers (0.9 miles) and even this small predicted interference zone could possibly pose a potential problem to other stations only if the LP-1000 station was located very near the outer edge of the protected station's service contour. | |||
The FCC states that in 1997, they eliminated third-adjacent channel protections for full-power "grandfathered short spaced stations" including those operating at substantially higher power levels than LP-1000 stations. | |||
Relaxed interference standards for LPFM stations may be the only way of "finding" sufficient spectrum in medium or larger markets to create any viable service of 100 watts or more. According to a staff analysis, with a third-adjacent protection requirement, no LP-100 or LP-1000 stations could be authorized in Denver, and only 3 LP-100 stations could be authorized in Minneapolis, where without the third-adjacent requirements, one LP-1000 or four LP-100 stations might location in Denver and perhaps one LP-1000 or nine LP-100 stations could be located in Minneapolis. | |||
=== Second-adjacent channel protection === | === Second-adjacent channel protection === | ||
The FCC had found that in cases where a "grandfathered short spaced" FM station was permitted to modify facilities without regard to second or third-adjacent channels between 1964 and 1987, they did not receive any interference complaints from such modifications. They found only a small risk of interference in that context, which was outweighed by improved service. The FCC has also found this to be the case in the noncommercial service in the case of "Raleigh Waivers" where the FCC has been able to accept small amounts of second and third adjacent channel interference where such interference is counterbalanced by substantial service gains. | |||
Concern regarding second-adjacent channel protections has also been made in connection with the deployment of In Band On Channel (IBOC) digital radio, now known as HD Radio. It is possible that one or more of the variations of IBOC that would use the outer edges of a channels specified bandwidth or portions of the adjacent channel to transmit a digital signal. The elimination of second-adjacent would reduce the frequency separation (guard band) that insulates between channels. | |||
Staff analysis suggests that second-adjacent protection standards would be a substantially larger impediment to LPFM service than the third-adjacent channel standard, especially in large and medium size cities. The Commission questions whether a reduced bandwidth or a second-adjacent channel protection requirement is necessary for LPFM. | |||
=== Emissions and Bandwidth === | === Emissions and Bandwidth === | ||
The FCC believes that the extent to which LPFM stations would degrade second-adjacent channels would be considerably limited due to lower ERP and HAAT levels. The FCC is also seeking to know other technical means to reduce interference. These could include establishing a strict emission mask and/or reducing the bandwidth for LPFM stations. The FCC is also proposing that all LPFM stations use certified transmitters, which they believe would be necessary especially if the LPFM service does not include any second- or third-adjacent channel protection requirements. | |||
The NPRM goes into length about the benefits of LPFM stations operating at reduced bandwidth and how radio receivers would perform attempting to receive those lower bandwidths. | |||
== Ownership and Eligibility == | == Ownership and Eligibility == | ||