Radio broadcasting: AM broadcasters using directional antennas; regulatory requirements reduction,

[Federal Register: July 27, 1999 (Volume 64, Number 143)]

[Proposed Rules]

[Page 40539-40542]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr27jy99-18]

FEDERAL COMMUNICATIONS COMMISSION

47 CFR Part 73

[MM Docket No. 93-177; FCC 99-126]

Reduction of Regulatory Requirements For AM Broadcasters Using Directional Antennas

AGENCY: Federal Communications Commission

ACTION: Notice of proposed rulemaking.

SUMMARY: In this Notice of Proposed Rule Making, the Commission proposes substantial reductions in the proof of performance requirements for AM directional antenna systems. These proposals are intended to alleviate unnecessary financial burdens imposed on AM broadcasters by such requirements without jeopardizing the Commission's policy objectives of controlling interference and assuring adequate community coverage by AM stations. The Commission previously issued a Notice of Inquiry in this proceeding in response to a joint petition for rule making by five broadcast consulting engineering firms requesting a thorough reexamination of testing and verification procedures for AM radio stations that use directional antennas.

DATES: Submit comments on or before September 10, 1999 and reply comments on or before September 27, 1999.

ADDRESSES: Parties who choose to file comments concerning this Notice of Proposed Rule Making by paper should address their comments to Magalie Roman Salas, Office of the Secretary, TW-A306, Federal Communications Commission, 445 12th Street, S.W., Washington, D.C. 20554. Comments also should be submitted on a 3.5 inch diskette using WordPerfect 5.1 for Windows or compatible software to Son Nguyen, Federal Communications Commission, 445 12th Street, S.W., Room 2-A330, Washington, DC 20554.

FOR FURTHER INFORMATION CONTACT: Son Nguyen, Dale Bickel or William Ball at (202) 418-2660 or snguyen@fcc.gov, dbickel@fcc.gov, or wball@fcc.gov.

SUPPLEMENTARY INFORMATION: Comments and other data may be submitted via electronic mail to http://www.gcc.gov/e-file/ecfs.html.

The Commission proposes to amend 47 CFR Part 73 Subpart A as set forth below:

1. Computer Modeling versus Proofs of Performance. Several computer models have been developed over the years to calculate operating characteristics of particular importance to engineers designing, installing and adjusting AM antenna systems. Unlike the mathematical formulas for calculating the radiation characteristics of AM directional antennas contained in 47 CFR 73.150, 73.152 and 73.160, these computer models or ``NEC programs'' deal with ``internal'' array parameters such as impedances, currents and voltages at locations within the power distribution and radiation system. Several commentators suggested that proofs of performance may not be

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   necessary for directional arrays adjusted pursuant to NEC programs, arguing that such programs make possible the satisfactory adjustment of directional arrays without reliance on field strength measurements.

2. The Commission does not propose to adopt a methodology based on NEC programs to determine whether directional arrays conform to authorized radiation patterns. The Commission has two fundamental concerns. First, based on the present record, the Commission is concerned that it could not continue to accomplish its core regulatory function of preventing interference among AM broadcast stations if the requirement of proofs of performance were eliminated for stations adjusted pursuant to NEC programs. Second, the Commission is concerned that adopting a methodology based on NEC programs could draw it into controversial issues relating to the adequacy of adjustment programs and procedures, leading to delays in authorizing new service. The Commission generally does not regulate either the design of circuitry internal to antenna systems or the methodology employed in the adjustment of antenna systems. The Commission seeks comment on these matters.

3. Directional Antenna Proofs of Performance. A proof of performance establishes whether the radiation pattern of an AM directional array is in compliance with the radiation pattern authorized by the station's construction permit or license. A full proof of performance requires a large number of measurements of the station's signal to establish the shape of the radiation pattern. Each full proof generally consists of two sets of measurements-- nondirectional and directional measurements--and a minimum of 30 points along each of eight radials is required. Complex arrays require more radials and, therefore, more measurement points. A partial proof requires a lesser number of measurements to show that the station continues to operate as it did during the last full proof.

4. Full Proofs--Number of Radials. The Commission proposes to reduce the minimum number of radials required under 47 CFR 73.151 from eight to six for simple directional antenna patterns and to generally require no more than 12 radials to define complex patterns. (For AM stations operating with different daytime and nighttime directional antenna patterns, different radials may be required for each pattern.) If the major lobe, minor lobes, and nulls of the pattern cannot all be accounted for by the required 12 radials, pattern symmetry may be used to account for the remaining minor lobes and nulls. The radials would be distributed as follows: (A) One radial in the major lobe, at the pattern maximum; (B) At least five additional radials, as needed to definitely establish the pattern, generally at the peaks of minor lobes and at pattern nulls. This may include radials specified on the station's authorization. However, no two radials may be more than 90 degrees azimuth apart. If two radials would be more than 90 degrees apart, then an additional radial must be specified within that arc; and (C) Any radials specified on the construction permit or license.

5. Nondirectional antenna measurements would be taken along the radials used for directional measurements. In addition, the Commission proposes that those few nondirectional stations required to conduct a full proof (due to the proximity of reradiating structures or other atypical circumstances) be permitted to employ six evenly-spaced radials.

6. The Commission tentatively concludes that it can reasonably rely on fewer radials, in conjunction with the 90 degree maximum arc restriction, to establish nondirectional and directional patterns. It tentatively concludes that using a smaller number of radials, or permitting radials to be spaced more than 90 degrees apart, would not provide a sufficient number of points to identify distortion of a nondirectional pattern. Furthermore, the Commission believes that the above-stated proposals can sharply cut the time and cost of conducting a proof of performance. Comment is requested on these matters.

7. Full Proofs-- Number of Points per Radial, Length of Radials. The Commission proposes to reduce the number of points per radial required under 47 CFR 73.186(a)(1) to a minimum of 15, as well as to shorten the minimum length of the radial from 34 to 15 kilometers (``km''). These 15 measurement points would include the very important close-in measurement points (points at less than three km from the transmitter site) used to determine the inverse distance field. The Commission proposes to specify intervals between these points as follows: (A) The closest point at a distance 10 times the maximum distance between the elements of a directional array, or at a distance five times the vertical height of the antenna in the case of a nondirectional station; (B) Close-in measurements at 0.2 km intervals, out to a distance of three km (unchanged from the present requirements of 47 CFR 73.186); (C) Measurements at one km intervals between three and five km (three points); (D) Measurements at two km intervals between five and 15 km (five points); (E) Additional measurements as necessary at greater distances to achieve at least 15 points clear of potential reradiating structures; and (F) Measurements at any monitoring point locations along the radial (unchanged from the present rule).

8. The Commission tentatively concludes that the proposed reduced number of points and shorter radial length represent the minimum which would allow verification of the performance of the antenna system. The Commission tentatively concludes that the present measurement requirements for close-in measurements (within three km of the transmitter site) should not be modified. The Commission seeks comment on each aspect of this proposal.

9. For each measurement point, the Commission proposes that the applicant provide several pieces of data: the date(s) of the measurements; the azimuth of the radial; the distance from the center of the array to the measurement point; the pattern being measured (day/ night/critical hours); the time of the measurement; and the measured field strength value at that point. The Commission proposes to adopt a standardized format for the submission of the data in order to facilitate electronic filing and processing. The Commission seeks comment regarding the format that should be used for the compilation and submission of this data. Comment is also requested as to whether the time of each measurement should continue to be required with these submissions.

10. Partial Proofs--Number of Points Required. The Commission proposes to reduce from 10 to eight the minimum number of points per radial required under 47 CFR 73.154. The proof must include any monitoring point locations, and must use radial measurement point locations established in the last full proof of performance, as is the case under the current rule. The Commission believes that reducing the number of points would reduce the financial burden on AM directional licensees conducting partial proofs while still providing sufficient data to confidently verify directional array performance.

11. Partial Proofs--When Required. The Commission proposes to eliminate the requirement under 47 CFR 73.68 to conduct a partial proof of performance following replacement or modification of sampling system components mounted on the tower, provided the new components are mounted in the exact location of the old components,

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    measurements made at the monitoring points before and after installation establish that the substitution had no effect, and antenna monitor values remain within the tolerances specified in the Commission's rules or the station's authorization.

12. Proofs of Performance--Monitoring Points. Monitoring points are specific locations on selected proof radials where licensees regularly take field strength measurements to verify that a directional array remains within the radiation limits specified in the station's authorization. They are established at the time a station's full proof of performance is conducted. The Commission does not propose to eliminate monitoring point requirements, as suggested by some commentators, who argue that seasonal variations in ground conductivity affect the signal strengths measured at many monitoring points. The Commission tentatively concludes that monitoring point measurements remain a fundamental tool in verifying the performance of AM directional arrays independent of antenna monitor and antenna sampling system readings. The Commission also does not propose to adopt a suggestion to delete monitoring point measurements in exchange for yearly skeleton proofs taken on formerly monitored radials. The Commission seeks comment on these tentative conclusions.

13. Under 47 CFR 73.158, an informal application to change a monitoring point must include the results of a partial proof of performance taken on the radial containing the monitoring point to be changed. The Commission proposes to eliminate this requirement. Instead, the applicant would simply reference the measurements taken along that radial in the last full proof of performance submitted to the Commission. The staff would assign a radiation limit for the new monitoring point using the same procedure as described above. The field strength limit would be assigned based on the tolerance available between the radiation along the monitoring point radial as determined by the proof of performance and the radiation permitted by the authorized standard (or augmented) radiation pattern.

14. The Commission also proposes to eliminate the requirement for maps and directions indicating how to reach monitoring points for applicants using GPS-determined coordinates to identify monitoring point locations. A description of the monitoring point as well as a photograph would still be required to verify that the location is free of obstructions such as overhead power lines, see 47 CFR 73.151(a)(3) and 73.158(a)(4), to identify the precise location of the monitoring point with respect to nearby landmarks, and to identify the exact placement of measurement equipment. See CFR 73.151(a)(3) and 73.158(a)(2), (3). In order to achieve sufficient accuracy, a differential GPS receiver would be required. The Commission would specify monitoring point coordinates submitted in this manner on the station's license. Parties interested in locating these monitoring points could plot the specified coordinates onto topographical or other maps to determine the best route. The Commission asks for comment on these proposals.

15. AM Station Equipment & Measurements--Base Current Ammeters. Licensees are currently required under 47 CFR 73.58(b) to install base current ammeters or toroidal transformers (current registering devices) at the power feed point of each tower, typically at the base of the tower. The Commission proposes to delete the requirement for base current ammeters or toroidal transformers for those directional stations employing approved antenna sampling systems. Stations not using approved sampling systems have no reliable alternate on-site means of assessing antenna performance and, therefore, the Commission's rules would continue to require the installation and use of base current ammeters if the Commission has not approved the alternative system. The Commission seeks comment on this proposal.

16. Equipment & Measurements--Antenna Monitors. All AM directional stations are required to use an antenna monitor verified for compliance with the technical requirements in 47 CFR 73.53 as a means of verifying directional array performance. This rule also establishes detailed specifications that antenna monitors must meet. The Commission proposes to delete most of the antenna monitor construction and operational requirements of 47 CFR 73.53, with the exception of a few provisions that would be shifted to other existing rule sections. Specifically, the present requirement in 47 CFR 73.53(a) that the antenna monitor be verified for compliance with the Commission's technical requirements would be moved to 47 CFR 73.69, which deals with antenna monitors. Antenna monitor requirements for critical arrays would be moved from 47 CFR 73.53(c) to 73.69. Minimum readout levels in 47 CFR 73.53(b)(4) and (b)(5) would be moved to 47 CFR 73.1215. The Commission in recent years has eliminated detailed construction and operational requirements for other types of broadcast equipment, such as transmitters and metering equipment, and tentatively concludes that the instant proposal will encourage the development of more dependable, less expensive antenna monitors. Comment is requested on this proposal.

17. Several commentators requested that 47 CFR 73.68 be modified to permit licensees to use voltage sampling devices to feed antenna monitors in lieu of current sampling devices such as sampling transformers and pick-up loops. The Commission asks for comments as to the accuracy and reliability of voltage sampling devices, whether they are appropriate as sampling devices for assessing array performance, and whether the rules should be modified to permit their use.

18. Equipment & Measurements--Impedance Measurements Across a Range of Frequencies. Directional and nondirectional AM stations are currently required to take measurements of impedance across a range of frequencies under 47 CFR 73.54(c)(1) and (c)(2). The Commission proposes to delete this requirement. The Commission tentatively concludes that retention of 47 CFR 73.54(c) is not necessary because competition will serve as a sufficient incentive to maintain quality operations, as has proven to be the case with regard to other broadcast stations. The Commission seeks comment on this proposal.

19. Equipment & Measurements--Common Point Impedance Measurements. AM directional stations must take impedance (resistance and reactance) measurements at the common radiofrequency input location under 47 CFR 73.54(b). The reactance at this point is adjusted by the antenna matching network to a value of zero ohms. The Commission proposes to delete the requirement that the common point reactance be adjusted to zero ohms. The Commission seeks comment as to whether a limit should be set for the maximum amount of reactance permitted.

20. Critical Arrays--Antenna Monitors. Critical arrays are directional antennas which, because they are unusually sensitive to slight variations in internal operating parameters, are predicted to exceed their standard radiation pattern at normal operating tolerances and, therefore, pose a greater potential for causing objectionable interference. Licenses of stations with critical arrays specify tighter operating tolerances. To monitor these tighter tolerances, 47 CFR 73.69 requires stations with critical arrays to install

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    special precision monitors. The Commission proposes to discontinue specifying the use of expensive, specially designed precision antenna monitors for critical arrays. Instead, the Commission proposes to simply require that the monitor installed have a digital readout graduated in increments no larger than one-half of the critical parameter specified in the authorization. The Commission tentatively concludes that the rule can be relaxed to permit the use of off-the- shelf equipment without adverse impact on stations that are protected by critical arrays. Comment on this proposal is requested.

21. Critical Arrays--Designation. The Commission does not propose to discontinue the critical array classification system, as suggested by several commenters. Some directional antenna systems are inherently more unstable than others and more likely to cause objectionable interference to other AM stations. Authorizations for such stations are conditioned require more stringent monitoring. The Commission acknowledges that the staff has generally investigated an array for stability only if a petition or objection is filedagainst the application proposing the array. As a result, the staff has not identified and designated as critical arrays all unstable arrays. The Commission intends to change this practice by discontinuing reliance on petitions or objections as the primary method of identifying unstable arrays. Instead, the Commission proposes to apply a uniform screening process to all applications for directional facilities.

22. In addition, the Commission has analyzed all licensed AM directional antennas utilizing its stability criteria and tentatively concluded that the current criteria are too stringent, and that modifications are necessary to tag only those arrays that have the highest probability of causing ``real world'' interference under normal operating tolerances. Accordingly, the Commission proposes to relax its stability criteria in two ways. First, tests for array stability would be restricted to radiation pattern minima (nulls) and maxima of standard patterns in the horizontal plane only instead of testing at all azimuths and elevations. The studies would be restricted to the horizontal plane radiation pattern because only the horizontal plane pattern can be directly observed by means of field measurements. Second, the Commission proposes to classify an array as critical only if the standard pattern is exceeded at 10 percent or more of the possible parameter variation combinations. (The current test requires only one instance of excessive radiation.) The Commission believes that the proposed 10 percent standard will more realistically predict the likelihood of excessive radiation. The Commission seeks comments on both proposed relaxations to the current stability test criteria.

23. Finally, based on the results of studies the Commission has performed on the licensed AM directional patterns in the AM engineering database, the Commission propose to exclude all two-and three-tower arrays from designation as critical arrays. Furthermore, the Commission proposes to categorically exclude all daytime arrays, considering that objections have never been filedbased on daytime interference issues related to array instability. Thus, only nighttime and critical-hours directional proposals would be screened. Licensees with facilities currently classified as critical would be permitted to request staff review of their designation based on the revised criteria; however, the Commission does not propose to review the directional facilities of any station not currently classified as critical. The Commission seeks comment on each aspect of this proposal.

    List of Subjects in 47 CFR Part 73

    Radio.

    Federal Communications Commission. William F. Caton, Deputy Secretary.

    [FR Doc. 99-19096Filed7-26-99; 8:45 am]

    BILLING CODE 6712-01-P