[Federal Register Volume 64, Number 143 (Tuesday, July 27, 1999)]
[Proposed Rules]
[Pages 40539-40542]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19096]
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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.
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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
[[Page 40540]]
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,
[[Page 40541]]
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
[[Page 40542]]
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 filed against 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 filed based 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. 99-19096 Filed 7-26-99; 8:45 am]
BILLING CODE 6712-01-P
