ACP WGF12 WP 32 ACP WORKING GROUP F 12th MEETING Montreal by dyr60218


									                                                                        ACP/WGF12 - WP/32

                            ACP WORKING GROUP F 12th MEETING

                               (Montreal, Canada, Aug 23-27, 2004)

Agenda Item #: 8 – FM Broadcasting

                       Digital Audio Broadcasting in the United States

                          (Presented by the United States of America)


This paper summarizes the Federal Communications Commission (FCC) proposals for
Digital Audio Broadcasting (DAB) in the United States. Its potential impact on
Aeronautical Radionavigation Service is discussed.

1.                Introduction

In the United States, the 88-108 MHz band is used for Frequency Modulation (FM)
Broadcasting. The stations are channelized every 200 kHz beginning at 87.9 MH and
ending at 107.9 MHz. The AM broadcast band begins at 540 kHz and ends at 1600kHz.
There has been a desire amongst broadcasters to enhance and improve these services.
In 1990, the FCC first considered the feasibility of terrestrial and satellite digital radio
services. As to the former, the FCC concluded that the digital terrestrial systems then
under consideration were not fully developed and that it was premature to engage in
discussions regarding DAB standards, testing, licensing, and policy issues. In 1999, the
FCC, recognizing that the appropriate technology had matured, commenced this
proceeding to foster the further development of the system. The FCC published a
Further Notice of Proposed Rulemaking (FNPRM) on April 15, 2004 on Digital Audio
Broadcasting Systems and their Impact on the Terrestrial Radio Broadcast Service,
Docket No. 99-325. In that FNPRM, the Commission announced notification procedures
that will allow operating AM and FM radio stations to begin digital transmissions
immediately on an interim basis using the "in-band, on-channel" (IBOC) system. The
FCC concluded that the adoption of a single IBOC transmission standard will facilitate
the development of digital services for terrestrial broadcasters. The technology provides
for enhanced sound fidelity, improved reception, and new data services. It employs a
method of transmitting near-CD quality audio signals to radio receivers along with new
data services such as station, song and artist identification, stock and news information,
as well as local traffic and weather bulletins. This technology allows broadcasters to use
their current radio spectrum to transmit AM and FM analog signals simultaneously with
new higher quality digital signals. New channel plans are not necessary nor is a new
spurious emission mask being proposed.

2.                Discussion

2.1          The compatibility between the broadcasting service and the ILS localizer
and VOR receivers is addressed in ITU-R Recommendation IS.1009-1,

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108-137 MHz. In the United States a computerized Airspace Analysis Model (developed
by the FAA) is employed by the FAA as well as FM broadcast consultants to evaluate
new FM stations and new ILS locations and VOR stations for compatibility.

2.2             The FCC FNPRM set forth proposed rules for operation and solicited
comment. The proposed rules of most interest to WG-F are those dealing with
emissions. Under the FCC proposal, a given station could transmit both analog FM and
digital FM on the same frequency, with sufficient excess capacity for ancillary data. The
existing channel plan would not change. The emission mask is to be unchanged from
that specified for analog FM. When both are transmitted, the digital portion is to be 20
dB below the analog portion.

                                                      Attenuation below level of
                     Separation from center              unmodulated carrier
                        frequency, kHz                       frequency
                              120 to 240                         25
                               240-600                           35
                                >600                  43 dB + 10 log P(watts)1

                              For 100 kW transmitter, attenuation is 93 dB

2.3            ITU-R Resolution 413 (WRC-03), Use of the band 108-117.975 MHz by
aeronautical services, invites ITU-R, “to study any compatibility issues between the
broadcasting and aeronautical services that may arise from the introduction of these
additional aeronautical systems as referenced in noting a), or appropriate digital sound
broadcasting systems…”

2.4              Testing will be needed to determine if the addition of the new DAB affects
compatibility with ILS Localizer and VOR. While the compatibility between analog FM
broadcast and GBAS is captured in the GBAS SARPs, the compatibility with the DAB
will require testing.

3.                Conclusion

3.1            DAB is planned for implementation in the United States. It uses the same
frequencies as analog FM broadcasting. Its compatibility with ILS localizer, VOR and
GBAS has not been thoroughly studied. Testing will be needed to evaluate compatibility

4.                Recommendation

4.1               It is requested that the meeting take note of the information in this paper.

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