Federal Communications Commission FCC 96-407
Before the
Federal Communications Commission 
Washington, D.C. 20554
In the Matter of )
) Amendment of Part 87 to Permit the ) '
Use of 112-118 MHz for Differential Global ) WT Docket No. 96-211
Positioning System (GPS) Correction Data ) RM-8607, 8687
and the Use of Hand-held Transmitters )
on Frequencies in the Aeronautical )
Enroute Service )
) 
and )
) 
Amendment of Part 17 Concerning )
Construction, Marking, and Lighting of ) 
Antenna Structures )
NOTICE OF PROPOSED RULE MAKING
Adopted: October 9, 1996 Released: November 21, 1996 
Comment Date: January 15, 1997 
Reply Comment Date: January 30,1997 
By the Commission:
I. INTRODUCTION AND EXECUTIVE SUMMARY
1. This Notice of Proposed Rule Making (Notice) proposes to amend Part 87 of our rules 
to permit aeronautical ground stations to use frequencies in the 112-118 MHz band to transmit 
differential Global Positioning System (GPS)1 information to aircraft equipped to use advanced 
landing systems in response to a petition for rule making filed by the Federal Aviation 
Administration (FAA).2 This Notice also proposes to allow the use of hand-held radios for direct 
communications between ground service personnel and flight crews on frequencies allocated to
1 GPS and differential GPS technologies are described in para. 3 infra.
2 See Petition for Rule Making by Federal Aviation Administration (FAA), RM No. 8687 (filed August 7, 
1995) (FAA Petition).
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__________Federal Communications Commission FCC 96-407
the Aeronautical Enroute Service in response to a petition for rule making3 filed by Aeronautical 
Radio, inc. (ARINC).4 Finally, this Notice proposes to update Part 17 of our rules to incorporate 
by reference two recently revised FAA Advisory Circulars. We believe that adoption of these 
proposed rule changes would increase aircraft and airport safety and facilitate the efficient use 
of aeronautical radio spectrum.
n. DISCUSSION
A. Differential Global Positioning System Correction Data
2. On August 7, 1995, the FAA filed a request to permit Part 87 aeronautical ground 
stations at airports to use frequencies in the 112-118 MHz band5 to transmit differential GPS 
information to aircraft.6 According to the FAA, it has developed a Special Category I (SCAT-I) 
precision landing and approach specification to enable near-term use of GPS for aircraft landing 
operations by private users.7 It states that this specification was formalized in RTCA Document 
No. DO-217,* which established standards for a GPS augmentation system operating in the 112- 
118 MHz band.9 The FAA believes that this flexible use of the spectrum will increase aviation 
safety during landings and approaches by promoting the use of satellite technology to aid hi the 
precision landing of aircraft. The FAA's request was placed on Public Notice.10 No comments 
were received in response to the Public Notice.
1 See Petition for Rule Making by ARINC, RM No. 8607 (filed February 2, 1995) (ARINC Petition).
4 ARINC was established in 1929 by the airline industry to provide and coordinate aeronautical 
communications facilities and services. ARINC continues today to render its services on a non-profit basis with cost 
distributed in proportion to use. To a great extent, it designs, provides, and manages the industry's communications 
systems. Even though its principal stockholders as well as principal customers are the U.S. air carriers, ARINC 
provides communications services to all aircraft operators, including foreign airlines, business entities, and private 
individuals.
5 Frequencies in the 112-118 MHz band are now used by VHP omni-range (VOP) stations and, pursuant to 
47 C.F.R. § 87.475(a), all assignments are made in accordance with recommendations made by the FAA. VOR 
stations are beacons that transmit two phase-related radio signals to aircraft in flight. Signals received from two 
VOR beacons can be used by pilots to determine the position of an aircraft.
6 See supra note 1.
7 FAA Petition at 1.
8 RTCA Document No. DO-217, Minimum Aviation System Performance Standards/Differential Global 
Navigation Satellite System Instrument Approach System: Special Category I (SCAT-I), August 27, 1993.
9 FAA Petition at 1.
10 See FCC Public Notice No. 2095 (August 29, '095).
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Federal Communications Commission FCC 96-407
3. By way of background, the GPS is a satellite-based global navigation system originally 
developed by the U.S. Department of Defense to enhance the effectiveness of U.S. military 
forces. Over the years, GPS has also been used in civilian applications requiring precise location 
information (e.g., mapping, surveying, and navigation). The GPS consists of twenty-four 
satellites, with the orbits of these satellites designed so that multiple satellites are passing over 
any given spot on the earth's surface at any given time. Each satellite transmits a time-coded 
signal. A GPS receiver then uses data from multiple satellites to rapidly calculate the location, 
altitude, and velocity of the vehicle or. aircraft carrying the receiver.
4. The location accuracy achieved by a particular GPS receiver depends on the accuracy 
of each satellite's clock, variances in each satellite's orbit, and daily fluctuations in the radio 
propagation characteristics of the ionosphere. In addition, the accuracy of the GPS system is 
purposefully degraded by the Department of Defense for national security reasons. For civilian 
use, GPS receivers are generally considered to be accurate within approximately 100 meters 
horizontally. This accuracy can be improved to better than one meter, however, by using a 
technique called "differential GPS." Differential GPS employs two GPS units or receivers. In 
addition to the mobile GPS receiver (e.g., the receiver on an aircraft), another receiver (stationary 
receiver) is placed at a location where the precise coordinates are already known (reference 
point). The stationary receiver calculates the difference between the reference point and the 
predicted location using GPS data. The difference between the two locations is the error in the 
GPS signal. Error correction data can then be transmitted to a mobile GPS unit to increase the 
accuracy of the position information shown by that unit.
5. The FAA requests that we amend Part 87 of our rules to allow entities participating 
in its SCAT-I landing and approach system to use unassigned VOR frequencies in the 112-118 
MHz band to transmit error correction data obtained using differential GPS to units aboard 
aircraft. 11 Allowing Part 87 aeronautical ground stations at airports to use VOR frequencies in 
this manner would increase navigation accuracy and thereby increase safety in aircraft landings 
and approaches. By limiting such use to unassigned VOR frequencies, we eliminate the 
possibility of interference with VOR operations. Further, the Commission has granted nine 
developmental licenses for such systems12 and has received no complaints of harmful interference 
to VOR stations. Thus, we do not believe that allowing the operations proposed by the FAA will 
increase the incidence of harmful interference hi the 112-118 MHz band. As a result, we propose 
to allow aeronautical ground stations to use unassigned VOR frequencies in th-3 112-118 MHz
11 FAA Petition at 1.
12 The nine systems are Interstate Electronics Corp., (landing area not listed), Anaheim, CA, granted 6/11/96; 
Intersate Electronics Corp., Mojave Airport, Mojave, AZ, granted 6/11/96; Continental Airlines Inc., Newark 
International Airport, Newark, NJ, granted 6/05/96; Metropolitan Airports Commission, Minneapolis-St Paul 
International Airport, Minneapolis, MN, granted 4/04/96; Aeronautical Radio Inc., Alliance Fort Worth Airport, Fort 
Worth, TX, granted 9/15/95; Honeywell Inc., Rochester Airport, Rochester, MN, granted 6/30/95; State of Wisconsin, 
Wittman Regional Airport, Oshkosh, WI, granted 10/28/93; Aeronautical Radio Inc., (landing area not listed), 
Newark, NJ, granted 11/15/93; Aeronautical Radio Inc., (landing area not listed), Houston, TX, granted 11/15/93.
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Federal Communications Commission FCC 96-407
band to transmit differential GPS data. In order to expedite assignment of these frequencies, we 
also propose to require proof from the applicants that frequency assignments were coordinated 
with the FAA prior to seeking a Commission authorization.
6. Additionally, to accommodate the technical parameters of these proposed new ground 
station transmitters, we propose to amend 47 C.F.R. § 87.137(a) to include "14KG7D"13 as an 
authorized type of emission. We also propose to amend 47 C.F.R. § 87.171 to designate "RLP" 
as the symbol for the class of station for differential GPS ground stations. We invite comments 
concerning these proposals as well as any alternatives thereto. We also seek comment on the 
following issues:
(a) Should an applicant for a differential GPS ground station be required to notify the 
applicable airport authority or aviation service organizations prior to receiving an authorization 
for operation at a particular airport? Should the Commission prohibit multiple licensees from 
operating at a single airport or, in the alternative, limit the number of licensees operating at a 
single airport?
(b) What measures may be taken to expedite coordination procedures between applicants, 
the FAA, and the Commission concerning the assignment of a frequency and time slot for 
differential GPS ground stations?
(c) The proposed rules would require differential GPS transmitters to be type accepted 
in accordance with the proposed technical criteria set forth in Appendix B (47 C.F.R. §§87.131, 
87.133(a)(5), 87.137(a), 87.139Q), 87.145, and 87.147(d)), in lieu of the specifications contained 
in RTCA Document No. DO-217. We believe that this flexible approach promotes technological 
innovations in differential GPS equipment consistent with the National Airspace System (e.g., 
changes in coding methodology or data timing structure) without requiring the Commission's 
rules to be amended to incorporate changes unrelated to radiofrequency interference. Under our 
present treatment of transmitters operating in the 108-137 MHz band,14 the FAA is given a 21- 
day period to object to any application for type acceptance that would adversely affect the 
performance of the National Airspace System. Are these proposed requirements sufficient to 
ensure proper operation of differential GPS ground station transmitters? If not, what would 
constitute sufficient requirements?
B. Use of Hand-Held Transmitters on Aeronautical Enroute Service Frequencies
7. On February 2, 1995, ARINC filed a petition to permit use of hand-held radios on 
frequencies allocated to the Aeronautical Enroute Service so that flight crews can communicate
13 The emission designator "14KG7D" refers to a data or telemetry transmission with a necessary bandwidth 
of 14 kHz that is phase-modulated and contains one or more channels of digital information together with one or 
more channels of analog information. See 47 C SSL §
14 See 47 C.F.R. § 87.147(d).
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Federal Communications Commission FCC 96-407
directly with ground service personnel while the aircraft is "on the ground.15 According to 
ARINC, today's commercial aircraft require direct wireless contact between flight crews and 
ground service personnel in lieu of the present means of communications through a dispatch 
center or via a tethered communication line physically connecting ground personnel with an 
aircraft. ARINC contends that this need for a wireless radio link arises from recent FAA 
regulations concerning de-icing aircraft prior to take-off, increased traffic on airport runways, and 
the safety hazards associated with tethered connections.16 ARINC argues that the lack of a direct 
wireless communications capability compromises safety of airport personnel and often results in 
unnecessary delays in persons aboard aircraft being able to obtain service or supplies.17 ARINC's 
petition was placed on Public Notice.18 No comments were received in response to the Public 
Notice.
8. Aeronautical Enroute stations provide for operational control (e.g., flight management) 
of aircraft along domestic or international air routes. Operational control communications are 
defined as communications relating to the safe, efficient and economical operation of the 
aircraft.19 Examples of operational control communications are communications concerning fuel, 
weather, aircraft position and performance and requests for essential services and supplies. 
Currently, the rules do not permit direct communications between the flight crews and ground 
service personnel via hand-held radios. Instead, the flight crews and ground service personnel 
must communicate through the aeronautical enroute ground station (base station), or a wired 
connection to the plane on the ground.
9. Because of the concerns presented by ARINC, we tentatively conclude that allowing 
hand-held radio operation on aeronautical enroute frequencies will increase airport safety, promote 
the more efficient use of aviation spectrum, and reduce waiting times for aircraft to obtain 
essential services and supplies. Therefore, we propose to allow the use of hand-held radios at 
airports for communications by ground service personnel with aircraft or the associated enroute 
station. In order to reduce administrative burdens on both the public and the Commission, we 
further propose to permit such mobile units to operate under the same authorization and call sign 
as the associated aeronautical enroute station. This approach would eliminate the need for 
aviation service organizations to submit forms and fees to the Commission, while minimizing 
administrative burdens on the Commission. We seek comment on our proposal and tentative" 
conclusion. We also seek comment on the following issues:
15 See supra note 2.
18 ARINC Petition at 2.
17 ARINC Petition at 2.
" See FCC Public Notice No. 2059 (February 28, 1995).
19 See 47 CFR § 87.261.
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Federal Communications Commission FCC 96-407
(a) Should the present technical specifications and type acceptance requirements governing 
the use of aircraft hand-held radio equipment (47 C.F.R. 87.131, 87.133(a)(5), 87.137(a), 
87.139(a), 87.141(a), 87.145(b), and 87.147(d)) be applied to hand-held radio operation on 
aeronautical enroute frequencies?
(b) We do not propose to limit the number of hand-held transmitters authorized under 
an aeronautical enroute license. What would be the advantages and disadvantages of limiting the 
number of hand-held transmitters authorized at a single airport? If the number of hand-held 
transmitters was limited, what would be a reasonable maximum number? Is there a need for the 
Commission to keep track of the exact number of hand-helds being used at each airport?
(c) ARINC's petition requests that hand-held transmitters, which are commonly battery 
operated, low power, and of limited range, be permitted to operate on aeronautical enroute 
frequencies. Should the Commission allow such hand-held transmitters to be connected to 
external power sources or to high gain antennas that increase their range?
C. Revised FAA Advisory Circulars
10. In the Report and Order hi WT Docket No. 95-5, we incorporated, by reference, two 
FAA Advisory Circulars, "Obstruction Marking and Lighting" (AC 70/7460-1H), August 1991, 
as amended by Change 2, July 15, 1992, and "Specification for Obstruction Lighting Equipment" 
(AC 150/5345-43D), July 1988, in Part 17 of our rules.20 The Commission chose this approach 
in order to unify federal guidelines concerning the painting and lighting of antenna structures. 
In doing so, we stated that if the FAA makes substantive amendments to either of these Advisory 
Circulars, the Commission would initiate a public proceeding prior to updating Part 17 of our 
rules.21 In this connection, the FAA has recently made substantive amendments to both Advisory 
Circulars. Accordingly, we propose to incorporate the revised FAA Advisory Circulars, AC 
70/7460-1J (January 1,1996) and AC 150/5345-43E (October 19,1995), in Part 17 of our rules.22 
We propose not to require Antenna structure owners that were previously assigned painting and/or 
lighting requirements by the Commission to update their structures in accordance with the revised 
Advisory Circulars unless specifically recommended by the FAA. We seek comment on this
20 See Streamlining the Commission's Antenna Structure Clearance Procedure and Revision of Part 17 of the 
Commission's Rules Concerning Construction, Marking, and Lighting of Antenna. Structures, Report and Order, WT 
Docket No. 95-5, 11 FCC Red 4272 (1996). FAA Advisory Circulars are available upon request, free of charge, 
from Department of Transportation, Utilization and Storage Section (Publications), M443.2, 400 7th Street SW, 
Washington, DC 20591, telephone (202) 366-0039 or (202) 366-0451.
21 Id., para. 48.
22 The Advisory Circulars (which are attached as Appendix C) are available in the Commission's docket file 
in this proceeding or may be purchased from the Commission's copy contractor, International Transcription Service, 
Inc., 2100 M Street, Suite 140, Washington, D.C. 20037, telephone (202) 857-3800. The Commission must obtain 
authorization from the Director of the Federal Register prior to incorporating by reference the two FAA Advisory 
Circulars in Part 17 of our rules. See \ C.F.R. Part 51.
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______________ Federal Communications Commission __FCC 96-407
proposal.
ra. CONCLUSION
11. Accordingly, we propose to amend Part 87 of our rules to permit: (1) licensing of 
the frequencies 112-118 MHz for aeronautical ground stations transmitting differential GPS 
corrections; and (2) the use of frequencies hi the Aeronautical Enroute Service by hand-held 
radios under certain circumstances. We also propose to amend Part 17 of our rules to incorporate 
by reference two recently revised FAA advisory circulars concerning antenna structure painting 
and lighting. The proposed actions will increase the safety and efficiency of aircraft navigation 
and movement of aircraft in and around airports. Further, adoption of these proposals would 
promote the use of new radio technologies beneficial to aircraft without allocating additional 
spectrum.
IV. PROCEDURAL MATTERS 
A. Ex Parte Rules - Non-Restricted Proceeding.
12. This is a non-restricted notice and comment rule making proceeding. Ex Parte 
presentations are permitted, except during the Sunshine Agenda period, provided they are 
disclosed as provided hi Commission rules. See generally 47 C.F.R. §§ 1.1202, 1.1203, and 
1.1206(a).
B. Initial Regulatory Flexibility Analysis
13. An Initial Regulatory Flexibility Analysis is contained in Appendix A. 
C. Comment Dates
14. Pursuant to applicable procedures set forth hi Sections 1.415 and 1.419 of the 
Commission's Rules, 47. C.F.R. §§ 1.415 and 1.419, interested parties may file comments on or 
before January 15, 1997, and reply comments on or before January 30, 1997. To file formally 
in this proceeding, you must file an original and four copies of all comments, reply comments, 
and supporting comments. If you want each Commissioner to receive a personal copy of your 
comments, you must file an original plus nine copies. You must send comments and reply 
comments to Office of the Secretary, Federal Communications Commission, Washington, DC 
20554. You may also file informal comments by electronics mail. You should address informal 
comments to mayday@fcc.gov. You must put the docket number of the proceeding on the 
subject line ("WT Docket No. 96-211). You must also include your full name and Postal Service 
mailing address hi the text of the message. Formal and informal comments and reply comments 
will be available for public inspection during regular business hours in the F.C.C. Reference 
Center of the Federal Communications Commission, Room 239, 1919 M Street, N.W., 
Washington, DC 20554.
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Federal Communications Commission FCC 96-407
15. For further information, contact Mr. Jim Shaffer, Private Wireless Division, Wireless 
Telecommunications Bureau, at (202) 418-0680 or at mayday@fcc.gov.
16. Authority for issuance of this Notice of Proposed Rule Making is contained in 
Sections 4(i) and 303(r) of the Communications Act of 1934, as amended, 47 U.S,C. §§ 154(i) 
and 303(r).
FEDERAL COMMUNICATIONS COMMISSION
William F. Caton 
Acting Secretary
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Federal Communications Commission FCC 96-407
APPENDIX A
INITIAL REGULATORY FLEXIBILITY ANALYSIS
As required by Section 603 of the Regulatory Flexibility Act,23 the Commission has 
prepared an Initial Regulatory Flexibility Analysis (IRFA) of the expected significant 
economic impact on small entities by the policies and rules proposed in the Amendment of 
Part 87 to Permit the Use of 112-118 MHz for Differential Global Positioning System (GPS) 
Correction Data and the Use of Hand-held Transmitters on Frequencies in the Aeronautical 
Enroute Service, and Amendment of Part 17 Concerning Construction, Marking, and Lighting 
of Antenna Structures. Written public comments are requested on the IRFA. Comments must 
be identified as responses to the IRFA and must be filed by the deadlines for comments on 
the Notice of Proposed Rule Making, provided in paragraph 14 of the item.
I. Need for and Objectives of the Proposed Rule: The purpose of this Notice of Proposed 
Rule Making is to determine whether it is in the public interest, convenience, and necessity to 
amend our rules to permit licensing of frequencies in the 112-118 MHz band for aviation 
ground monitoring systems that are associated with the GPS; to permit under limited 
circumstances the use of frequencies in the aeronautical enroute service for hand held radios. 
These proposed actions should increase the safety and efficiency of aircraft navigation and 
movement of aircraft in and around airports. We also propose to incorporate by reference 
two recently revised FAA advisory circulars concerning antenna structure painting and 
lighting.
n. Legal Basis: Authority for issuance of this Notice of Proposed Rule Making is contained 
in Sections 4(i) and 303(r) of the Communications Act of 1934, as amended, 47 U.S.C. §§ 
154(i) and 303(r).
HI. Description and Estimate of the Number of Small Entities to Which Rule Will 
Apply: The proposed amendments will affect small businesses that use, manufacturer, design, 
import, or sell a GPS augmentation system operating in the 112-118 MHz band. We 
tentatively conclude that these small businesses are classified in Communications Equipment, 
N.E.C., (Standard Identification Code 3669) as entities employing less than 750 employees as 
defined in 13 CFR §121.201. We invite comment on whether this is the correct definition to 
use. The size data provided by the SBA shows that 469 firms out of 498 firms in the 
communications equipment, nee classification have less than 750 employees but does not 
enable us to make a meaningful estimate of the number of potential GPS manufacturers which
5 U.S.C. § 603.
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Federal Communications Commission FCC 96-407
are small businesses.24 However, based on information from the U.S. GPS Industry Council 
we estimate that this would include approximately 110 small businesses that would be affected 
by this proposed rule change.
IV. Description of Projected reporting, recordkeeping, and other compliance 
requirements: In order to facilitate operation of a GPS augmentation system operating in the 
112-118 MHz band, these proposed rules may have significant economic impact on a 
substantial number of small businesses. Prior to marketing a GPS augmentation system 
operating in the 112-118 MHz band in the U.S., a manufacturer must have the unit type 
accepted by the Commission under the technical criteria set forth in the RTCA Document No. 
DO-217, Minimum Aviation System Performance Standards/Differential Global Navigation 
Satellite System Instrument Approach System: Special Category I (SCAT-I), August 27, 1993. 
In order to have a unit type accepted, a small entity would have to test the radio equipment 
and provide clerical support to file the requisite FCC application forms. Both of these 
functions could be handled by a third party. We estimate that the initial cost to the 
manufacturer to meet this requirement, if done by a third party, is $900 to test the equipment 
and complete the filing information, and would require the electronic engineering professional 
skills. Additionally, there would be a $425 equipment authorization fee to file the application 
for type acceptance. These costs are one time costs to type accept the equipment and assure 
that interference to other radio users is minimized.
V. Significant Alternatives to Proposed Rules Which Minimize Significant Economic 
Impact on Small Entities and Accomplish Stated Objectives: The proposed rules would 
require differential GPS transmitters to be type accepted in accordance with the technical 
criteria set forth in Part 87 Subpart D of our rules, in lieu of the more exacting specifications 
contained in RTCA Document No. DO-217. We believe that this flexible approach promotes 
technological innovations in differential GPS equipment so long as such equipment is 
compatible with the National Airspace System. Under our present treatment of transmitters 
operating in the 108-137 MHz band, the FAA is given a 21-day period to object to any 
application for type acceptance that would adversely affect the performance of the National 
Airspace System. We seek comments on whether these proposed requirements are sufficient 
to ensure proper operation of differential GPS ground station transmitters or, if not, what 
would constitute sufficient requirements. The proposed rules also seek to take measures to 
minimize burden and expedite coordination procedures between applicants, the FAA, and the 
Commission concerning the assignment of a frequency and time slot for differential GPS 
ground stations. In order to reduce administrative burdens on both the public and the 
Commission, we further propose to permit mobile units in the aeronautical enroute service to 
operate under the same authorization and call sign as the associated aeronautical enroute 
station. This approach would eliminate the need for aviation service organizations to submit
24 U.S. Small Business Administration 1992 Economic Census Industry and Enterprise Report, Table ID, SIC 
Code 3669, (Bureau of the Census data adapted by the Office of Advocacy of the U.S. Small Business 
Administration).
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Federal Communications Commission FCC 96-407
forms and fees to the Commission. These decision benefits small entities and give them an 
opportunity to provide recommendations to further improve the impact and processes.
VI. Federal rules which overlap, duplicate or conflict with these rules: None
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Federal Communications Commission FCC 96-407
APPENDIX B
Parts 17 and 87 of Chapter I of Title 47 of the Code of Federal Regulations are 
proposed to be amended as follows:
PART 17 - CONSTRUCTION, MARKING, AND LIGHTING OF ANTENNA 
STRUCTURES
1. The authority citation for Part 17 continues to read as follows:
Authority: Sees. 4, 303, 48 Stat. 1066,1082, as amended; 47 U.S.C. 154, 303. 
Interpret or apply sees. 301, 303 48 Stat. 1081,1085 as amended, 47 U.S.C. 301, 309.
2. Section 17.23 is revised to read as follows: 
§ 17.23 Specifications for painting and lighting antenna structures.
Unless otherwise specified by the Commission, each new or altered antenna structure to be 
registered on or after January 1, 1996, must conform to the FAA's painting and lighting 
recommendations set forth on the structure's FAA determination of "no hazard," as referenced 
in the following FAA Advisory Circulars: AC 70/7460-U, "Obstruction Marking and 
Lighting," January 1, 1996, and AC 150/5345-43E, "Specification for Obstruction Lighting 
Equipment," October 19, 1995. These documents are incorporated by reference in accordance 
with 5 U.S.C. 552(a). The documents contain FAA recommendations for painting and 
lighting structures which pose a potential hazard to air navigation. For purposes of this part, 
the specifications, standards, and general requirements stated in these documents are 
mandatory. The Advisory Circulars listed above are available for inspection at the 
Commission Headquarters in Washington, DC, or may be obtained from Department of 
Transportation, Property Use and Storage Section, Subsequent Distribution Office, M483.6, 
Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785, telephone (301) 
322-4961, facsimile (301) 386-5394.
PART 87 - AVIATION SERVICES
1. The authority citation for Part 87 continues to read as follows:
Authority: 48 Stat 1066,1082, as amended; 47 U.S.C. 154, 303, unless otherwise 
noted. Interpret or apply 48 Stat 1064-1068,1081-1105, as amended, 47 U.S.C. 151-156, 
301-609.
2. Section 87.131 is amended by adding to the end of the table, the class of station 
for Differential GPS to read as follows:
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§ 87.131 Power and emissions.
Class of Station Frequency band/frequency Authorized emission Maximum power1
Aircraft earth UHF G1D,G1E,G1W 60 watts.8 
Differential GPS VHP G7D Various.2
1 The power is measured at the transmitter output terminals and the type of power is
determined according to the emission designator as follows:
(i) Mean power (pY) for amplitude modulated emissions and transmitting both sidebands
using un modulated full carrier.
(ii) Peak envelope power (pX) of all emissions designators other than those referred to in
paragraph (i) of this row.
2 Power and antenna height are restricted to the minimum necessary to achieve the
required service.
*****
* Power may not exceed 60 watts per carrier. The maximum EIRP may not exceed 2000 
watts per carrier.
3. Section 87.133 is amended by adding to the table in paragraph (a) in the (5) Band- 
100 to 137 MHz: entry, the category of station Differential GPS to read as follows:
§ 87.133 Frequency stability.
Frequency band (lower limit exclusive,upper limit Tolerance1 Tolerance2 
inclusive), and categories of stations.
(5) Band-100 to 137 MHz:
Aeronautical stations 450 50*****
Radionavigation stations 20 20
Differential GPS 2*****
1 This tolerance is the maximum permitted until January 1, 1990, for transmitters installed 
before January 2, 1985, and used at the same installation. Tolerance is indicated in parts in 
106 unless shown as Hertz (Hz).
2 This tolerance is the maximum permitted after January 1, 1985, for new and replacement 
transmitters after January 2, 1990. Tolerance is indicated in parts in 106 unless shown as
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Federal Communications Commission FCC 96-407
Hertz (Hz). *****
4 The tolerance for transmitters type accepted between January 1, 1996, and January 1, 1974, 
is 30 parts in 10*. The tolerance for transmitters type accepted after January 1, 1974, and 
stations using offset carrier techniques is 20 parts in 106.
*****
4. Section 87.137 is amended by adding to the table in paragraph (a) in its 
alphabetical order, the class of emission G7D to read as follows:
§ 87.137 Types of emission.
*****
Class of emission Emission 
designator
Below 50 
MHz
*****
Authorized bandwidth (kilohertz) 
Above 50 Frequency 
MHz deviation
G7D. 14KOG7D 25
*****
5. Section 87.139 is amended by revising paragraph (a), and adding a new paragraph 
(j) to read as follows:
§ 87.139 Emission limitations.
(a) Except of ELTs and when using single sideband (R3E, H3E, J3E), or frequency 
modulation (F9) or digital modulation (F9Y) for telemetry or telecommand in the frequency 
bands 1435-1535 MHz and 2310-2390 MHz or digital modulation (G7D) for differential GPS, 
the mean power of any emission must be attenuated below the mean power of the transmitter 
(pY) as follows:
*****
(j) When using G7D for differential GPS in the 1 12-1 18 MHz band, the amount of power 
during transmission under all operating conditions when measured over a 25 kHz bandwidth 
centered on either of the second adjacent channels shall not exceed -25 dBm and shall 
decrease 5 dB per octave until -52 dBm.
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Federal Communications Commission FCC 96-407
6. Section S7.171 is amended by adding in its alphabetical order the symbol and class 
of station for RLP to read as follows:
§ 87.171 Class of station symbols.
RLP - Differential GPS
*****
7. Section 87.173 is amended by revising the frequency table in paragraph (b) to add 
the listing 112-118 MHz.
§ 87.173 Frequencies
(b) * * *
Frequency or frequency band Subpart Class of station Remarks
*****
112-118 MHz.................. Q RLP Differential GPS
*****
8. Section 87.261 is amended by adding paragraph (e) to read as follows:
§ 87.261 Scope of Service *****
(e) Hand-held units may be operated under an aeronautical enroute station 
authorization so long as the units are limited to use at an airport and are only used to 
communicate with aircraft on the ground or the associated aeronautical enroute station. Hand 
held units are further limited to operation on the VHP frequencies Usted in 87.263(a)(l).
9. Section 87.475 is amended by adding paragraph (e) to read as follows:
§ 87.475 Frequencies.
*****
(e) Frequencies available for differential GPS stations. Frequencies in the
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Federal Communications Commission FCC 96-407
112-118 MHz band may be assigned to Special Category I (SCAT-I) ground stations for 
differential GPS data links.
(1) The frequencies available are on 25 kHz centers with the lowest assignable 
frequency being centered at 112.000 MHz and the highest assignable frequency being centered 
at 117.950 MHz
(2) Applicants must obtain a frequency and time slot assignment from the FAA.
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