Goto Section: 25.225 | 25.250 | Table of Contents

FCC 25.228
Revised as of October 1, 2020
Goto Year:2019 | 2021
  §  25.228   Operating and coordination requirements for earth stations in
motion (ESIMs).

   (a) GSO FSS ESIM transmissions must comport with the applicable EIRP
   density limits in § 25.218, unless coordinated pursuant to the
   requirements in § 25.220.

   (b) Each FSS ESIM must be self-monitoring and, should a condition occur
   that would cause the ESIMs to exceed its authorized off-axis EIRP
   density limits in the case of GSO FSS ESIMs or any emission limits
   included in the licensing conditions in the case of NGSO FSS ESIMs, the
   ESIM must automatically cease transmissions within 100 milliseconds,
   and not resume transmissions until the condition that caused the ESIM
   to exceed those limits is corrected.

   (c) Each FSS ESIM must be monitored and controlled by a network control
   and monitoring center (NCMC) or equivalent facility. Each ESIM must
   comply with a "disable transmission" command from the NCMC within 100
   milliseconds of receiving the command. In addition, the NCMC must
   monitor the operation of each ESIM in its network, and transmit a
   "disable transmission" command to any ESIM that operates in such a way
   as to exceed the authorized off-axis EIRP density limit for GSO FSS
   ESIMs or any emission limits included in the licensing conditions in
   the case of NGSO FSS ESIMs. The NCMC must not allow the ESIM(s) under
   its control to resume transmissions until the condition that caused the
   ESIM(s) to exceed the authorized EIRP density limits is corrected.

   (d) ESIM licensees must ensure installation of ESIM terminals on
   vehicles by qualified installers who have an understanding of the
   antenna's radiation environment and the measures best suited to
   maximize protection of the general public and persons operating the
   vehicle and equipment. An ESIM terminal exhibiting radiation exposure
   levels exceeding 1.0 mW/cm2 in accessible areas, such as at the
   exterior surface of the radome, must have a label attached to the
   surface of the terminal warning about the radiation hazard and must
   include thereon a diagram showing the regions around the terminal where
   the radiation levels could exceed the maximum radiation exposure limit
   specified in 47 CFR 1.1310 Table 1.

   (e) The following requirements govern all ESV operations:

   (1) ESV operators must control all ESVs by a NCMC or equivalent
   facility located in the United States, except that an ESV on
   U.S.-registered vessels may operate under control of a NCMC location
   outside the United States provided the ESV operator maintains a point
   of contact within the United States that will have the capability and
   authority to cause an ESV on a U.S.-registered vessel to cease
   transmitting if necessary.

   (2) There must be a point of contact in the United States, with phone
   number and address, available 24 hours a day, seven days a week, with
   authority and ability to cease all emissions from the ESVs, either
   directly or through the facilities of a U.S. NCMC or a NCMC located in
   another country with which the United States has a bilateral agreement
   that enables such cessation of emissions.

   (3) ESV NCMC operators communicating with ESVs on vessels of foreign
   registry must maintain detailed information on each such vessel's
   country of registry and a point of contact for the relevant
   administration responsible for licensing those ESVs.

   (f) For all VMES operations, there must be a point of contact in the
   United States, with phone number and address, available 24 hours a day,
   seven days a week, with authority and ability to cease all emissions
   from the VMESs.

   (g) The following requirements govern all ESAA operations:

   (1) There must be a point of contact in the United States, with phone
   number and address, available 24 hours a day, seven days a week, with
   authority and ability to cease all emissions from the ESAAs.

   (2) All ESAA terminals operated in U.S. airspace, whether on
   U.S.-registered civil aircraft or non-U.S.-registered civil aircraft,
   must be licensed by the Commission. All ESAA terminals on
   U.S.-registered civil aircraft operating outside of U.S. airspace must
   be licensed by the Commission, except as provided by section 303(t) of
   the Communications Act.

   (3) Prior to operations within a foreign nation's airspace, the ESAA
   operator must ascertain whether the relevant administration has
   operations that could be affected by ESAA terminals, and must determine
   whether that administration has adopted specific requirements
   concerning ESAA operations. When the aircraft enters foreign airspace,
   the ESAA terminal must operate under the Commission's rules, or those
   of the foreign administration, whichever is more constraining. To the
   extent that all relevant administrations have identified geographic
   areas from which ESAA operations would not affect their radio
   operations, ESAA operators may operate within those identified areas
   without further action. To the extent that the foreign administration
   has not adopted requirements regarding ESAA operations, ESAA operators
   must coordinate their operations with any potentially affected

   (h) The following requirements govern all operations in the 3700-4200
   MHz (space-to-Earth) and 5925-6425 MHz (Earth-to-space) frequency bands
   of ESVs receiving from or transmitting to GSO satellites in the
   Fixed-Satellite Service:

   (1) ESVs must not operate in the 5925-6425 MHz (Earth-to-space) and
   3700-4200 MHz (space-to-Earth) frequency bands on vessels smaller than
   300 gross tons.

   (2) ESV operators transmitting in the 5925-6425 MHz (Earth-to-space)
   frequency band to GSO satellites in the Fixed-Satellite Service (FSS)
   must not seek to coordinate, in any geographic location, more than 36
   megahertz of uplink bandwidth on each of no more than two GSO FSS

   (3) ESVs, operating while docked, for which coordination with
   terrestrial stations in the 3700-4200 MHz band is completed in
   accordance with § 25.251, will receive protection from such terrestrial
   stations in accordance with the coordination agreements, for 180 days,
   renewable for 180 days.

   (4) ESVs in motion must not claim protection from harmful interference
   from any authorized terrestrial stations to which frequencies are
   already assigned, or any authorized terrestrial station to which
   frequencies may be assigned in the future in the 3700-4200 MHz
   (space-to-Earth) frequency band.

   (5) ESVs operating within 200 km from the baseline of the United
   States, or within 200 km from a U.S.-licensed fixed service offshore
   installation, must complete coordination with potentially affected
   U.S.-licensed fixed service operators prior to operation. The
   coordination method and the interference criteria objective will be
   determined by the frequency coordinator. The details of the
   coordination must be maintained and available at the frequency
   coordinator, and must be filed with the Commission electronically via
   the International Bureau Filing System
   ( to be placed on public notice. The
   coordination notifications must be filed in the form of a statement
   referencing the relevant call signs and file numbers. Operation of each
   individual ESV may commence immediately after the public notice that
   identifies the notification sent to the Commission is released.
   Continuance of operation of that ESV for the duration of the
   coordination term must be dependent upon successful completion of the
   normal public notice process. If, prior to the end of the 30-day
   comment period of the public notice, any objections are received from
   U.S.-licensed Fixed Service operators that have been excluded from
   coordination, the ESV licensee must immediately cease operation of that
   particular station on frequencies used by the affected U.S.-licensed
   Fixed Service station until the coordination dispute is resolved and
   the ESV licensee informs the Commission of the resolution. As used in
   this section, "baseline" means the line from which maritime zones are
   measured. The baseline is a combination of the low-water line and
   closing lines across the mouths of inland water bodies and is defined
   by a series of baseline points that include islands and "low-water
   elevations," as determined by the U.S. Department of State's Baseline

   (6) An ESV must automatically cease transmission if the ESV operates in
   violation of the terms of its coordination agreement, including, but
   not limited to, conditions related to speed of the vessel or if the ESV
   travels outside the coordinated area, if within 200 km from the
   baseline of the United States, or within 200 km from a U.S.-licensed
   fixed service offshore installation. Transmissions may be controlled by
   the ESV network control and monitoring center. The frequency
   coordinator may decide whether ESV operators should automatically cease
   transmissions if the vessel falls below a prescribed speed within a
   prescribed geographic area.

   (7) ESV transmissions in the 5925-6425 MHz (Earth-to-space) band shall
   not exceed an EIRP spectral density towards the radio-horizon of 17
   dBW/MHz, and shall not exceed an EIRP towards the radio-horizon of 20.8
   dBW. The ESV network shall shut-off the ESV transmitter if either the
   EIRP spectral density towards the radio-horizon or the EIRP towards the
   radio-horizon is exceeded.

   (i) For ESAA transmissions in the 14.0-14.5 GHz band from international
   airspace within line-of-sight of the territory of a foreign
   administration where fixed service networks have primary allocation in
   this band, the maximum power flux density (pfd) produced at the surface
   of the Earth by emissions from a single aircraft carrying an ESAA
   terminal must not exceed the following values unless the foreign
   Administration has imposed other conditions for protecting its fixed
   service stations:

   -132 + 0.5  th dB(W/(m^2  MHz)) For th <= 40°.
   -112            dB(W/(m^2  MHz)) For 40° 25.228(j)(3)--Applicable Radio Astronomy Service (RAS)
   Facilities and Associated Coordination Distances
   Observatory Latitude (north) Longitude (west) Radius (km) of
   coordination zone
   Arecibo, Observatory, Arecibo, PR 18°20'37'' 66°45'11'' Island of
   Puerto Rico.
   Green Bank, WV 38°25'59'' 79°50'23'' 160.
   Very Large Array, near Socorro, NM 34°04'44'' 107°37'06'' 160.
   Pisgah Astronomical Research Institute, Rosman, NC 35°11'59''
   82°52'19'' 160.
   U of Michigan Radio Astronomy Observatory, Stinchfield Woods, MI
   42°23'56'' 83°56'11'' 160.
   Very Long Baseline Array (VLBA) stations:
   Owens Valley, CA 37°13'54'' 118°16'37'' 160*.
   Mauna Kea, HI 19°48'05'' 155°27'20'' 50.
   Brewster, WA 48°07'52'' 119°41'00'' 50.
   Kitt Peak, AZ 31°57'23'' 111°36'45'' 50.
   Pie Town, NM 34°18'04'' 108°07'09'' 50.
   Los Alamos, NM 35°46'30'' 106°14'44'' 50.
   Fort Davis, TX 30°38'06'' 103°56'41'' 50.
   North Liberty, IA 41°46'17'' 91°34'27'' 50.
   Hancock, NH 42°56'01'' 71°59'12'' 50.
   St. Croix, VI 17°45'24'' 64°35'01'' 50.

   *Owens Valley, CA operates both a VLBA station and single-dish

   (4) When NTIA seeks to provide similar protection to future RAS sites
   that have been coordinated through the IRAC Frequency Assignment
   Subcommittee process, NTIA will notify the Commission's International
   Bureau that the site is nearing operational status. Upon public notice
   from the International Bureau, all Ku-band ESIMs licensees must cease
   operations in the 14.47-14.5 GHz band within the relevant geographic
   zone (160 kms for single-dish radio observatories and Very Large Array
   antenna systems and 50 kms for Very Long Baseline Array antenna systems
   for ESVs and VMESs, radio line of sight for ESAAs) of the new RAS site
   until the licensees complete coordination for the new RAS facility.
   Licensees must notify the International Bureau once they have completed
   coordination for the new RAS site and must submit the coordination
   agreement to the Commission. Upon receipt of such notification from a
   licensee, the International Bureau will issue a public notice stating
   that the licensee may commence operations within the coordination zone
   in 30 days if no party opposed the operations. The ESIMs licensee then
   will be permitted to commence operations in the 14.47-14.5 GHz band
   within the relevant coordination distance around the new RAS site,
   subject to any operational constraints developed in the coordination

   (5) ESIMs licensees must use Global Positioning Satellite-related or
   other similar position location technology to ensure compliance with
   the provisions of subparagraphs 1-3 of this paragraph.

   [ 84 FR 53656 , Oct. 8, 2019, as amended at  85 FR 44787 , July 24, 2020]


Goto Section: 25.225 | 25.250

Goto Year: 2019 | 2021
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