§ 27.53   Emission limits.

   (a) For operations in the 2305-2320 MHz band and the 2345-2360 MHz
   band, the power of any emission outside a licensee's frequency band(s)
   of operation shall be attenuated below the transmitter power P (with
   averaging performed only during periods of transmission) within the
   licensed band(s) of operation, in watts, by the following amounts:

   (1) For base and fixed stations' operations in the 2305-2320 MHz band
   and the 2345-2360 MHz band:

   (i) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2305 and 2320 MHz and on all frequencies between 2345 and 2360
   MHz that are outside the licensed band(s) of operation, and not less
   than 75 + 10 log (P) dB on all frequencies between 2320 and 2345 MHz;

   (ii) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2300 and 2305 MHz, 70 + 10 log (P) dB on all frequencies
   between 2287.5 and 2300 MHz, 72 + 10 log (P) dB on all frequencies
   between 2285 and 2287.5 MHz, and 75 + 10 log (P) dB below 2285 MHz;

   (iii) By a factor of not less than 43 + 10 log (P) dB on all
   frequencies between 2360 and 2362.5 MHz, 55 + 10 log (P) dB on all
   frequencies between 2362.5 and 2365 MHz, 70 + 10 log (P) dB on all
   frequencies between 2365 and 2367.5 MHz, 72 + 10 log (P) dB on all
   frequencies between 2367.5 and 2370 MHz, and 75 + 10 log (P) dB above
   2370 MHz.

   (2) For fixed customer premises equipment (CPE) stations operating in
   the 2305-2320 MHz band and the 2345-2360 MHz band transmitting with
   more than 2 watts per 5 megahertz average EIRP:

   (i) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2305 and 2320 MHz and on all frequencies between 2345 and 2360
   MHz that are outside the licensed band(s) of operation, and not less
   than 75 + 10 log (P) dB on all frequencies between 2320 and 2345 MHz;

   (ii) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2300 and 2305 MHz, 70 + 10 log (P) dB on all frequencies
   between 2287.5 and 2300 MHz, 72 + 10 log (P) dB on all frequencies
   between 2285 and 2287.5 MHz, and 75 + 10 log (P) dB below 2285 MHz;

   (iii) By a factor of not less than 43 + 10 log (P) dB on all
   frequencies between 2360 and 2362.5 MHz, 55 + 10 log (P) dB on all
   frequencies between 2362.5 and 2365 MHz, 70 + 10 log (P) dB on all
   frequencies between 2365 and 2367.5 MHz, 72 + 10 log (P) dB on all
   frequencies between 2367.5 and 2370 MHz, and 75 + 10 log (P) dB above
   2370 MHz.

   (3) For fixed CPE stations operating in the 2305-2320 MHz and 2345-2360
   MHz bands transmitting with 2 watts per 5 megahertz average EIRP or
   less:

   (i) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2305 and 2320 MHz and on all frequencies between 2345 and 2360
   MHz that are outside the licensed band(s) of operation, not less than
   55 + 10 log (P) dB on all frequencies between 2320 and 2324 MHz and
   between 2341 and 2345 MHz, not less than 61 + 10 log (P) dB on all
   frequencies between 2324 and 2328 MHz and between 2337 and 2341 MHz,
   and not less than 67 + 10 log (P) dB on all frequencies between 2328
   and 2337 MHz;

   (ii) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2300 and 2305 MHz, 55 + 10 log (P) dB on all frequencies
   between 2296 and 2300 MHz, 61 + 10 log (P) dB on all frequencies
   between 2292 and 2296 MHz, 67 + 10 log (P) dB on all frequencies
   between 2288 and 2292 MHz, and 70 + 10 log (P) dB below 2288 MHz;

   (iii) By a factor of not less than 43 + 10 log (P) dB on all
   frequencies between 2360 and 2365 MHz, and not less than 70 + 10 log
   (P) dB above 2365 MHz.

   (4) For mobile and portable stations operating in the 2305-2315 MHz and
   2350-2360 MHz bands:

   (i) By a factor of not less than: 43 + 10 log (P) dB on all frequencies
   between 2305 and 2320 MHz and on all frequencies between 2345 and 2360
   MHz that are outside the licensed band(s) of operation, not less than
   55 + 10 log (P) dB on all frequencies between 2320 and 2324 MHz and on
   all frequencies between 2341 and 2345 MHz, not less than 61 + 10 log
   (P) dB on all frequencies between 2324 and 2328 MHz and on all
   frequencies between 2337 and 2341 MHz, and not less than 67 + 10 log
   (P) dB on all frequencies between 2328 and 2337 MHz;

   (ii) By a factor of not less than 43 + 10 log (P) dB on all frequencies
   between 2300 and 2305 MHz, 55 + 10 log (P) dB on all frequencies
   between 2296 and 2300 MHz, 61 + 10 log (P) dB on all frequencies
   between 2292 and 2296 MHz, 67 + 10 log (P) dB on all frequencies
   between 2288 and 2292 MHz, and 70 + 10 log (P) dB below 2288 MHz;

   (iii) By a factor of not less than 43 + 10 log (P) dB on all
   frequencies between 2360 and 2365 MHz, and not less than 70 + 10 log
   (P) dB above 2365 MHz.

   (5) Measurement procedure. Compliance with these rules is based on the
   use of measurement instrumentation employing a resolution bandwidth of
   1 MHz or greater. However, in the 1 MHz bands immediately outside and
   adjacent to the channel blocks at 2305, 2310, 2315, 2320, 2345, 2350,
   2355, and 2360 MHz, a resolution bandwidth of at least 1 percent of the
   emission bandwidth of the fundamental emission of the transmitter may
   be employed. A narrower resolution bandwidth is permitted in all cases
   to improve measurement accuracy provided the measured power is
   integrated over the full required measurement bandwidth (i.e., 1 MHz).
   The emission bandwidth is defined as the width of the signal between
   two points, one below the carrier center frequency and one above the
   carrier center frequency, outside of which all emissions are attenuated
   at least 26 dB below the transmitter power.

   (6) [Reserved]

   (7) The measurements of emission power can be expressed in peak or
   average values, provided they are expressed in the same parameters as
   the transmitter power;

   (8) Waiver requests of any of the out-of-band emission limits in
   paragraphs (a)(1) through (a)(7) of this section shall be entertained
   only if interference protection equivalent to that afforded by the
   limits is shown;

   (9) [Reserved]

   (10) The out-of-band emissions limits in paragraphs (a)(1) through
   (a)(3) of this section may be modified by the private contractual
   agreement of all affected licensees, who must maintain a copy of the
   agreement in their station files and disclose it to prospective
   assignees, transferees, or spectrum lessees and, upon request, to the
   Commission.

   (b) For WCS Satellite DARS operations: The limits set forth in
   § 25.202(f) of this chapter shall apply, except that Satellite DARS
   operations shall be limited to a maximum power flux density of −197
   dBW/m2/4 kHz in the 2370-2390 MHz band at Arecibo, Puerto Rico.

   (c) For operations in the 746-758 MHz band and the 776-788 MHz band,
   the power of any emission outside the licensee's frequency band(s) of
   operation shall be attenuated below the transmitter power (P) within
   the licensed band(s) of operation, measured in watts, in accordance
   with the following:

   (1) On any frequency outside the 746-758 MHz band, the power of any
   emission shall be attenuated outside the band below the transmitter
   power (P) by at least 43 + 10 log (P) dB;

   (2) On any frequency outside the 776-788 MHz band, the power of any
   emission shall be attenuated outside the band below the transmitter
   power (P) by at least 43 + 10 log (P) dB;

   (3) On all frequencies between 763-775 MHz and 793-805 MHz, by a factor
   not less than 76 + 10 log (P) dB in a 6.25 kHz band segment, for base
   and fixed stations;

   (4) On all frequencies between 763-775 MHz and 793-805 MHz, by a factor
   not less than 65 + 10 log (P) dB in a 6.25 kHz band segment, for mobile
   and portable stations;

   (5) Compliance with the provisions of paragraphs (c)(1) and (c)(2) of
   this section is based on the use of measurement instrumentation
   employing a resolution bandwidth of 100 kHz or greater. However, in the
   100 kHz bands immediately outside and adjacent to the frequency block,
   a resolution bandwidth of at least 30 kHz may be employed;

   (6) Compliance with the provisions of paragraphs (c)(3) and (c)(4) of
   this section is based on the use of measurement instrumentation such
   that the reading taken with any resolution bandwidth setting should be
   adjusted to indicate spectral energy in a 6.25 kHz segment.

   (d) [Reserved]

   (e) For operations in the 775-776 MHz and 805-806 MHz bands,
   transmitters must comply with either paragraphs (d)(1) through (5) of
   this section or the ACP emission limitations set forth in paragraphs
   (d)(6) to (d)(9) of this section.

   (1) On all frequencies between 758-775 MHz and 788-805 MHz, the power
   of any emission outside the licensee's frequency bands of operation
   shall be attenuated below the transmitter power (P) within the licensed
   band(s) of operation, measured in watts, by a factor not less than 76 +
   10 log (P) dB in a 6.25 kHz band segment, for base and fixed stations;

   (2) On all frequencies between 758-775 MHz and 788-805 MHz, the power
   of any emission outside the licensee's frequency bands of operation
   shall be attenuated below the transmitter power (P) within the licensed
   band(s) of operation, measured in watts, by a factor not less than 65 +
   10 log (P) dB in a 6.25 kHz band segment, for mobile and portable
   stations;

   (3) On any frequency outside the 775-776 MHz and 805-806 MHz bands, the
   power of any emission shall be attenuated outside the band below the
   transmitter power (P) within the licensed band(s) of operation,
   measured in watts, by at least 43 + 10 log (P) dB;

   (4) Compliance with the provisions of paragraphs (e)(1) and (e)(2) of
   this section is based on the use of measurement instrumentation such
   that the reading taken with any resolution bandwidth setting should be
   adjusted to indicate spectral energy in a 6.25 kHz segment;

   (5) Compliance with the provisions of paragraph (e)(3) of this section
   is based on the use of measurement instrumentation employing a
   resolution bandwidth of 100 kHz or greater. However, in the 100 kHz
   bands immediately outside and adjacent to the frequency block, a
   resolution bandwidth of at least 30 kHz may be employed.

   (6) The adjacent channel power (ACP) requirements for transmitters
   designed for various channel sizes are shown in the following tables.
   Mobile station requirements apply to handheld, car mounted and control
   station units. The tables specify a value for the ACP as a function of
   the displacement from the channel center frequency and measurement
   bandwidth. In the following tables, “(s)” indicates a swept measurement
   may be used.

   6.25 kHz Mobile Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         6.25                           6.25  −40
         12.5                           6.25  −60
         18.75                          6.25  −60
         25.00                          6.25  −65
         37.50                         25.00  −65
         62.50                         25.00  −65
         87.50                         25.00  −65
         150.00                        100.00 −65
         250.00                        100.00 −65
         350.00                        100.00 −65
         >400 kHz to 12 MHz            30(s)  −75
         12 MHz to paired receive band 30(s)  −75
         In the paired receive band    30(s)  −100

   12.5 kHz Mobile Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         9.375                         6.25  −40
         15.625                        6.25  −60
         21.875                        6.25  −60
         37.50                         25.00 −60
         62.50                         25.00 −65
         87.50                         25.00 −65
         150.00                         100  −65
         250.00                         100  −65
         350.00                         100  −65
         >400 to 12 MHz                30(s) −75
         12 MHz to paired receive band 30(s) −75
         In the paired receive band    30(s) −100

   25 kHz Mobile Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         15.625                        6.25  −40
         21.875                        6.25  −60
         37.50                          25   −60
         62.50                          25   −65
         87.50                          25   −65
         150.00                         100  −65
         250.00                         100  −65
         350.00                         100  −65
         >400 kHz to 12 MHz            30(s) −75
         12 MHz to paired receive band 30(s) −75
         In the paired receive band    30(s) −100

   150 kHz Mobile Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP relative (dBc)
         100                         50   −40
         200                         50   −50
         300                         50   −50
         400                         50   −50
         600-1000                   30(s) −60
         1000 to receive band       30(s) −70
         In the receive band        30(s) −100

   6.25 kHz Base Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         6.25                          6.25  −40
         12.50                         6.25  −60
         18.75                         6.25  −60
         25.00                         6.25  −65
         37.50                          25   −65
         62.50                          25   −65
         87.50                          25   −65
         150.00                         100  −65
         250.00                         100  −65
         350.00                         100  −65
         >400 kHz to 12 MHz            30(s) −80
         12 MHz to paired receive band 30(s) −80
         In the paired receive band    30(s) ^1−85

   ^1Although we permit individual base transmitters to radiate a maximum
   ACP of −85 dBc in the paired receive band, licensees deploying these
   transmitters may not exceed an ACP of −100 dBc in the paired receive
   band when measured at either the transmitting antenna input port or the
   output of the transmitter combining network. Consequently, licensees
   deploying these transmitters may need to use external filters to comply
   with the more restrictive ACP limit.

   12.5 kHz Base Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         9.375                         6.25  −40
         15.625                        6.25  −60
         21.875                        6.25  −60
         37.5                           25   −60
         62.5                           25   −65
         87.5                           25   −65
         150                            100  −65
         250                            100  −65
         350.00                         100  −65
         >400 kHz to 12 MHz            30(s) −80
         12 MHz to paired receive band 30(s) −80
         In the paired receive band    30(s) ^1−85

   ^1Although we permit individual base transmitters to radiate a maximum
   ACP of −85 dBc in the paired receive band, licensees deploying these
   transmitters may not exceed an ACP of −100 dBc in the paired receive
   band when measured at either the transmitting antenna input port or the
   output of the transmitter combining network. Consequently, licensees
   deploying these transmitters may need to use external filters to comply
   with the more restrictive ACP limit.

   25 kHz Base Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         15.625                         6.25  −40
         21.875                         6.25  −60
         37.5                            25   −60
         62.5                            25   −65
         87.5                            25   −65
         150                            100   −65
         250                            100   −65
         350                           100.00 −65
         >400 kHz to 12 MHz            30(s)  −80
         12 MHz to paired receive band 30(s)  −80
         In the paired receive band    30(s)  ^1−85

   ^1Although we permit individual base transmitters to radiate a maximum
   ACP of −85 dBc in the paired receive band, licensees deploying these
   transmitters may not exceed an ACP of −100 dBc in the paired receive
   band when measured at either the transmitting antenna input port or the
   output of the transmitter combining network. Consequently, licensees
   deploying these transmitters may need to use external filters to comply
   with the more restrictive ACP limit.

   150 kHz Base Transmitter ACP Requirements
   Offset from center
   frequency
   (kHz) Measurement bandwidth
   (kHz) Maximum ACP
   (dBc)
         100                   50   −40
         200                   50   −50
         300                   50   −55
         400                   50   −60
         600-1000             30(s) −65
         1000 to receive band 30(s) −75 (continues at −6dB/oct
         In the receive band  30(s) ^1−85

   ^1Although we permit individual base transmitters to radiate a maximum
   ACP of −85 dBc in the paired receive band, licensees deploying these
   transmitters may not exceed an ACP of −100 dBc in the paired receive
   band when measured at either the transmitting antenna input port or the
   output of the transmitter combining network. Consequently, licensees
   deploying these transmitters may need to use external filters to comply
   with the more restrictive ACP limit.

   (7) ACP measurement procedure. The following procedures are to be
   followed for making ACP transmitter measurements. For time division
   multiple access (TDMA) systems, the measurements are to be made under
   TDMA operation only during time slots when the transmitter is on. All
   measurements must be made at the input to the transmitter's antenna.
   Measurement bandwidth used below implies an instrument that measures
   the power in many narrow bandwidths (e.g., 300 Hz) and integrates these
   powers across a larger band to determine power in the measurement
   bandwidth.

   (i) Setting reference level. Using a spectrum analyzer capable of ACP
   measurements, set the measurement bandwidth to the channel size. For
   example, for a 6.25 kHz transmitter, set the measurement bandwidth to
   6.25 kHz; for a 150 kHz transmitter, set the measurement bandwidth to
   150 kHz. Set the frequency offset of the measurement bandwidth to zero
   and adjust the center frequency of the spectrum analyzer to give the
   power level in the measurement bandwidth. Record this power level in
   dBm as the “reference power level”.

   (ii) Non-swept power measurement. Using a spectrum analyzer capable of
   ACP measurements, set the measurement bandwidth as shown in the tables
   above. Measure the ACP in dBm. These measurements should be made at
   maximum power. Calculate the coupled power by subtracting the
   measurements made in this step from the reference power measured in the
   previous step. The absolute ACP values must be less than the values
   given in the table for each condition above.

   (iii) Swept power measurement. Set a spectrum analyzer to 30 kHz
   resolution bandwidth, 1 MHz video bandwidth and sample mode detection.
   Sweep ±MHz from the carrier frequency. Set the reference level to the
   RMS value of the transmitter power and note the absolute power. The
   response at frequencies greater than 600 kHz must be less than the
   values in the tables above.

   (8) Out-of-band emission limit. On any frequency outside of the
   frequency ranges covered by the ACP tables in this section, the power
   of any emission must be reduced below the unmodulated carrier power (P)
   by at least 43 + 10 log (P) dB.

   (9) Authorized bandwidth. Provided that the ACP requirements of this
   section are met, applicants may request any authorized bandwidth that
   does not exceed the channel size.

   (f) For operations in the 746-758 MHz, 775-788 MHz, and 805-806 MHz
   bands, emissions in the band 1559-1610 MHz shall be limited to −70
   dBW/MHz equivalent isotropically radiated power (EIRP) for wideband
   signals, and −80 dBW EIRP for discrete emissions of less than 700 Hz
   bandwidth. For the purpose of equipment authorization, a transmitter
   shall be tested with an antenna that is representative of the type that
   will be used with the equipment in normal operation.

   (g) For operations in the 600 MHz band and the 698-746 MHz band, the
   power of any emission outside a licensee's frequency band(s) of
   operation shall be attenuated below the transmitter power (P) within
   the licensed band(s) of operation, measured in watts, by at least 43 +
   10 log (P) dB. Compliance with this provision is based on the use of
   measurement instrumentation employing a resolution bandwidth of 100
   kilohertz or greater. However, in the 100 kilohertz bands immediately
   outside and adjacent to a licensee's frequency block, a resolution
   bandwidth of at least 30 kHz may be employed.

   (h) AWS emission limits—(1) General protection levels. Except as
   otherwise specified below, for operations in the 1695-1710 MHz,
   1710-1755 MHz, 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000-2020
   MHz, 2110-2155 MHz, 2155-2180 MHz, and 2180-2200 bands, the power of
   any emission outside a licensee's frequency block shall be attenuated
   below the transmitter power (P) in watts by at least 43 + 10 log10 (P)
   dB.

   (2) Additional protection levels. Notwithstanding the foregoing
   paragraph (h)(1) of this section:

   (i) Operations in the 2180-2200 MHz band are subject to the out-of-band
   emission requirements set forth in § 27.1134 for the protection of
   federal government operations operating in the 2200-2290 MHz band.

   (ii) For operations in the 2000-2020 MHz band, the power of any
   emissions below 2000 MHz shall be attenuated below the transmitter
   power (P) in watts by at least 70 + 10 log10(P) dB.

   (iii) For operations in the 1915-1920 MHz band, the power of any
   emission between 1930-1995 MHz shall be attenuated below the
   transmitter power (P) in watts by at least 70 + 10 log10(P) dB.

   (iv) For operations in the 1995-2000 MHz band, the power of any
   emission between 2005-2020 MHz shall be attenuated below the
   transmitter power (P) in watts by at least 70 + 10 log10(P) dB.

   (3) Measurement procedure. (i) Compliance with this provision is based
   on the use of measurement instrumentation employing a resolution
   bandwidth of 1 megahertz or greater. However, in the 1 megahertz bands
   immediately outside and adjacent to the licensee's frequency block, a
   resolution bandwidth of at least one percent of the emission bandwidth
   of the fundamental emission of the transmitter may be employed. The
   emission bandwidth is defined as the width of the signal between two
   points, one below the carrier center frequency and one above the
   carrier center frequency, outside of which all emissions are attenuated
   at least 26 dB below the transmitter power.

   (ii) When measuring the emission limits, the nominal carrier frequency
   shall be adjusted as close to the licensee's frequency block edges,
   both upper and lower, as the design permits.

   (iii) The measurements of emission power can be expressed in peak or
   average values, provided they are expressed in the same parameters as
   the transmitter power.

   (4) Private agreements. (i) For AWS operations in the 2000-2020 MHz and
   2180-2200 MHz bands, to the extent a licensee establishes unified
   operations across the AWS blocks, that licensee may choose not to
   observe the emission limit specified in paragraph (h)(1), above,
   strictly between its adjacent block licenses in a geographic area, so
   long as it complies with other Commission rules and is not adversely
   affecting the operations of other parties by virtue of exceeding the
   emission limit.

   (ii) For AWS operations in the 2000-2020 MHz band, a licensee may enter
   into private agreements with all licensees operating between 1995 and
   2000 MHz to allow the 70 + 10 log10(P) dB limit to be exceeded within
   the 1995-2000 MHz band.

   (iii) An AWS licensee who is a party to a private agreement described
   in this section (4) must maintain a copy of the agreement in its
   station files and disclose it, upon request, to prospective AWS
   assignees, transferees, or spectrum lessees and to the Commission.

   (i) When an emission outside of the authorized bandwidth causes harmful
   interference, the Commission may, at its discretion, require greater
   attenuation than specified in this section.

   (j)(1) For operations in the unpaired 1390-1392 MHz band and the paired
   1392-1395 MHz and 1432-1435 MHz bands, the power of any emission
   outside the licensee's frequency band(s) of operation shall be
   attenuated below the transmitter power (P) by at least 43 + 10 log (P)
   dB. Compliance with these provisions is based on the procedures
   described in paragraph (a)(4) of this section.

   (2) In the 1390-1395 MHz and 1432-1435 MHz bands, licensees are
   encouraged to take all reasonable steps to ensure that unwanted
   emission power does not exceed the following levels in the band
   1400-1427 MHz:

   (i) For stations of point-to-point systems in the fixed service: −45
   dBW/27 MHz.

   (ii) For stations in the mobile service: −60 dBW/27 MHz.

   (k) For operations in the 1670-1675 MHz band, the power of any emission
   outside the licensee's frequency band(s) of operation shall be
   attenuated below the transmitter power (P) by at least 43 + 10 log (P)
   dB. Compliance with these provisions is based on the procedures
   described in paragraph (a)(4) of this section.

   (l) [Reserved]

   (m) For BRS and EBS stations, the power of any emissions outside the
   licensee's frequency bands of operation shall be attenuated below the
   transmitter power (P) measured in watts in accordance with the
   standards below. If a licensee has multiple contiguous channels,
   out-of-band emissions shall be measured from the upper and lower edges
   of the contiguous channels.

   (1) Prior to the transition, and thereafter, solely within the MBS, for
   analog operations with an EIRP in excess of −9 dBW, the signal shall be
   attenuated at the channel edges by at least 38 dB relative to the peak
   visual carrier, then linearly sloping from that level to at least 60 dB
   of attenuation at 1 MHz below the lower band edge and 0.5 MHz above the
   upper band edge, and attenuated at least 60 dB at all other
   frequencies.

   (2) For digital base stations, the attenuation shall be not less than
   43 + 10 log (P) dB, unless a documented interference complaint is
   received from an adjacent channel licensee with an overlapping
   Geographic Service Area. Mobile Satellite Service licensees operating
   on frequencies below 2495 MHz may also submit a documented interference
   complaint against BRS licensees operating on channel BRS No. 1 on the
   same terms and conditions as adjacent channel BRS or EBS licensees.
   Provided that a documented interference complaint cannot be mutually
   resolved between the parties prior to the applicable deadline, then the
   following additional attenuation requirements shall apply:

   (i) If a pre-existing base station suffers harmful interference from
   emissions caused by a new or modified base station located 1.5 km or
   more away, within 24 hours of the receipt of a documented interference
   complaint the licensee of the new or modified base station must
   attenuate its emissions by at least 67 + 10 log (P) dB measured at 3
   megahertz, above or below, from the channel edge of its frequency block
   and shall immediately notify the complaining licensee upon
   implementation of the additional attenuation. No later than 60 days
   after the implementation of such additional attenuation, the licensee
   of the complaining base station must attenuate its base station
   emissions by at least 67 + 10 log (P) dB measured at 3 megahertz, above
   or below, from the channel edge of its frequency block of the new or
   modified base station.

   (ii) If a pre-existing base station suffers harmful interference from
   emissions caused by a new or modified base station located less than
   1.5 km away, within 24 hours of receipt of a documented interference
   complaint the licensee of the new or modified base station must
   attenuate its emissions by at least 67 + 10 log (P)−20 log (Dkm/1.5) dB
   measured at 3 megahertz, above or below, from the channel edge of its
   frequency block of the complaining licensee, or if both base stations
   are co-located, limit its undesired signal level at the pre-existing
   base station receiver(s) to no more than −107 dBm measured in a 5.5
   megahertz bandwidth and shall immediately notify the complaining
   licensee upon such reduction in the undesired signal level. No later
   than 60 days after such reduction in the undesired signal level, the
   complaining licensee must attenuate its base station emissions by at
   least 67 + 10 log (P) dB measured at 3 megahertz, above or below, from
   the channel edge of its frequency block of the new or modified base
   station.

   (iii) If a new or modified base station suffers harmful interference
   from emissions caused by a pre-existing base station located 1.5 km or
   more away, within 60 days of receipt of a documented interference
   complaint the licensee of each base station must attenuate its base
   station emissions by at least 67 + 10 log (P) dB measured at 3
   megahertz, above or below, from the channel edge of its frequency block
   of the other licensee.

   (iv) If a new or modified base station suffers harmful interference
   from emissions caused by a pre-existing base station located less than
   1.5 km away, within 60 days of receipt of a documented interference
   complaint: (a) The licensee of the new or modified base station must
   attenuate its OOBE by at least 67 + 10 log (P)−20 log (Dkm/1.5)
   measured 3 megahertz above or below, from the channel edge of its
   frequency block of the other licensee, or if the base stations are
   co-located, limit its undesired signal level at the other base station
   receiver(s) to no more than −107 dBm measured in a 5.5-megahertz
   bandwidth; and (b) the licensee causing the interference must attenuate
   its emissions by at least 67 + 10 log (P) dB measured at 3 megahertz,
   above or below, from the channel edge of its frequency block of the new
   or modified base station.

   (v) For all fixed digital user stations, the attenuation factor shall
   be not less than 43 + 10 log (P) dB at the channel edge.

   (3) Prior to transition and thereafter solely within the MBS, and
   notwithstanding paragraph (l)(2) of this section, the maximum
   out-of-band power of a digital transmitter operating on a single 6 MHz
   channel with an EIRP in excess of −9 dBW employing digital modulation
   for the primary purpose of transmitting video programming shall be
   attenuated at the 6 MHz channel edges at least 25 dB relative to the
   licensed average 6 MHz channel power level, then attenuated along a
   linear slope to at least 40 dB at 250 kHz beyond the nearest channel
   edge, then attenuated along a linear slope from that level to at least
   60 dB at 3 MHz above the upper and below the lower licensed channel
   edges, and attenuated at least 60 dB at all other frequencies.

   (4) For mobile digital stations, the attenuation factor shall be not
   less than 40 + 10 log (P) dB on all frequencies between the channel
   edge and 5 megahertz from the channel edge, 43 + 10 log (P) dB on all
   frequencies between 5 megahertz and X megahertz from the channel edge,
   and 55 + 10 log (P) dB on all frequencies more than X megahertz from
   the channel edge, where X is the greater of 6 megahertz or the actual
   emission bandwidth as defined in paragraph (m)(6) of this section. In
   addition, the attenuation factor shall not be less that 43 + 10 log (P)
   dB on all frequencies between 2490.5 MHz and 2496 MHz and 55 + 10 log
   (P) dB at or below 2490.5 MHz. Mobile Satellite Service licensees
   operating on frequencies below 2495 MHz may also submit a documented
   interference complaint against BRS licensees operating on channel BRS
   Channel 1 on the same terms and conditions as adjacent channel BRS or
   EBS licensees.

   (5) Notwithstanding the provisions of paragraphs (l)(2) and (l)(4) of
   this section, prior to transition, a licensee may continue to operate
   facilities deployed as of January 10, 2005 provided that such
   facilities operate in compliance with the emission mask applicable to
   those services prior to January 10, 2005.

   (6) Measurement procedure. Compliance with these rules is based on the
   use of measurement instrumentation employing a resolution bandwidth of
   1 megahertz or greater. However, in the 1 MHz bands immediately outside
   and adjacent to the frequency block a resolution bandwidth of at least
   one percent of the emission bandwidth of the fundamental emission of
   the transmitter may be employed; for mobile digital stations, in the 1
   megahertz bands immediately outside and adjacent to the frequency block
   a resolution bandwidth of at least two percent may be employed, except
   when the 1 megahertz band is 2495-2496 MHz, in which case a resolution
   bandwidth of at least one percent may be employed. A narrower
   resolution bandwidth is permitted in all cases to improve measurement
   accuracy provided the measured power is integrated over the full
   required measurement bandwidth (i.e. 1 megahertz or 1 percent of
   emission bandwidth, as specified; or 1 megahertz or 2 percent for
   mobile digital stations, except in the band 2495-2496 MHz). The
   emission bandwidth is defined as the width of the signal between two
   points, one below the carrier center frequency and one above the
   carrier center frequency, outside of which all emissions are attenuated
   at least 26 dB below the transmitter power. With respect to television
   operations, measurements must be made of the separate visual and aural
   operating powers at sufficiently frequent intervals to ensure
   compliance with the rules.

   (7) Alternative out of band emission limit. Licensees in this service
   may establish an alternative out of band emission limit to be used at
   specified band edge(s) in specified geographical areas, in lieu of that
   set forth in this section, pursuant to a private contractual
   arrangement of all affected licensees and applicants. In this event,
   each party to such contract shall maintain a copy of the contract in
   their station files and disclose it to prospective assignees or
   transferees and, upon request, to the FCC.

   (n) When an emission outside of the authorized bandwidth causes harmful
   interference, the Commission may, at its discretion, require greater
   attenuation than specified in this section.

   [ 62 FR 16497 , Apr. 7, 1997]

   Editorial Note: For Federal Register citations affecting § 27.53, see
   the List of CFR Sections Affected, which appears in the Finding Aids
   section of the printed volume and at www.fdsys.gov.

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