Goto Section: 27.52 | 27.54 | Table of Contents

FCC 27.53
Revised as of October 2, 2015
Goto Year:2014 | 2016
§ 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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