Sec.  87.139   Emission limitations.

   (a) Except for 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:

   (1) When the frequency is removed from the assigned frequency by more than
   50 percent up to and including 100 percent of the authorized bandwidth the
   attenuation must be at least 25 dB;

   (2) When the frequency is removed from the assigned frequency by more than
   100 percent up to and including 250 percent of the authorized bandwidth the
   attenuation must be at least 35 dB.

   (3) When the frequency is removed from the assigned frequency by more than
   250 percent of the authorized bandwidth the attenuation for aircraft station
   transmitters must be at least 40 dB; and the attenuation for aeronautical
   station transmitters must be at least 43 + 10 log[10] pY dB.

   (b) For aircraft station transmitters and for aeronautical station
   transmitters first installed before February 1, 1983, and using H2B, H3E,
   J3E, J7B or J9W, the mean power of any emissions must be attenuated below
   the mean power of the transmitter (pY) as follows:

   (1) When the frequency is removed from the assigned frequency by more than
   50 percent up to and including 150 percent of the authorized bandwidth of
   4.0 kHz, the attenuation must be at least 25 dB.

   (2) When the frequency is removed from the assigned frequency by more than
   150 percent up to and including 250 percent of the authorized bandwidth of
   4.0 kHz, the attenuation must be at least 35 dB.

   (3) When the frequency is removed from the assigned frequency by more than
   250 percent of the authorized bandwidth of 4.0 kHz for aircraft station
   transmitters the attenuation must be at least 40 dB; and for aeronautical
   station transmitters the attenuation must be at least 43 + 10 log[10] pY dB.

   (c) For aircraft station transmitters first installed after February 1,
   1983, and for aeronautical station transmitters in use after February 1,
   1983, and using H2B, H3E, J3E, J7B or J9W, the peak envelope power of any
   emissions must be attenuated below the peak envelope power of the
   transmitter (pX) as follows:

   (1) When the frequency is removed from the assigned frequency by more than
   50 percent up to and including 150 percent of the authorized bandwidth of
   3.0 kHz, the attenuation must be at least 30 dB.

   (2) When the frequency is removed from the assigned frequency by more than
   150 percent up to and including 250 percent of the authorized bandwidth of
   3.0 kHz, the attenuation must be at least 38 dB.

   (3) When the frequency is removed from the assigned frequency by more than
   250 percent of the authorized bandwidth of 3.0 kHz for aircraft transmitters
   the attenuation must be at least 43 dB. For aeronautical station
   transmitters with transmitter power up to and including 50 watts the
   attenuation must be at least 43 + 10 log[10] pX dB and with transmitter
   power more than 50 watts the attenuation must be at least 60 dB.

   (d) Except for telemetry in the 1435–1535 MHz band, when the frequency is
   removed from the assigned frequency by more than 250 percent of the
   authorized bandwidth for aircraft stations above 30 MHz and all ground
   stations the attenuation must be at least 43+10 log[10] pY dB.

   (e) When using frequency modulation or digital modulation for telemetry or
   telecommand in the 1435–1535 MHz and 2310–2390 MHz frequency bands with an
   authorized bandwidth equal to or less than 1 MHz the emissions must be
   attenuated as follows:

   (1) On any frequency removed from the assigned frequency by more than 100
   percent of the authorized bandwidth up to and including 100 percent plus 0.5
   MHz, the attenuation must be at least 60 dB, when measured in a 3.0 kHz
   bandwidth. This signal need not be attenuated more than 25 dB below 1
   milliwatt.

   (2) On any frequency removed from the assigned frequency by more than 100
   percent of the authorized bandwidth plus 0.5 MHz, the attenuation must be at
   least 55 + 10 log[10] pY dB when measured in a 3.0 kHz bandwidth.

   (f) When using frequency modulation or digital modulation for telemetry or
   telecommand in the 1435–1535 MHz or 2310–2390 MHz frequency bands with an
   authorized bandwidth greater than 1 MHz, the emissions must be attenuated as
   follows:

   (1) On any frequency removed from the assigned frequency by more than 50
   percent of the authorized bandwidth plus 0.5 MHz up to and including 50
   percent of the authorized bandwidth plus 1.0 MHz, the attenuation must be 60
   dB, when measured in a 3.0 kHz bandwidth. The signal need not be attenuated
   more than 25 dB below 1 milliwatt.

   (2) On any frequency removed from the assigned frequency by more than 50
   percent of the authorized bandwidth plus 1.0 MHz, the attenuation must be at
   least 55 + 10 log[10] pY dB, when measured in a 3.0 kHz bandwidth.

   (g) The requirements of paragraphs (e) and (f) of this section apply to
   transmitters approved after January 1, 1977, and to all transmitters first
   installed after January 1, 1983.

   (h) For ELTs operating on 121.500 MHz, 243.000 MHz and 406.0–406.1 MHz the
   mean power of any emission must be attenuated below the mean power of the
   transmitter (pY) as follows:

   (1) When the frequency is moved from the assigned frequency by more than 50
   percent up to and including 100 percent of the authorized bandwidth the
   attenuation must be at least 25 dB;

   (2) When the frequency is removed from the assigned frequency by more than
   100 percent of the authorized bandwidth the attenuation must be at least 30
   dB.

   (i) In case of conflict with other provisions of  Sec. 87.139, the provisions of
   this paragraph shall govern for aircraft earth stations. When using G1D,
   G1E, or G1W emissions in the 1646.5–1660.5 MHz frequency band, the emissions
   must be attenuated as shown below.

   (1) At rated output power, while transmitting a modulated single carrier,
   the composite spurious and noise output shall be attenuated by at least:


------------------------------------------------------------------------
              Frequency (MHz)                    Attenuation (dB)\1\
------------------------------------------------------------------------
0.01 to 1525..............................  -135 dB/4 kHz
1525 to 1559..............................  -203 dB/4 kHz
1559 to 1585..............................  -155 dB/MHz
1585 to 1605..............................  -143 dB/MHz
1605 to 1610..............................  -117 dB/MHz
1610 to 1610.6............................  -95 dB/MHz
1610.6 to 1613.8..........................  -80 dBW/MHz\3\
1613.8 to 1614............................  -95 dB/MHz
1614 to 1626.5............................  -70 dB/4 kHz
1626.5 to 1660............................  -70 dB/4 kHz2, 3, 4
1660 to 1670..............................  -49.5 dBW/20 kHz2, 3, 4
1670 to 1735..............................  -60 dB/4 kHz
1735 to 12000.............................  -105 dB/4 kHz
12000 to 18000............................  -70 dB/4 kHz
------------------------------------------------------------------------
\1\ These values are expressed in dB referenced to the carrier for the
  bandwidth indicated, and relative to the maximum emission envelope
  level, except where the attenuation is shown in dBW, the attenuation
  is expressed in terms of absolute power referenced to the bandwidth
  indicated.
\2\ Attenuation measured within the transmit band excludes the band
   ± 35 kHz of the carrier frequency.
\3\ This level is not applicable for intermodulation products.
\4\ The upper limit for the excess power for any narrow-band spurious
  emission (excluding intermodulation products within a 30 kHz
  measurement bandwidth) shall be 10 dB above the power limit in this
  table.

   (2) The transmitter emission limit is a function of the modulation type and
   symbol rate (SR). Symbol Rate is expressed in symbols per second.

   (3) While transmitting a single modulated signal at the rated output power
   of the transmitter, the emissions must be attenuated below the maximum
   emission level by at least:


------------------------------------------------------------------------
                                                             Attenuation
            Frequency Offset (normalized to SR)                  (dB)
------------------------------------------------------------------------
 ±0.75 x SR..........................................            0
 ±1.40 x SR..........................................           20
 ±2.95 x SR..........................................           40
------------------------------------------------------------------------

   Where:

   SR = Symbol Rate,

   SR = 1 × channel rate for BPSK,

   SR = 0.5 × channel rate for QPSK.

   The mask shall be defined by drawing straight lines through the above
   points.

   (j) When using G7D for differential GPS in the 112–118 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.

   (k) For VHF aeronautical stations and aircraft stations operating with G1D
   or G7D emissions:

   (1) The amount of power measured across either first adjacent 25 kHz channel
   shall not exceed 2 dBm.

   (2) For stations first installed before January 1, 2002, the amount of power
   measured across either second adjacent channel shall be less than −25 dBm
   and the power measured in any other adjacent 25 kHz channels shall
   monotonically decrease at a rate of at least 5 dB per octave to a maximum
   value of −52 dBm. For stations first installed on or after January 1, 2002,

   (i) The amount of power measured across either second adjacent 25 kHz
   channel shall be less than −28 dBm;

   (ii) The amount of power measured across either fourth adjacent 25 kHz
   channel shall be less than −38 dBm; and

   (iii) From thereon the power measured in any other adjacent 25 kHz channel
   shall monotonically decrease at a rate of at least 5 dB per octave to a
   maximum value of −53 dBm.

   (3) The amount of power measured over a 16 kHz channel bandwidth centered on
   the first adjacent 25 kHz channel shall not exceed −18 dBm.

   [ 53 FR 28940 , Aug. 1, 1988, as amended at  56 FR 11518 , Mar. 19, 1991;  57 FR 45749 , Oct. 5, 1992;  58 FR 30127 , May 26, 1993;  58 FR 67695 , Dec. 22, 1993;
    59 FR 35269 , July 11, 1994;  63 FR 36607 , July 7, 1998;  64 FR 27475 , May 20,
   1999;  66 FR 26799 , May 15, 2001;  67 FR 4676 , Jan. 31, 2002;  69 FR 32881 ,
   June 14, 2004]