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, 
the mean power of any emissions must be attenuated below the mean power 
of the transmitters (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 log10 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 log10 pY dB.
    (c) For aircraft station transmitters first installed after February 
1, 1983,

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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 
log10 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 
log10 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 log10 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 log10 pY dB, when 
measured in a 3.0 kHz bandwidth.
    (g) The requirements of paragraphs (e) and (f) of this section apply 
to transmitters type accepted 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 406.025 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 my 
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 
below the mean power of the transmitter, pY, by at least:

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------------------------------------------------------------------------
  Frequency                                                             
    (MHz)                        Attenuation (dB) \1\                   
------------------------------------------------------------------------
.005-1559...  83 or (65+10 log10 pY), whichever is greater.             
1559-18000..  55 or (37+10 log10 pY) \2\, whichever is greater.         
------------------------------------------------------------------------
\1\ These values are expressed in dB below the carrier referenced to a 4
  kHz bandwidth and relative to the maximum emission envelope level.    
\2\ Excluding the frequency band of +/-35 kHz or +/-4.00 x the symbol   
  rate (SR), about the carrier frequency, whichever is the greater      
  exclusion.                                                            

    (2) For transmitters rated at 60 watts or less:
    When transmitting two unmodulated carriers, each 3 dB below the 
rated power, the mean power of any intermodulation products must be at 
least 24 dB below the mean power of either carrier.
    (3) The transmitter emission limit is a function of the modulation 
type and symbol rate (SR). Symbol Rate is expressed in symbols per 
second.
    (4) 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 
+/-2.80 x SR...............................................          40 
+/-4.00 x SR or +/-35 kHz..................................          Fm 
Whichever is greater.......................................             
------------------------------------------------------------------------

Where:

Fm=55 or (37+10log10 pY), whichever is greater
SR=Symbol Rate
SR=1 x channel rate for BPSK
SR=0.5 x channel rate for QPSK

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