Sec.  22.861   Emission limitations.

   The rules in this section govern the spectral characteristics of emissions
   for commercial aviation systems in the Air-Ground Radiotelephone Service.
   Commercial aviation air-ground systems may use any type of emission or
   technology that complies with the technical rules in this subpart.

   (a) Out of band emissions. The power of any emission outside of the
   authorized operating frequency ranges must be attenuated below the
   transmitting power (P) by a factor of at least 43 + 10 log (P) dB.

   (b) Measurement procedure. Compliance with these rules is based on the use
   of measurement instrumentation employing a resolution bandwidth of 100 kHz
   or greater. 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. 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., 100 kHz or 1 percent of
   emission bandwidth, as specified). 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.

   (c) Alternative out of band emission limit. The licensee(s) of commercial
   aviation air-ground systems, together with affected licensees of Cellular
   Radiotelephone Service systems operating in the spectrum immediately below
   and adjacent to the commercial aviation air-ground bands, may establish an
   alternative out of band emission limit to be used at the 849 MHz and 894 MHz
   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.

   (d) Interference caused by out of band emissions. If any emission from a
   transmitter operating in this service results in interference to users of
   another radio service, the FCC may require a greater attenuation of that
   emission than specified in this section.

   [ 70 FR 19310 , Apr. 13, 2005]