Home' RTCA Documents for Review : DO-343B Contents Appendix C
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signal from a single Inmarsat SBB transmitter to a message arriving at a single
Iridium Block 1 receiver operation in the same Core Europe airspace is also
small, on the order of
. See C.3.3
3. The probability of undesired signal out of band and spurious emissions from a
single of Inmarsat SBB transmitter causing interference to a multiplicity of
Iridium Block 1 aircraft operating in the same Core Europe Airspace is negligibly
small. See C.3.3
4. The probability of desired signal from the ensemble of simultaneously
transmitting Inmarsat SBB transmitters causing significant interference to a
large number of Iridium Block 1 receivers operating in the same Core Europe
Airspace is very small. See C.3.4
C.1.2 Referenced Documents
E. F. C. LaBerge, "Updated Analysis of Inmarsat and Iridium Aeronautical Services in the
Same Oceanic Airspace," International Civil Aviation Organization, Aeronautical
Communications Panel WG-M/12, Montreal, WGM/12-WP-7, 18 June, 2008.
"Minimum Operational Performance Standards for Avionics Supporting Next Generation
Satellite Systems," RTCA, Inc, Washington, DC, June 17, 2015.
"ADS-B Technical Link Assessment Report," RTCA/Eurocontrol, March 2001, 2001.
"Minimum Aviation System Performance Standards for Aeronautical Mobile Satellite (Route)
Services (AMS(R)S)," RTCA, Inc., Washington, DC, DO-270 Change 1, April 14, 2009.
"EUROCONTROL 7 YEAR FORECAST: Flight Movements and Service Units 2015-2021."
Brussels: EUROCONTROL, 2015.
A. O. Allen, Probability, Statistics and Queueing Theory, Second ed. Boston: Academic Press,
A. Papoulis, Probability, Random Variables, and Stochastic Processes. New York: McGraw-
C. Therrien and M. Tummala, Probability for Electrical and Computer Engineers. New York:
CRC Press, Inc., 2004.
C.2 CHARACTERIZATION OF THE INTERFERENCE MECHANISM
Iridium is a time-domain duplex system that uses orthogonal time slots to both transmit
and receive on the same frequencies. The Iridium operating band is 1616-1626.5 MHz,
which is adjacent to the band that Inmarsat uses to transmit in the aircraft to satellite
direction. Therefore, it is possible that an Iridium receiver could be attem pting to receive
and process low-level satellite-to-aircraft transmissions in close proximity to Inmarsat
high-power transmissions. The resultant susceptibility to emissions from Inmarsat
transmitters is an inherent characteristic of the Iridium design. The purpose of this
Appendix is to develop and use a methodology by which the operational effects of such
susceptibility can be estimated prior to widespread implementation of both systems in
the same airspace.
Such a model relies on a series of assumptions about how the airspace is populated
(the aircraft traffic model), how the Inmarsat and Iridium links are used for safety service
(the data model), the performance of the Inmarsat transmitter and Iridium receiver (the
equipment model), and the characteristics of the Inmarsat and Iridium constellations
and signal formats (the system models). These models are described in order in the
For the purpose of the June 2016 revision of this Appendix, the Inmarsat system under
consideration is the Swift Broadband (SBB) system described in the main body of this
document, with AES4 and AES6 equipment described in DO-262B Change 1 and later
versions of that document. The Iridium system under consideration is Iridium Block 1,
described in DO-270, Change 1  with equipment described in DO-262B Change 1
. A future revision to this appendix will be required to consider future Iridium
equipment, variously known as Certus or Iridium NEXT.
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