Home' RTCA Documents for Review : DO-XYZ_ED-ABC_FRAC_SC236_MASPS Contents 2
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It is expected that this MASPS document will be referenced by the future SARPs to assure
consistency of international standards for WAIC.
Scope of the Document
This document addresses the unique coexistence aspects of WAIC that arise from the use
of the frequency band 4200-4400 MHz. Specific aspects that are addressed are:
A. that a WAIC system does not cause harmful interference to radio altimeters on
board other aircraft,
B. that a WAIC system does not cause harmful interference to WAIC systems on
board other aircraft,
C. that a WAIC system performs its intended function in the presence of radio
emissions from radio altimeters on board other aircraft,
D. that a WAIC system performs its intended function in the presence of radio
emissions from WAIC systems on board other aircraft.
The issue A above stems directly from Resolution 424 (WRC-15)  giving radio
altimeters priority over WAIC systems. The issues B, C and D stem from WAIC being
related to safety and regularity of flight and the resulting need to assure they can operate
in presence of other users of the band, namely radio altimeters and WAIC systems on board
The issues A and B above are addressed in this MASPS by the introduction of a limit on
the aggregate power spectral flux density of a WAIC system installed on board an aircraft,
as specified by the requirement PR#1 (see section 22.214.171.124). The aggregate power limit
assures that the interference power received by radio altimeters and WAIC systems on
board other aircraft will not cause any degradation of performance for those systems. The
issues C and D above are addressed by introducing the requirement PR#2 (see section
126.96.36.199) and the associated interference susceptibility of WAIC systems. Jointly, the
requirements PR#1 and PR#2 assure coexistence of a WAIC system installed on board the
aircraft that is subject to certification with radio altimeters and WAIC systems on board
This MASPS does not address the coexistence of WAIC systems with radio altimeters on
board the same aircraft. As all systems on board a single aircraft are under the control of
the system integrator, coexistence on board the same aircraft can be assured and
demonstrated by various appropriate means that need not be constrained by this standard.
Therefore, this aspect is out of scope of this document.
For the same reason this MASPS does not address the coexistence of different WAIC
communication links on board the same aircraft. Throughout this document, a WAIC
system is understood as the entirety of all WAIC components on board the same aircraft.
That is, a single aircraft contains only a single WAIC system. Assuring that different
components of a single WAIC system can coexist is assumed to be the responsibility of the
system integrator and is out of scope of this document.
This MASPS does not address the issue of how to define and quantify the intended function
of a WAIC system. It is expected that WAIC will serve various onboard applications which
will place different requirements on the wireless communication links. In broad terms, it is
understood that the intended function of a WAIC system is to satisfy the data transfer
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