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2.5.2.2 In future systems, AES transmission within an
EIRP range satisfactory to satellite service operators may
require a different control range. For example, the higher GE
of future spot beam satellites could require less AES EIRP,
leading to a need for a larger control range. The range cannot
be closely predetermined because spot beam size that affects
satellite Gfl is a future operator design choice.
2.5.3 Out-of-b~ndE IRP spectral density. The out-ofband
EIRP including spurious, harmonics, intermodulation
products and noise radiated by the AES should not cause
harmful interference to other radio services. In particular, they
should not interfere with other aeronautical communications/
navigation radio services such as global positioning system
(GPS) which operates in the band 1 565 to 1 585 MHz, global
orbiting navigation satellite system (GLONASS) operating in
the band 1 598 to 1 609 MHz, the AMSS receive band 1 525
to 1 559 MHz. and the VHF band 108 to 137 MHz.
2.5.3.1 Table 4-3 contained in Annex 10, Volume 111,
Part I, Chapter 4, provides for a maximum EIRP density of
-155 dBc/l MHz in the 1 565 to 1 585 MHz band, which
protects GPS receiver operation on the same aircraft as AMSS,
and also GPS operation on nearby aircraft.
2.5 Transmitter requirements
2.5.1 EIRP limits. An AES that is capable of an EIRP
of 13.5 dBW should always be able to use the 0.6 kbitls R and * Ail figures are located at the end of this attachment.
Aaaehment A to Pmt I Annex 10 - Aeronautical Telecommunications
2.5.3.2 Table 4-3 contained in Annex 10, Volume III,
Part I, Chapter 4, also indicates that the maximum EIRP
spectral density should be -105 dBcll MHz in the 1 602 to
1 605 MHz band and -85 dBc/l MHz in the 1 605 to 1 610
MHz band. These limits wiIl improve protection for
GLONASS receiver operation (assuming a future move
downward in frequency of the upper edge of the GLONASS
band) on nearby aircraft. The AMSS Recommendation for a
maximum density of -140 dBc/l MHz, contained in Annex
10, Volume III, Part I, Chapter 4, 4.2.3.5.8.2, is intended to
protect GLONASS receiver operation on the same aircraft as
AMSS assuming 40 dB of antenna isolation. The EIRP density
should not be greater than -105 dBc/MHz to protect navigation
equipment in that band on other nearby aircraft.
2.5.4 Irttermodulation (IM) pmducts. Control of
unwanted emissions from the AES is important to system
operations in order to avoid blocking channels and reducing
needed spectrum. Intermodulation occurs during multicarrier
(Level 4) operation on predictable frequencies related to
wanted signals due to component non-linearities. Potential
sources are many, but can be controlled. Minimizing IM
effects is accomplished both in AES design for linearity
meeting the standards and in operation.
2.5.4.1 Intermodulation products (IM) that may be
emitted by a Level 4 AES in multicarrier operation arise both
from the high-power amplifier (HPA) and from other passive
components that are subject to high AES RF power levels.
Passive components causing IM may include connectors, particularly
if they are subject to corrosion or looseness; and the
diodes used in phased-array antennas. Depending on the choice
of frequencies and levds in the GES, such W1 can appear at
frequencies and levels in the AES receiver that will degrade
BER, disable reception, or affect reception of signals by other
aircraft equipment.
2.5.4.2 AES-transmitted lM can block GES receivers.
The HPA is a primary IM source because its linearity is
limited by technology and heat dissipation.
2.5.4.3 Intersystem effects may arise from Level 4 AESs
that may radiate IM. An AES operating with a global beam
satellite must transmit higher ElRP than an AES operating
with a more sensitive spot beam satellite. Therefore, this
higher level of IM would be more readily received by the spot
beam satellite for relay to its GES, where it could impair
reception of that channel. Even if the two satellites are using
separated portions of the frequency band and therefore cannot
reuse the same assigned channel frequencies, the global beam
AES transmitter's IM that is out of assigned channels could
fall into the spot beam satellite's band. All GES frequency and
EIRP level assignments should account for this possibility.
2.5.5 Frequency manngernenr. Careful frequency
management is needed because:
a) AMSS includes safety services;
b) there is concern about the availability of adequate
AMSS spectrum, and adequate capacity for AMSS
safety services; and
C) the difficulty in co-ordinating mobile satellite networks
　
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