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DO-253D Change 1
Sensitivity and Dynamic Range
This MOPS defines one equipment architecture with respect to an active antenna that
includes a preamplifier as shown in Figure 2-2.
Minimum requirements for a minimum standard active antenna are defined in RTCA/DO-
301. Manufacturers that restrict their sensor interoperability to a specific antenna can use
the unique characteristics of their active antenna in defining the sensitivity and dynamic
range (and associated test conditions) as described in this document. All antennas shall
[LAAS-293] comply with RTCA/DO-301, and to the extent non-standard antenna
performance is used to define the equipment requirements, that performance shall [LAAS-
294] be validated in accordance with the tests and methods described in RTCA/DO-301.
Throughout this section (and the test procedures), signal and interference power levels are
specified at the input to the preamplifier (antenna port in Figure 2-2) unless otherwise
stated. The manufacturer must specify the minimum and maximum preamplifier gain
(minimum gain is specified in RTCA/DO-301 but the maximum gain is not) and the
corresponding minimum and maximum installation loss (Lmin and Lma x in Figure 2-2).
These limits should be defined in the installation instructions.
a) Equipment compatible with a minimum standard RTCA/DO-301-compliant
antenna: The equipment shall [LAAS-295] accommodate GPS and SBAS signals
with a minimum input signal power of -136.5 dBm and a maximum input signal
power of -115.5 dBm (although acceptable acquisition and tracking performance
may not be achievable throughout this entire range). The equipment shall [LAAS-
296] have the capability of acquiring and tracking GPS, and if included, SBAS
satellites with a minimum input signal power of -134 dBm in the presence of sky
and antenna thermal noise density (Nsky,antenna) of -172.5 dBm/Hz and the Appendix
D interference conditions. The equipment shall [LAAS-297] have the capability of
acquiring and tracking GPS satellites with a maximum power of at least -121 dBm.
If SBAS satellites are included, the equipment shall [LAAS-298] have the
capability of acquiring and tracking SBAS satellites with a maximum power of at
least -115.5 dBm.
b) Equipment compatible with a specific RTCA/DO-301-compliant antenna: All
signal-in-space power levels in this paragraph are referenced to the output of a 0
dBi circularly polarized antenna. The equipment shall [LAAS-299] accommodate
GPS and SBAS signals with a minimum signal-in-space power of -131 dBm and a
maximum signal-in-space power of –119.5 dBm (although acceptable acquisition
and tracking performance may not be achievable throughout this entire range). The
equipment shall [LAAS-300] have the capability of acquiring and tracking GPS,
and if included, SBAS satellites with a minimum signal-in-space power of -128.5
dBm in the presence of sky and antenna thermal noise density (Nsky,antenna) for a
specific antenna and the Appendix D interference conditions. The equipment shall
[LAAS-301] have the capability of acquiring and tracking GPS satellites with a
maximum signal-in-space power of at least -123 dBm. If SBAS satellites are
included, the equipment shall [LAAS-302] have the capability of acquiring and
tracking SBAS satellites with a maximum signal-in-space power of at least –119.5
The manufacturer must specify any unique antenna requirements (e.g., minimum gain at 5
degree elevation angle, G/T ratio). The manufacturer must determine the minimum and
maximum signal power levels at the antenna port, accounting for the antenna radiation
pattern. The maximum signal power level may account for the combined satellite antenna
and specific antenna radiation patterns. For the minimum standard antenna, this effect
results in a 2 dB reduction in the maximum GPS signal power level with respect to the sum
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