Home' RTCA Documents for Review : DO-253D_Change1_FRAC Contents 174
© 2019 RTCA, Inc.
DO-253D Change 1
pattern (taking into account the satellite gain characteristics); and the CW interference
levels, adjusted by the minimum frequency selectivity of the specific antenna/preamplifier.
The test signals presented to the equipment under test, unless otherwise specified, shall
[LAAS-311] account for the minimum preamplifier gain and maximum loss (Lma x) between
the antenna port and the receiver port. Unless otherwise specified, the interference tests
are conducted with one satellite at maximum power (-121 dBm which includes maximum
combined satellite and antenna radiation pattern gain), one satellite at minimum power (-
134 dBm which includes minimum radiation pattern gain), and remaining satellites 3 dB
above the satellite at minimum power.
For interference tests conducted with all satellites at maximum power, the test signals
presented to the equipment under test shall [LAAS-312] be the maximum input signal at
the receiver port accounting for the maximum preamplifier gain and minimum fixed loss
(Lmin) between the antenna port and the receiver port.
The test setup must provide the total specified broadband noise at the input to the test
amplifier. This total noise comes from the simulator, a noise generator (as appropriate),
and the test amplifier. The simulator noise (ISimulator) includes all noise generated by the
test equipment up to the input to the test amplifier. The test amplifier noise figure is NFAmp,
and broadband noise from the noise generator is ING. The test setup must ensure that:
Note that additional noise is included in the test from the GNSS signals that are simulated
and from the noise contribution of the loss block.
1. The specified test procedures provide a representative level of self-interference
when acquiring, re-acquiring, and tracking the minimum signal. The test
represents a reasonable baseline scenario with respect to self-interference caused
by C/A code GPS and SBAS signals, P(Y) and Earth Coverage M code GPS signals,
Galileo signals, and QZSS signals.
2. Authorized emissions are regulated to a level below the external interference levels
(as described in Appendix D) to provide a safety margin.
3. The IGNSS,Test used is based upon limiting the number of SBAS PRNs to 19 (i.e., PRNs
120-138) and RTCA/DO-235B. The effect on IGNSS from expanding the number of
SBAS PRNs to 39 (i.e., PRNs 120-158) is documented in RTCA Paper 266-16/SC-
159-1053. The RTCA Paper indicates the assumptions and link budget previously
used still provide sufficient margin even with the increase in IGNSS so it is not
necessary to change Table D-4 in Appendix D and IGNSS,Test for the tests below.
RTCA/DO-235B with RTCA Paper 266-16/SC-159-1053 will remain as the basis
for noise interference in RTCA/DO-253D. GNSS noise and IGNSS,Test will be updated
in the dual-frequency/multi-constellation MOPS consistent with RTCA/DO-235C.
4. Refer to Appendix H for examples of the broadband noise calibration.
The purpose of the Accuracy Test is to validate that the equipment meets the accuracy
requirements of Section 126.96.36.199 under the specified interference conditions. It is also
intended to verify that the σnoise used in the protection level equations are appropriate
bounds on the residual errors allocated to the receiver tracking performance.
Links Archive DO-246_revE_Change1-FRAC ED-ABC_DO-XYZ_OC_FRAC_Profiles_SC223_WG108 Navigation Previous Page Next Page