As part of the Galileo Project, ESA is funding many
activities focusing on trade-offs, implementation and
performance related to the Specifications of the Galileo
Signals. The results presented in this paper are extracted from
a report of signal analysis lead by Astrium Germany [1,2]
11 in the frame of the Galileo Phase contract [3]. Those
results aim at supporting the specifications of the interface
between the Galileo Satellites and the Galileo Signals
based receivers, and consequently produce some elements
for Payload and Receivers requirements specifications.
However, due to the generic approach that has been
retained, the results applicability is going far beyond the
Galileo context.
The degradation of code tracking accuracy parameters due
to generic linear signal distortions for BOC(m,n)-type
random signals and non-linear distortions on multiplexed
signals with non-constant envelope is investigated in
dependency of distortion parameters. The assessment
parameters are power loss, correlation loss, S-curve-slope
and bias. Linear distortions under investigation are
sinusoidal amplitude ripple, linear amplitude slope, sinusoidal
phase ripple, quadratic and cubic phase variation, band-
limitation and spurious emission. Non-linear distortion is
based on a general form of AM-AM and AM-PM for Tricode
Hexaphase multiplexing, which is the main candidate
method for non-constant envelope modulation within
Galileo. Moreover, a specialisation to a third order
polynomial for the AM-AM envelope transfer characteristic is
considered. With these types of distortions, the most
relevant degradations relative to an ideal payload and receiver
are included. As far as possible, respective investigations
are based on analytical considerations to get extensively
applicable statements. But additionally, also base-band
signal simulations are used.