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Satellite Navigation
Satellite clock parameters
Satellite clock offset ΔClock
lows:
ΔClock
●
t
●
a
sage.
Polynomial coefficients
In GPS, Galileo, BeiDou and QZSS, these are:
●
a
●
a
●
a
GLONASS considers the first order version of the polynomial (i.e. a
only two clock parameters:
●
Τ
a
●
Γ
a
12.1.4 Simulating Errors
Per default, the broadcasted navigation message parameters per SV are set automati-
cally to match the simulated orbit, clock and pseudorange parameters. For example,
the clock parameters in the navigation message of GPS SV ID#1 resembles the simu-
lated clock values for this satellite.
Errors are deviations between the simulated and broadcasted navigation mes-
sage parameters
Changing the default navigation message values leads to deviation between the simu-
lated and the broadcasted navigation information and thus deliberated errors. To simu-
late clock errors, change for example, the parameter a
message of SV#1 but maintain the a
You can also simulate unusual stations, like, for example, the wrongly broadcasted
clock bias between UTC and GPS system clocks. Such situations are simulated by
configuring different time conversion sets for the UTC-GPS conversion parameters in
the broadcasted navigation message and in the simulated UTC time parameters.
User Manual 1178.6379.02 ─ 01
= a
+ a
(t – t
) + a
SV
f0
f1
0c
is the reference time of clock
0c
, a
and a
are three coefficients that are broadcasted in the navigation mes-
f0
f1
f2
: SV clock offset
f0
: SV clock drift
f1
: SV clock drift rate
f2
: SV clock offset, where:
n
= -Τ
f0
n
: SV relative frequency offset
n
= Γ
f1
n
Perturbations and Errors Simulation
is described by a second order polynomial given as fol-
SV
2
(t – t
)
, where:
f2
0c
value of the simulated clock.
f0
About the Errors Sources
= 0) and transmits
f2
in the broadcasted navigation
f0
105
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