Thales NSS 100S-1 Component Maintenance Manual With Illustrated Parts List page 45

COPYRIGHT SEXTANT Avionique 1995
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COMPONENT MAINTENANCE MANUAL
1 3D+T mode (5 to 8 satellites usable)
This mode (3 dimensions with time) is the preferred operating mode
of the RPU.
It provides the functions generally available in the 3D+T mode;
moreover, the use of a fifth satellite adds dual redundancy to PVT
(speed time position) processing, which makes it possible to check
measurement consistency.
The functions provided are:
- 3-dimensional GPS position-fixing and readjustment of GPS time
(clock bias),
- Checking measurements using satellite redundancy.
2 3D+T mode (4 satellites usable)
This mode represents the standard GPS operating mode.
by the RPU during those periods when 4 satellites are available
with a satisfactory geometry ("GDOP" criteria) and if the 3D+T mode
(5 satellites) cannot be used.
The following functions are provided:
- GPS position-fixing (3 dimensions) and readjusting the GPS time
- Checking the position-fixing solution by checking consistency
with the aids.
3 3D mode (3 satellites usable in the short term)
This mode (clock coasting) is the preferred mode of operation with
3 satellites (or 4, but with a geometry that does not authorize
the shift into the 3D+T mode). Its duration of use is limited to
a few minutes.
The following functions are provided:
- GPS position-fixing (3 dimensions),
- Utilization of the filtered clock drift on the RPU, computed in
3D+T mode,
- Using the aids to check the measurements
procedure).
C17004
It is used
(less effective
34-57-96
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MAY 30/95