NAVIOR-24S
™
CHAPTER IV
Operation and Performance
57
NAVIOR-24S ™
Revision
V1.00 20.05.2008
Elevation Mask
Satellites which are below a 5° elevation are not used in the position solution. Although low
elevation satellites can contribute to a lower PDOP, the signals from low elevation satellites have
poorer quality, since they suffer greater tropospheric and ionospheric distortion than the signals
from higher elevation satellites. These signals travel further through the ionospheric and
tropospheric layers.
In addition, low elevation satellites can contribute to frequent constellation switches, since the
signals from these satellites are more easily obscured by buildings and terrain. Constellation
switches can cause noticeable jumps in the position output. Since worldwide GPS/GLONASS
satellite coverage is generally excellent, it is not usually necessary to use satellites which are below
a 5° elevation to improve GPS coverage time. In some applications, like urban environments, a
higher mask may be warranted to minimize the frequency of constellation switches and the impact
of reflected signals.
RMS Mask
RMS Mask sets maximum value of RMS, when PVT solution is considered true. Default RMS
Mask value is 200 m.
Note
- The independent mask for GPS and GLONASS satellites is absent. It is possible to set only
common mask for GPS and GLONASS satellites via BINR protocol: Packet 0Dh –mask setting.
BINR outputs may be controlled with BINR packet 51h. (See Appendix A for details on key setup
parameters.)
