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5-30
Rev 1
initialization process the receiver begins the acquisition
process. During this time, the visible satellites are being
acquired and data from them is obtained.
The transition state indicates an adequate number of
satellites for navigation has been acquired and is being
tracked but no position data can yet be produced.
Normal navigation is indicated by a NAV, NAV A, or
NAV D GPS state. NAV A indicates that the altitude
input is being used in the position solution. NAV D indi-
cates that besides calculating position, the receiver is
collecting and storing in its memory additional data infor-
mation from the satellites (called ephemeris and
almanac data).
• The specific GPS satellites or “space vehicles” (SV)
being received are displayed in the left column.
Each satellite has its own identification number. A *
symbol to the left of the satellite number indicates
this particular satellite is not presently being used in
the navigation position solution.
• The satellite’s “health” is indicated to the right of the
satellite number. This health information is transmit-
ted by the satellites:
B bad
W weak
- unknown
blank good
• The signal-to-noise ratio (SNR) for each satellite
being received is displayed in the middle column and
indicates the signal strength for each satellite. The
higher the SNR value the stronger the signal.
Values usable for navigation will be in the mid 30s to
mid 50s; however, typical values are in the middle of
this range.
• The elevation (ELE) above the horizon for each
satellite is provided in the right column and will range
from 5° to 90°.
A representative Status 2 page is shown in figure 5-102.
The STA 2 page displays the system’s estimate of the
position error expressed in nautical miles. The KLN
90B’s position error depends upon such factors as the
number of satellites being received, the strength of the
GPS signals, and the geometry of the satellites
presently being used for navigation.
Figure 5-102
ESTIMATED |
POSN ERROR |
.07nm|
|
|
|
STA 2