Table 3D-17. GPS Status Codes
Navigation with altitude aiding
Navigation with data collection
receiver is in the process of initializing itself and
collecting information such as the date, time, and last
position. Next the receiver collects data from its own
memory to determine which satellites should be
visible. After completing the initialization process, the
receiver begins the acquisition process. During this
time, the visible satellites are being acquired and data
from them is being obtained.
adequate number of satellites for navigation has been
acquired and is being tracked but no position data can
yet be produced.
(3) Normal navigation is indicated by a Nav,
NAV A, or a NAV D GPS state. NAV A indicates that
the altitude input is being used in the position solution.
NAV D indicates that besides calculating position, the
receiver is collecting and storing in its memory
ephemera and almanac data information.
(4) The specific GPS satellites or Space
Vehicles (SV), being received are displayed in the left
column. Each satellite has its own identification
number. An * to the left of the satellite number
indicates this particular satellite is not presently being
used in the navigation solution.
(5) The satellite's health is indicated to the
right of the satellite number. The health information is
transmitted by the satellite. Health designators are
defined in Table 3D-18.
(6) The Signal to Noise Ratio (SNR) for each
satellite being received is displayed in the middle
column and indicated the signal strength for each
satellite. The higher the SNR value the stronger the
signal. Values usable for navigation will be in the mid
30's to mid 50's. Typical values are in the middle of
Table 3D-18. Satellite Health
(7) The elevation (ELE) above the horizon for
each satellite is provided in the right column and will
range from 5º to 90º. Refer to Figure 3D-111.
SV SNR ELE
02 40 11o
11 42 47o
16 36 06o
*18B 33 65o
Figure 3D-111. STA 1 Page
b. STA 2 Page. The STA 2 page displays the
systems estimate of the position error expressed in
nautical miles. Refer to Figure 3D-112. The KLN
90Bs position error depends on 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 3D-112. STA 2 Page
c. STA 3 Page. The STA 3 page displays the
software revision status of the KLN 90B host computer
and of the GPS receiver. A field called OBS CAL is
also included on this page. The value indicates the
calibration of the internal resolver circuitry of the KLN