Bendix Commercial Vehicle Systems Bendix/King Global Positioning System KLN 35A - Manual (Page 93)

Basic GPS Operation
3-58 Effective Date 5/95 006-08791-0000 Rev 0
Basic GPS Operation
Chapter 3
A representative OTH 1 page is
shown in figure 3-168. The OTH 1
page displays the GPS receiver state
and the system’s estimate of the posi-
tion error expressed in nautical miles.
The GPS state is indicated on line 1.
The possibilities are:
INIT initialization
ACQ acquisition
TRAN transition
NAV navigation
NAV A navigation with altitude aiding
NAV D navigation with data collection
DEGRD navigation with position degradation
FAILR receiver failure
In the initialization state the GPS receiver is in the process of
initializing itself, collecting information such as the date, time, and last
present 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 is obtained from them.
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 indicates that besides calculation position,
the receiver is collecting and storing in its memory additional data
from the satellites (called ephemeris and almanac data).
Lines 3 and 4 of the OTH 1 page display the KLN 35A’s estimated
position error. The KLN 35A’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.
APT VOR NDB SUP ACT NAV FPL CAL SET OTH
åå.ånm State NAV D
ееееее
>Leg Estimated Posn
OTH 1 Error 0.02nm
Figure 3-168