(d) GPS key connector. Connects GPS
(e) Load switch. This pushbutton switch
initiates loading process.
Load status indicator light. Illuminates
to indicate load status.
(g) Dust cap. Covers GPS key connector
when not in use.
Connects observer microphone.
pushbutton switch is used to transmit GPS time of day
to Have Quick II radios.
GPS System Modes of Operation.
(1) Off Mode. When the PULL OFF mode has
been selected, power is removed from the system,
except panel lighting.
Critical memory and other circuits
which cannot be turned off remain
powered by batteries in the receiver.
(2) Initialize Mode. When the INIT (initialize)
mode has been selected, position and time estimates
can be entered via the keypad. Waypoint data may be
entered and examined, and option selections made. No
navigation functions can be performed.
(3) Navigation Mode. Selection of the NAV
(navigation) mode enables normal GPS functions
(satellite tracking and navigation), including data
transfer to and from other aircraft systems.
(4) Test Mode. Selection of the PULL TEST
mode initiates a full command test of GPS user
identification and isolation.
GPS Normal Operation.
(1) GPS Start Procedures. The GPS must be
initialized prior to being used for navigation. There are
three types of start: normal, quick, and cold. A position
estimate, time estimate, and almanac (or ephemeris)
data are required for a normal start. A quick start uses
stored position, time, and recent ephemeris information.
A cold start is used only when the GPS is unable to
perform a normal start-up.
(a) GPS Normal Start.
Mode selector switch - INIT. When built-in-test
corresponding to the data selector switch
Data display will not be illuminated
for about 30 seconds after GPS has
been turned on. Ensure that the
display bright- ness control has been
set to the full clockwise position to
receive the INIT display, then adjust
If the GPS has been OFF for more
than 30 seconds when INIT mode
was selected, the set will perform the
approximately 30 seconds.
Data selector switch - POS. If ENTER POS
message is displayed press line select key 3
next to message. Position must be entered.
Displayed position - Check. Verify or enter new
updated position and altitude as required.
Data selector switch - TRK-GS. Verify correct
track and groundspeed are displayed. If not
valid, enter correct values.
Slew key - Press. Enter current time, year, and
day of year on page 2.
Prior to next step; ensure all required
initialization data has been entered
correctly, as they cannot be changed
after selection of NAV mode.
Mode selector switch - NAV. GPS will begin to
search for satellite signals.
If COLD alternates with the figure of
merit display, the GPS is performing
a cold start.
Data selector switch - STAT.
The number of satellites (SAT) being
observed. Estimated position error
(EPE) and figure of merit (FM) can be
monitored. The GPS will be ready
for use when SAT 3 or SAT 4 is
displayed on STAT page 1.