TM 1-1520-238-10
3-40
Change 3
Table 3-12.
AN/ASN-128 Control and Indicator Functions – continued
Control/Indicator
Function
(Right Display)
Longitude of destination set on DEST DISP thumbwheel.
SPH-VAR
(left Display)
Spheroid code of destination set on DEST DISP thumbwheel.
(Right Display)
Magnetic variation (in degrees and tenths of degrees) of destination set on DEST DISP
thumbwheel.
MEM Indicator Lamp
Lights when radar portion of navigation set is in nontrack condition.
MAL Indicator Lamp
Lights when navigation set malfunction is detected by built in self-test.
DIM Control
Control light intensity of display characters.
Left, Right, and
Center Display
Lamps
Lights to provide data in alphanumeric and numeric characters, as determined by setting of
DISPLAY switch, MODE switch, and operation of keyboard.
Target Storage
Indicator
Displays destination number (memory location) in which present position will be stored when
TGT STR pushbutton is pressed.
TGT STR
Pushbutton
Stores present position data when pressed.
KYBD Pushbutton
Used in conjunction with the keyboard to allow data to be entered into the computer. Also
lights up keyboard when pushed the first time.
DEST DISP
Thumbwheel switch
DISPLAY
Destination display thumbwheel switch is used along with DEST-TGT and SPH-VAR position
of switch to select destination whose coordinates or magnetic variation are to be displayed or
entered. Destinations are 0 though 9, P (Present Position) and H (Home).
Keyboard
Used to set up data for entry into memory. When the DISPLAY switch is tuned to the position
in which new data is required and the KYBD pushbutton is pressed, data may be displayed
on the appropriate left, right, and center display. To display a number, press the
corresponding key or keys (1 through 0). To display a letter, first depress the key
corresponding to the desired letter. Then depress a key in the left, middle, or right column,
corresponding to the position of the letter on the key. Example: to enter an L, first depress L,
then 3, 6, or 9 in the right column.
FLY-TO DEST
Thumbwheel switch
Selects the destination for which XTK/TKE and DIST/BRG/TIME are displayed when the
DISPLAY switch is turned to either of these positions from which steering information is
desired. Destinations are 0 through 9, and H (Home).
ENT key
Enters data set up on keyboard into memory when pressed.
CLR key
Clears last entered character when pressed once. When pressed twice, clears entire display
panel under keyboard control.
