TM  1-1520-240-10 3-3-24            LEFT DISPLAY RIGHT DISPLAY REMARKS GO Doppler has completed Built in Test (BIT) and is operating satisfactorily, GPS is still performing BIT (GPS has 2 minute BIT cycle maximum). Note that a rotating bar in the display indicates that the GPS is still per- forming self test. GO ALL The entire system has completed BIT and is operating satisfactorily. GO P Pitch or Roll data is missing or exceeds 90_. In this case, pitch and roll in the computer are both set to zero and navigation in the Doppler mode continues with degrade operation. Problem may be in the vertical gyro or aircraft cabling. NG C, R, S, or H fol- lowed by a nu- meric code A failure has occurred in the Computer Display Unit or the Signal Data Converter Power Supply. The operator should not use the system. DN GPS failure code GPS has failed but operator can use doppler to perform all navigation. DF Doppler failure code Doppler has failed. GPS is still performing self test. GN Doppler failure code Doppler has failed but operator can use GPS to perform all navigation. e.  Procedure for Displaying or Selecting GPS M or Y Operating Mode, Doppler, GPS, or Combined Operation, and Displaying Groundspeed and Track. (1) Set MODE switch to MGRS position (LAT/ LONG or GPS LDG position may also be used). (2) Set DISPLAY switch to GS/TK/NAV M. (3) The display indicates the current GPS and navigation mode on the top line: (a) Selected Fly to waypoint. (b) EPE (GPS Estimated Position Error in Meters. An asterisk (*) in the character position of the EPE display indicates an EPE of greater than 999 or data unavailable. (c) GPS mode of operation: M for mixed C\A and P/Y code GPS reception Y for only Y code GPS reception. (d) DGNS mode of operation: C for combined Doppler and GPS D for Doppler only G for GPS only R for remembered velocities * for no navigation. (e) Target destination where the present position will be stored next time TGT/STR is depressed. NOTE In MGRS mode, ground speed is displayed in km/hr; in LAT/LONG mode, ground speed is displayed in knots. Only mode C, G, and D may be selected as the primary navigation mode. Modes R and * are  automatic  fall  back  modes  used  when both the Doppler and GPS are unavailable. (4) Selection of GPS mode of operation: As an example, consider selection of Y-only mode. De- press KYBD key. Observe that the GPS mode blinks. To enter Y (for Y mode) depress key LTR LEFT followed by key 9. A Y will be displayed. Depress ENT key. The entire display will blank out for less than one second and the center display will now indicate: Y. (5) Selection of DGNS mode of operation. As an example, consider selection of GPS-only mode of operation. Depress KYBD key twice. Observe that the DGNS mode blinks. To enter G (for GPS mode) depress key LTR LEFT followed by key 3. A G will be displayed. Depress ENT key. The entire display will blank out less than one second and the DGNS Mode will now indicate: G (or * if GPS is not available). (6) Ground Speed and Ground Track Angle are displayed on lines 3 and 4. f.  Procedure  for  Entering/Displaying  Present  posi- tion or One of the 100 Possible Destinations in MGRS. The DGNS has the capability to display 100 destinations (numbered 00 through 99). 100 destinations -00 to 69 Standard Waypoints -70 to 89 Data Load-only Waypoints, Ob- servable but not changeable via CDU keyboard. Used for Nation- al Airspace Data Such as VORs, NDB’s and intersections. -90 to 99 Target Store Waypoints (Usable as Standard Waypoints)