OBS  N  E  S  W  3  33  24  21  15  12  30  6  GS  NAV  OBS  N  E  S  W  3  33  24  21  15  12  30  6  GS  NAV  OBS  N  E  S  W  3  33  24  21  15  12  30  6  GS  NAV  I00  90  II0  80  60  I30  I00  40  240 220  200  I80  I50  I20  I00  80 60  40  KNOTS 240 220  200  I60  I00  80  60 40  KNOTS  – – OBS  N  E  S  W  3  33  24  21  15  12  30  6  GS  NAV  90Hz  150Hz  OBS  N  E  S  W  3  33  24  21  15  12  30  6  GS  NAV  Point of intersection runway and glideslope extended. Figure 9-33. Instrument landing systems. courses, respectively. The localizer provides course guidance,  transmitted at 108.1 to 111.95 MHz (odd tenths only),  throughout the descent path to the runway threshold from a  distance of 18 NM from the antenna to an altitude of 4,500  feet above the elevation of the antenna site.  [Figure 9-34] The localizer course width is defined as the angular  displacement at any point along the course between a full  “fly-left” (CDI needle fully deflected to the left) and a full  “fly-right” indication (CDI needle fully deflected to the right).  Each localizer facility is audibly identified by a three-letter  designator transmitted at frequent regular intervals. The ILS  identification is preceded by the letter “I” (two dots). For  example, the ILS localizer at Springfield, Missouri, transmits  the identifier ISGF. The localizer includes a voice feature on  9-36