TACTICAL AIR NAVIGATION (TACAN)
The TACAN Set, AN/ARN-84(V), is a radio
navigational set that operates in conjunction with a
TACAN ground station. Together they provide the
aircrew with continuous bearing and range from the
aircraft to the station. The TACAN set can also
operate as both the interrogator and transponder with
another aircraft equipped with TACAN.
The ground station, acting as a reference position,
develops a complex signal on which bearing
information is superimposed (fig. 2-12). This signal
may be on any of 126 channel frequencies in the X
mode. Pulse coding gives ground equipment the
capability of an additional 126 channels in the Y
mode. Channels are separated at 1-MHz intervals in
these modes. The station identifies itself by
transmitting its call letters, in Morse code, every 37.2
seconds. Knowing the time that has elapsed between
the interrogation signal and the reply signal facilitates
calculation of slant range from the aircraft to the
station.
Figure 2-12.-Typical TACAN station bearing antenna and radiation pattern.
2-13
