12 ELEMENTS OF AIRBORNE RADAR SYSTEMS DESIGN PROBLEM 



(b) 



Beacon Station at a 



Known Geographical 



Location 



Fig. 1-7 Radar Beacon System. 



The angular position of the beacon relative to the aircraft is measured 

 by the airborne radar. Since the pilot knows his own heading in space and 

 the geographical position of the beacon, the knowledge of relative range 

 and bearing of the beacon permits him to determine his own geographical 

 location. 



It is quite common for an airborne radar to have a beacon mode as an 

 auxiliary function. Despite the apparent simplicity of the mode, the 

 proper integration of this function into an airborne radar system is often 

 difficult, particularly if early systems planning neglects to include the 

 cooperative beacon itself. Variations of the beacon mode of operation are 

 also quite common in guided missile applications. 



An airborne radar possesses an inherent capability for providing still 

 another type of navigational information — true ground speed — achieved 

 through the use of the doppler effect mentioned above in the discussion 

 of the tracking function. This application will be discussed in detail in 

 Chapter 6. 



Communications. The transmitted radar signal may also be used as 

 a carrier for the transmission of communications intelligence. While such 

 transmission is limited essentially to line-of-sight because of the inherent 



