AP 3302 Pt. 3
Section 1
CHAPTER 1
PULSE-MODULATED RADAR
Indication of Bearing
A range trace, such as that produced by a type A display, if made to start at the centre of the c.r.t. and extend to the edge, will look like the hand of a clock. If at the same time echoes are made to appear as 'bright-up' spots the result will be as shown in Fig 18.
If the trace could be made to point towards 'twelve o'clock' when the radar aerial is pointing due North then any echoes appearing on the trace must be from targets due North.
When the aerial is turned towards the East any echoes appearing on the trace must then be from targets East of North. If at the same time the trace could be moved clockwise by the same amount as the aerial moved towards the East the new echoes would appear in their correct relative position on the screen. By continuing this process right through 3600, the trace moving in synchronism with the aerial, the trace on the c.r.t. will look like the hand of a clock rotating steadily with the aerial and the echoes will appear as bright spots at appropriate parts of the
