CALCULATING TRUE GROUND SPEED
Radar - Doppler Effect
RADIATION PATTERN OF DOPPLER NAVIGATION
Heart of the HIDAN method is an electronic ground speed and track sensing device employing two forward and two rear microwave beams radiating from the aircraft to the ground.
Thus the aircraft is in effect "walking" on four invisible spidery legs.
Electronic calculation of any difference between the two pairs of beams indicates true ground speed and any deviation from course.
Original Caption by Science Service
Publication 1959 - FOR
AN AGE OF PRECISION with
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