The detection of the flying object

PARASOL permanently records the original signal. Over time, the electromagnetic signals generate a specific pattern like the bittings of a notched key. If an echo signal now hits the sensor, the specific pattern of the echo can be shifted backwards on the timeline of the received original signals until the two key patterns fit. Through this correlation calculation, the echo is assigned to the original signal. This turns the time difference between the original signal and its echo into a known quantity.

The time difference allows to calculate the extra distance travelled by the echo in contrast to the distance of the original signal. This leads to the deduction that the detected object can be located at any point that represents a diversion of the corresponding distance compared to the direct connecting line.

In three-dimensional space, the possible positions of the detected object now form the surface of an ellipsoid. Three sensors are necessary to determine the exact position: The flying object is located at the point where the three ellipsoids meet.