Goniometer (radar)
In a radar device, a goniometer is a device for measuring the angle of elevation of an incoming echo signal. The altitude of the aircraft from which the echo signal originates can then be calculated on the basis of the altitude angle and the distance.
A height determination with a goniometer requires a radar antenna with two antenna planes placed one above the other. The goniometer measures the phase difference between the two signals received by the antenna planes. The high-frequency echo signals are placed on circularly curved line sections, on each of which they generate a standing wave . A wiper continuously moved back and forth by a motor scans the signals on these line sections and creates a difference between the signals from the upper and lower antenna levels. At a certain point this difference is zero. The angular position of this zero point is the measure of the current elevation angle of the target.
The goniometer is located between the two display cabinets in the Russian P-12 NP (NATO designator: & # 132; Spoon Rest B & # 148;). In the picture, the E-scope is on the left , the PPI-scope on the right and the goniometer is located between the control panels under the viewing devices: easily recognizable by the illuminated green circular scale.