Pegmantite-3

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a drawing of the P-3 antenna

Pegmantit-3 ( P-3 for short ; NATO code : Dumbo ) was the first Soviet 3D radar device , which was developed towards the end of the Second World War .

The station was produced in a mobile (P-3M) and stationary version (P-3A). The mobile station was placed in box bodies on two trucks. Transmitting and receiving systems were housed in one cabin. The display device still had linear deflection with A-scope .

But if the viewing device is only an A-scope, then rapid continuous rotation of the antenna is impossible. It is more likely that the azimuth measurement was a kind of bearing process. The specified accuracy of 4 ° can otherwise hardly be achieved with a single pair of Yagi antennas.

The elevation angle determination with an accuracy of 1.5 ° was possibly already carried out with a goniometer , as it was used in several successor models of meter wave radar (e.g. the Knife Rest radar family P-8 and P-10 ). For the purpose of determining the elevation angle, the radar device needs two antenna planes one above the other. The phase difference between the antenna planes is the measure of the elevation angle of the target. There were two slip rings in the goniometer on which the received RF impulses of the respective antenna plane produced a standing wave. Two sliders moved synchronously and compared the HF voltages on both slip rings with one another. In a certain position the HF voltage difference was zero; this mechanical position was assigned an elevation angle. The conversion of the altitude angle into a flight altitude was distance-dependent and could be done with a nomogram .

Technical data P-3 Dumbo
Frequency range   VHF band
Pulse repetition time  
Pulse repetition frequency  
Transmission time (PW)  
Reception time  
Dead time  
Pulse power  
Average performance  
displayed distance   120… 150 km
Distance resolution   1.5 km
Opening angle  
Hit count  
Antenna round trip time  

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