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P- 12 NP “Spoon Rest B”

Description of the radar set, tactical-technical characteristics Описание; Основные тактико-технические характеристики (Базы данных)
P-12 Sichtgeräte Goniometer

Figure 1: Scopes of the “Spoon Rest B”

Specifications
frequency: 150 - 170 MHz
(lower VHF-Band)
pulse repetition time (PRT): 2.77 milliseconds
pulse repetition frequency (PRF): 360 Hz
pulsewidth (τ): 6 µs
receive time: 2.4 milliseconds
dead time: 377 µs
peak power: 160 to 250 kW
average power: up to 540 watts
instrumented range: 200 nm
range resolution: ½ nm
beamwidth:
hits per scan: > 15
antenna rotation: 6 ... 30 seconds
(0 ... 10 rpm.)

P- 12 NP “Spoon Rest B”

The former Soviet Union had considerable successes in the development of VHF- radar units. The assortment of VHF- radar units in the army and the air force sufficed of the P 8 over the P 12 up to the P 18 radar sets. One of them is the mobile variant NP, a version of the P 12 installed into two caravans.

The radar unit also has an E-scope next to the plan position indicator (PPI). The elevation angle measures the goniometer (the green luminescent scale between the maintenance paneels) by a phase comparison between the two echo signals received by the both antenna planes.

The Goniometer produced a standing wave of the received RF impulses on two slip rings fed by the two antenna groups. An electrical engine alternately moves a measuring contact on the slip rings and simultaneous a variable resistor delivers the vertical deflecting voltage to the RHI-scope. The voltage difference of the slip rings reaches the value zero in a certain position. The mechanical angle of this position corresponds to the elevation angle of the target. With a nomogram on the screen the shown elevation angle could be converted to a height. But the method reduces, however, the maximum range of the radar unit. Therefore the crew usually switched off the Goniometer.

The radar unit P 12 can be synchronized with other radar units and then the PPI-scope shows both received echos. If two stations working by the same frequency are in a favorable distance to each other, her maximum obtainable range can be increased by interference.

The Goniometer produced a standing wave of the received RF impulses on two slip rings fed by the two antenna groups. An electrical engine alternately moves a measuring contact on the slip rings and simultaneous a variable resistor delivers the vertical deflecting voltage to the RHI-scope. The voltage difference of the slip rings reaches the value zero in a certain position. The mechanical angle of this position corresponds to the elevation angle of the target. With a nomogram on the screen the shown elevation angle could be converted to a height. But the method reduces, however, the maximum range of the radar unit. Therefore the crew usually switched off the Goniometer.

The radar unit P 12 can be synchronized with other radar units and then the PPI-scope shows both received echos. If two stations working by the same frequency are in a favorable distance to each other, her maximum obtainable range can be increased by interference.

The trailer-mounted P-12 NP (1RL 14 PIR) “Spoon Rest B” is a derivate of the truck-mounted P-12 MA “Spoon Rest A”. The later version P-12 NA is a truck-mounted version again.

Picture gallery of P-12
Antennenwagen der P-12 MA

Figure 2: Antenna-truck of the “Spoon Rest A”

Figure 3: Block diagramm of P-12 MA