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P-70 Lena-M

Description of the radar set, tactical-technical characteristics

Figure 1: P-70

Figure 1: P-70

Specifications
frequency: VHF-band
pulse repetition time (PRT):
pulse repetition frequency (PRF): 70 and 140 Hz
pulsewidth (τ): 50 µs
receiving time:
dead time:
peak power: 2 × 65 MW
average power: 2 × 10 kW
instrumented range: 2 300 km
range resolution:
accuracy: 650 m, 0.7°
beamwidth:
hits per scan:
antenna rotation:
MTBCF:
MTTR:

P-70 Lena-M

The P-70 Lena-M (Cyrillic: П-70 «Лена M», 5N117) was a fully coherent early warning radar operating in the VHF-band. It was the first series-produced radar in the world to use intra pulse modulation. The radar was developed from 1940 to 1958 and was tested as fit for troop use in 1959. In the period from 1960 to 1968, 11 such radars were built.

The radar electronics were housed in a two-story building, which was clad in steel and hermetically sealed. On the roof, the antenna rotated on a track with roller bearings. The antenna’s reflector had dimensions of 45 × 25 m. The antenna offered two antenna patterns (high- and low-beam) with different polarization. In addition, a short beam and a long beam channel were distinguished. The maximum reconnaissance altitude was 160 km.

The transmission pulses had a pulse duration of 50 µs with internal linear frequency modulation and a bandwidth of about 1 MHz. The transmitter was located on the upper floor and consisted of four channels of narrow-band tube amplifiers operating in parallel, among which the transmit bandwidth was divided. Pulse compression was performed in an ultrasonic delay line with a length of 30 cm. The compressed pulse duration was 1 µs.