P-30 "Khrustal" / BIG MESH
P-30 Khrustal radar (NATO: Big Mesh). Introduced in 1955, it was an improved P-20. Range was 180 km, and peak power was 1 mw. BIG MESH, the second Soviet V-beam radar, was observed in 1956. The BIG MESH is a V-beam radar with sails slightly longer and wider than those of the TOKEN and appear to have a thinner mesh structure. Most distinguishing difference from a far distance is the pointed appearance of the top of the slant sail of the BIG MESH as compared to the blunt top of the TOKEN slant antenna. BIG MESH is larger than the V-beam TOKEN, and was believed to have higher power capabilities than TOKEN.
The aircraft detection and guidance station P-30 (chief designer V.V. Samarin) was intended for use in the radio engineering troops of the country's air defense, in the air force and in coastal air defense units of the Navy. This station was then also used in the radar companies of the first radio formations (regiments, battalions) of the army air defense. In 1955, the P-30 radar passed state tests at NIZAP GAU and was put into service.
The station provided the detection range of a fighter aircraft 170-180 km at altitudes of 8-12 km with a pulse power of 1 MW, receiver sensitivity 4x10'14 W, DND width in azimuth of 4.5 ° and elevation of 0.6-1.7 ° . The station consisted of an indicator machine, a trailer with an antenna system and receiving and transmitting equipment, two machines with power supply units and trailers for the transportation of two antennas. Unlike the P-20 radar, the P-30 station had UHF on a traveling wave tube, more advanced indicator equipment, radio equipment for broadcasting radio information "Phase", a new distribution of working frequencies was adopted by channels, antenna reflectors were increased, the system was paired with recognition and instrumentation of the active response "Globus".
The duty factor of BIG MESH was found to be more than three times that of TOKEN. BIG MESH not only has the five beams in the S-band frequency as did TOKEN, but also was found to have an L-band frequency. This indicated an acknowledgement by the Soviets of the ECCM advantages of the diversification of frequencies.
The P-30 was an early warning ground control and interception radar for the Soviet Air Defence Forces, airforce and navy of the Soviet Union. Crystal was a development of an earlier radar design, the P-20 radar with which it shares many similarities. The radar was developed under the direction of chief designer V. Samarin and by 1955 the radar had completed state trials and was accepted into service. In 1958 the P-30 was upgraded to provide a 10-15% improvement in the detection range as well as improvements to the systems reliability, the modernised variant entered service in 1959 after completion of state trials. The P-30 has now been superseded by its successors, the P-35 and P-37 radar, which at their turn have been replaced by more modern phased array radars which give a 3D image of the surroundings.
The P-30 is a semi-mobile (it takes some time to build it up and break it down for transport) radar consisting of a trailer mounting the control cabin and transmitter equipment, two Zil trucks carrying the power supply equipment and antenna trailers. The antenna system of the P-30 is composed of two open frame truncated parabolic antenna accomplishing both transmission and reception. Both antenna are fed by a stacked beam composed of six feed horns. The radar uses two antenna to determine target altitude by the V-beam system with azimuth scanned mechanically. The upper antenna is tilted to an angle of 25 degrees from horizontal which results in each target appearing twice on the indicator, the distance between the two allows the targets altitude to be approximately estimated by the operator. The left hand side of the lower antenna carried the antenna array of the NRS-20 IFF secondary radar, which was used to identify detected aircraft as friend or foe. The radar can scan a full 360° with a range of 180km and a height of 12km.
This large 2-D ground-controlled interception and search radar is trailer-mounted equipment that has two large truncated paraboloid reflectors with clipped corners. An approximate height determination of the target could be carried out by the sloping position of the upper antenna (the so-called V-beam). If the target on the screen is shown twice, this means that the accompanying aircraft flies at a larger height. The further away this two parts of the target were shown on the screen, the targets height was the larger. The attached to the left corner of the lower reflector vertical beacon is the compensation antenna of the included identification friend-or-foe secondary radar unit (NRS 20). This “active answer” should make a better identification of own airplanes possible and was established with the introduction of the MiG 21. Due to the possibilities of digital target recognition and local tracking accompanied by a modern Plotextraktor this radar got a revival and was reissued under the name 1L117. The plot extractor can process up to 200 targets simultaneously. The accuracy in height determination is 400 m. In the late 1940s, the US Air Force and Navy began trying to obtain aerial photography of the Soviet Union. In 1950 there was a major change in Soviet policy. Air defense units became very aggressive in defending their airspace, attacking all aircraft that came near the borders of the Soviet Union. Despite the growing risks associated with aerial reconnaissance of the Soviet Bloc, senior US officials strongly believed th.at such missions were necessary.
US reconnaissance experts believed that the Air Force should emphasize high-altitude photoreconnaissance. Underlying their advocacy of high-altitude photoreconnaissance was the belief that Soviet radars would not be able to track. aircraft flying above 65,000 feet. This assumption was based on the fact that the Soviet Union used American-built radar sets that had been supplied under Lend-Lease during World War II. Although the SCR-584 (Signal Corps Radio) target-tracking radar could track targets up to 90,000 feet, its high power consumption burned out key components quickly, so this radar was normally not turned on until an early warning radar had detected a target. The SCR-270 early warning radar could be left on for much longer periods and had a greater horizontal range (approximately 120 miles) but was limited by the curvature of the earth to a maximum altitude of 40,000 feet.
The problem with this assumption was that the Soviet Union; unlike Britain and the United States, had continued to improve radar technology after the end of World War II. The Soviets quickly recognized their technological lag in radar as early as 1945 when they obtained through lend-lease the U.S. SCR-584 and, through wartime aid from the United States and Britain, gained a ready base of radar technology. Based upon that and in recognition of their wartime experience and other operations (surprise attack and V-2 rockets) they quickly determined a need for effective early warning. Before 1950, they developed and fielded a Soviet-produced acquisition radar — DUMBO — and followed that soon thereafter with a product of native design, TOKEN, which quickly spread across the country in the early 1950s.
The TOKEN development and deployment gave evidence of Soviet technological capacity since it marked a modest time lag between appearance of a prototype and the subsequent large-scale deployment. It provided a practical demonstration of the great strides made by the Soviets in mastering Western technology, but in particular, seemed to underscore the sense of urgency and purpose in Soviet air defense developments.
The American pre-war arrogance and confidence in the technological backwardness of the USSR was in some cases misplaced. The MIG-15 and TOKEN radar, for example, were the equal of anything produced in the West. Even after evidence of improved Soviet radar capabilities became available, however, many advocates of high-altitude overflight continued to believe that aircraft flying above 65,000 feet were safe from detection by Soviet radars. This belief was based on a 1952 study of Soviet World War II-vintage radars and on 1955 tests using US radars, which - unknown to US officials - were not as effective as Soviet radars against high-altitude targets.
In 1954, the number of TOKEN radars increased markedly. Soviet technicians were clearly more successful at maintaining them at an operational level than the U.S. had initially anticipated. The difficulties that the United States had expected the Soviets to encounter were based on U.S. experiences with the AN/ CPS-6, a similar radar. It was found, however, that the basic design of the TOKEN radar was considerably simpler. As of 1954, TOKEN was considered to be the best Soviet radar. It was also found that radars of older design (i.e., KNIFE REST, RUS II and DUMBO) were deployed near many of the TOKEN sites to serve as gap fillers and traffic controllers. TOKEN with longer range but a height capability of only 45,000 feet was aided by these older radars of shorter range but a height capability of nearly 60,000 feet. The TOKEN, and in general the V-beam radars, represented a vast improvement over prior Soviet capabilities. This was true to such an extent that one of the most important implications of the V-beam radars was the high degree of electronic capability attained by the Soviet scientists.
One completely fortuitous development from the Project GENETRIX balloon overflight program had nothing to do with the cameras but involved a steel bar. This bar served a dual purpose: the rigging of the huge polyethylene gasbag was secured to the top of the har and the camera-payload and automatic-ballasting equipment was attached to the bottom. By sheer chance, the length of the bar - 91 centimeters - corresponded to the wavelength of the radio frequency used hy a Soviet radar known by its NATO designator as 'TOKEN. This was an S-band radar used by Soviet forces for early warning and ground-controlled intercept. The har on the GENETRIX balloons resonated when struck by TOKEN radar pulses, making it possible for radar operators at US and NATO installations on the periphery of the Soviet Union to locate a number of previously unknown TOKEN radars.
Eisenhower had to make a decision about the overflights. Estimates based on previous intelligence data had shown the Communist's advantage, with hundreds of M-4s (and Tu-16s) being visualized, that is, at least in American heads - the bomber gap. Khrushchev had already spoken of Soviet ballistic missiles equipped with a hydrogen bomb, and in the beginning, the United States was really lagging behind. The CIA also said that the Soviets would not usually notice the U-2 over their territory.
The main reason for Eisenhower's approval of the U-2 program was that a US National Intelligence Assessment (NIE) report stated that the Soviet standard P-20 V-beam radar (NATO codename "TOKEN") was unable to detect targets above 18,300 meters in height. Eisenhower hoped to carry out reconnaissance on all key targets in the Soviet Union as soon as possible. He also made it clear that if the U-2 is tracked by the Soviet radar, he will stop flying in Soviet airspace.
Shortly before U-2 operations began, however, the CIA's Office of Scientific Intelligence (OSI) conducted a vulnerability study of the U-2 that was published on 28 May 1956. The study's conclusion was that "Maximum Soviet radar detection ranges against the Project aircraft at elevation in excess of 55,000 feet would vary from 20 to 150 miles..... In our opinion, detection can therefore be assumed." Completed just three weeks before the initation of overflights, this study seems to have had little impact on the thinking of the top project officials. They continued to believe that the Soviets would not be able to track the U-2 and might even fail to detect it, except for possible vague indications.
Reports on Soviet radar coverage of the first two overflights of the Soviet Union became available on 06 July 1956. These reports showed that, although the Soviets did detect the aircraft and made several very unsuccessful attempts at interception, they could not track U-2s consistently. Interestingly, the Soviet radar coverage was weakest around the most important targets Moscow and Leningrad, and the Soviets did not realize that U-2s had overflown these two cities.
Many wanted to "get the Gold Star and wealth" [ie, win the Hero of the Soviet Union award]. Many people tried to shoot down a high-altitude American reconnaissance aircraft, but always with a constant result - a negative one. In 1957, over the Primorye, two MiG-17Ps from the 17th Fighter Aviation Regiment attempted to intercept U-2, but without success. All hopes were placed on a new anti-aircraft missile system, the C-75 / SA-2. On April 9, 1960, at the altitude of 19–21 km 430 km south of the city of Andijan, the intruder was found.
|pulse repetition time (PRT)||??|
|pulse repetition frequency (PRF)||??|
|peak power||1 MW|
|average power||50 kW|
|instrumented range||360 km|
|range resolution||500 m|
|beamwidth||0,6 - 1,7°|
|hits per scan||??|
|antenna rotation||6 rpm|
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