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Urządzenie rozpoznania radiolokacyjnego LEMUR-20 : konstrukcja, przeznaczenie, wyniki badań modelu

Stolarski Z.

Biuletyn Wojskowej Akademii Technicznej

2007

Vol. 56, nr sp.2

401-408

W Oddziale Wrocławskim Przemysłowego Instytutu Telekomunikacji zakończone zostały prace badawcze nad modelem nowego urządzenia RWR/ESM o oznaczeniu LEMUR-20. W porównaniu z dotychczasowymi konstrukcjami PIT, urządzenie cechują m.in. poszerzone pasmo pracy (1-18 GHz) oraz zmniejszone gabaryty. Dzięki temu urządzenie może być instalowane na średniej wielkości pojazdach lądowych, okrętach i kontenerach stacji brzegowych. Artykuł opisuje budowę, funkcje poszczególnych elementów urządzenia oraz przedstawia wyniki badań funkcjonowania modelu. Prezentowane są uzyskane wartości parametrów, takich jak czułość, dokładność pomiaru częstotliwości i parametrów czasowych oraz błąd określania kierunku opromieniowania.

Radar Warning Receivers and Electronic Support Measure systems play very important role in armed forces activity in peace and conflict time. It can be foreseen that in the future, this type of systems will be of constantly growing significance. Applied on every kind of air, naval and ground platform, they create the vital asset in a modern combat electronic environment. Monitoring, analyzing and identifying radar emission, the ESM system works out the data needed to establish the complete air and surface tactical situation. The fact that monitoring can be carried out in a hidden way, render it an ideal warfare sensor. The Wroclaw Division of the Telecommunications Research Institute in Poland has finished a development work on a model of new RWR/ESM system called LEMUR-20. The LEMUR-20 is developed from the LEMUR-10 and the ESM-10 prototype system, installed on the naval patrol aircraft An-28 Bryza 1RM Bis. However, the LEMUR-20 differs fundamentally from the aircraft version — mostly in the construction of the antenna front-end unit and technical parameters. Directional antennas and low noise amplifiers (located in the ESM-10 system at ends of wings) are integrated under a common radome. Such construction results from planned applications (light vehicles, boats and coast stations) and the extended frequency band (1 to 18 GHz). The antenna system consists of extra four L band directional spiral antennas and one omnidirectional ultrawideband conical antenna. Relating to the former ESM systems, a direct frequency measurement using the omni antenna is a meaningful change. Antenna characteristics cover azimuth and elevation space and enable to estimate the bearing angle to the source of radiolocation emission. In the range from 2 to 18 GHz, the direction finding system bases on six directional spiral antennas. The angle of arrival is determined with high accuracy by the monopulse amplitude comparison method. Except the antenna unit, the LEMUR-20 consists of the microwave receiver module, signal processing module and mobile computer. A modular construction, both of microwave and digital part, simplifies assembling, operating and repairing processes in the system. The microwave receiver module includes receiver (DLVA) units and DIFM units (frequency discriminators for L and S-Ku band are separate). Due to space limitation, the new version of the DIFM unit for L band was designed and built. It is based on a single phase 6-bit discriminator with a short delay line. To make the auto test procedure of the system possible, the microwave receiver module includes the modernized Built In Test Equipment (BITE). The VCO with a new PLL circuit has improved long-term frequency stability. The Signal Processing Module includes DSP system with de-interleaving unit, control unit, LAN, navigation system and on-board radars blanking interface. The functionality of the application software was expanded with the visualization of the radiolocation environment on the digital map and the semiautomatic location of emitters. Results of research and measurements proved that in comparison with the ESM-10 system, the LEMUR-20 model has a better sensitivity (min. 55 dBm), high flatness of gain characteristics and lower internal noise. The estimation of the angle of arrival works correctly both in the 6- and 4-antenna direction finding system. Thanks to reduced overall dimensions and low power consumption, the LEMUR-20 can be installed and used on light mobile platforms (e.g. command vehicles, fast attack crafts).