S.Yu. Abrashov – Head of Department – Deputy Main Product Engineer, JSC V.Tikhomirov NIIP (Zhukovsky, Moscow region)
A.V. Avdeev – Head of Sector, JSC V.Tikhomirov NIIP (Zhukovsky, Moscow region)
P.A. Komyagin – Part-programming engineer, JSC V.Tikhomirov NIIP (Zhukovsky, Moscow region)
S.V. Zorin – Head of Department, JSC V.Tikhomirov NIIP (Zhukovsky, Moscow region)
M.N. Zhukov – Ph. D. (Eng.), Associate Professor, JSC «OKB Traverz» (Moskow)
V.E. Makaev – Ph. D. (Eng.), Associate Professor, JSC «OKB Traverz» (Moskow)
Detection of air targets by pulse-Doppler radar is performed by high and medium frequency monitoring impulses. Basic signal processing operation is signing out of the signal totality Doppler spectrum. Traditional echo signal processing makes it very difficult to detect an outlaying helicopter in hover mode. Most part of difficulties may be explained by the fact that any helicopter is a low-flying and often low-speed target.
The article describes possibility of an all-aspect helicopter tracking algorithm realization using high and medium frequency impulses. The authors emphasize specific characteristics of helicopter echoed signals, define fundamental mode of data processing in routine mode of pulse-Doppler radar.
Helicopter primary structure elements that influence echoed signal characteristics are fuselage, rotary wing, antitorque rotor, turbine engine compressors, cooling fan (if required by helicopter design). Rotary wing and antitorque rotor echoed signal may be represented as a series of wide-band flickers. To identify an air target as «helicopter» it is necessary to use all types of echoed signals.
Space scanning in high and medium frequency mode may be organized by routine cycle sheet. Calculation of possible helicopter location is made simultaneously. Echo signals from fuselage and engine compressors are processed, using routine algorithms, rotary wing and antitorque rotor echoed signal flickers are processed by additional procedures.
The first stage of signal processing consists in data coherent integration. Traditional algorithms for high and medium frequency impulses mode are implemented. The second stage of signal processing consists in narrowband spectrum processing. These allow «high-speed targets» detecting and interference elimination. Secondary information processing is the third stage of the procedure. The result of all these manipulations is detection, distance measurement and tracking of fast-moving targets as well as «helicopter» type targets.
In conclusion, the authors note that detection and tracking of helicopters by pulse-Doppler radar require allocation of additional computing resources. Nonetheless modern radar computation systems allow highly effective realization of all-aspect helicopter tracking algorithms.