One of the tasks performed by contemporary radars is the classification of a type of detected objects. Among many types of objects, helicopters, and especially hovering ones, are of special interest in radar’s self-defence. The echo signal of such object possesses specific properties of its spectrum that result from the construction of the object. A characteristic property of the echo signal is the presence of the spectral components from the hull of the helicopter as well as from the main rotor. The parameters of the latter components depend on the rotary speed of the rotor, the number of the blades and their length.
Inverse synthetic aperture radar is a system allowing for acquiring of high resolution images of moving objects. The image synthesis algorithms base on coherent integration of observed object’s echo signals, which requires the exact knowledge of the object’s movement parameters in order to compensate two fundamental phenomena: echo’s initial phase modulation and range cell migration of the signal. In this paper results of research on range migration compensation method applying the keystone transform are presented.
On a freeway, a sudden stop of a vehicle poses serious threat to all the road users in the following vehicles and it often leads to accidents. Due to high speed and intensity of the traffic, in such situations multiple crashes often occur. The detection of a stopped vehicle on a freeway and possibly early warning of the other drivers, that they should lower their speed and maintain caution may contribute to decreasing of the number and limiting the consequences of car crashes. In the article a structure of a system for traffic on a freeway monitoring and an algorithm allowing for detection of stopped vehicles in such system are presented.
The protection of critical infrastructure objects such as airports, sea ports or border crossings is one of the essential security problems. In order to perform this task an electromagnetic emission passive monitoring method may be used. This is realized with distributed passive wideband radio frequency (RF) sensors utilizing the time difference of arrival (TDoA) method of electromagnetic emission source location. The complexity of the algorithms implemented in such systems requires high computational power of the signal and data processing systems. This implies the need for computational complexity reduction of implemented algorithms. In this article a computationally efficient algorithm for cross-correlation of received signals in time difference of arrival method is presented.
The paper presents a synthetic information on a UAV-based radar terrain imaging system, its purpose, structure and working principle as well as terrain images obtained from flight experiments. A SAR technology demonstrator has been built as a result of a research project conducted by the Military University of Technology and WB Electronics S.A. under the name WATSAR. The developed system allows to obtain high resolution radar images, both in on-line and off-line modes, independently of the light conditions over the observed area. The software developed for the system allows to determine geographic coordinates of the imaged objects with high accuracy. Four LFM-CW radar sensors were built during the project: two for S band and two for Ku band, working with different signal bandwidths. Acquired signals were processed with the TDC algorithm, which allowed for a number of analyses in order to evaluate the performance of the system. The impact of the navigational corrections on a SAR image quality was assessed as well. The research methodology of the in-flight experiments of the system is presented in the paper. The projects results show that the developed system may be implemented as an aid to tactical C4ISR systems.