The simple analysis method of nonlinear frequency distortions in FMCW radar, Journal of Telecommunications and Information Technology, 2001, nr 4

The paper presents a simple method for estimating nonlinear frequency distortions of linear frequency modulated (LFM) signals used in FMCW radars. This method, derived from the polynomial model of the nonlinear FM signal phase, is based on finding the maximum of two-dimensional chirp-like transform of the IF video signal. The IF signal is obtained by mixing transmitted FM signal with its delayed copy. Using suggested transform we show that the presented method is able to detect and classify signal distortions

Implementation and Results of New High Resolution SAR Modes for an Airborne Maritime Patrol Radar

The paper presents new high resolution SAR results of real-life measurements using an updated ARS-400/ARS-800 SAR sensor installed on the maritime patrol aircraft M-28. The main role for such radars is surveying the sea surface, and the imaging of selected targets (e.g. ships, roads, vehicles, buildings, etc.) to help the operator in classifying them. In the present day increasing computing power, improved algorithms and general technological progress has allowed the obtaining of better results in SAR imagery

Wearable Pulse Oximeter for Swimming Pool Safety

The purpose of this research was to develop an algorithm for a wearable device that would prevent people from drowning in swimming pools. The device should detect pre-drowning symptoms and alert the rescue staff. The proposed detection method is based on analyzing real-time data collected from a set of sensors, including a pulse oximeter. The pulse oximetry technique is used for measuring the heart rate and oxygen saturation in the subject’s blood. It is an optical method; subsequently, the measurements obtained this way are highly sensitive to interference from the subject’s motion. To eliminate noise caused by the subject’s movement, accelerometer data were used in the system. If the acceleration sensor does not detect movement, a biosensor is activated, and an analysis of selected physiological parameters is performed. Such a setup of the algorithm allows the device to distinguish situations in which the person rests and does not move from situations in which the examined person has lost consciousness and has begun to drown

Multipath Propagation of Acoustic Signal in a Swimming Pool—Source Localization Problem

This paper explores the problem of severe multipath propagation of underwater acoustic signals in a swimming pool. The problem appeared in a study that examined a system used to signal emergency situations (i.e., pre-drowning symptoms detected by a wearable device on a pool user’s wrist) and locate the signal source. A swimming pool acoustic environment is characterized by the presence of large flat reflecting planes surrounding a small volume of water. The reflections are numerous and much stronger than in typical hydroacoustic applications. In this paper, we attempted to create a model of the swimming pool response, one that is suitable for simulation experiments with detection and localization of emergency signals. Then, we explore the possible remedies for the localization system, applied on the transmit side (waveform design) and on the receive side (receiver placement and signal processing). Finally, we present an algorithm for object localization, considering the possible reflections with a multi-hypothesis approach

Experimental Verification of the Concept of Using LOFAR Radio-Telescopes as Receivers in Passive Radiolocation Systems

The paper presents a new idea of using a low-frequency radio-telescope belonging to the LOFAR network as a receiver in a passive radar system. The structure of a LOFAR radio-telescope station is described in the context of applying this radio-telescope for detection of aerial (airplanes) and space (satellite) targets. The theoretical considerations and description of the proposed signal processing schema for the passive radar based on a LOFAR radio-telescope are outlined in the paper. The results of initial experiments verifying the concept of a LOFAR station use as a receiver and a commercial digital radio broadcasting (DAB) transmitters as illuminators of opportunity for aerial object detection are presented