Rudolf Seller

The communication subsystem of Masat-1, the first Hungarian satellite

The first Hungarian satellite, Masat-1 is designed and built at the Budapest University of Technology and Economics. Instead of working from pre-built components, the members develop the whole satellite, including design, implementation and testing. This paper introduces the key issues about designing a small satellite, with a detailed description of the Communication subsystem. In the paper, special attention is being paid for the digital signal processing part of the development, as it is the key to fulfill the easy detection constraint. The possible solutions are examined and there is a recommendation of a method which could easily fulfill the proposed requirements.

Digital television broadcast -based passive radar research and development

Nowadays passive radars are gaining ground and become more popular. Now, that the so far insurmountable technological limitations begin to disappear, beside the theoretical researches the investigation of realizations with the recently available hardware technologies are becoming more important. This paper presents a feasibility experiment of such a passive radar that uses DVB-T (Digital Video Broadcast - Terrestrial) signal to detect airplanes. In this paper the he principle operation of the passive radar systems has confirmed both with simulations and measurements.

Quad channel DVB-T based passive radar

The detection performance of the passive radars systems is limited by the direct path interference. The application of digital beamforming antenna arrays in the surveillance channel has been proposed so far. The suppression can be accomplished with the proper beampattern synthesization. In this paper real measurement data utilising the spatial filtering techniques are presented. The detected target SINR is analyzed using different surveillance channel beam space processing techniques.

Koch fractal antenna application in monopulse antenna array

This paper addresses the design and evaluation of monopulse antenna array used in UAV on-board collision avoidance radar. The antenna array use the advantages of the fractal geometry. The inverted Koch square patch fractal antenna has been modified in order to gain more control over the efficiency degradation originating from production difficulties and to meet the requirements of a monopulse collision avoidance radar. Simulation and measurement results show the applicability of fractal geometry in antenna arrays.

Time domain filter comparison in passive radar systems

The detection performance of a passive radar systems is generally determined by the received reference and surveillance signals purity. In recent times a number of interference cancellation techniques have been researched to deal with the disturbances on the surveillance channel. The variety of different methods operate in the space, time and frequency domains with having different implementations. This paper aims to examine and compare the performances of the fundamental temporal filtering methods in real environment using field measurement data.

Maneuvering target tracking in wide area multilateration radar system

The Radar Research Group of the Budapest University of Technology and Economics has been developing a distributed passive radar system. Multilateration principle is used to locate aircraft in the zone defined by the location of the receivers. The measurement principle challenges the conventional tracking algorithms, therefore a new solution was developed.

On problems occurring at close vicinity usage of WiFi and radars, especially ATC and weather

The goal of my paper is to analyze mutual effects of radars and wireless systems on each other. In practice it occurred in many cases that these systems interfered with each other in their normal mode of operation. I studied the problem on radars working in the L band (1– 2 GHz) and in the C band (4–8 GHz). In the first case we experienced that the radar created a notable loss in the quality of the established connection. In the second case the WiFi connections distracted the radars normal measurement.

Synthetic aperture radar using spread spectrum modulation

An X-band SAR is developed, being upraded and tested. It uses solid state electronics and phase modulated impulses. The first results using corner reflectors prove the concept.

Air traffic control radar tester

Our aim had been to develop a radar tester equipment for commercial and military services. The task is to create one (or more) target or clutter on the radar screen with given distance, velocity and fluctuation. This equipment is placed within few hundred meters from the radar, so it is able to analyze the whole radar system from the antenna, via microwave hardware elements, to the DSP unit.

Space-Time Adaptive Cancellation in Passive Radar Systems

A critical issue in the realization of passive radar systems is the effective suppression of the zero Doppler interference (ZDI). The performance of the clutter cancellation relies much on the used algorithms. Several state-of-the-art approaches consist in the independent use of spatial and temporal algorithms for ZDI suppression. In this paper, a novel interference cancellation algorithm is proposed, which jointly exploits the available information from both space and time domains. We call this novel method Space-Time Adaptive Cancellation (STAC), and it differs from previous schemes included among the tools of Space-Time Adaptive Processing (STAP). The STAC algorithm is able to cancel out the high power direct and multipath signals on all the surveillance antenna channels prior to the beamforming and other space domain processing methods. The proposed preprocessing technique facilitates the detection of targets even in the direction of the illuminator or large static scatterers. Moreover, the interference rejection capability is also enhanced in the space domain. The performance of the presented algorithm is verified through simulations and field measurements. The experiments show improvement over the currently available filtering techniques.