Passive bistatic radar does not emit energy by itself but relies on the energy emitted by illuminators of opportunity, such as radio or television transmitters. Ground-based passive radars are relatively well-developed, as numerous demonstrators and operational systems are being built. Passive radar on a moving platform, however, is a relatively new field. In this paper, an experimental seaborne passive radar system is presented. The radar uses digital radio (DAB) and digital television (DVB-T) for target detection. Results of clutter analysis are presented, as well as detections of real-life targets.

Digital Audio Broadcast (DAB) transmitters can be successfully used as illumination sources in Passive Coherent Location (PCL). However, extending the integration time in such a configuration leads to the occurrence of periodical artifacts in the bistatic range/Doppler plots, resulting from the time structure of the DAB signal. In this paper, we propose some methods of signal preprocessing (based on symbol removal, substitution by noise, and duplication) that operate on the DAB transmission frame level and improve the received signal’s correlation properties. We also demonstrate that two of these methods allow us to avoid the mentioned artifacts and thus to improve the quality of the range/Doppler plots with detection results. We evaluate the performance of the proposed methods using real DAB signals acquired in an experimental PCL platform. We also provide the analysis of the Signal to Noise Ratio (SNR) during the detection of a moving target which shows that the proposed solution, based on symbol duplication, can offer around 3 dB of gain in SNR. Finally, we carry out the computational complexity analysis showing that the proposed method can be implemented with a minimal cost after some optimizations.

In this paper, a brief overview of hardware platforms with multiple RF input channels that can be employed in the area of Passive Coherent Location (PCL) and passive Synthetic Aperture Radar (SAR) is given. Two families of the platforms are considered, i.e. Field-Programmable Gate Array (FPGA) based development boards, and generalpurpose Software-Defined Radio (SDR) receivers. Practical solutions that have been validated in field experiments are described: a high-performance four-channel platform, and its lightweight version that perfectly suits the needs of low-power moving installations. The preliminary results of target detections are presented that are obtained from the signals acquired with the lightweight PCL platform. Our results prove that besides its simplicity, the small and low-power platform can be successfully used in PCL applications that use Digital Audio Broadcasting (DAB) transmitters as the source of illumination.

In this paper we present the radio signal acquisition module designed and build in our team for Software Radio and RADAR experiments. The module allows sampling RF and IF signals from two sources and to transfer acquired data to a Personal Computer via USB 2.0 interface. Thanks to built-in FPGA chip, it is possible to perform on-board signal preprocessing before transferring the data to PC. The PC is responsible for module configuration, triggering and data storage. We present the preliminary performance results obtained in practical experiments and measurements. The example application in Passive Coherent Location (PCL) experiments is also described.

The use of ultrasound in air as a means of digital communications has been demonstrated in recent years. Due to electromagnetic compatibility, privacy and security issues, this kind of transmission fits the requirements of many medical applications, body-area networks and general wireless short-range systems, where the transmission takes place in a single room with the distance up to 10 m. In the literature, different models of airborne ultrasound transmission have been investigated, but not supported by discussion of the channel theoretical capacity. On the other hand, knowledge of this measure is essential in the design of an efficient communication link and allows identifying its potential areas of applications. In this paper we calculate estimates of the Shannon limit for five different configurations of airborne ultrasound digital communication channels. Our evaluation is based on the numerical results available in the literature. The obtained estimates show that in case of systems with multichannel transmission and higher-order modulation schemes, the achieved data rates are closest to theoretical boundaries, but still further work is needed in order to achieve more efficient data transmission in airborne ultrasound communication channels.

Photovoltaic (PV) technology is an attractive power source for systems with no wired connections to any network. Because of seasonal variations of solar irradiation, designing such a system requires careful analysis in order to provide required level of reliability. In this paper we present results of 16-month measurements of experimental PV system located in Poland. Obtained irradiation values have been verified with reference data from independent sources. The results of this work may be helpful in forecasting the performance of similar PV systems in the same region and allow to make more precise forecasts of power system performance than based only on average monthly irradiation tables.