2015/4

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    Multi-Core DSP Based Parallel Architecture for FMCW SAR Real-Time Imaging
    (Společnost pro radioelektronické inženýrství, 2015-12) Gu, Chengfei; Chang, Wenge; Li, Xiangyang; Liu, Zhaohe
    This paper presents an efficient parallel processing architecture using multi-core Digital Signal Processor (DSP) to improve the capability of real-time imaging for Frequency Modulated Continuous Wave Synthetic Aperture Radar (FMCW SAR). With the application of the proposed processing architecture, the imaging algorithm is modularized, and each module is efficiently realized by the proposed processing architecture. In each module, the data processing of different cores is executed in parallel, also the data transmission and data processing of each core are synchronously carried out, so that the processing time for SAR imaging is reduced significantly. Specifically, the time of corner turning operation, which is very time-consuming, is ignored under computationally intensive case. The proposed parallel architecture is applied to a compact Ku-band FMCW SAR prototype to achieve real-time imageries with 34 cm x 51 cm (range x azimuth) resolution.
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    Video Tracking for Visual Degraded Aerial Vehicle with H-PMHT
    (Společnost pro radioelektronické inženýrství, 2015-12) Pakfiliz, Ahmet G.
    The work presented in this paper describes a novel approach for automatic video tracking of visual degraded air vehicles in daylight with sky background. The offered and applied video object tracking method is based on Histogram Probabilistic Multi Hypothesis Tracker algorithm. The H-PMHT is an expectation maximization based algorithm developed for tracking objects in intense clutter environment by using intensity modulated data streams. Basically H-PMHT algorithm is suitable for linear-Gaussian point spread function case. However, recent studies have indicated that the algorithm is also applicable for non-linear and non-Gaussian target shapes. Thus H-PMHT becomes a suitable alternative for tracking applications with sonar, high resolution radars,IR, UV sensors and cameras. In this work H-PMHT algorithm is used for video tracking of visual degraded air vehicles. For this purpose RGB video data is processed by using a reciprocal pixel intensity measurement for meeting the requirements of the tracking process. A simulation study is conducted in order to demonstrate the video tracking performance of H-PMHT against visual degraded air vehicles. Also the results obtained with H-PMHT algorithm are compared with the results of amplitude information added Interacting Multi Model Probabilistic Data Association algorithm.
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    Generalized Propagation Channel Model for 2GHz Low Elevation Links Using a Ray-tracing Method
    (Společnost pro radioelektronické inženýrství, 2015-12) Zeleny, Jan; Perez-Fontan, Fernando; Pechac, Pavel
    Unmanned Aerial Vehicles (UAV) will increasingly be used for responding to emergencies or for law enforcement in civil surveillance applications. Transferring the enormous amounts of information from UAV-mounted cameras or sensors will require large bandwidths, unlike the information required for remotely controlling a UAV, thus necessitating higher frequency bands typically in the vicinity of 2 or 5 GHz. Novel hardware developments will need to rely on a versatile propagation channel model for the envisaged scenarios ranging from deep shadow urban areas to open fields. This paper studies more complex intermediate scenarios, which fall between the aforementioned ones, and which are more difficult to model. A semi-deterministic model, first developed for open, flat areas, has been generalized to accommodate any possible operational scenario and was tested in built-up areas. The model involves a stochastic part and a determinist which is a ray-tracing based part used to compute the long term mean (LTM) of the signal's coherent component.
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    Energy Efficient Power Allocation for Distributed Antenna System over Shadowed Nakagami Fading Channel
    (Společnost pro radioelektronické inženýrství, 2015-12) Wang, Ying; Yu, Xiangbin; Li, Yang; Wu, Binbin
    In this paper, the energy efficiency (EE) of downlink distributed antenna system (DAS) with multiple receive antennas is investigated over composite fading channel that takes the path loss, shadow fading and Nakagami-m fading into account. Our aim is to maximize EE which is defined as the ratio of the transmission rate to the total consumed power under the constraints of maximum transmit power of each remote antenna. According to the definition of EE and using the upper bound of average EE, the optimized objective function is provided. Based on this, utilizing Karush-Kuhn-Tucker (KKT) conditions and mathematical derivation, a suboptimal energy efficient power allocation (PA) scheme is developed, and closed-form PA coefficients are obtained. The developed scheme has the EE performance close to the existing optimal scheme. Moreover, it has relatively lower complexity than the existing scheme because only the statistic channel information and less iteration are required. Besides, it includes the scheme in composite Rayleigh channel as a special case. Simulation results show the effectiveness of the developed scheme.
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    Analysis of Coexistence of DRM Plus and FM Broadcasting Systems
    (Společnost pro radioelektronické inženýrství, 2015-12) Ulovec, Karel
    This paper deals with DRM (Digital Radio Mondiale) Plus and FM (Frequency Modulation) radio broadcasting systems coexistence. It brings results based on measurement of mutual interferences of each to other. Minimal necessary value of the signal to interference power ratio is measured under the given reception criteria. Results are useful for broadcasting networks planning. Different DRM Plus modes (i.e. combinations of various protection levels and data carriers modulations) are assumed in the case of DRM Plus reception interfered with by FM broadcasting. The differences for various modes are crucial for coverage design of DRM Plus system, while protection ratios have been recommended for only two of eight modes until now. Corrections of protection ratios for other modes are proposed in this paper. Different waveforms types of modulating signal for interfering FM signal are tested. The both mono and stereo FM mode and various sound quality criteria are considered in the case of FM broadcasting reception interfered with by DRM Plus. The influence of peak to average power ratio reduction of interfering DRM Plus signal is observed.