A new concept for determining the individual heat consumption in the heating systems of the apartment houses, which was realized in the intellectual system, developed by authors, for controlling the individual heat consumption, is proposed. Concept is based on the use of virtual measuring channels, determined by the technology of intellectual precise temperature sensors and flow meters for heat carrier in heating systems. Configuration of measuring channels is determined by software means, and can be operatively changed during exploitation. Methods and mathematical models for the calculation of individual heat consumption were determined, including calculation and distribution of total house heat consumption. Design principle of intellectual system for controlling the individual heat consumption was determined. Original design solutions, and hardware and software means for electronic components were developed. System carries out direct measurements of heat consumption, and performs data reception and transmission from electronic measuring and controlling components using radio channel at frequencies of 434 or 868 MHz, then it is performing calculations and displaying results. Results of calculations in real measuring units are displayed on the local retranslator and apartment monitor. Exclusive feature of this concept is associated with the possibility of measuring of total house heat consumption. Estimation of confidence limits of systematic measurement error of the individual heat consumption was carried out. It was shown that average weighted error for determination of heat consumption by one apartment during the heating season does not exceed 6.5%.
In the paper a problem of target detection in continuous-wave noise radar in the presence of impulsive external noise is addressed. Noise radar uses random or pseudo-random waveform as a sounding signal. Classical correlation receiver used in noise radar is optimal for external noise with Gaussian distribution. If the external noise has distribution different than Gaussian, for example impulsive noise, the performance of the detection is degraded. In order to restore the sensitivity lost due to the impulsive noise, a robustification method is proposed. In the method, a nonlinear function is applied to the signal in order to remove the outliers. The method is verified on real-life signals.
In high frequency radar, we should avoid noise disturbances in the radar's working-frequency segment. Moreover, the sidelobes of strong targets interfere with the detection of weak targets. A new method based on an adaptive selecting working-frequency is proposed. Frequency spectrum monitor is designed for selecting quiet frequency segment for the radar. Frequency spectrum monitor and the receiver of the radar are arranged to work according to special time periods respectively. So the radar can work in the frequency segments with lower noise disturbances. Moreover, there is no correlation between the noise and the useful echo signal, though the correlation between noises over very short time periods is strong, the noise data produced by frequency spectrum monitor can be exploited effectively. Adjusting system parameters in real-time by adaptive methods can be utilized to reduce noise disturbances. Algorithm based on the properties of crosscorrelation between noise and target is exploited for suppressing sidelobe disturbances of strong targets. Lastly, the feasibility of the methods is verified by processing actual radar data.
A passive coherent location radar makes use of transmitters already present in its environment that illuminate the surveyed area. A passive radar consists solely of a receiver that collects the waves reflected from objects of interest (targets in radar terminology) and correlates them with a direct wave from the transmitter. As the illumination is continuous, the radar suffers from near-far effect: strong echoes from near objects blind the detector from detecting weaker echoes of far objects. This may be mitigated with CLEAN method, which, however, requires precise strong echo modelling to be effective. The paper presents a method for accurate modelling of an echo in case of compact target - i.e. when signal bandwidth is insufficient for accurate resolving the target details. The method is based on the assumed sparsity of the target, which is usually adequate, as a typical object acts as a small number of point scatterers with respect to radar waves. The modelling method is analyzed with respect to the residual power after removal of modelled echo from the original signal.
A new technique of identifying orientation angles of walls of buildings has been proposed in this paper. The present method is based on multilook processing. The aim of this work is to find the relationships between the received signals reflected from uniform targets (e.g. walls, parts of buildings, etc.) positioned at different orientation angles towards the radar platform. The technique is dedicated for synthetic aperture radars systems. It can be used to extend target identification in synthetic aperture radars images obtained by a single-channel antenna. In this paper, theoretical analysis is presented and verified with simulated radar data.
Modification of the weighting raised cosine with a power n function by time convolution with auxiliary changeable time duration uniform rectangular window is presented in this paper. The analytical form of the modified weighting raised cosine function for fixed power in frequency domain was derived. Proposed method was applied to fine tuning of properties of the nonlinear frequency modulation of radar signals. Synthesis of nonlinear frequency modulation radar signals problem was solved using the well-known principle of stationary phase. The selected testing results are shown and some final conclusions are formulated.
The aim of this research was to verify if It is possible to solve the synthesis problem of polyphase codes efficiently with an acceptable quality in the context of radar applications - with the greatest possible effectiveness of the recognition of such signals in the presence of the noise and occurrence of the Doppler effect. The received results confirmed that the implemented optimization algorithm can search polyphase sequences successfully with a low level of sidelobes and an enhanced tolerance to the Doppler effect. Applying optimization methods allows to form ambiguity function in a measure in the assumed optimization range which seems to be encouraging for future examinations in the field of the computer optimization for the coded radar signals synthesis.
Pulse compression with a small sidelobe level is one of challenges in designing of modern radar, sonar or ultrasound imaging systems. It may be performed by means of matched filter, that is by correlating the received sounding signal with a stored replica of the transmitted signal. The advantage of the pulse compression method is the increase of the average transmission power while retaining the range resolution corresponding to a short pulse. Phase coding is one of the early techniques for pulse compression of radar signals. Polyphase sequences, which have low sidelobe levels, ensure an easily detectable peak in the output of a matched filter, in other words an easy detection of a received sounding signal. In this paper, an evolutionary algorithm combined with a local optimizer is used to search for polyphase codes with a small sidelobe level of an aperiodic autocorrelation function. The evolutionary algorithm is based on a floating-point representation and the Gaussian mutation is used to produce offspring for the next generation. The self-adaptation mechanism is used to control the mutation operator during the evolutionary process. This research demonstrates that optimization methods can effectively find polyphase sequences with low autocorrelation and seems to be very promising for the future research in area of computer optimization for polyphase codes synthesis.
The signal time-frequency structure designing is the important problem of radar system solution optimisation. The radar ambiguity function is the very useful signal characteristic that enables to know the signal potential possibilities. The effective numerical methods of the radar ambiguity function calculation give possibility for synthesis of the radar signal having expected features. The synthesis method concerning the nonlinear frequency modulation radar signal is presented in the paper. For the radar ambiguity function calculation the Zak transform is used in the method. The nonlinear frequency modulation signal model was described in which application limitations were taken into account. Examples of simulation research results are presented as a comment of the considerations.
The optimization of the transmitted signal time-frequency structure is the very important part of the radar system design from the point of view of the radar system effectiveness. In this meaning the radar ambiguity function is the basic tool used for the radar system features testing. The synthesis procedure of the signal with simultaneous amplitude and phase manipulation is presented in the paper. The procedure is based on the Zak transform that is connected with the radar ambiguity function. The Legendre polynomials were applied in the procedure mentioned above. The results of the simulation tests are presented as examples of the consideration main effects.
This paper presents the results of the research considering the influence of the initial frequency on linear frequency modulation signal compression. The signal compression has been performed using the digital matched filtration in the time domain. The ratio of peak to side lobe ratio with the width of the main lobe equaling one sampling period is the measure of the quality of compression. In general, a lower value of peak to side lobe ratio is obtained for linear frequency modulation signals with a non-zero initial frequency than with a zero initial frequency. The peak to side lobe ratio is systematically decreasing with the increase of the initial frequency f_1. The existing methods of band signals sampling, where the spectrum of the signals is transferred by means of the carrier signal f_0 of a significantly higher frequency than the band B (f_0 ≫ B) may be effectively used for sampling signals considered in this study, which do not have a carrier. As a result, for the linear frequency modulation signals with a non-zero initial frequency f_1 = nB and a final frequency f_2 = (n + 1) B, n = 1, 2, ..., the same peak to side lobe ratio values will be obtained as for linear frequency modulation signals with a zero initial frequency and the identical band and time duration. The results of this research could be implemented in sonar and radiolocation techniques and medicine.
A phased array antenna is designed for multifunction phased array radar simulation test bed. Effect of element pattern, mutual coupling between elements, phase quantization, amplitude and phase error and elements failure rates on array pattern are discussed. Target angle measurement and side lobe cancelling, in order to reduce jamming power through side lobes, is illustrated in this antenna. Also antenna beam width is broadened with different methods and compared with narrow beam characteristics. It is shown that, for special broadening factors, beam broadening may lead to a better coverage and power efficiency relative to narrow beam antenna.
The idea of microwave quadrature correlation as well as the block diagram of the microwave broadband correlation receiver and principle of quadrature correlation detection of noise signals using an analog microwave correlator are presented in the paper. Measurement results for the correlation function of noise signals are shown and application of such solution in the noise radar for precise determination of distance changes and velocity of these changes is also presented. Results for short range noise radar operation are presented both for static and moving. Experimental results using 2.6-3.6 GHz noise like waveform for the signal from a breathing human is presented. Conclusions and future plans for the use of presented detection technique in broad-band noise radars close the paper.
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