Satellite altimeters play a key role in Earth remote sensing programs. To attain a centimeter accuracy level within the limited energy budget the altimeter probing signal should have a processing gain of the order of tens of thousands. Un-der such circumstances both of the angle modulation modes (LFM, BPSK) are equivalent as for their tactical performance. Preference of LFM in modern foreign devices is based on the tendency to reduce demands to digital processing operation speed by transferring wide-band processing to the analog receiver part. However, modern circuitry capabilities allow to implement digital processing of the signals with the bandwidth of hundreds MHz, giving thereby the way to involving BPSK signals which are not that susceptible to various drifts and external disturbances, do not require frequency modulation super-linearity, etc. In the paper both modulation formats are compared and recommendations are given on how to choose the structure and parameters of BPSK signal.

In this paper differences between Fisher Information Matrix (FIM) and inverse covariation matrix of normalized correlation estimations for white and colored noise are investigated. It’s shown that implementation of normalized correlation function estimation leads to modification of maximum likelihood estimation FIM elements, so in case of arbitrary energy affected parameter vector, variance of estimation by normalized correlation function maximization is not equal to Cramer–Rao lower bound. Statistical characteristics of joint Doppler stretch and delay estimation by maximization of normalized correlation function for signal with nuisance parameters are derived in this paper. It’s shown that normalized correlator is equal to wideband ambiguity function, but this method of estimation follows from Cauchy–Schwarz inequality without using energy conservation assumptions. Besides, it is proved that estimation of Doppler stretch and delay by normalized correlation function or WBAF of signal with random initial phase and gain is asymptotically unbiased and effective.

Optimization of iterative algorithms for channel state estimation in a sparse coding multiple-access system (SCMA) is performed to reduce computational costs of the receiver. It is shown that when a signal-to-noise ratio (SNR) does not exceed 10 dB, one iteration of the algorithm is sufficient, and an increase in the number of iterations does not lead to an increase in spectral efficiency. Simulation demonstrates a possibility of a reasonable choice of the total number of decoder iterations and their distribution between different stages of the channel estimation. For an uncoded system, iterative re-estimation of the channel is proposed, as well as ways to reduce computational costs during its calculation. In the coded system, at a low SNR the achieved spectral efficiency values are approximately similar to those with pilot-only channel estimation. The article provides recommendations for the placement of data symbols and pilot signals in re-source blocks to increase the system spectral efficiency.

The article presents the basic principles of design and development of integrated middle range Coastal Surveillance System (CSS) used for water surface lookout. It provides solutions for such missions as command and control of maritime forces, border monitoring and control, prevention of illegal activities such as piracy, smuggling, illegal immigration, illegal fishing, supporting search and rescue (SAR) operations, and creates a common situation awareness picture of the Naval Theatre. The system structure diagram is designed to solve computational overload problem when processing large volume of data received from radar stations. The measurement-level fusion algorithm is developed based on the JPDA framework, in which radar data received from a single or group of radars and AIS data is aggregated in a processing center. The servers and workstations make use of local area network (LAN), using standard Gigabit Ethernet technologies for local network communications. Acquisition, analysis, storage and distribution of target data is executed in servers, then the data is sent to automated operator stations (console), where functional operations for managing, identifying and displaying of target on digital situational map are performed.

The expediency of developing expressions for mutual inductance of rectangular and square coplanar contours is caused by configuration of frame antennas typical for RFID-technologies. Expressions presented in this article are aimed at simplifying calculation of induction coefficients when designing loop antennas. Expressions for mutual inductance of rectangular coplanar contours with symmetrical internal arrangement are obtained on the basis of the method of sections. It is shown that under certain conditions the expressions obtained can be reduced to intrinsic inductances of the square and rectangular frames encountered in antenna configurations. The analysis allows to estimate regions of resonance frequencies of frame receiving antennas. Simultaneously, a comparative analysis of a number of expressions for the intrinsic inductance of rectangular and square frames is performed, and attention is drawn to the difference in estimates. Recommendations for clarifying square contour external inductance are provided.

The method for determining the optimal duration of monitoring interval of non-stationary Poisson failure rate of radio-electronic equipment (REE) for a wide range of stationary processes, modulating it by intensity. To know the optimal du-ration of monitoring interval, taking into account the flow double stochasticity is necessary to calculate and predict REE reliability factor, operating in near-Earth space as a part of artificial Earth satellites (AES). In the course of calculation REE is exposed to ionizing radiation of unsteady flows and electrostatic charges, leading to short duration or irreversible failures. Based on the known linear model of double stochastic point process a detailed mathematical analysis is made for the first time ever and analytical expressions were obtained for the optimal monitoring time interval with respect to minimum combined standard uncertainty. Since the true nature of unsteadiness is unknown, analysis is carried out for Gaussian and Gauss-Markov modulating processes, covering a wide range of random processes. The analysis results confirm practical similarity of optimal monitoring time interval values for a wide range of modulating processes.

The approaches to the evaluation of the efficiency of the functioning of heterogeneous video information systems are considered. It is shown that the hierarchy model as a quantitative description of the structural and functional organization can serve as a means of analyzing information flows and system efficiency in terms of graph theory. The criterion of dominance for the evaluation of the efficiency of heterogeneous video information systems is analytically presented. It is shown that in the loaded graph of a heterogeneous system the weights of individual nodes represent the efficiency of this node, and with its increase the degree of influence (dominance) of this node on the remaining nodes of the system and on the system as a whole grows, and conversely, with a decrease in the weight of the node it rises its dependence on other nodes. The influence of the length of interstitial paths on the efficiency of the system is taken into account, taking into account the partial loss of information during its propagation through the graph. Numerical calculations of the efficiency of systems based on the dominance criterion are given, the results of which confirm the indicated theoretical positions.

One of the fundamental properties of modern radio electronic equipment (REE) is jammer-induced performance in particular when located near REE, when they significantly affect the parameters of electromagnetic field generated and/or received by REE. One of the ways of antijamming is its rapid detection by REE for elimination purpose. In solving this problem, both the minimum detection time and the accuracy of the noise source location are equally important.  In this article, the problem is considered using the example of radar detection with a multi-channel receiving device and thrown noise transmitter located close to its antenna field. The schemes displaying the problem geometry for phase and difference-distance-measuring methods for determining of jammer position are presented. Expressions are formed that determine the area of uncertainty zone when jammer detecting and connection of this value with radar parameters – ranging and azimuth accuracy. The necessity of using expressions free of far zones assumptions with respect to the radar and jammer relative position is explained. Ranging based on the signal received by radar in the mode of circular or sector review is considered. The results obtained confirm the necessity to take into account the distance between the jammer and REE when implementing the basic methods for determining radiation source location.

A method for analysis of dispersion characteristics of guided optical modes propagating in the optical waveguides with small cross-sections is proposed. The method is based on introduction of a correction factor for a longitudinal wavenumber of propagating modes. The correction factor arises when a cross-section of the basic rectangular waveguide is subjected to perturbation. The electromagnetic field distributions along with the mode longitudinal wavenumber are found by means of variable separation method. The longitudinal wavenumber correction factor is analytically calculated in terms of coupled mode theory. The combined use of the complete set of equations of electrodynamics together with the concept of effective sources gives rise to the correction factor in the form of an intermodal coupling coefficient. It is pointed out that the coupling coefficient consists of two components, namely bulk and surface, owing to accurate account of the electrodynamics boundary conditions. Using the method proposed, the dispersion characteristics of the fundamental modes propagating in the practically employed optical waveguides having a trapezoidal cross-section are calculated. An impact of the waveguide cross-section shape to cladding dielectric constant ratio on the mode dispersion characteristics is analyzed. The necessity to take into consideration an imperfection of the waveguide cross-section in a wide range of operating wavelengths is demonstrated.

The article is devoted to investigation of microwave power converter temperature dependence caused by changes in the current-voltage characteristic of diodes. The analytical expressions are given for such diode parameters as junction resistance and diode saturation current that allow to estimate temperature influence on diode detector output voltage. This paper presents a comparison of two methods, i.e. correlation based on a terminological method that works in con-junction with an arithmetic-logical mechanism. The first method implies that the temperature stabilizes by use of identical pair of diodes one of which compensates for temperature-induced changes of the second diode junction resistance. The second method involves formation of correction factors that allow performing temperature correction of measurement results in a wide range of capacities. Based on the conducted temperature tests of microwave power meters with the use of a temperature sensor in the microwave unit, the thermal correction algorithm was implemented. It allows to reduce the changes in the readings from ±15 to ±1.5%. Data from the results of experimental studies that can be used in measuring microwave equipment of various types. The results of experimental studies of detectors based on low-barrier diodes ZB-28 with a boundary speed exceeding 100 GHz and a tangential sensitivity of 1 nW are presented.

 The article investigates ways to expand the dynamic range of broadband microwave receiving devices. The task is to lim-it the output signals while increasing the upper boundary of the dynamic range by the criterion of the thirdorder inter-modulation component suppression. The main relations  determining the dynamic range boundary conditions are pre-sented. Experimental studies of three variants of constructing the broadband microwave receiver output path in two-ton mode of operation are carried out for:

– an output amplifier with a point of 1 dB of output power compression at the level corresponding to safe output power;

– a powerful output amplifier with a passive diode limiter on the output;

– a powerful output amplifier with an automatic attenuation adjustment circuit connected to its input.

The measurement results of the magnitude of intermodulation distortions suppression and output power are presented as a function of the input signal level for various nonlinear elements. Based on the analysis of the measured characteristics, an optimal technical solution is found for constructing an output path. The dynamic range is extended by more than 20 dB. Suppression of intermodulation components of the third order exceeds 60 dB. Effective functioning of the broadband receiver in multisign mode is ensured.