Satellite radar altimetry is a universal tool for global all-weather monitoring of the surface of the Earth. Substantial contribution to the satellite altimeter error is made by a component associated with noise and random nature of the echo-signal itself. When simulating a scattering surface with an array of specular points the altimeter echo-signal represents Gaussian process waveform received against AWGN. In such a case, the conventional statistical design produces an optimal echo-signal delay estimator in the form of the bank of identical energy receivers where decision is made according to maximal response. The Cramer-Rao bound defines the dependence of potential delay estimate accuracy on power and spectral resources used by altimeter, and the form of received power profile. The validity of analytical results obtained is confirmed by MATLAB simulation. It is also shown that the routine method of delay estimate based on threshold crossing yields manifold to the optimal one in measuring accuracy.

The goal of our research is development and study of different demodulation techniques for a frequency shift keyed signals. The signal under study is a frequency-shift keyed (FSK) signal when the information signal regulates the carrier frequency. We consider a model imitating data transmission channels and allowing us to perform error counting. The data transmission channels have ideal synchronization. Several techniques of demodulator design are introduced for demodulating frequency-shift keyed (FSK) signal and we compare the techniques using the criterion of error number of a demodulated signal relative to a signal prior to modulation for different signal-to-noise ratio. Signal-to-noise ratio is calculated as a ratio of the energy of the information symbol to the noise power spectral density. We have tested different demodulation techniques with different signal-to-noise ratio and produced a table containing information on demodulation accuracy for different techniques. Overall, we have simulated 100 sec. of continuous bit packages. We indicate that the best results for signal-to-noise ratio exceeding 5 dB are provided with the technique based on double correlation, and for signal-to-noise ratio less than 5 dB - with the technique based on the fast Fourier transform.

To ensure the required interference immunity of a radio link is a crucial task nowadays. The existing solutions in this field are based on signal spectrum spreading methods. In the age of radio engineering development application of specific technical solutions when building a noise immune radio system is ineffective. In this case, one of the most challenging tasks is taking into account the dynamic effects on the radio link resources. The solution to this problem can be obtained by the development of complex operation algorithms for radio system. This paper proposes noise immune radio link model taking into account the dynamic intentional impact on its resources. A distinctive feature of the proposed approach is determination of radio link resource control strategy. For that purpose, a concept of vector of elementary control methods is introduced. On the base of the random process theory a noise immunity radio link model is developed.

The article considers structural and technological parameters affecting breakdown voltage of a BSIT transistor cell. The main objective of the scientific research in that field is optimization of manufacturing techniques of power electronics transistor configurations in order to improve the instrument output characteristics and reliability. One of the key electrical parameters characterizing this instrument is breakdown voltage. In p-n junction at specific value of reverse bias the breakdown effect is present that appears as sharp increase of reverse current in p-n junction. For thermal breakdown to occur the thermal self-heating of the structure is necessary. It takes place in case of considerable reverse current in p-n junction. Typically, thermal breakdown happens after tunnel or avalanche breakdown of p-n junction. Breakdown voltage of real diffused p-n junction is defined by value of avalanche breakdown voltage of spherical part of the junction. Thus, breakdown voltage of p-n of junction strongly depends on its geometry.

Ring antenna arrays find wide application in radio systems of various purpose. However, in many cases it is necessary to use quasi-ring antenna arrays when the emitters are not located in a circle. Such a transition leads to a change in the radiation pattern, i.e. to a shift in its main maximum, an increase in the level of the side lobes, and appearance of two maxima of the radiation pattern. Therefore, to ensure the formation of a directional pattern with specified parameters, it is necessary to correct the amplitude-phase distribution of the quasi-annular antenna array. In this paper, features are considered and an algorithm for the synthesis of the amplitude-phase distribution of a quasi-annular antenna array is developed. The possibilities of preserving the parameters of the directional pattern during the transition from the ring to the quasi-annular antenna array are analyzed.

The propagation of plane harmonic wave parallel to the boundary between vacuum and uniaxial anisotropic medium is considered. The so-called penetration effect is described. It is shown that bulk wave must exist in anisotropic medium, and reflected wave must propagate perpendicular to the interface. Behavior of two types of waves within anisotropic medium is studied: an ordinary wave and an extraordinary wave behavior. For the case considered, the reflection and transmission coefficients are obtained. It is interesting to note that in case of extraordinary wave the reflection coefficient is equal to zero. Besides, surface charges and surface currents are found to exist at the interface in case of ordinary and extraordinary waves respectively. Note that all expressions are derived directly from the Maxwell’s equations by means of accurate algebraic transformation.

The article considers the problem of increasing efficiency for antennas embedded in dissipative media that has limited number of solutions today. The author makes attempts to study the possibility of using plate antennas for different parameters of dissipative media. The research is carried out by means of analytical and computer electromagnetic methods. It makes possible to refine some effects and reveal new patterns. The article provides sound approaches to increase efficiency of antennas embedded in dissipative media. The results are confirmed with numerical calculations. The article presents the methods of increasing efficiency of antennas embedded in soil with different electrical parameters. The results of numerical analysis of antenna length, gain and impedances for embedded antennas of various constructions are given. Comparative analysis of the efficiency of cylindrical and plate antennas is provided. Special considerations of plate antenna construction and their advantages over embedded antennas of different types are revealed.

We consider a problem of adaptive parameter selection of short-wave data transmission systems such as information signal type, noise combating code type and parameters, operating frequency in case of step-by-step control of transmission process in dynamically changing conditions of radio wave propagation and interference environment. We have obtained explicit expressions of objective functions for reaching the maximum information rate of data transmission and maximum probability of exact message delivery within the time not exceeding the given time. The distinguishing feature of the objective functions is the fact that they do not depend on threshold values established subjectively. The feasibility of the suggested algorithms is guaranteed due to the fact that all the original data required for adaptive control including information on standby frequencies are formed with the given accuracy during information exchange by means of analyzing working signals and secondary decoding products.

A method of side lobe suppression for PSK signals based on the compound Barker codes with a small number of distinct weights is considered. Mismatched filters are then used in cascade with the matched filter to suppress the side lobes. The mismatched filter is based on an implementation of inverse of the autocorrelation function of the compound Barker code used. The technique of SNR loss estimation of compound Barker codes is presented. The different combinations of compound Barker codes with SNR losses not exceeding 1dB are given. The possibility to increase processing gain up to the value of 10⁶ is described.

The paper deals with the problem of detection of slow-moving ground targets in the multi-static ultra wideband forward-scatter radar. The existing methods of ground target detection cannot simultaneously provide high efficiency in conditions of clutter and required resolution. The author proposes algorithms of UWB signal forming and processing which provides the increase of the coverage when detecting ground targets and high range resolution. The considered approach is based on the use of ultra-wideband signal with high repetition rate. Such signal is generated by means of combination of a number of sequences with different repetition periods. Integration of target reflected signal at the receiving side is performed in separate channels for each sequence. After that, the results of integration are summed up coherently. This approach allows to disambigue range measurements and increase total energy of the signal. The coverage of forward-scatter radar when using UWB probing signal is analyzed. The estimation of UWB FSR coverage is obtained for the case when different numbers of quasi-orthogonal sequences with different repetition periods are used for complex probing signal formation. It is shown that the increase of the number of sequences allows the reduction of the required number of positions when keeping the controlled perimeter or the increase of controlled perimeter with the same number of positions.