Shahtarin

The authors consider possibilities of aircraft landing on unprepared airfields and sites using radar (SAR) with synthetic aperture and beacons. They study two methods which estimate the aircraft coordinates and parameters. The proposed algorithms provide landing meteorological conditions of categories I-II of International Civil Aviation Organization (ICAO).

Effect of a harmonic interferer on phase-lock results in distortion of information received in input signals, and in the loss of stability of the phase-lock. The authors consider the influence of harmonic interference on synchronization processes in the first-order loop. Also the paper presents an analysis of cases of signal capture and the capture of the disturbance in the phase-lock.

A comparative analysis of statistical characteristics of phase locked loop was carried out, when harmonic interference along with noise influences on its entrance. As the result of solving of Fokker-Planck-Kolmogorov equation (FPK), the probability density function (PDF) of the error signal, the average time until loss of synchronization and the probability of skipped cycle were obtained. The comparison of two approaches of obtaining of statistical characteristic was carried out.

The harmonic interference affecting the phase locked loop can cause a number of unwanted effects, reducing stability of the phase locked loop and distorting the information contained in the incoming signal. Several dynamic characteristics of phase locked loop were obtained by the method of harmonic balance, under the stipulation that the frequency of harmonic interference lies outside the phase locked loop synchronization band.

A sigma-delta modulator with negative feedback was considered in this article. The structure and working principles of devices built on the basis of sigma-delta modulation were presented. Application areas of the sigma-delta modulators were explored. Mathematical models of the sigma-delta modulator’s operation in the time domain were described. Analysis of operation of the sigma-delta modulator of the first and the second orders was also presented in the article. It was determined that a noise band appeared in the sigma-delta modulator because modulator was a chaotic attractor. Sigma-delta modulator’s ability to form the frequency fractionality in output spectrum was also indicated. Mathematical models without additive noise were considered; the conclusion on the influence of the modulator’s order on the noise level. The graphics, which displayed basic characteristics of sigma-delta modulator’s operation with different inputs were included.

Dynamic characteristic of phase locked loop in the presence of harmonic interference at its entrance along with desired signal were considered; this interference was out of PLL synchronization band. Critical values of parameters of system and interference were obtained with harmonic balance method.

Average time before tracking loss and average value of frequency disagreement of phase lock loop were considered when adaptive combination of signal, harmonic interference and noise was received as an input signal.