Vol 59, No 12 (2017)

Nontraditional methods of detecting and correcting errors in data transmitted via noisy communication channels are discussed. The basis for synthesizing these errors is the mathematical apparatus of the applied theory of finite fields. Data-telemetry software for testing of aircraft are used as an example to illustrate the feasibility of these methods for comprehensive solution of telemetry problems.

A new method is proposed for calibrating scanning electron microscopes (SEM) with magnification in the 10–50000^× range using an end gauge and an auxiliary structure. Use of a certified end gauge ensures traceability of the calibration results to the primary standard for the meter. The relative expanded uncertainty of measurements on an S-4800 SEM at magnifications of 1000, 10000, and 50000^× is less than 0.14%.

The principle of photogrammetric measurements is considered. The procedure of calibration of a camera which is a component of a photogrammetric system and a method of evaluating calibration performance are described. Results from experiments designed to determine the optimal disposition of markers in space in a calibration procedure are presented.

We describe a method for determining the position and orientation of an object in a varying magnetic field generated by two flat coils which are arranged horizontally in one plane. We present an algorithm for computing position and orientation of a measurement unit, consisting of a three-axis alternating magnetic field sensor, and a microelectromechanical (MEMS) accelerometer.

The problem of increasing the precision with which the pitch frequency of speech signals is measured is considered. Existing algorithms for determining this frequency are presented and a new algorithm based on complementary ensemble empirical mode decomposition is developed. The results of the investigations confirm the robustness of the algorithm in the presence of frequency modulation of the pitch of speech signals.

A UHF method and a device based on the method for monitoring the moisture content of solid, friable, and fibrous materials are considered. A measurement chain for UHF hygrometers for use with raw cotton and cotton materials is proposed.

We describe an approach for processing measurement information obtained using high-precision measurement methods for random variation of the data in the range of several discrete units. We present formulas for estimating the quantity to be measured. We consider an example of the use of the indicated approach.

We present an empirical method of measuring geometric noise in matrix photoreceptors included in an intelligent system developed for detecting obstacles in the path of a train. A reference calibration field uses thermal images of crossties. Measurement of geometric noise sensitivity and dark current is based on selected levels of homogeneity in the reference image. The experimental results demonstrated the advantage of the proposed method compared to a conventional two-point calibration.

The first results are presented for experimental studies of a method of pulsed optical pumping for the purpose of creating a compact quantum frequency standard on a rubidium vapor cell, comparable in stability level with passive hydrogen masers.

A new contactless method is proposed for measuring and analyzing the parameters of the vibrational displacement of components in electronic equipment. A mathematical model is developed to relate the parameters of traces of vibrational blurring in an image of a circular marker to the parameters of the amplitude vector of vibrational displacements at a test point on the surface of these components.

A high-frequency magnetometer with a sensitivity of 2.5·10^–7 T/Hz^1/2 based on two Hall transducers has been developed. It is used to measure magnetic field dependences of the density of captured magnetic flux in single-crystal samples of Bi₂Sr₂CaCu₂O_8+x and YBa₂Cu₃O_7–x.

Questions related to experimental investigations of vibrations experienced by spindle assemblies in metalcutting machine tools are considered. It is shown that the use of three-component vibration sensors increases the precision of the measurements, expands the capability of the search for defects, makes it possible to analyze the attractors of the vibratory motion, estimate the performance of a set of spindle assemblies, and perform monitoring of the current state of the assemblies.

An evaluation of an idealized mathematical model of monitoring the moisture content of grain by a dielcometric method is presented. The method graphically represents the electrophysical processes in weevils under the effect of an electric field while the relationship between the moisture content and the electric parameters of grain may be analytically expressed by equ circuits. An analysis of certain techniques and methods of effective use of the dielcometric method is presented. An example of the development of an electrical device for monitoring the moisture content of grain with instrumental error less than 0.1% is considered.