Radioelectronics and Communications Systems

Infrared image iterative enhancement in frequency domain

Mon, 24 Jun 2024 00:00:00 +0300

This paper proposes an approach to infrared image enhancement involving iterative wrapping of the enhancement core within an image upscale/downscale loop. It highlights and suppresses distortion and blurs fine image details. This is the aim of the current study. Therefore, the isotropic pixel resolution of the digital image is chosen as an evaluation criterion. This criterion attunes the pre-processing result to the visual interpretation requirements of the infrared image. All processing workflow is performed inside the frequency domain, which is beneficial regarding computational burden. The actual infrared UAV image processing demonstrates an improvement in isotropic pixel resolution by a factor of 1.9–2.1, which is slightly superior to known single-pass algorithms. The proposed approach is flexible and modular and can be easily implemented in ground-based and onboard infrared imagery processing.

Phenomenon of microwave reflection reduction for liquid foams at initial stage of their existence

Oleg Drobakhin, Leonid Filinskyy — Mon, 24 Jun 2024 00:00:00 +0300

Coating metal surfaces with liquid foams is a promising approach to reducing microwave reflectivity. Due to disintegration processes, liquid foams quickly change their properties over time. The objective of this study is to experimentally evaluate changes in the masking properties of liquid foam with time. The measurements were carried out in the frequency range of 38–52 GHz using original measuring equipment that implements the principle of Fourier holography in the frequency-time domain. Measurements are carried out in less than 1 second with median averaging and synthesizing time pulses with a duration of 70 ps at 3 dB of the envelope. It is shown that for the observation period from 0 to 15 minutes, the reflection coefficient in the range of millimeter waves decreases from 0.008 to 0.001, remaining at a level sufficient for masking problem solution. The novelty of the results is the study of the initial stage of the existence of liquid foam during the first 25 minutes.

Differential amplifier for biomedical signal acquisition applications based on stacked transistors

Prateek Jain, Vivekanand Mishra, Sandip A. Mehta — Mon, 24 Jun 2024 00:00:00 +0300

This study presents a two-stage differential amplifier circuit that has been improved for use in a realistic biomedical signal conditioning system. CMOS technology serves as the foundation for the circuit. A MOS-based low-pass filter using stacked transistors creates a low-power differential amplifier with low noise and high common-mode rejection ratio (CMRR) for portable electrocardiogram (ECG) signal conditioning. Stack transistors with MOS connected at the output terminal are used to improve the design for electrocardiogram (ECG) signal conditioning and other types of signal conditioning for biomedical devices. Standard 45nm CMOS process technology was used in the construction of the amplifier that is being discussed. The amplifier runs at a supply voltage of 0.85 V. The simulation findings are produced using the Cadence Analogue Virtuoso Spectre Simulator to generate the simulation. The differential amplifier described demonstrates a CMRR = 140 dB at frequency of 80 Hz, a power supply rejection ratio (PSRR) of 68 decibels, and a power dissipation of 1.3 mW. These characteristics conform to the simulation results. While the slew rate is 11 V/s, the input-referred noise is 2.62 mV/Hz1/2. Compared to the conventional differential amplifier, the performance characteristics generated by this approach are better and more efficient than those created by the standard circuit. The proposed design improves the noise performance of the differential amplifier developed in the past, which enhances noise performance.

Parameters of ribbon electron beam formed by HVGD guns: study of plasma boundary position

I. V. Melnyk, Serhii Tuhai, O. M. Kovalenko, M. Y. Skrypka — Mon, 24 Jun 2024 00:00:00 +0300

In the first part of the paper, analytical relations are obtained to calculate the plasma boundary position relative to the cathode surface in the high-voltage glow discharge electrode system forming a ribbon electron beam with a linear focus. The calculations assume that in systems with different electrode geometries, the anode plasma occupies the same volume under the same accelerating voltage and pressure. The simulated graphical dependencies of the plasma boundary position on the accelerating voltage and gas pressure are presented. The theoretical and experimental studies show that the calculated data for the plasma boundary position relative to the cathode differ from the experimental data by no more than 10% in the case of medium and high-pressure values in the gas discharge gun chamber.

Computer simulation methods can determine the electric field distribution and focal parameters of a linearly focused ribbon electron beam, as in high-voltage glow discharge electrode systems, where the anode plasma is a source of ions and an electrode with potential.

Cumulant detector of non-Gaussian signals against background of non-Gaussian interferences

Aleksandr Krasilnikov, Viktor Beregun — Mon, 24 Jun 2024 00:00:00 +0300

The definition of a cumulant detector of an arbitrary order of non-Gaussian signals against the background of non-Gaussian interferences is introduced, and its sensitivity coefficient is determined. Dependencies of the sensitivity coefficient on the signal-to-interference ratio and the ratio of the cumulant coefficients of signal and interference are analyzed, and general conditions under which a cumulant detector of a given order is more sensitive than a cumulant detector of a different order are determined. In particular, the sensitivities of cumulant detectors of arbitrary orders are compared with the sensitivity of the power detector, which is the second-order cumulant detector. The validity of a cumulant detector is defined as the probability of the correct signal detection that depends on the sample size, parameters of the signal and interference distributions, and the probability of error of the first kind. The paper considers an example of the theoretical and experimental analysis of the sensitivity and reliability of the cumulant detector for the case when both the interference and the signal have Student’s distributions with different shape parameters. To experimentally verify the sensitivity and validity of the second- and fourth-order cumulant detectors, the computer simulation of the interference, signal, and their mixture was performed, and the sensitivity estimates of coefficients, the probability estimates of correct signal detection, and their relative errors were obtained.