Sensitivity Criterion and Law on a Navigation Receiver under Single Frequency Electromagnetic Radiation

To objectively assess the anti-electromagnetic interference ability of the navigation receiver, the sensitivity criterion of a certain type of navigation receiver is tested under single-frequency continuous wave electromagnetic radiation with an optimized testing method. The experimental results show that it is difficult to guarantee the accuracy of the measurement value of the sensitivity level by using the carrier-to-noise density ratio (C/N0) as the sensitivity criterion, but the initial C/N0 of each satellite can be used as the basis for identifying whether the navigation system has recovered from the interference. The experimental error is dramatically decreased when the sensitivity criterion of “the sensitive phenomenon appears within the first 4 s, and the loss of positioning lasts for 30 s” is employed, the variable interference power step size is adopted and all of the satellites C/N0 are required to recover to the initial value after an interference. The critical interference field intensity error can be controlled within 1 dB by using all these measures. The sensitivity law of the navigation receiver is the same under different working signal intensities. It is significantly sensitive in the working frequency bandwidth. It is also quite sensitive in −11.5 MHz~55.5 MHz of the frequency offset range. The positive sensitive bandwidth is about 5 times that of the negative sensitive bandwidth.

Stabilization of noise parameters during annealing of highly alloyed structures of noise diodes

Stabilization of residual point defects at the finishing stages of noise diodes can be ensured by the selection of appropriate ignition modes and the environment of its conduct. The method and technology of reducing the concentration of point defects in the structure of p-n-transition, taking into account the content of impurities of secondary metals, oxygen and nitrogen is proposed. It has been established that the burning of readymade structures and diodes of noise generators in nitrogen environments at temperatures of 450…600 °С for (80 ± 3) min leads to an increase in spectral noise density and a significant (twice) reduction of its unevenness. The most important result of this burn is a reduction in the spread of the average values of the noise parameters studied: by 61.2 % in effective noise voltage; spectral density by 34.2 %; at the boundary frequency of the signal by 34.9 %; in non-linear density by 25.9 %. This improves the quality of random numerical sequences in information protection software systems.

Development of Optimized Algorithm and Field Programmable Gate Array Implementation for Bio Medical Image Denoising for Health Informatics Applications

Denoising images is a most difficult task in applications for image processing. The image specifics are preserved and the additional sounds found in the images are removed. It is also a challenge to remove noise from medical and satellite images. It improves the diagnostic capacity of medical images and satellite images visual clarity. The noise in the images varies and its density varies depending on imaging techniques. The algorithms in the literature were suggested based on the noise density and the forms of noise. The aim of this paper is to eliminate the noise from ultrasound, magnetic resonance images and satellite images using an effective denoisation algorithm Hybrid Wiener Adaptive Weighted Median filter (HWAWMF) which is the combination of Wiener and Adaptive Centre Pixel Weighted Median Filter (ACPWMEF). In terms of performance parameters with an improved Peak to Signal Noise Ratio(PSNR), the hybrid filter shows better results than ACPWMEF. The Vienna filter takes out the additional noises in the images thus blurs the image’s optical perception. And also uses optimization approaches to enhance the image consistency. This paper proposes HWAWMF (PSO HWAWMF) based on particle swarm optimization and HWAWMF based on dragonfly optimization algorithms (DOAF HWAWMF). Visual vision and PSNR also have been improved by using the optimising algorithm at an average of 3.18 db, 4.83 db, and 3.14 db for lower noise (0.0% to 30%), medium noise (40% to 60%) as well as high noise density (70% to 90%). The efficacy of the algorithm using MATLAB R2013 is verified through both medical images, simulated and actual. In order to assess the computer complexity of the Altera algorithm for location, power and time using Cyclone II EP2C35F672C6, Cyclone II and Stratix III EP3SL150F1152C2, this algorithm is also implemented in the Altera Field Programable Gate Array (FPGA).

Impulsive Noise Removal with an Adaptive Weighted Arithmetic Mean Operator for Any Noise Density

Many computer vision algorithms which are not robust to noise incorporate a noise removal stage in their workflow to avoid distortions in the final result. In the last decade, many filters for salt-and-pepper noise removal have been proposed. In this paper, a novel filter based on the weighted arithmetic mean aggregation function and the fuzzy mathematical morphology is proposed. The performance of the proposed filter is highly competitive when compared with other state-of-the-art filters regardless of the amount of salt-and-pepper noise present in the image, achieving notable results for any noise density from 5% to 98%. A statistical analysis based on some objective restoration measures supports that this filter surpasses several state-of-the-art filters for most of the noise levels considered in the comparison experiments.

An Iterative Weighted-Mean Filter for Removal of High-Density Salt-and-Pepper Noise

Salt-and-pepper noise, which is often introduced by sharp and sudden disturbances in the image signal, greatly reduces the quality of images. Great progress has been made for the salt-and-pepper noise removal; however, the problem of image blur and distortion still exists, and the efficiency of denoising requires improvement. This paper proposes an iterative weighted-mean filter (IWMF) algorithm in detecting and removing high-density salt-and-pepper noise. Three steps are required to implement this algorithm: First, the noise value and distribution characteristics were used to identify the noise pixels, effectively improving the accuracy of noise detection. Second, a weighted-mean filter was applied to the noisy pixels. We adopted an un-fixed shape symmetrical window with better detail preservation ability. Third, this method was performed iteratively, avoiding the streak effect and artifacts in high noise density. The experimental results showed that IWMF outperformed other state-of-the-art filters at various noise densities, both in subjective visualization and objective digital measures. The extremely fast execution speed of this method is quite suitable for real-time processing.

A SIMULATION MODEL FOR THE ANALYSIS OF THE RELATIONSHIP BETWEEN NOISE LEVEL AT THE AMPLIFIERS OUTPUT AND AMBIENT TEMPERATURE

Представлена имитационная модель, позволяющая оценить уровень шума на выходе усилительного тракта от температуры окружающей среды. Модель построена для усилительного тракта, выполненного как на одном, так и на двух усилительных каскадах, и основана на известных аналитических выражениях, что позволяет с высокой долей вероятности получать достоверные результаты в ходе моделирования. Определена зависимость спектральной плотности шума на выходе усилительного тракта от температуры окружающей среды, изменяющейся от 213 до 333 K (± 60 оС). The article presents a simulation model that allows estimating the dependence of the noise level at the output of the amplifier path on the ambient temperature. The developed model is built for the amplification path made on both one and two amplification stages and is based on well-known analytical expressions, which makes it possible to obtain reliable results with a high degree of probability during the simulation. The dependence of spectral noise density at the output of the amplification path on ambient temperature varying from 213 to 333 K (±60oC) is determined.

Silence is sexy: soundscape complexity alters mate choice in túngara frogs

Many animals acoustically communicate in large aggregations, producing biotic soundscapes. In turn, these natural soundscapes can influence the efficacy of animal communication, yet little is known about how variation in soundscape interferes with animals that communicate acoustically. We quantified this variation by analyzing natural soundscapes with the mid-frequency cover index and by measuring the frequency ranges and call rates of the most common acoustically communicating species. We then tested female mate choice in the túngara frog (Physalaemus pustulosus) in varying types of background chorus noise. We broadcast two natural túngara frog calls as a stimulus and altered the densities (duty cycles) of natural calls from conspecifics and heterospecifics to form the different types of chorus noise. During both conspecific and heterospecific chorus noise treatments, females demonstrated similar preferences for advertisement calls at low and mid noise densities but failed to express a preference in the presence of high noise density. Our data also suggest that nights with high densities of chorus noise from conspecifics and heterospecifics are common in some breeding ponds, and on nights with high noise density, the soundscape plays an important role diminishing the accuracy of female decision-making.