Adaptive notch filter is a well-known approach for frequency estimation and extraction of sinusoidal signals. The structure of ANF is composed of a second order band-pass filter (BPF) (and its complementary notch filter) and a frequency update law that continuously adjusts the center frequency of the BPF. The performance of the ANF degrades when the sinusoidal input is polluted by some harmonics. In this paper، a method has been proposed to improve the performance of the ANF in the presence of harmonics. The proposed method is based on the use of a window function in the frequency update law. Window functions have extensively been used in some algorithms like discrete Fourier transform and phase-locked loop to provide better estimation of the parameters of sinusoidal signal in the presence of harmonics. It was shown that using a rectangular window enhances the ANF performance.

In this paper, different cases of the stability of Multiple Adaptive Notch Filter (MANF) are studied. The structure of MANF is composed of N parallel subfilters. Each subfilter estimates the parameters of one the components of quasi periodic signals including the sum of N periodic signals. For this structure, there are three different cases of stability for N=K, N>K and N

As nowadays the GPS navigation system has more usage in different areas, increasing its efficiency and accuracy has gained more importance. The transmitted signal travels a long distance from the satellites to reach the receivers on the ground, so its power fades. This faded signal can easily be affected by intentional noises, the so-called jamming, or unintentional noises. One of the most destructive kinds of jamming is the continuous wave (CW) jamming. The most favored method for countering this jamming is the notch filter. Therefore, in this paper, an adaptive notch filter (ANF) with a narrow response in proposed to reduce the effects of CW jamming. A kind of PSO evolutionary algorithm called the improved particle swarm optimization algorithm (IPSO) is used to adapt the filter’s coefficients according to the power and frequency of the jamming signal. Evolutionary algorithms are used in problems without any straight forward answer, and that is why we chose this method for designing the filter. It also reduces the complexity of solving such mathematical problems. Finally, the efficiency of the proposed method is compared to other similar solutions, showing a significant improvement in the similarity of recovered signal to the original signal (up to 99%), as well as an increase in the number of observed satellites up to 6, and error reduction in determining the user coordinates which is the primary goal of the GPS system.

Solar cell is known as a sustainable and environment friendly source of energy in nature. It converts sunlight directly into electricity with zero emission and also without side-effects on the environment. But, solar cells have optical and mechanical defects which include the type of micro crack, the size of crack, and the noise from electrical or electromechanical interference during the image acquisition. This paper through image processing techniques presents several groups of methods to compare between two types of solar cell images, which are from solar cells with crack and without crack. In the first step, there are some methods such as Gaussian filter, Diffusion filter, Wavelet filter; Fast Fourier Transform and notch filter to de-noise images. In the next level, the study presents Gray Level Co-occurrence Matrix (GLCM) method to feature extraction of images and also the Hough transform to perform crack detection and analysis. Finally, the results confirm that the image from the solar cell with crack has the highest “S” measure compared to good images which have lower “S” measure levels.

Power decoupling of pulsating grid side power from constant source side power is one of the paramount issues in single phase-phase grid-connected renewable systems. The principal aim of such systems is the decrease of the capacitance of the decoupled capacitor. However, this causes some problems such as an increase in the total harmonic distortion (THD) of injected current to the grid and bus voltage fluctuations. By considering the aforementioned explanation, utilizing control strategies is critical to modify system performance. The voltage controller is responsible for adjusting the bus voltage, suppressing the second-order harmonic, and providing a trade-off between system cost and total harmonic distortion as well as bus voltage fluctuations. This paper presents a digital notch filter in order to improve the system transient response and remove the harmonic ripples. The relations between system cost, THD, and bus voltage fluctuations have been described completely. Moreover, the mathematical expressions of the proposed digital notch filter have been provided. The analyzed system is 250 W PV panel connected to a 220 V RMS, 50 HZ grid. The THD of injected current to the grid is approximately 0.6%.

In this paper, a scheme is presented for the control of Dynamic Voltage Restorer using Adaptive Notch Filter (ANF) and PD controller. In order to increase the speed of dynamic response and reduce system losses, the resistor of the output LC filter is eliminated and the oscillations in the control system are actively damped. For this purpose, the current of the output filter capacitor is used as feedback to the control system and current mode control is implemented in the inner loop, which is more stable system. Frequency, amplitude and phase of the main component of voltage is extracted using the ANF. In addition to the use of frequency response correction, PD controller is used to improve the speed of dynamic response. Correct functioning under frequency deviation, faster response in the case of voltage sag/swell and harmonics mitigation are among the merits of this type of controller. Simulations in the MATLAB software environment demonstrate the effectiveness performance of the DVR in test system under different conditions.

Low-cost and highly effective noise reduction has recently become one of the substantial challenges for industrial manufacturers. This paper presents the design and construction of a cost-effective system for attenuating single-frequency annoying noise generated from industrial products and machines. To achieve this goal, narrowband active noise control using Filtered-x Least Mean Square (FxLMS) method has been used with the help of a two-factor digital adaptive filter, called the adaptive notch filter. Therefore, a duct structure has been designed and experimental tests have been performed on it. To reduce implementation costs, the Arduino Uno board, which has an AVR microcontroller (ATmega328P), has been used as the controller. About 15dB noise attenuation at 400Hz and 750Hz frequencies and about 30dB noise attenuation at 650Hz and 950Hz frequencies have been achieved. Then, active noise control for two separate and simultaneous frequencies has been performed, which had somewhat effective results, and in one of these frequencies, noise attenuation of about 18dB has been observed.

Noise figure of the Low Noise Amplifier (LNA) is added directly to the system noise figure; therefore, the performance of the Low Noise Amplifiers determines the system's performance in terms of noise. In this paper, Low Noise Amplifiers have been designed in the UWB system, one of them with the ability of out of band rejection and the other with the capability of improving noise and circuit linearity by CMOS technology. In the design of LNA, subthreshold bias technique is used for low power design, chebyshev filtering for matching input impedance and cascode technique to increase inverse isolation and increase gain. In the design of the LNA, using a dual band notch filter which is implemented with low power active inductor, the out of band rejection are improved 42dB at a frequency of 2.4GHz, and 36dB at a frequency of 5.2GHz. Also by using the noise and linearity improvement techniques, 2.3dB reduction in the noise, and 9dB improvement in the circuit linearity (IIP3) is established. The designed LNA,s with a bandwidth of 3 to 5 GHz by using the 0.18 μm CMOS technology, are consumed 2.8mW and 1.9mW from a 1.8V supply voltage, respectively.

A critical protection requirement for grid connected distributed generators (DG) is anti-islanding protection. In this paper, a new islanding detection method for any possible network loading is proposed based on utilizing and combining various system parameter indices. In order to secure the detection of islanding, eight intentional disturbances are imposed to the system under study in which two sets of them simulate the islanding condition. The proposed technique uses the adaptive notch filters for extracting the frequency of oscillation of generator’s output waveform as one of the output parameter indices. An advantage of this technique is that it does not necessitates varying the islanding detection boundaries under various system loading conditions.

The aim of this paper is to improve the performance of the conventional Goertzel algorithm in determining the protein coding regions in deoxyribonucleic acid (DNA) sequences. First, the symbolic DNA sequences are converted into numerical signals using electron ion interaction potential method. Then by combining the modified anti-notch filter and linear predictive coding model, we proposed an efficient algorithm to achieve the performance improvement in the Goertzel algorithm for estimating genetic regions. Finally, a thresholding method is applied to precisely identify the exon and intron regions. The proposed algorithm is applied to several genes, including genes available in databases BG570 and HM 195 and the results are compared to other methods based on the nucleotide level evaluation criteria. Results demonstrate that our proposed method reduces the number of incorrect nucleotides which are estimated to be in the noncoding region. In addition, the area under the receiver operating characteristic curve has improved by the factor of 1.35 and 1.12 in HMR195 and BG570 datasets respectively, in comparison with the conventional Goertzel algorithm.