Noise Frequency Response Research Articles

Noise modelling and mitigation for broadband in‐door power line communication systems

AbstractCommunication systems are greatly hampered by many disruptive noises in powerline communication systems (PLC), which come with strong interference, resulting in the malfunction of PLC systems. Hence, there is a need to model noise and its effect on communication systems. This paper presents noise modelling and mitigation techniques for indoor broadband powerline communication systems. To model the PLC noise, frequency domain measurements employing the GSP‐930 spectrum analyser were carried out to determine the noise frequency response in the frequency range of 1–30 MHz. The results obtained were plotted. While the analytical model for the noise model is presented, furthermore, noise mitigation techniques for multiple input multiple output PLC (MIMO‐PLC) systems in the form of spatial modulation PLC systems have been proposed. The SM‐PLC system employs the indices of the individual transmit lines to increase the data rate, as opposed to the traditional MIMO‐PLC systems, where the symbol to be transmitted is transmitted by duplicating the symbol across all lines. The proposed system uses the maximum likelihood (ML) detector at the receiver to obtain estimates of the transmitted symbols. The simulation results of the SM‐PLC system are compared with the already existing MIMO‐PLC system and show a significant improvement of ≈6 dB and 5.2 dB in signal‐to‐noise ratio (SNR) at a bit error rate of 10(−5) for spectral efficiencies of 4 bits per channel use (bpcu) and 6 bpcu, respectively. On comparison of the SM‐PLC system having a combination of additive white Gaussian noise and impulse noise at the receiver, the SM‐PLC system outperformed the traditional MIMO‐PLC by 3.5 and 3.8 dB in SNR for 4 and 6 bpcu, respectively.

Preliminary analysis of operating conditions of acoustic sounder (SODAR) before the installation

The SOnic Detection And Ranging (SODAR) is a surface-based remote sensing instrument, based on Doppler effect and sound signal. This paper discusses the operating conditions of Monostatic SODAR system, error in the measured Atmospheric Boundary Layer (ABL) height by taking account of the antenna characteristics which are pulse transmission, receiving durations, spectral augmentation of the received echo and atmospheric refraction effects. The Monostatic SODAR is able to receive even very weak echo by providing a good directional response with high conversion efficiency. The location and orientation of the antenna are finalized after a detailed analysis of the site with relative to several parameters like comparative measurement of acoustic background noise and frequency response of noise. Also, before installation of the system, the transducer has to be individually characterized for it’s transmitted and received conversion efficiency, and variations in the product of these efficiencies (conversion gain). The antenna is systematically characterized, in an acoustic anechoic and reverberation chamber, with respect to its conversion efficiencies and directional response.

Formation flow rate control method in multi-layer production

The article describes a method of flow rate control of separate formations in multilayer production by noises frequency response (FR). The noise FR is converted into electrical signals scaled in proportion to the flow rates using secondary facilities. The pump noise is suggested to be reduced with the quarter-wave acoustic resonator working as an acoustic filter.

Audible Noise Characteristics of Filter Capacitors Used in HVDC Converter Stations

This paper presents a detailed investigation of audible noise characterization of filter capacitors by investigating the noise radiation characteristics and analyzing the effect of voltage frequency, phase angle, and magnitude on a single capacitor unit. First, the noise radiation for capacitor surfaces was characterized theoretically using finite rectangular plate model and experimentally measured in a semianechoic room. Second, voltage frequency impact on the noise distribution was investigated through simulation. The simulation results show that noise directivity increases with increasing frequency. The excitation frequency impact on the radiation ratio and the noise level was characterized through a sweep-frequency experiment. Our investigations show that the noise frequency response below 500 Hz is quite low, while from 500 to 2000 Hz, it is significant and increases slowly. Third, the impact of the voltage phase angle on the noise level was investigated. The results show a noise-level difference of 3.9 dB for different phase angles. Finally, we present the voltage magnitude impact on the noise level. Our theoretical analysis and experimental study show a linear relationship between the sound power level and the logarithm of the voltage magnitude with a slope of 40.

A new approach to frequency-domain noise analysis and design of a very-low noise amplifier in radio and microwave frequencies

This work presents a new idea to design and optimization of noise with a very-low-noise amplifier (VLNA). Noise optimization is done using suitable filters. An appropriate filter can convert circuit noise frequency response into a band stop. This is while the amplifier gain is in bandpass state. Hence, suitable gain and minimum noise are achieved in band pass. Using this approach in 0.13µm CMOS technology, a VLNA in the frequency range of 20–1000MHz is designed with the following specifications: minimum noise figure 0.95dB, transfer gain 15.39dB, third order intercept point −15.2dBm at 900MHz, die area of 0.075mm2, and power dissipation of 18.16mW. To our knowledge, by comparison with recently reported LNAs, the presented LNA achieves the highest figure of merit (FOM) by taking into account the NF.

Focus on software and data acquisition

Focus on software and data acquisition

A New Lossy Substrate Model for Accurate RF CMOS Noise Extraction and Simulation With Frequency and Bias Dependence

A lossy substrate model is developed to accurately simulate the measured RF noise of 80-nm super-100-GHz fT n-MOSFETs. A substrate RLC network built in the model plays a key role responsible for the nonlinear frequency response of noise in 1-18-GHz regime, which did not follow the typical thermal noise theory. Good match with the measured S-parameters, Y-parameters, and noise parameters before deembedding proves the lossy substrate model. The intrinsic RF noise can be extracted easily and precisely by the lossy substrate deembedding using circuit simulation. The accuracy has been justified by good agreement in terms of Id,gm, Y-parameters, and f T under a wide range of bias conditions and operating frequencies. Both channel thermal noise and resistance induced excess noises have been implemented in simulation. A white noise gamma factor extracted to be higher than 2/3 accounts for the velocity saturation and channel length modulation effects. The extracted intrinsic NFmin as low as 0.6-0.7 dB at 10 GHz indicates the advantages of super-100 GHz fT offered by the sub-100-nm multifinger n-MOSFETs. The frequency dependence of noise resistance Rn suggests the bulk RC coupling induced excess channel thermal noise apparent in 1-10-GHz regime. The study provides useful guideline for low noise and low power design by using sub-100-nm RF CMOS technology

Efficient modeling of 1/f/sup /spl alpha// noise using multirate process

In order to verify the system performance of mixed-signal systems on chip (SoCs), computer-aided design (CAD) tools are required to generate 1/f/sup /spl alpha// noise that degrades the performance of most analog circuits. Current techniques for generating discrete sequences of 1/f/sup /spl alpha// noise require a large amount of computations that place an excessive burden on the computation engine and random number generators. In this paper, the authors propose a low-complexity 1/f/sup /spl alpha// noise generation scheme, which is based on a multirate filter bank. In this scheme, each branch in the filter bank processes signals in a different frequency band while allowing for arbitrary selection of /spl alpha/ in each bank. The proposed approach greatly reduces computations when compared to traditional noise generation processes of using a single noise-shaping filter. Furthermore, it allows selecting different combinations of noise frequency response in different frequency bands, thus allowing calibration of noise generated in simulation to the one measured in the laboratory from test chips. A comparison of various noise generation schemes is also presented.

MIMO Noise Control System Design by Using Subband-based Partial Model Matching on Frequency Domain

In this paper, a practical method to design a noise reduction controller is proposed. In this method frequency domain of interest is divided into subbands taking frequency response of noise into account. And on each subband, it is proposed that the controller is tuned based on partial model matching on frequency domain. The proposed method is practical since it requires only input-output data for the tuning process instead of identified mathematical model of the plant. In order to show validity of the method, it was applied to an actual room with a stereo audio system. The experimental result shows that the proposed controller designed succeeded 45% attenuation of multiple peak noise.

Signal Recovery From Noise in Electronic Instrumentation

Low-pass filtering and visual averaging multiple time averaging and drift phase-sensitive detector methods spectral view of signal recovery 1/F noise frequency response calculations frequency-domain view of the phase-sensitive detector digitation and noise magnitude determination for transient signals of known shape and timing measurement of the time of occurrence of a signal transient.

Aurally sensitized flat frequency response noise reduction compansion system

A flat frequency response compansion noise reduction system employs both input signal and control signal preemphasis and deemphasis in its encoder and decoder networks respectively. The linear range of the frequency response curve of the input signal deemphasis is selected to approximate the frequency range within the audio spectrum at which the human ear is most sensitive, typically having a high frequency end of 3.617 kHz. The frequency response curve of the input signal preemphasis is a mirror image of the frequency response curve of the input signal deemphasis. The linear range of the frequency response curve of the control signal preemphasis is selected to provide an encoder output signal having a substantially flat response. The frequency response curve of the control signal deemphasis is a mirror image of the frequency response curve of the control signal preemphasis. The amount of preemphasis is maximized to the limits of the recording medium, typically ranging from 0 db to 20 db.