scholarly journals Influence of Analog-To-Digital Conversion and Decimation Parameters on the Signal-To-Noise Ratio in the Radar Path

2021 ◽  
Vol 24 (6) ◽  
pp. 38-50
Author(s):  
S. R. Heister ◽  
V. V. Kirichenko
Keyword(s):  
Signal To Noise Ratio ◽  
Sampling Rate ◽  
Quantization Noise ◽  
Least Significant Bit ◽  
Signal To Noise ◽  
Analog To Digital ◽  
Noise Interference ◽  
Analog To Digital Conversion ◽  
Wide Range ◽  
Noise Ratio

Introduction. The digital representation of received radar signals has provided a wide range of opportunities for their processing. However, the used hardware and software impose some limits on the number of bits and sampling rate of the signal at all conversion and processing stages. These limitations lead to a decrease in the signal-to-interference ratio due to quantization noise introduced by powerful components comprising the received signal (interfering reflections; active noise interference), as well as the attenuation of a low-power reflected signal represented by a limited number of bits. In practice, the amplitude of interfering reflections can exceed that of the signal reflected from the target by a factor of thousands.Aim. In this connection, it is essential to take into account the effect of quantization noise on the signal-tointerference ratio.Materials and methods. The article presents expressions for calculating the power and power spectral density (PSD) of quantization noise, which take into account the value of the least significant bit of an analog-to-digital converter (ADC) and the signal sampling rate. These expressions are verified by simulating 4-, 8- and 16-bit ADCs in the Mathcad environment.Results. Expressions are derived for calculating the quantization noise PSD of interfering reflections, which allows the PSD to be taken into account in the signal-to-interference ratio at the output of the processing chain. In addition, a comparison of decimation options (by discarding and averaging samples) is performed drawing on the estimates of the noise PSD and the signal-to-noise ratio.Conclusion. Recommendations regarding the ADC bit depth and sampling rate for the radar receiver are presented.

VCO-BASED CONTINUOUS-TIME SIGMA DELTA ADC BASED ON A DUAL-VCO-QUANTIZER-LOOP STRUCTURE

2013 ◽  
Vol 22 (09) ◽  
pp. 1340013 ◽  
Author(s):  
Z. T. XU ◽  
X. L. ZHANG ◽  
J. Z. CHEN ◽  
S. G. HU ◽  
Q. YU ◽  
...  
Keyword(s):  
Continuous Time ◽  
Signal To Noise Ratio ◽  
Quantization Noise ◽  
Cmos Process ◽  
Voltage Controlled Oscillator ◽  
Loop Structure ◽  
Signal To Noise ◽  
Sigma Delta ◽  
Analog To Digital ◽  
Sigma Delta Adc

This paper explores a continuous time (CT) sigma delta (ΣΔ) analog-to-digital converter (ADC) based on a dual-voltage-controlled oscillator (VCO)-quantizer-loop structure. A third-order filter is adopted to reduce quantization noise and VCO nonlinearity. Even-order harmonics of VCO are significantly reduced by the proposed dual-VCO-quantizer-loop structure. The prototype with 10 MHz bandwidth and 400 MHz clock rate is designed using a 0.18 μm RF CMOS process. Simulation results show that the signal-to-noise ratio and signal-to-noise distortion ratio (SNDR) are 76.9 and 76 dB, respectively, consuming 37 mA at 1.8 V. The key module of the ADC, which is a 4-bit VCO-based quantizer, can convert the voltage signal into a frequency signal and quantize the corresponding frequency to thermometer codes at 400 MS/s.

Efficient Response Amplification of Electrothermally Driven Resonators Using Magnets

2021 ◽  
Author(s):  
Ghanimah Abuhaimed ◽  
Nizar Jaber ◽  
Nouha Alcheikh ◽  
Mohammad I. Younis
Keyword(s):  
Parametric Excitation ◽  
Energy Demand ◽  
Signal To Noise Ratio ◽  
Ambient Pressure ◽  
Thermal Relaxation ◽  
Primary Resonance ◽  
Signal To Noise ◽  
Electrothermal Actuation ◽  
Wide Range ◽  
Noise Ratio

Abstract Micro/Nano-electromechanical systems, MEMS/NEMS-based resonators are presently an important part of a wide range of applications. However, many of these devices suffer from the low signal-to-noise ratio and the need for a large driving force. Different principles were proposed to enhance the sensitivity and improve their signal-to-noise ratios (SNR), such as bifurcations, jumps and higher-order excitation. However, these methods require special designs and high actuation voltages, which are not always available in the standard function generators and power supplies. Also, it increases the devices’ overall cost and power requirements. Furthermore, parametric excitation is explored as an option to amplify the signal at a lower cost and energy demand. However, this type of excitation requires specific geometrical settings, in addition to very low damping conditions. Electrothermal actuation is investigated to achieve excitation of primary resonance, which can be used for parametric excitation. This type of excitation is desirable due to its simplicity, robustness and ability to create large internal forces at low voltages. However, the time response is limited by the thermal relaxation time. In this work, we demonstrate the use of electromagnetic actuation to significantly amplify the response of electrothermally actuated clamped-clamped resonators at first mode (primary) resonance. At ambient pressure, experimental data show 18 times amplification of the response amplitude compared with electrothermal actuation only. The method is based on introducing a permanent magnetic field to induce an out-of-plane Lorentz-force. The results show the great potential of this technique being used for a variety of sensing and signal processing applications, especially, where a large signal-to-noise ratio is required while using low operational voltages.

Gray Level Transforms and Lesion Detectability in Echographic Images

1988 ◽  
Vol 10 (3) ◽  
pp. 171-195 ◽  
Author(s):  
J.M. Thijssen ◽  
B.J. Oosterveld ◽  
R.F. Wagner
Keyword(s):  
Order Statistics ◽  
Signal To Noise Ratio ◽  
Ideal Observer ◽  
Sigmoid Function ◽  
Gray Level ◽  
Power Functions ◽  
Signal To Noise ◽  
Amplitude Data ◽  
Wide Range ◽  
Noise Ratio

In search of the optimal display of echographic information for the detection of focal lesions, a systematic study was performed considering a wide range of gray level transforms (i.e., lookup tables). This range comprised power functions of the echo envelope signal (1/8 ≤ n ≤ 8), power functions of the logarithmic transform and a sigmoid function. The implications of the transforms on the first order statistics (histogram, “point signal-to-noise ratio” SNRp) and on the second order statistics (autocorrelation function) could be derived both analytically, and from the analysis of simulated and experimentally obtained echograms of homogeneously scattering tissue models. These results were employed to estimate the lesion signal-to-noise ratio SNRQ, which specifies the detectability of a lesion by an ideal observer. It was found, both theoretically and practically, that the intensity display corresponds to the optimal transform (i.e., n=2) for a low contrast lesion. When the data were first logarithmically compressed, the lesion SNR appeared to increase with increasing power (1/8 ≤ n ≤ 8). A logarithmic transform followed by a sigmoid compression did not produce much improvement. These effects of gray level transforms on the SNRQ were shown to be relatively small, with the exception of powers n > 2 when applied to linear (i.e. amplitude) data. In the case of high lesion contrast, the sequence of log compression, followed by a square law produced the optimum SNRQ. This sequence is equivalent to the processing within echographic equipment, where the TV monitor has a gamma of the order of 2.

scholarly journals Uniform Quantization of Signals with Clipped and Truncated Laplace Distributions

2020 ◽  
Author(s):  
Jerald Bauck
Keyword(s):  
Signal To Noise Ratio ◽  
Laplace Distribution ◽  
Analog To Digital Converter ◽  
Digital Converter ◽  
Signal To Noise ◽  
Analog To Digital ◽  
Traditional Test ◽  
Uniform Quantization ◽  
Long Tails ◽  
Noise Ratio

Many natural and man-made signals including much of speech and music are well-modeled by the Laplace distribution. Methods of synthesizing such signals are available and sometimes preferred over traditional test signals. However, sometimes those Laplace-like signals are clipped or do not exhibit infinitely-long tails. These situations are analyzed to determine their variances with an application of estimating signal-to-noise ratio as they are quantized by an analog-to-digital converter.

scholarly journals Skema Penyembunyian Data pada Gambar Berbasis Interpolasi Kubik B-Spline Menggunakan Metode Least Significant Bit (LSB)

2019 ◽  
Vol 5 (3) ◽  
pp. 255
Author(s):  
Garno Garno ◽  
Riza Ibnu Adam
Keyword(s):  
Mean Squared Error ◽  
Signal To Noise Ratio ◽  
Image Interpolation ◽  
Cover Image ◽  
Original Image ◽  
Least Significant Bit ◽  
Signal To Noise ◽  
B Spline ◽  
Squared Error ◽  
Noise Ratio

Maraknya kasus pencurian data menyebabkan sistem keamanan pesan harus ditingkatkan. Salah satu cara untuk mengamankan pesan adalah dengan memasukkan pesan ke dalam gambar digital. Penelitian ini bertujuan untuk meningkatkan kualitas gambar digital dalam sistem keamanan pesan tersembunyi. Teknik yang digunakan untuk keamanan pesan adalah steganografi. Cover image akan dikonversi menjadi bit piksel dalam domain spasial. Cover image digunakan dalam bentuk gambar digital dengan format .jpg. Teknik meningkatkan kualitas dan kapasitas gambar digital dilakukan dengan menambahkan dan meningkatkan bit piksel menggunakan metode interpolasi Cubik B-Spline. Cover image yang telah di interpolasi, kemudian disisipi pesan menggunakan metode least significant bit (LSB) untuk memperoleh stegoimage. Pesan yang diselipkan berbentuk file .doc, .docx, .pdf, .xls, .rar, .iso dan .zip dengan ukuran berbeda-beda kapasitasnya. Teknik uji dibuat dengan bantuan perangkat lunak MATLAB versi 2017a. Penelitian melakukan uji dengan mengukur nilai kualitas penyamaran dari stegoimage menggunakan Peak Signal to Noise Ratio (PSNR) dengan rata-rata perolehan stegoimage terhadap Original image 29.06 dB dan stegoimage terhadap Image interpolation 64.34 dB dan uji mean squared error (MSE) dengan rata-rata perolehan 97.54 dB pada Image interpolation terhadap original image dan 97.55 dB pada stegoimage terhadap original image, 0.13 dB nilai MSE stegoimage terhadap Image interpolation. Hasil uji pada penelitian dengan proses interpolasi pada coverimage dengan Cubic B-Spline mempengaruhi terhadap nilai samar atau Nilai PSNR.

scholarly journals Steganographic Techniques Using Modified Least Significant Bit and Modification Reshape Transposition Methods

2021 ◽  
Vol 13 (1) ◽  
pp. 67-77
Author(s):  
Guntoro Barovih ◽  
Fadhila Tangguh Admojo ◽  
Yoda Hersaputra
Keyword(s):  
Mean Square Error ◽  
Signal To Noise Ratio ◽  
Lossless Compression ◽  
Mean Square ◽  
Least Significant Bit ◽  
Signal To Noise ◽  
Image File ◽  
Modification Technique ◽  
Noise Ratio

A message is a form of conveying information. Various ways are used to secure the information conveyed in the form of messages either in encrypted form or in the form of applying a password in the message. Messages can also be encrypted and embedded in other media such as images (steganography). This research aimed to insert a message into the form of an image by combining the Modified Least Significant Bit (MLSB) method in encrypting messages and reshape modification technique to determine at which position the message encryption will be embedded in the image. Tests were carried out to obtain the quality of the encryption process using the parameters of Fidelity, mean square error, peak signal to noise ratio, testing on file type, robustness, and comparison of message contents. The results of the tests showed that the files that can be used are files with the image file type in the lossless compression category, the rotation can be done at 90, 180, 270 without destroying the message in it, and changing the pixel in the image file will destroy the message inside

scholarly journals A non-invasive, quantitative study of broadband spectral responses in human visual cortex

2017 ◽  
Author(s):  
Eline R. Kupers ◽  
Helena X. Wang ◽  
Kaoru Amano ◽  
Kendrick N. Kay ◽  
David J. Heeger ◽  
...  
Keyword(s):  
Human Brain ◽  
Neuronal Activity ◽  
Signal To Noise Ratio ◽  
Spike Rate ◽  
Signal To Noise ◽  
Electrical Fields ◽  
Non Invasive ◽  
Rate Dependent ◽  
Wide Range ◽  
Noise Ratio

AbstractCurrently, non-invasive methods for studying the human brain do not reliably measure signals that depend on the rate of action potentials (spikes) in a neural population, independent of other responses such as hemodynamic coupling (functional magnetic resonance imaging) and subthreshold neuronal synchrony (oscillations and event-related potentials). In contrast, invasive methods - animal microelectrode recordings and human intracortical recordings (electrocorticography, or ECoG) - have recently measured broadband power elevation spanning 50-200 Hz in electrical fields generated by neuronal activity as a proxy for the locally averaged spike rates. Here, we sought to detect and quantify stimulus-related broadband responses using a non-invasive method - magnetoencephalography (MEG) - in individual subjects. Because extracranial measurements like MEG have multiple global noise sources and a relatively low signal-to-noise ratio, we developed an automated denoising technique, adapted from Kay et al, 2013 (1), that helps reveal the broadband signal of interest. Subjects viewed 12-Hz contrast-reversing patterns in the left, right, or bilateral visual field. Sensor time series were separated into an evoked component (12-Hz amplitude) and a broadband component (60–150 Hz, excluding stimulus harmonics). In all subjects, denoised broadband responses were reliably measured in sensors over occipital cortex. The spatial pattern of the broadband measure depended on the stimulus, with greater broadband power in sensors contralateral to the stimulus. Because we obtain reliable broadband estimates with relatively short experiments (~20 minutes), with a sufficient signal-to-noise-ratio to distinguish responses to different stimuli, we conclude that MEG broadband signals, denoised with our method, offer a practical, non-invasive means for characterizing spike-rate-dependent neural activity for a wide range of scientific questions about human brain function.Author SummaryNeuronal activity causes perturbations in nearby electrical fields. These perturbations can be measured non-invasively in the living human brain using electro- and magneto-encephalography (EEG and MEG). These two techniques have generally emphasized two kinds of measurements: oscillations and event-related responses, both of which reflect synchronous activity from large populations of neurons. A third type of signal, a stimulus-related increase in power spanning a wide range of frequencies (‘broadband’), is routinely measured in invasive recordings in animals and pre-surgical patients with implanted electrodes, but not with MEG and EEG. This broadband response is of great interest because unlike oscillations and event-related responses, it is correlated with neuronal spike rates. Here we report quantitative, spatially specific measurements of broadband fields in individual human subjects using MEG. These results demonstrate that a spike- rate-dependent measure of brain activity can be obtained non-invasively from the living human brain, and is suitable for investigating a wide range of questions about spiking activity in the human brain.

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