scholarly journals On the application of frequency tagging

2020 ◽  
Author(s):  
Zoltan Derzsi
Keyword(s):  
Phase Noise ◽  
Detection Probability ◽  
Signal To Noise Ratio ◽  
Lower Probability ◽  
Weak Signal ◽  
Signal To Noise ◽  
Noise Component ◽  
Spectral Evaluation ◽  
Human Electrophysiology ◽  
Additional Phase

To detect a weak signal in human electrophysiology that is a response of a periodic external stimulus, spectral evaluation is mostly used. The recorded signal’s amplitude and phase noise components of the signal are statistically independent from each other, but both of them are decreasing the signal-to-noise ratio, which results in a lower probability of successful signal detection. Provided that the phase information of the stimuli is preserved, we found that a way to reject an additional phase noise component, which improves the detection probability considerably, by analysing the signal’s phase coherency instead of its spectrum.

The Design and Simulation of Cycled Amplifying Circuit

2013 ◽  
Vol 462-463 ◽  
pp. 632-635
Author(s):  
Na An ◽  
Cheng Long Gong ◽  
Weng Ming Su
Keyword(s):  
Adaptive Control ◽  
Error Compensation ◽  
Signal To Noise Ratio ◽  
Weak Signal ◽  
Detection Error ◽  
Signal To Noise ◽  
Analog Switch ◽  
Data Acquisition And Processing ◽  
Double Channel ◽  
Device Noise

There are many traditional methods to detect the weak signal(such as, locking -receive, synchronous cumulative and double channel de-noising) When the signal is very weak which easily submerged by the device noise,the error that measured by the above methods is too big. This paper mainly introduces the principle of a adaptive control faint signal cycle amplifier and through the method of error compensation to amplify signal cycled , which improve the signal-to-noise ratio and reduce the detection error. The structure of this system is simple and it cost low. besides,it convenient for use and debug. The circuit can also be applied to data acquisition and processing of weak signal and its significance is very widely .This paper designs a simulation circuit and analyzes sample-hold and analog switch.

ASSESSMENT OF TARGET DETECTION ABILITY FOR LASER FUZES IN FOG CONDITIONS

2021 ◽  
pp. 8-16
Author(s):  
Linh
Keyword(s):  
Target Detection ◽  
Detection Probability ◽  
Detection Efficiency ◽  
Signal To Noise Ratio ◽  
Evaluation Model ◽  
Laser System ◽  
Weather Conditions ◽  
Signal To Noise ◽  
Detection Ability ◽  
Bad Weather

The article presents a method to evaluate the target detection efficiency of laser fuzes operating in foggy conditions. The evaluation model is built from: the distance equation of the laser system, the attenuation of the beam in two-way propagation, the disturbances affecting the system; the signal to noise ratio SRN has determined the detection probability of the receiver. The model was used to evaluate with wavelengths: 850 nm, 1000 nm and 1550 nm, when propagating in three different bad weather conditions. The results show that the most effective detection of the target when using a wavelength of 1550 nm in visibility in haze and mist conditions (visibility V > 500 m). In fog conditions (visibility V < 500 m), the above three wavelengths provide the same detection efficiency. The article provides the method and instructions for choosing the wavelength of the laser fuze.

Adaptation of Telegraph Diffusion Equation for Noise Reduction on Images

2017 ◽  
Vol 17 (02) ◽  
pp. 1750010 ◽  
Author(s):  
Pandry Koffi Ghislain ◽  
Georges Lausanne Loum ◽  
Ouattara Nouho
Keyword(s):  
Diffusion Equation ◽  
Noise Reduction ◽  
Local Structure ◽  
Signal To Noise Ratio ◽  
Input Image ◽  
Weak Signal ◽  
Signal To Noise ◽  
Reduction Processes ◽  
Fine Structures

The Telegraph Diffusion Equation (TDE) used in some noise reduction processes in an image includes two main parameters: the damping coefficient and the relaxation time. Classically, the first is determined globally for a given input image, while the second one is set constant. In this paper, we propose to determine the values of these parameters according to the information and the image local structure. We then get an adaptive diffusion equation that permits to better control the degree of smoothness and preserve fine structures and image contours avoiding speckles phenomena and staircase. The acquired results show that the proposed method improves the quality of images that have a weak signal-to-noise ratio, comparatively to the methods based on the TDE whose parameters are not adaptive.

scholarly journals Coherent Power Measurements with a Compact Airborne Ka-Band Precipitation Radar

2018 ◽  
Vol 35 (1) ◽  
pp. 3-20 ◽  
Author(s):  
Andrew L. Pazmany ◽  
Samuel J. Haimov
Keyword(s):  
Signal To Noise Ratio ◽  
Power Estimation ◽  
Noise Power ◽  
Signal Power ◽  
Signal To Noise ◽  
Precipitation Radar ◽  
Noise Component ◽  
Ka Band ◽  
Noise Ratio ◽  
Conventional Signal

AbstractCoherent power is an alternative to the conventional noise-subtracted power technique for measuring weather radar signal power. The inherent noise-canceling feature of coherent power eliminates the need for estimating and subtracting the noise component, which is required when performing conventional signal power estimation at low signal-to-noise ratio. The coherent power technique is particularly useful when averaging a high number of samples to improve sensitivity to weak signals. In such cases, the signal power is small compared to the noise power and the required accuracy of the estimated noise power may be difficult to achieve. This paper compares conventional signal power estimation with the coherent power measurement technique by investigating bias, standard deviation, and probability of false alarm and detection rates as a function of signal-to-noise ratio and threshold level. This comparison is performed using analytical expressions, numerical simulations, and analysis of cloud and precipitation data collected with the airborne solid-state Ka-band precipitation radar (KPR) operated by the University of Wyoming.

scholarly journals Weak Signal Extraction from Lunar Penetrating Radar Channel 1 Data Based on Local Correlation

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 573 ◽  
Author(s):  
Zhuo Jia ◽  
Sixin Liu ◽  
Ling Zhang ◽  
Bin Hu ◽  
Jianmin Zhang
Keyword(s):  
Signal To Noise Ratio ◽  
Lunar Regolith ◽  
Signal Extraction ◽  
Weak Signal ◽  
Human Beings ◽  
Subsurface Structure ◽  
Local Correlation ◽  
Signal To Noise ◽  
Near Surface ◽  
Noise Ratio

Knowledge of the subsurface structure not only provides useful information on lunar geology, but it also can quantify the potential lunar resources for human beings. The dual-frequency lunar penetrating radar (LPR) aboard the Yutu rover offers a Special opportunity to understand the subsurface structure to a depth of several hundreds of meters using a low-frequency channel (channel 1), as well as layer near-surface stratigraphic structure of the regolith using high-frequency observations (channel 2). The channel 1 data of the LPR has a very low signal-to-noise ratio. However, the extraction of weak signals from the data represents a problem worth exploring. In this article, we propose a weak signal extraction method in view of local correlation to analyze the LPR CH-1 data, to facilitate a study of the lunar regolith structure. First, we build a pre-processing workflow to increase the signal-to-noise ratio (SNR). Second, we apply the K-L transform to separate the horizontal signal and then use the seislet transform (ST) to reserve the continuous signal. Then, the local correlation map is calculated using the two denoising results and a time–space dependent weighting operator is constructed to suppress the noise residuals. The weak signal after noise suppression may provide a new reference for subsequent data interpretation. Finally, in combination with the regional geology and previous research, we provide some speculative interpretations of the LPR CH-1 data.

scholarly journals An Integrated 5 GHz Wideband Quadrature Modem for OFDM Gbit/s Transmission in SiGe:C BiCMOS

2007 ◽  
Vol 2007 ◽  
pp. 1-8 ◽  
Author(s):  
Klaus Schmalz ◽  
Eckard Grass ◽  
Frank Herzel ◽  
Maxim Piz
Keyword(s):  
Phase Noise ◽  
Signal To Noise Ratio ◽  
Phase Locked Loop ◽  
Frequency Divider ◽  
Signal To Noise ◽  
Ofdm Signal ◽  
Bicmos Technology ◽  
Sige Bicmos ◽  
5 Ghz ◽  
Quadrature Signals

This paper presents a 5 GHz wideband I/Q modulator/demodulator for 650 MHz OFDM signal bandwidth, which is integrated with a 5 GHz phase locked loop for I/Q generation. The quadrature signals are derived from a 10 GHz CMOS VCO followed by a bipolar frequency divider. The phase noise at 1 MHz offset is −112 dBc/Hz for the modulator as well as for the demodulator. The chips were produced in a 0.25 μm SiGe BiCMOS technology. The signal-to-noise ratio (SNR) of transmitted/received OFDM signal and the corresponding I/Q mismatch versus baseband frequency are given. The modulator achieves an SNR of 22–23 dB, and the demodulator realizes an SNR up to 22 dB. The modulator reaches a data rate of 2.16 Gbit/s using 64 QAM OFDM, and the demodulator realizes 1.92 Gbits/s.

Quantitative Spectral Evaluation of Shimmer and Jitter

1985 ◽  
Vol 28 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Fritz Klingholz ◽  
Frank Martin
Keyword(s):  
Vocal Fold ◽  
Signal To Noise Ratio ◽  
Voice Disorders ◽  
Voice Disorder ◽  
Wave Spectra ◽  
Noise Levels ◽  
Signal To Noise ◽  
Low Frequencies ◽  
Synthesized Speech ◽  
Spectral Evaluation

A vowel [a]-like, synthesized speech wave was perturbated by defined and comparable jitter and shimmer levels. The signal-to-noise ratio was calculated from the speech wave spectra. Noise emerges in those spectral regions in which the harmonics have high amplitudes, that is, at low frequencies and in the formant regions. Jitter created noise levels significantly higher than shimmer. To verify the theoretical findings, the voices of 32 women with functional voice disorders were analyzed for shimmer and jitter. It was found that only jitter is relevant for differentiating between hypo- and hyperfunctional voice disorders. Jitter was reduced in hyperfunctional voice disorder. This is presumed to be an effect of the high vocal fold tension found in the disorder.

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