scholarly journals On the use of geometric and harmonic means with the generalized cross-correlation in the time domain to improve noise source maps

2016 ◽  
Vol 140 (1) ◽  
pp. EL56-EL61 ◽  
Author(s):  
Thomas Padois ◽  
Olivier Doutres ◽  
Franck Sgard ◽  
Alain Berry
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Noise Source ◽  
The Time Domain ◽  
Harmonic Means

scholarly journals Cross-Correlation of THz Pulses from the Electron Storage Ring BESSY II

2020 ◽  
Vol 5 (2) ◽  
pp. 24
Author(s):  
Ulrich Schade ◽  
Peter Kuske ◽  
Jongseok Lee ◽  
Barbara Marchetti ◽  
Michele Ortolani
Keyword(s):  
Synchrotron Radiation ◽  
Storage Ring ◽  
Time Domain ◽  
Cross Correlation ◽  
Bunch Length ◽  
Pump Probe ◽  
Electron Storage ◽  
Coherent Synchrotron Radiation ◽  
Longitudinal Length ◽  
The Time Domain

Coherent synchrotron radiation from an electron storage ring is observed in the THz spectral range when the bunch length is shortened down to the sub-mm-range. With increasing stored current, the bunch becomes longitudinally unstable and modulates the THz emission in the time domain. These micro-instabilities are investigated at the electron storage ring BESSY II by means of cross-correlation of the THz fields from successive bunches. The investigations allow deriving the longitudinal length scale of the micro bunch fluctuations and show that it grows faster than the current-dependent bunch length. Our findings will help to set the limits for the possible time resolution for pump-probe experiments achieved with coherent THz synchrotron radiation from a storage ring.

Research on Time-Domain Correlation Technique Based on ZC Sequences in OFDM System

2014 ◽  
Vol 519-520 ◽  
pp. 500-503
Author(s):  
Chang Jiang Huang ◽  
Yu Hua ◽  
Yong Hui Hu ◽  
Yu Xiang
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Random Noise ◽  
Correlation Technique ◽  
Ofdm System ◽  
Auto Correlation ◽  
Modulation Signal ◽  
The Time Domain ◽  
Correlation Properties ◽  
Time Domain Correlation

OFDM modulation signal based on different Pseudo-random Noise sequences cant be discriminated in time domain in OFDM system. In order to resolve this problem, the time-domain sliding correlation technique based on ZC sequences is proposed, and the relations between the time-domain correlation properties and the length of the sequence are analyzed. On the basis of the analysis of the technique, the optimum scheme of time-domain sliding correlation is done by the aid of the comparison of the auto-correlation gain on the condition of limited symbol length and band-width. Simulation results in AWGN channel show that OFDM demodulation signal based on ZC sequences designed newly in this work has good auto-correlation and cross-correlation properties in time domain.

Time domain analysis of oxygen uptake during pseudorandom binary sequence exercise tests

1991 ◽  
Vol 71 (4) ◽  
pp. 1620-1626 ◽  
Author(s):  
R. L. Hughson ◽  
L. A. Cuervo ◽  
A. E. Patla ◽  
D. A. Winter ◽  
H. C. Xing ◽  
...  
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Binary Sequence ◽  
Model Fit ◽  
Exercise Tests ◽  
Pseudorandom Binary Sequence ◽  
Two Component ◽  
Shaped Pulse ◽  
The Time Domain ◽  
Base Width

Pseudorandom binary sequence (PRBS) exercise tests involve repeated switching between two work rates (WR) according to a computer-generated pattern. This paper presents an approach to analysis of O2 uptake (VO2) in the time domain. First, the autocorrelation function (ACF) of the input WR was recognized to be a triangular-shaped pulse that can be taken to be equivalent to a ramp increase followed by a ramp decrease in WR. Then the cross-correlation function of the input (WR) and the output (VO2) was treated as if it were the response to a triangular-shaped pulse. The cross-correlation function was analyzed by fitting a linear summation of the ramp form of a two-component exponential function to this triangular pulse. VO2 responses of eight subjects were obtained from two different PRBS tests, as well as step changes in WR. The first PRBS test consisted of 15 units, each 30 s in duration. Its ACF had a base width of 60 s. The ramp increase-ramp decrease model fit the data throughout the range of response. The second PRBS test had 63 units, each 5 s in duration; thus its ACF base width was 10 s. Again, the ramp model fit adequately. The data from the second PRBS test could be fit by the impulse form of the two-component exponential equation, although the fit in the first 30 s tended to be poorer. The time constants of VO2 dynamics estimated from step and PRBS tests were not significantly different. PRBS tests can be analyzed in the time domain, and the indicators of system dynamics reflect physiological properties similar to those investigated during step changes in WR.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain

Measurements of single-phase and two-phase flows in a vertical pipe using ultrasonic pulse Doppler method and ultrasonic time-domain cross-correlation method

2013 ◽  
Vol 35 (3) ◽  
Author(s):  
Tat Thang Nguyen ◽  
Hiroshige Kikura ◽  
Ngoc Hai Duong ◽  
Hideki Murakawa ◽  
Nobuyoshi Tsuzuki
Keyword(s):  
Time Domain ◽  
Cross Correlation ◽  
Single Phase ◽  
Ultrasonic Pulse ◽  
Phase Flow ◽  
Beam Diameter ◽  
Vertical Pipe ◽  
Two Phase ◽  
Ultrasonic Time ◽  
Pulse Doppler

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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