Q-phase compensation of seismic records in the frequency domain

1996 ◽  
Vol 86 (4) ◽  
pp. 1179-1186
Author(s):  
Maksim Bano
Keyword(s):  
Wave Field ◽  
Frequency Domain ◽  
Real Data ◽  
Processing Technique ◽  
Signal Spectrum ◽  
Variable Model ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Seismic Wavelet ◽  
Inverse Q Filtering

Abstract The attenuation process acts as a low-pass filter that attenuates the high frequencies (absorption) of the signal spectrum and also changes the phase of the seismic wavelet (dispersion). Seismic frequency losses are usually recovered according to an appropriate processing technique (such as deterministic or statistical deconvolution methods), while phase distortions are generally disregarded. Therefore, accurate processing of seismic data requires a careful investigation of the relationship between absorption and phase. In this article, a procedure is presented to accomplish this goal. To account for anelastic losses, a complex power function of frequency for the phase velocity is introduced into the one-way wave-field equation in 1D. The compensation, for both effects (absorption and dispersion) described here, is analyzed in the context of wave-field extrapolation in one dimension 1D, equivalent to that in the f-k domain as phase-shift and/or Stolt migration. The phase-only inverse Q filtering works in the frequency domain. It provides for dispersion according to a constant-Q (frequency-independent) model and is valid for any positive value of Q. The extension of this algorithm for a Q depth-variable model is also shown. The amplitude compensation is accomplished through the use of a standard statistical approach. Synthetic and real data are shown to illustrate both amplitude and phase inverse Q filtering of seismic reflection records.

An optical regenerative wavelength conversion scheme for satellite based on SPM of SOA and offset filter

2021 ◽  
Author(s):  
Yi Dong ◽  
Zemin Ji ◽  
Peng Zhou ◽  
Lin Zhou ◽  
Aoyun Wu
Keyword(s):  
Wavelength Conversion ◽  
Optical Amplifier ◽  
Input Power ◽  
Signal Spectrum ◽  
Pump Light ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Signal Light ◽  
Low Pass ◽  
Conversion Scheme

Abstract An optical regenerative wavelength conversion scheme without separated pump laser is put forward to promote the wavelength utilization ratio in distributed satellite network. The scheme adopts the self-phase modulation(SPM) in semiconductor optical amplifier(SOA) to broaden the signal spectrum toward both higher and lower frequency owing to the property that the time of carrier recover is less than pulsewidth. Then the signal light and pump light are extracted by a high-pass filter and a low-pass filter respectively. Finally, the wavelength conversion is realized based on the four-wave mixing(FWM), where the signal light and pump light are passing through another SOA. The simulation results demonstrate that the conversion efficiency can be more than 15dB, and the Q factor improvement can reach to 4dB when input power is small than -22dBm.

scholarly journals On Relationship Between Time-Domain and Frequency-Domain Disturbance Observers and Its Applications

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Jinya Su ◽  
Wen-Hua Chen ◽  
Jun Yang
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Disturbance Observer ◽  
Matching Condition ◽  
Existence Condition ◽  
Design Guideline ◽  
Pass Filter ◽  
Functional Disturbance ◽  
Low Pass Filter ◽  
Unity Gain

This paper provides a generic analysis of the relationship between time- and frequency-domain disturbance observer (DOB) design methodology. It is discovered that the traditional frequency-domain DOBs using a low-pass filter with unity gain can only handle disturbances satisfying matching condition, while the traditional time-domain DOBs always generate an observer with a high-order. A functional disturbance observer (FDOB) is proposed to improve the existing results together with its design guideline, frequency analysis, and existence condition. Compared with the existing frequency-domain DOBs, the proposed FDOB can handle more classes of disturbances, while compared with the existing time-domain DOBs, the proposed FDOB can generate an observer with a lower-order. Numerical examples are presented to illustrate the main findings of this paper including a rotary mechanical system of nonminimum phase.

Filtering of Electronic Speckle Correlation Fringes

2012 ◽  
Vol 198-199 ◽  
pp. 1202-1207
Author(s):  
Fei Guo ◽  
Mei Zhao ◽  
Xiu Ying Fan ◽  
Jin He Bao ◽  
Wen Bang Sun
Keyword(s):  
Frequency Domain ◽  
Speckle Noise ◽  
Filter Medium ◽  
Space Domain ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Speckle Correlation ◽  
Low Pass ◽  
Mean Filter

Speckle correlation fringes include a large quantity of speckle noise. It is first to consider how to reduce speckle noise before using phase formula to calculate. Filter is usually used to reduce speckle noise. From two aspects of frequency domain and space domain, we adopted mean filter, medium filter, Butterworth low-pass filter and homomorphism filter to process the speckle correlation fringes obtained by experiment. It is shown that the speckle correlation fringes are clearer and more easily interpreted and automatic processed after being filtered.

FFT Thermoelastic Solutions for Moving Heat Sources

1997 ◽  
Vol 119 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Y. Ju ◽  
T. N. Farris
Keyword(s):  
Heat Source ◽  
Frequency Domain ◽  
Hot Spot ◽  
Surface Displacement ◽  
Elastic Half Space ◽  
Heat Sources ◽  
Moving Heat Source ◽  
Line Heat Source ◽  
Pass Filter ◽  
Low Pass Filter

An analytical frequency domain solution is obtained using the spatial Fourier transform for thermal and thermoelastic fields due to an arbitrary heat source or thermal distribution moving at constant speed over the surface of an insulated, traction free elastic half space. Conversions between the space and frequency domains for the input and output are performed efficiently and robustly using FFT techniques. The method is validated by comparison to the analytical result for the moving line heat source in which it is shown that numerical evaluation of the analytical solution is problematic for large speeds or distances from the heat source. The utility of the method is illustrated on the constant patch moving heat source and discretely distributed multiple heat sources known as the “hot spot” problem. It is shown, through several examples, that the effect of hot spots on surface displacement and tangential stress is small. Finally, this conclusion is generalized by quantifying the frequency domain solution for the moving heat source problem as a low pass filter.

The research of time-frequency characteristics of buried mine of seismic waves in shallow sea

2020 ◽  
Vol 51 (3) ◽  
pp. 35-43
Author(s):  
Shuang Zhao ◽  
Jian Zhang ◽  
Dongwei Kou ◽  
Cean Guo
Keyword(s):  
Wave Field ◽  
Seismic Wave ◽  
Seismic Waves ◽  
Propagation Characteristics ◽  
Shallow Sea ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Rock Density ◽  
Time Frequency ◽  
Simulation Results

To study the variation of the wave field of seismic waves in shallow sea of buried mines, the wave field of buried mine was simulated by employing LS-DYNA software. The effects of different distances ( R), rock density ( ρ2), buried depth ( h), and seawater height ( H) on the variation of wave field were obtained. The time-frequency analysis of the simulation results was carried out by using wavelet transform, and it was determined that the frequency domain of shallow sea is mainly concentrated below 25 Hz. To get the propagation characteristics of shallow sea seismic wave, the wave field below 25 Hz on the surface of buried mine was filtered by the low-pass filter. The buried depth has the greatest influence on the wave field of buried mine. The underwater target can be identified by the propagation characteristics of shallow sea seismic wave. The simulation results are consistent with the experimental results. The research results can provide an important reference for development of buried mine fuse.

Design of Programmable Wideband Low Pass Filter with Continuous-Time/Discrete-Time Hybrid Architecture

2017 ◽  
Vol E100.C (10) ◽  
pp. 858-865 ◽  
Author(s):  
Yohei MORISHITA ◽  
Koichi MIZUNO ◽  
Junji SATO ◽  
Koji TAKINAMI ◽  
Kazuaki TAKAHASHI
Keyword(s):  
Discrete Time ◽  
Continuous Time ◽  
Hybrid Architecture ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

ANALYSIS AND IMPROVEMENT TECHNIQUES FOR THE TRANSFER FUNCTION OF A PLANAR LOW - PASS FILTER

2016 ◽  
Vol 15 (12) ◽  
pp. 2579-2586
Author(s):  
Adina Racasan ◽  
Calin Munteanu ◽  
Vasile Topa ◽  
Claudia Pacurar ◽  
Claudia Hebedean
Keyword(s):  
Transfer Function ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass
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