On: “Accurate depth migration by a generalized phase‐shift method” by Dan Kosloff and David Kessler (GEOPHYSICS 52, 1074–1084, August 1987).

Geophysics ◽  
1989 ◽  
Vol 54 (2) ◽  
pp. 271-272
Author(s):  
D. M. Pai
Keyword(s):  
Phase Shift ◽  
New Method ◽  
Shift Method ◽  
Depth Migration ◽  
Matrix Layer ◽  
Phase Shift Method

I would like to point out that the “generalized phase‐shift method” (Kosloff and Kessler, 1987) introduced for solution continuation — and referred to as a new method — is essentially identical to the “generalized Haskell matrix/layer eigenstate propagator (GHM/LEP)” method I presented earlier (Pai, 1985). Unfortunately, Kosloff and Kessler did not reference that paper.

Three‐dimensional depth migration by a generalized phase‐shift method

1986 ◽  
Author(s):  
Mickey Edwards ◽  
Chris Hsiung ◽  
David Kessler ◽  
Dan Kosloff ◽  
Moshe Reshef
Keyword(s):  
Phase Shift ◽  
Three Dimensional ◽  
Shift Method ◽  
Depth Migration ◽  
Phase Shift Method

Accurate depth migration by a generalized phase‐shift method

Geophysics ◽  
1987 ◽  
Vol 52 (8) ◽  
pp. 1074-1084 ◽  
Author(s):  
Dan Kosloff ◽  
David Kessler
Keyword(s):  
Phase Shift ◽  
Velocity Structure ◽  
Shift Method ◽  
Depth Migration ◽  
Integration Techniques ◽  
Matrix Diagonalization ◽  
Offset Time ◽  
Zero Offset ◽  
Spatially Variant ◽  
Phase Shift Method

A new depth migration method derived in the space‐frequency domain is based on a generalized phase‐shift method for the downward continuation of surface data. For a laterally variable velocity structure, the Fourier spatial components are no longer eigenvectors of the wave equation, and therefore a rigorous application of the phase‐shift method would seem to require finding the eigenvectors by a matrix diagonalization at every depth step. However, a recently derived expansion technique enables phase‐shift accuracy to be obtained without resorting to a costly matrix diagonalization. The new technique is applied to the migration of zero‐offset time sections. As with the laterally uniform velocity case, the evanescent components of the solution need to be isolated and eliminated, in this case by the application of a spatially variant high‐cut filter. Tests performed on the new method show that it is more accurate and efficient than standard integration techniques such as the Runge‐Kutta method or the Taylor method.

A HIGHLY ACCURATE ULTRASONIC MEASUREMENT SYSTEM FOR TREMOR USING BINARY AMPLITUDE-SHIFT-KEYING AND PHASE-SHIFT METHOD

2003 ◽  
Vol 15 (02) ◽  
pp. 61-67 ◽  
Author(s):  
MENG-HSIANG YANG ◽  
K. N. HUANG ◽  
C. F. HUANG ◽  
S. S. HUANG ◽  
M. S. YOUNG
Keyword(s):  
Phase Shift ◽  
Measurement System ◽  
Low Cost ◽  
Phase Shifts ◽  
Ultrasonic Waves ◽  
Shift Method ◽  
Narrow Bandwidth ◽  
Shift Keying ◽  
Modulation Signal ◽  
Phase Shift Method

A highly accurate Binary Amplitude-Shift-Keyed (BASK) ultrasonic tremor measurement system for use in isothermal air is developed. In this paper, we present a simple but efficient algorithm based upon phase shifts generated by three ultrasonic waves of different frequencies. By the proposed method, we can conduct larger range measurement than the phase-shift method and also get higher accuracy compared with the time-of-flight (TOF) method. Our microcomputer-based system includes two important parts. One of which is BASK modulation signal generator. The other is a phase meter designed to record and compute the phase shifts of the three different frequencies and the result motion is then sent to either an LCD for display or a PC for calibration. Experiments are done in the laboratory using BASK modulation for the frequencies of 200 Hz and 1 kHz with a 40 kHz carrier. The measurement accuracy of this measurement system in the reported experiments is within +/- 0.98 mm. The main advantages of this ultrasonic tremor measurement system are high resolution, narrow bandwidth requirement, low cost, and easy to be implemented.

A digital phase shift method for phase compensation of electronic transformer

2017 ◽  
Vol 40 (13) ◽  
pp. 3690-3695 ◽  
Author(s):  
Wei Wei ◽  
Han-miao Cheng ◽  
Fan Li ◽  
Deng-ping Tang ◽  
Shui-bin Xia
Keyword(s):  
Phase Shift ◽  
Phase Error ◽  
Recursion Formula ◽  
Rogowski Coil ◽  
Shift Method ◽  
Electronic Transformer ◽  
Digital Phase ◽  
Fitting Algorithm ◽  
Fixed Phase ◽  
Phase Shift Method

When sampling analog signal, the electronic transformer generally produces a fixed phase error that will compromise the measurement accuracy and require a phase shift method for correction. In this paper, we propose a digital phase shift method based on least squares fitting algorithm and derive the recursion formula of digital phase shift. The simulation has also been done to analysis its performance. The result shows that the method has high phase shift resolution and precision. By applying the method to an electronic transformer based on Rogowski coil, we have experimentally verified the feasibility and validity of the method.

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