Wave per unit distance (typically per meter), can be associated with the wavelength by the relation The period formula_33 is the time for one complete cycle of an oscillation of a wave. The frequency formula_34 is the number of periods per unit time (per second) and is typically measured in hertz denoted as Hz. These are related by: In other words, the frequency and period of a wave are reciprocals. The angular frequency formula_28 represents the frequency in radians per second. It is related to the frequency or period by The wavelength formula_30 of a sinusoidal waveform traveling at constant speed
Coda Wave Interferometry The unperturbed travel time is given by formula_8 where formula_9 is the coda wave velocity. The perturbed travel time is formula_10 where formula_11 is the velocity perturbation. Thus formula_12 . If the relative velocity perturbation is assumed constant, then formula_13 where t is the center time of the employed time window. Thus, the travel time perturbation depends on the arrival time of the coda wave, but not of the particular path followed. Coda Wave Interferometry Coda Wave Interferometry is an ultrasound technique for detection of weak and local changes in complex inhomogeneous media. Sound waves that travel through a medium