s [m]	Starting depth	N_rep [-]	Number of repetition per profile
w [m]	Channel width	PRF [Hz]	Pulse Repetition Frequency
W [m]	Length of measurement window	N [-]	Number of elements in array sensor
h [m]	Channel distance	t [s]	Time
x_tx [m]	x-coordinate of transmitting element in array sensor	A [-]	Time domain signal
x_rx [m]	x-coordinate of receiving element in array sensor	H [-]	Hilbert transformation of raw signal
y_tx [m]	y-coordinate of transmitting element in array sensor	P [-]	Pixels of imaging area
y_rx [m]	y-coordinate of receiving element in array sensor	D [-]	Directivity function of transmitting & receiving elements
u₁ [m/s]	Velocity component that measured by sensor-1	a [m]	Element width
u₂ [m/s]	Velocity component that measured by sensor-2	λ [m]	Wavelength
d₁ [m]	Distance from sensor to intersection point in sensor 1	b [m]	Element height
d₂ [m]	Distance from sensor to intersection point in sensor 2	c [m]	Inter-element spacing
θ [deg]	Azimuth angle	R [m]	Curvature
Ch [-]	Intersecting channel number	I [-]	Sound pressure
V [-]	Velocity value along x and y direction	∆t [s]	Time resolution
∆x [m]	Spatial resolution	Rf [-]	Autocorrelation function
I(t) [-]	In phase signal	Q(t) [-]	Quadrature signal
z(t) [-]	Envelope signal	φ [-]	Phase shift between echo signals
Subscripts
i,j	Transmitting and Receiving elements	2D	Two-dimension
Abbreviations
FDNPP	Fukushima Daiichi Nuclear Power Plant	UVP	Ultrasonic Velocity Profiler
PCV	Primary Containment Vessel	TFM	Total Focusing Method
RPV	Reactor Pressure Vessel	TX	Sensor
TMI	Three Mile Island	PRF	Pulse Repetition Frequency
SPL	Sound Pressure Level	PR	Pulse Repetition
MUX	Multiplexer	FWHM	Full Width at Half Maximum
PIV	Particle Image Velocimetry	LOA	Limit Of Agreement
SD	Standard Deviation	sinc	sine cardinal
RF	Relative Frequency