mil.navy.nps.rra

Class SSP

java.lang.Object

mil.navy.nps.rra.SSP

public class SSP
extends Object

Sound Speed Profile (SSP) describes the acoustic characteristics of refraction for the local volume of water which the Ray is passing through.

The speed of sound in water is dependendent on water temperature, depth and salinity. Changes in SSP cause refraction (bending) of sound waves, which can be considered a continuous case of Snell's Law. In practice, an SSP can be obtained from Conductivity-Temperature-Density (CTD) measurements, Expendable Bathythermographic Thermistor (XBT) measurements or historical datasets. Because SSP can return values of arbitrary resolution in depth and position, and since SSP is a principal influence on sound path refraction (bending), this computaional approach makes the rra algorithm of general use under a wide range of underwater conditions.

Currently the SSP class provides five representative profiles:

1. no gradient: constant sound velocity of 1500 m/s
2. positive gradient: constantly increasing sound velocity starting with 1500 m/s and having a slope of .017 m/s/m
3. negative gradient: constantly decreasing sound velocity starting with 1500 m/s and having a slope of .017 m/s/m
4. parabolic: velocity profile obeying 1490 + 4e-5 *(500 - depth)^2
5. traditional: velocity profile forming a typical deep sound channel as follows

   Depth range	Sound speed
   0 m	1500 m/s
   0..100 m	positive (+) slope of .016 m/s/m
   100..1000 m	negative (-) slope of .02956 m/s/m
   > 1000 m	positive (+) slope of .03 m/s/m

Further methods will be needed for importing CTD, XBT and historical datasets.

Version:

$Revision: 1.6 $

Author:

LT Timothy M. Holliday USN

Contact: Don Brutzman (web.nps.navy.mil/~brutzman) brutzman@nps.navy.mil

Source Code:

~vrtp/mil/navy/nps/rra/SSP.java

http://web.nps.navy.mil/~brutzman/vrtp/mil/navy/nps/rra/SSP.java

History:

25 Oct 97	Timothy M. Holliday	New
17 Mar 98	Timothy M. Holliday	Added HTML comment convention
9 Oct 98	Don Brutzman	Javadoc updates for jdk1.2b4
25 April 99	Don Brutzman	Javadoc updates for jdk1.2.1

Reference:

Holliday, Timothy, Real-Time 3D Sonar Modeling and Visualization, Master's Thesis, Naval Postgraduate School, Monterey California, June 1998. Available at vrtp/rra/HollidayRRAthesis.pdf. and web.nps.navy.mil/~brutzman/vrtp/rra/HollidayRRAthesis.pdf. Slideset available in Powerpoint and Acrobat .pdf formats.

See Also:

Surface

Constructor Summary

Constructors

Constructor and Description
SSP(double[] lev, double[] val) Sets levels, values and environment values.
SSP(String sspType) The sspType argument is one the the following five sound speed profile types: "constant", "+gradient", "-gradient", "parabolic" and "traditional"

Method Summary

Modifier and Type	Method and Description
double	C(Vec3d position) Method used to calculate the speed of sound for each of the six standard profiles.
Vec3d	generalgradC(Vec3d starPosition) Method used to calculate the gradient of sound speed from any sound speed profile.
Vec3d	gradC(Vec3d starPosition) Method used to calculate the gradient of sound speed for each of the five standard profiles.
double	SSP6(Vec3d position) Calculates the sound of speed used from the Vec3d object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SSP

public SSP(String sspType)

The sspType argument is one the the following five sound speed profile types: "constant", "+gradient", "-gradient", "parabolic" and "traditional"

Parameters:

sspType - jThe five sound speed profile types.

SSP

public SSP(double[] lev,
           double[] val)

Sets levels, values and environment values.

Parameters:

lev - Levels of the sound speed profile.

val - Values of the sound speed profile.

Method Detail

gradC

public Vec3d gradC(Vec3d starPosition)

Method used to calculate the gradient of sound speed for each of the five standard profiles.

Parameters:

starPosition - Vec3d object.

Returns:

The gradient of sound speed for each of the six standard profiles.

generalgradC

public Vec3d generalgradC(Vec3d starPosition)

Method used to calculate the gradient of sound speed from any sound speed profile.

Parameters:

starPosition - Vec3d object.

Returns:

The gradient being set the x, y and z positions.

C

public double C(Vec3d position)

Method used to calculate the speed of sound for each of the six standard profiles.

Parameters:

position - Vec3d object.

Returns:

The speed of sound.

SSP6

public double SSP6(Vec3d position)

Calculates the sound of speed used from the Vec3d object.

Parameters:

position - Vec3d object.

Returns:

The sound of speed.