an isotropic hydrophone for sonar applications. An isotropic hydrophone
has the same response in all signal directions. The response is the
output voltage of the hydrophone per unit sound pressure. The response
for a hydrophone is also call its sensitivity. You can specify the
response using the
To compute the response of a hydrophone for specified directions:
Instead of using the
step method to perform
the operation defined by the System
object, you can call the object
with arguments, as if it were a function. For example,
= step(obj,x) and
y = obj(x) perform
a isotropic hydrophone System
hydrophone = phased.IsotropicHydrophone
an isotropic hydrophone System
object, with each specified property
hydrophone = phased.IsotropicHydrophone(
to the specified
Value. You can specify additional
name-value pair arguments in any order as (
FrequencyRange— Operating frequency range of hydrophone
[0 100e6](default) | real-valued 1-by-2 vector
Operating frequency range of hydrophone, specified as a real-valued
1-by-2 row vector of the form
This property defines the frequency range over which the hydrophone
has a response. The hydrophone element has zero response outside this
frequency range. Units are in Hz.
VoltageSensitivity— Voltage sensitivity of hydrophone
-120(default) | scalar | real-valued 1-by-K row vector
Voltage sensitivity of hydrophone, specified as a scalar or
real-valued 1-by-K row vector. When you specify
the voltage sensitivity as a scalar, that value applies to the entire
frequency range specified by
When you specify the voltage sensitivity as a vector, the frequency
range is divided into K-1 equal intervals. The sensitivity values
are assigned to the interval end points. The
interpolates the voltage sensitivity for any frequency inside the
frequency range. Units are in dB//1V/μPa. See Hydrophone Sensitivity for more details.
BackBaffled— Backbaffle hydrophone element
Backbaffle hydrophone element, specified as
Set this property to
true to backbaffle the hydrophone.
When the hydrophone is backbaffled, the hydrophone response for all
azimuth angles beyond ±90° from broadside are zero. Broadside
is defined as 0° azimuth and 0° elevation.
When the value of this property is
the hydrophone is not backbaffled.
|directivity||Directivity of isotropic hydrophone|
|pattern||Plot isotropic hydrophone directivity and patterns|
|patternAzimuth||Plot isotropic hydrophone directivity and response patterns versus azimuth|
|patternElevation||Plot isotropic hydrophone directivity and response patterns versus elevation|
|step||Voltage sensitivity of isotropic hydrophone|
Examine the response and patterns of an isotropic hydrophone operating between 1 kHz and 10 kHz.
Set up the hydophone parameters. Obtain the voltage sensitivity at five different elevation angles: -30°, -15°, 0°, 15° and 30°. All elevation angles are at 0°. The sensitivities are computed at the signal frequency of 2 kHz.
hydrophone = phased.IsotropicHydrophone('FrequencyRange',[1 10]*1e3); fc = 2e3; resp = hydrophone(fc,[0 0 0 0 0;-30 -15 0 15 30]);
Draw a 3-D plot of the voltage sensitivity.
pattern(hydrophone,fc,[-180:180],[-90:90],'CoordinateSystem','polar', ... 'Type','powerdb')
Examine the response and patterns of an isotropic hydrophone at three different frequencies. The hydrophone operates between 1 kHz and 10 kHz. Specify the voltage sensitivity as a vector.
Set up the hydrophone parameters and obtain the voltage sensitivity at 45° azimuth and 30° elevation. Compute the sensitivities at the signal frequencies of 2, 5, and 7 kHz.
hydrophone = phased.IsotropicHydrophone('FrequencyRange',[1 10]*1e3, ... 'VoltageSensitivity',[-100 -90 -100]); fc = [2e3 5e3 7e3]; resp = hydrophone(fc,[45;30])
resp = 14.8051 29.2202 24.4152
Draw a 2-D plot of the voltage sensitivity as a function of azimuth.
Hydrophone sensitivity measures the response of a hydrophone to input sound pressure.
Hydrophone voltage sensitivity is the open circuit voltage (OCV) at the output of a hydrophone for a given input sound intensity. Another term for hydrophone sensitivity is open circuit receiving response (OCRR). Specifically, OCRR is the voltage generated by a hydrophone per µPa of sound intensity. OCRR is generally a function of frequency. If the sound intensity level (SIL) is expressed in dB//µPa and the output voltage is expressed in dB//1V, then OCRR is expressed in dB//1V/µPa. The output voltage of a hydrophone is related to the input sound level by
VdB = SIL + OCRR.
VdB = SIL + OCRR = 120 dB + (–160) dB = –40 dB//1V.
In linear units,
V = 10VdB/10 = 100 µV.
 Urick, R.J. Principles of Underwater Sound. 3rd Edition. New York: Peninsula Publishing, 1996.
 Sherman, C.S., and J.Butler. Transducers and Arrays for Underwater Sound. New York: Springer, 2007.
 Allen, J.B., and D. Berkely. “Image method for efficiently simulating small-room acoustics”, Journal of the Acoustical Society of America. Vol. 65, No. 4. April 1979, , pp. 943–950.
 Van Trees, H. Optimum Array Processing. New York: Wiley-Interscience, 2002, pp. 274–304.
Usage notes and limitations:
patternElevation methods are not supported.
See System Objects in MATLAB Code Generation (MATLAB Coder).