System object™ creates 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 of a hydrophone is also
called 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
y = step(obj,x) and
y = obj(x)
perform equivalent operations.
creates an isotropic hydrophone System object,
hydrophone = phased.IsotropicHydrophone
creates an isotropic hydrophone System object, with each specified property
hydrophone = phased.IsotropicHydrophone(
Name set 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
[LowerBound HigherBound]. 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
FrequencyRange. 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
step method interpolates the
voltage sensitivity for any frequency inside the frequency range. Units are
in dB//1V/μPa. See Hydrophone Sensitivity for more
BackBaffled— Backbaffle hydrophone element
Backbaffle hydrophone element, specified as
true. Set this property 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°
When the value of this property is
hydrophone is not backbaffled.
Compute and display beamwidth of sensor element pattern
Directivity of isotropic hydrophone
Plot isotropic hydrophone directivity and patterns
Plot isotropic hydrophone directivity and response patterns versus azimuth
Plot isotropic hydrophone directivity and response patterns versus elevation
Voltage sensitivity of isotropic hydrophone
|Common to All System Objects|
Allow System object property value changes
Examine the response and patterns of an isotropic hydrophone operating between 1 kHz and 10 kHz.
Set up the hydrophone parameters. Obtain the voltage sensitivity at five different elevation angles: , , , and . All azimuth angles are at . 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 = 1×3 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
See System Objects in MATLAB Code Generation (MATLAB Coder).