System object™ creates an isotropic sound projector for sonar applications. An isotropic projector
has the same response in all directions. The response is the radiated sound intensity per unit
input voltage to the projector. You can adjust the response using the
To compute the response of a projector 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,
y = step(obj,x) and
y = obj(x) perform equivalent
isotropic projector System object,
projector = phased.IsotropicProjector
creates an isotropic projector System object,
projector = phased.IsotropicProjector(
projector, with each specified property
Name set to the specified Value. You can specify additional name-value pair
arguments in any order as
FrequencyRange— Operating frequency range of projector
[0 100e6](default) | real-valued 1-by-2 vector
Operating frequency range of projector, specified as a 1-by-2 row vector in the form of
[LowerBound HigherBound]. The projector defines the nonzero response range
over which the hydrophone has a response. The projector has zero response outside this
frequency range. Units are Hz.
VoltageResponse— Voltage response of projector
120(default) | scalar | real-valued 1-by-K row vector
Voltage response of projector, specified as a scalar or real-valued
1-by-K row vector. When you specify voltage response 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 response values are assigned to the interval end points. Then, the
step method interpolates the voltage response for any
frequency inside the frequency range. Units are in dB ref: 1 μPa/V. See Projector Voltage Response for more details.
BackBaffled— Backbaffle response of projector
Backbaffle response of projector, specified as
true. Set this property to
true to backbaffle the
projector response. When the projector is backbaffled, the projector 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
false, the projector is not
Compute and display beamwidth of sensor element pattern
Directivity of isotropic projector
Plot isotropic projector directivity and patterns
Plot isotropic projector directivity and response patterns versus azimuth
Plot isotropic projector directivity and response patterns versus elevation
Voltage sensitivity of isotropic projector
|Common to All System Objects|
Allow System object property value changes
Examine the response and patterns of an isotropic projector operating between 1 kHz and 10 kHz.
Set the projector parameters and obtain the voltage response at five different elevation angles: -30°, -15°, 0°, 15° and 30°. All elevation angles at 0° azimuth angle. The voltage response is computed at 2 kHz.
projector = phased.IsotropicProjector('FrequencyRange',[1,10]*1e3); fc = 2e3; resp = projector(fc,[0,0,0,0,0;-30,-15,0,15,30]);
Draw a 3-D plot of the voltage response.
pattern(projector,fc,[-180:180],[-90:90],'CoordinateSystem','polar', ... 'Type','power')
Examine the response and patterns of an isotropic projector at three different frequencies. The projector operates between 1 kHz and 10 kHz. Specify the voltage response as a vector.
Set up the projector parameters, and obtain the voltage response at 45° azimuth and 30° elevation. Compute the responses at signal frequencies of 2, 5, and 7 kHz.
projector = phased.IsotropicProjector('FrequencyRange',[1 10]*1e3, ... 'VoltageResponse',[90 95 100 95 90]); fc = [2e3 5e3 7e3]; resp = projector(fc,[45;30]); resp
resp = 1×3 0.0426 0.0903 0.0708
Next, draw a 2-D plot of the voltage response as a function of azimuth.
pattern(projector,fc,[-180:180],0,'CoordinateSystem','rectangular', ... 'Type','power')
The voltage response of a projector relates the transmitted sound intensity to the input voltage.
For a sound projector, the transmitting voltage response (TVR) is the sound intensity in µPa per volt, when measured at one meter from the projector. TVR is generally a function of frequency. If the sound intensity level (SIL) is expressed in dB//µPa and the output voltage (VdB) is expressed in dB//1V, then TVR is expressed in dB//µPa/1V. The output sound pressure level of a hydrophone is related to the input voltage level by
SIL = TVR + VdB.
SIL = TVR + VdB = 160 + 23 = 173 dB//µPa.
 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).