widebandTwoRayChannel
Description
The widebandTwoRayChannel
System object™ models a wideband two-ray propagation channel. A two-ray propagation
channel is the simplest type of multipath channel. You can use a two-ray channel to
simulate propagation of signals in a homogeneous, isotropic medium with a single
reflecting boundary. This type of medium has two propagation paths: a line-of-sight
(direct) propagation path from one point to another and a ray path reflected from the
boundary. The Earth's surface is common boundary.
You can use this widebandTwoRayChannel
object for short-range radar and mobile
communications applications where the signals propagate along straight paths and the
Earth is assumed to be flat. You can also use this object for sonar and microphone
applications. For acoustic applications, you can choose nonpolarized fields and adjust
the propagation speed to be the speed of sound in air or water. You can use
widebandTwoRayChannel
to model propagation from several points
simultaneously.
Although the widebandTwoRayChannel
object works for all frequencies, the
attenuation models for atmospheric gases and rain are valid for electromagnetic signals
in the frequency range 1–1000 GHz only. The attenuation model for fog and clouds is
valid for 10–1000 GHz. Outside these frequency ranges, the widebandTwoRayChannel
object uses the nearest valid value.
The widebandTwoRayChannel
object applies range-dependent time delays to the
signals, as well as gains or losses, phase shifts, and boundary reflection loss. When
either the source or destination is moving, the widebandTwoRayChannel
object also
applies Doppler shifts to the signals.
Signals at the channel output can be kept separate or be combined. If you keep the signals separate, both signals arrive at the destination separately and are not combined. If you choose to combine the signals, the two signals from the source propagate separately but are coherently summed at the destination into a single quantity. Choose this option when the difference between the sensor or array gains in the directions of the two paths is insignificant.
In contrast to the phased.WidebandFreeSpace
and phased.WidebandLOSChannel
System objects, the widebandTwoRayChannel
System object does not support two-way propagation.
To compute the propagation delay for specified source and receiver points:
Create the
widebandTwoRayChannel
object and set its properties.Call the object with arguments, as if it were a function.
To learn more about how System objects work, see What Are System Objects?
Creation
Description
creates a two-ray propagation channel System object, channel
= widebandTwoRayChannelchannel
.
Properties
Usage
Description
returns the resulting signal, prop_sig
= channel
(sig
,origin_pos
,dest_pos
,origin_vel
,dest_vel
)prop_sig
, when a wideband
signal, sig
, propagates through a two-ray channel from the
origin_pos
position to the
dest_pos
position. Either the
origin_pos
or dest_pos
arguments
can have multiple points but you cannot specify both as having multiple points.
Specify the velocity of the signal origin in origin_vel
and
the velocity of the signal destination in dest_vel
. The
dimensions of origin_vel
and dest_vel
must agree with the dimensions of origin_pos
and
dest_pos
, respectively.
In the two-ray environment, two signal paths connect every signal origin and destination pair. For N signal origins (or N signal destinations), there are 2N paths. The signals for each origin-destination pair do not have to be identical. The signals along the two paths for any source-destination pair can have different amplitudes or phases.
The CombinedRaysOutput
property controls whether the two
signals at the destination are kept separate or
combined. Combined means that the
signals at the source propagate separately along the two paths but are
coherently summed at the destination into a single quantity.
Separate means that the two signals are not summed at
the destination. To use the combined option, set
CombinedRaysOutput
to true
. To use
the separate option, set
CombinedRaysOutput
to false
. The
combined option is convenient when the difference
between the sensor or array gains in the directions of the two paths is not
significant.
Input Arguments
Output Arguments
Object Functions
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named obj
, use
this syntax:
release(obj)
Examples
More About
References
[1] Proakis, J. Digital Communications. New York: McGraw-Hill, 2001.
[2] Skolnik, M. Introduction to Radar Systems, 3rd Ed. New York: McGraw-Hill.
[3] Saakian, A. Radio Wave Propagation Fundamentals. Norwood, MA: Artech House, 2011.
[4] Balanis, C. Advanced Engineering Electromagnetics. New York: Wiley & Sons, 1989.
[5] Rappaport, T. Wireless Communications: Principles and Practice, 2nd Ed New York: Prentice Hall, 2002.
[6] Radiocommunication Sector of the International Telecommunication Union. Recommendation ITU-R P.676-12: Attenuation by atmospheric gases. 2019.
[7] Radiocommunication Sector of the International Telecommunication Union. Recommendation ITU-R P.840-6: Attenuation due to clouds and fog. 2013.
[8] Radiocommunication Sector of the International Telecommunication Union. Recommendation ITU-R P.838-3: Specific attenuation model for rain for use in prediction methods. 2005.
Extended Capabilities
Version History
Introduced in R2021a