Patent Application
20190086527
This invention relates generally to radar wave emissions and, more particularly, to automatic control of radar wave emissions.
The operation and use of radar systems which utilize electromagnetic wave emissions to determine the range, angle, or velocity of objects is well established. Radar systems will typically include a transmitter, one or multiple antennas, a receiver and processor. The transmitter works with the antennas to produce electromagnetic waves. The receiver works with the antennas to receive electromagnetic waves which have been reflected off object(s). The processor works with the output of the receiver to determine properties such as location and speed of the object(s) from which the electromagnetic waves were deflected. In many embodiments, radar systems employ electromagnetic waves in the radio or microwave domain (referred to generally herein as “radar waves” or “wave signals”).
In many implementations, radar systems employ an antenna that rotates three hundred sixty degrees (360°) and generates a continuous stream of active wave signals. In such implementations, active wave signal generation is often controlled by a hardware or software switch. In cases wherein it has been desired to selectively shut off active wave signal generation, it typically has been done manually.
As such, a problem which still exists is that in a typical implementation of radar system with a continually rotating antenna, it may be impossible to automatically control the active wave signal generation based on the antenna's real time bearing so as to control the active illumination of the radar wave. It is well known that standard radar sweeps enable listening stations to detect and calculate the exact location of a platform emitting radar waves, which is an undesirable effect when attempting to operate covertly. For example, surface-to-air missile operators have historically learned to turn off their radar when an anti-radiation missile was being fired at them, and turn it back on later. These operators have shut off the radar by hand, and thus reduced the amount of data the other party could acquire. These operators, however could not continue their mission while they were trying to remain stealthy.
In addition, it is well known that interference noise can be created when radar waves intersect signals from another sensor or device on the same structure to which the radar system is attached (or a sensor or device adjacent thereto).
Thus, there remains a need for a system and method which automatically activates and deactivates through a software application the emitted wave signals on a continuously rotating radar antenna based on the bearing of the antenna, thereby providing more stealth and enabling the concept of masking to reduce interference noise.
The present disclosure describes a system and method for automatic control of radar wave emissions from a rotating antenna based on the real time angular position of the rotating antenna. In accordance with one embodiment of the present disclosure, a method is provided for automatic control of radar wave emission from an antenna. The method includes: providing a radar system having a rotating antenna and a transmitter; receiving by a controller integrated with the radar system an encoder input which identifies a real time rotation angle of the rotating antenna; comparing the real time rotation angle of the rotating antenna to at least one of a desired target rotation angle and a target rotation angle range; and causing by the controller at least one of an active emission of electromagnetic waves from the rotating antenna to stop and an inactive emission of electromagnetic waves from the antenna to commence.
Applicant's invention described herein provides a method and system which enable the automatic activation and/or deactivation of the emission of radar wave signals from a radar system having a continuous rotating radar antenna. Current radar hardware usually spins continuously three hundred and sixty (360) degrees as it actively generates wave signals, which are large bursts of electromagnetic waves. There is currently no automatic method to turn the active radiation on and off at discrete angles for precise targeted detection. The instant invention allows for automatic activation and deactivation of the wave signals for sub-second intervals for specific discrete angles. This allows the radar to acquire information but still be stealthy.
Referring now to
The control switch 141 is operatively connected to the controller 140 so as to allow the controller 140 to send electrical signals to the control switch 141 which may be used by the control switch 141 as input signals. The controller 140 is also electrically connected to the rotary encoder 112 which is integrated with the shaft 111 of the antenna 110 and operative to convert the angular position or motion of the shaft 111, as a reflection of the rotation angle of the antenna, to an analog or digital signal. The controller 140 includes one or more software applications contained thereon or otherwise accessible thereto which enable it to compare the angular position of the shaft 111, as provided by the rotary encoder 112, to a reference angle or angle range that has been provided to or calculated by the controller 140, and, based on the comparison, send an electrical signal to the control switch 141 that causes the control switch 141 to close or open the connection between the transmitter 120 and the antenna 110. In this regard, the controller 140 is operative to control when and if the antenna 110 receives the alternating current from the transmitter 120 and thus produces radar waves.
Referring now to
If the angular position of the antenna is not equal to the target angle (or not within a target range), the controller again receives at step 220 an input from the rotary encoder which defines the real time angular position of antenna (provided the antenna is still rotating). When the antenna is no longer rotating, however, the process ends. It is contemplated that while the antenna is rotating, the controller will receive the real time angular position of antenna from the encoder in sub-second intervals.
In an embodiment of the process illustrated by
Referring now to
With the control switch now open, the controller again receives, at step 350, an input from the rotary encoder which defines the real time angular position of antenna and then determines, at step 360, if the angular position of the antenna has re-entered the target angle range. If so, the controller sends a signal, at step 370, to the control switch. The signal causes the control switch to close the electrical connection between the transmitter and antenna, and thus reactivate the antenna's generation of radar waves from the transmitter's alternating current. If not, the controller will continue to receive, at step 350, an input from the rotary encoder and determine, at step 360, if the angular position of the antenna has re-entered the target angle range.
If, at step 330, the angular position of the antenna is inside the target angle range, the controller again receives, at step 320, an input from the rotary encoder which defines the real time angular position of antenna (provided the antenna is still rotating). When the antenna is no longer rotating, however, the process ends. It is contemplated that while the antenna is rotating, the controller will receive the real time angular position of antenna from the encoder in sub-second intervals.
In an embodiment of the process illustrated by
Referring now to
It is contemplated that the calculation of the target angle range may be (1) performed in advance and based on a determination of which rotation angles of the antenna are directed into (or outside of) the target geospatial coordinates relative to a planned position and trajectory of the radar system, (2) performed in real time based on the target geospatial coordinates relative to a current position and trajectory of the radar system as determined by a geospatial positioning system, or (3) performed in advance with real time updates.
In one implementation, it is appreciated that the instant invention could be used in conjunction with the registration of radar returns and a priori coastlines, as described in U.S. Pat. No. 8,154,438, wherein only portions of the radar return are needed to perform accurate registration. The instant invention would allow the controller to determine the angles of active illumination needed for the registration algorithm and reduce the amount of active radiation on the rest of the coastline, thus preserving the possibility of radar detection by a receiver positioned on the coastline.
Another application would be to deactivate the radiation for the angles that are obstructed by other antennae or hardware on the same platform, to reduce noise levels in the returns of the proposed radar system as well as reduce noise in the returns of the obstructing sensors.
Yet another application is that the instant invention can be used to actively detect targets such as tracking an enemy contact for intelligence and reconnaissance or for determining relative position of other friendly vessels to be used for relative localization.
It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described and illustrated to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.
The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Research and Technical Applications, Space and Naval Warfare Systems Center, Pacific, Code 72120, San Diego, Calif. 92152; telephone (619) 553-5118; email: ssc_pac_t2@navy.mil. Reference Navy Case No. 103,512.
