Communications: radio wave antennas – Antennas – Body-attached or connected
Reexamination Certificate
2002-07-03
2004-08-03
Vannucci, James (Department: 2821)
Communications: radio wave antennas
Antennas
Body-attached or connected
C343S751000
Reexamination Certificate
active
06771224
ABSTRACT:
FIELD OF INVENTION
This invention relates to the determination of the existence and direction of incoming electromagnetic radiation, and, more particularly, to a body-worn system for pinpointing the source of such electromagnetic radiation.
BACKGROUND OF THE INVENTION
For police work and, indeed, for military purposes, is oftentimes required that the source of an electromagnetic radiation be detected so that appropriate police or military action can take place. The electromagnetic radiation can come from as diverse sources as cell phones, military radios or any of a wide variety of transmitters, which, in general, are mobile, the location of which is important to the authorities.
For instance, in a border patrol scenario, when border patrol agents are seeking to locate individuals seeking to cross a border, if they are communicating with electromagnetic radiation, it is important to be able to find the direction of the sources, if not to pinpoint the source of the electromagnetic radiation, and, thereby, catch the invading border crossers.
Likewise, in a military situation, it is often required to be able to locate the source of a particular communications signal and to do so by direction finding means. In general, more accurate direction finding provides a bearing line indicating the direction of the enemy triangulation using multiple direction finders. It is also important for accuracy to be able to have a number of different direction finding units in the field so that through triangulation, the direction finding results from each of the units in the field as to the source can be pinpointed. The more direction finding units, the lower the area of uncertainty. The area of uncertainty, amongst other things, is dependent upon the number of direction finding fixes that are made.
While direction finding apparatus has been used in the past from fixed locations or mobile vehicles, it is important to be able to provide such signal detection and source location determination at each police officer or soldier assuming each of the police officers or troops could be provided with a simple direction finding apparatus, the operation of which is transparent to the individual as he or she carries out his or her duties.
There is therefore a need for the ability to detect where a communication is coming from to pinpoint the sources of electromagnetic radiation, and to do so in the manner that does not impede or impair other functions of the police officers or troops as they carry out their assigned duties. It is also a requirement that it not be necessary for the police officers or the troops to have any active partcipation in the detection of and location of the incoming electromagnetic signals. In short, it is a requirement that the system be a completely automatic so that nothing carried by the police officer or the soldier needs to be activated or in any way interacted with during the course of the maneuvers for which the system was intended.
SUMMARY OF THE INVENTION
In order to find a portable direction finding receiver so that the direction of a source can be ascertained or so that multiple direction fixes may be used to pinpoint its location of a source, in the subject system, a plurality of direction finding antennas are embedded into a wearable garment, with the multiple antennas being arranged such that a direction finding algorithm based on their outputs can be used to determine the direction of an incoming electromagnetic signal so that the line of bearing to the source of the signal can be ascertained.
Just providing the general direction is extremely useful so that an individual can quickly determine the direction of the source. This is done by computing a bearing line and indicating the bearing line direction to the individual. This can be done simply with a series of vibrators embedded about the garment and by activating the vibrator which lays closest to the bearing line. Thus, a soldier can get a quick indication of where the enemy is.
Having numbers of such bearing lines from different individuals results in the ability to pinpoint the source of the incoming electromagnetic signal by triangulation.
For border patrol scenarios, this means being able to quickly find the direction of an individual making a wireless call and with a number of bearing lines to locate the individual with sufficient accuracy that they can be apprehended.
In addition to the direction finding apparatus, which is body-worn, in one embodiment a transmitter is also located within the wearable garment so that the results of the direction finding procedure can be transmitted to a central location where through the receipt of numbers of bearing lines, the precise location of the source can be calculated. For this purpose, both a GPS receiver and a compass are required for each individual.
It is obviously important to be able to detected and locate electromagnetic signals over a wide variety of frequencies. Since the frequency of the electromagnetic radiation is unknown, it is important to be able to provide wide-bandwidth antennas capable of detecting radiation from frequencies of 2 MHz to 40 GHz.
One type of wide-band width antenna particularly well-suited for this application is the meander line loaded antenna described in U.S. Pat. No. 6,323,814 issued to John Apostolos and incorporated herein by reference.
This antenna, in general, is comprised of two parallel plates connected together through a meander line, one purpose of which is to minimize the overall size of the antenna. As described in the above referenced patent, the meander line provides a series of delays through phase discontinuities such that the effective length of the antenna is increased over that which the physical size of the elements would dictate. One of the plates is a ground plane. However, when body-worn, the ground plane would pass through the body of the individual wearing the antennas. In one embodiment at a corresponding series of meander line loaded antennas are provided on the back of the vest, with the combined action of antennas on the front and back of the vest forming a virtual ground plane which runs through the individual's body where the real ground plane should go.
This means that effective broadband antennas can be brought down to a size that is wearable by an individual.
In one embodiment, as many as eight antennas are located on the body-worn garment, in one embodiment, a vest. An omni-directional mode is provided such that the presence of incoming electromagnetic radiation from any direction may be detected. The output pairs of antennas provide a so-called spigot, with omni-directional detection involving the spigots being fed in phase.
Once an incoming electromagnetic signal has been detected, direction finding analysis is conducted by sampling the spigots separately and proceeding with a correlation interferometric direction finding algorithm.
Knowing the geographical position and orientation of the antennas at any given moment in time through the utilization of a compass and a GPS receiver, the line of bearing from a precise point may be ascertained relative to magnetic north. With a number of transmissions of bearing lines from a number of locations to a central location the source of the electromagnetic radiation can be pinpointed.
The system is designed to operate whether the individual is standing upright or is lying on the ground, as would be the case during a military or border patrol operation. This is accomplished by processing the outputs of different pairs of antennas, whether the individual is standing up or is prone is determined by a sensor so that processing can be switched from the standing mode to the prone mode.
In one embodiment, the individual wearing the vest is unaware of the detection of incoming signals, or, in fact, the transmission of a bearing line, with the detection and direction finding being transparent to the individual as he or she goes about his or her duties. Alternatively, the individual can be immediately alerted as to the existence of a transmission and the direction
BAE Systems Information and Electronic Systems Integration Inc.
Long Daniel J.
Tendler Robert K.
Vannucci James
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