Methods for detecting, computing and disseminating location information of weapons of mass destruction

The present invention relates systems and methods to determine the location information of a signal made from a radioactive device or hazardous material. The system employs multiple radiation sensor devices, which his capable of determining the signal strength and the angle of arrival of a radioactive signal. The mobile switching center sends a request along with radiation information to a location processor, which controls devices. The location processor sets up each sensor device to track the radiation signal. If at least two devices are successful in tracking the radioactive signals and returning information about the radiation signal, then the location processor can determine the location of the radioactive device or hazardous material by using a triangulation method.

TECHNICAL FIELD

This invention is related to the field of radiological detection, particularly to nuclear weapons of mass destruction and hazardous material waste, and more particularly to locating a radioactive device within the coverage area of a radiotelephony system.

BACKGROUND OF THE INVENTION

The advent of mobile communication technology has led to the proliferation of radiotelephones (also known as wireless telephone). Now, a person can carry with them a radiotelephone anywhere they go. A person can make a telephone call from almost anywhere to another person and can also receive a telephone call from anywhere.

Radiotelephones are generally linked to the Public Switched Telephone Network (PSTN) through a network of antennas, base stations, and mobile switching centers. Each radiotelephone is in communication with at least one antenna and switches from one antenna to another when it moves from one antenna cell to another antenna cell. This “cellular” infrastructure will be utilized for my invention to transmit the sensors information through the PSTN switching centers, to the processing centers.

My technique, based upon signal (radiation) strength and trilaterialization can be employed, but they are generally effective in line-of-sight conditions, such as rural settings.

In dense urban areas, radioactive waves reflect on buildings before reaching a receiving antenna on a mobile device, and the mobile device receives radioactive signals both directly from an emitting antenna and from reflections. This phenomenon is known as multipath signals, and it is well known in the wireless telephony art. The multipath phenomenon renders most analytical location computational techniques such as time-of-arrival (TOA) or time-difference-of-arrival (TDOA) substantially useless in urban areas. Radiation (different frequencies) may have the same characteristics.

SUMMARY OF THE INVENTION

Briefly described, the present invention is a system and method for determining the geographical position of a nuclear weapon of mass destruction and hazardous radioactive material wastes within a radiotelephony system. A system according to the present invention employs multiple sensor devices in multiple wireless transmission tower sites, one or more (directional sensors mounted to each of the three faces of a cellular antenna array) devices per each transmission tower site. The devices are connected to a signal strength location processor, where the position calculations are performed. The location processor is in communication with a Mobile Switching Center (MSC).

An emitter (radiological source) is tracked by a system according to the present invention, and its position is determined by a method disclosed in the present invention. When an emitter is received by a sensor at a wireless transmission tower and sent to a base station (BS), the BS forwards the information to a mobile switching center (MSC), where it is interpreted. The MSC alerts a location processor to determine the physical location. The MSC also proceeds to forward the information to a PSAP (Public Safety Answering Point).

The location processor is a processor that controls a plurality of devices and determines the location of a radioactive signal's source. The location processor obtains the radioactive signal's information from the MSC and sends this information to the devices. Each device attempts to determine the signal strength of radioactive signals relative to the position of the device. Preferably, two or more sensor devices can determine the angles of arrival. This information is sent to the location processor.

The location processor uses the signal strength and angle of arrival information and the information on the location of sendor devices to calculate the geographical coordinates of the source of radioactive signal. The geographical coordinates calculated are then used to determine the street address of the emitter.

If more than two sensor devices detect the radioactive signal, the location processor will determine several pairs of geographical coordinates by pairing devices differently. From these pairs of geographical coordinates the location processor will select a best fit set and use it to determine the location of the source of the radioactive signal.

If only one tower sensor device detects the radioactive signal, then the angle of arrival (multiple sensors on each of the three faces at a single site) is provided to the MSC and the location processor does not calculate the location of the radioactive signal's source.

DETAIL DESCRIPTION OF THE INVENTION

Referring now in greater detail to the drawings, in which like numerals represent like components throughout several views,FIG. 1depicts architecture of a wireless communication network10. The wireless communication network10has a plurality of communication towers12, also known as wireless transmission towers, connected to a base station (BS)14. The wireless transmission towers12are distributed geographically to cover a wide area, and each tower12typically covers a “cell.” A BS14may support one or more transmission towers12and are in communication with a MSC16. A MSC16may support several BS′14.

The MSC16performs call-processing function for the wireless communication system10. The MSC16routes a call from a mobile device or a radiotelephone22to its destination. The call routing may be through a Public Switched Telephone Network (PSTN)18. If an emitter is received by a transmission tower12and forwarded by a BS to the MSC16. The MSC16routes the information through the PSTN to a 911 Dispatching Center or a Public Safety Answering Point (PSAP)20.

Typically, an operator at PSAP20needs to know the location of the emitter in order to dispatch emergency service personnel to the location, if needed. Dispatching of emergency service vehicles may be delayed or impossible, unless the wireless communication network10is equipped with location finding devices.

A device installed on a wireless transmission tower12can provide information about the signal strength and the angle of arrival of a radioactive signal. The present invention employs a commercially available radioactive detection device.

FIG. 2is an illustration of a device30installed on a wireless transmission tower12. Generally, one device30is installed to one wireless transmission tower12. A device30typically has a set of sensors32connected to a receiver34and controlled by a processor36. The device30tries to determine the angle of arrival of a radioactive signal by sequentially sampling the radioactive signals through each of the sensors32attached to the receiver34. The receiver34samples the signals received before sending them to the processor36for processing. The processor36processes the signal received and attempts to determine the angle of arrival of the signal received. The processor36controls the sampling of radioactive signals by the sensors32and determines which radioactive type to sample.

In an alternate embodiment, the receiver34and the processor36may be enclosed in one physical unit, i.e., the receiver34and the processor36may be different circuits of a single device.

Generally, the processor36is in communication with a location processor38. The location processor38preferably is connected to and receives information from multiple devices30. The location processor38is also connected to a MSC16. The location processor38receives radioactive signal information, such as radioactive type used (type of radiation), etc., about the notification from the MSC16.

The location processor38transmits the radioactive signal information to multiple devices30, so each device30can attempt to track this radioactive signal. It is preferred if the radioactive signal from an emitter can be tracked by more than one device30. Each device30provides a unique angle of arrival information, which when combined with the information from other devices30allows calculation of the physical location of the transmitting device.

FIG. 3is a block diagram of a location calculation process40performed by a location processor38. The process starts when the location processor38receives from MSC16information about the radioactive signal of an emitter, block42. The location processor38sends this information to devices30and requests the devices to scan for the radioactive signal of this emitter, block43. Each device30scans for the radioactive signal and attempts to determine the signal strength and the angle of arrival of the radioactive signal. After determining the signal strength and the angle of arrival, the devices30send this information to a location processor38.

When a location processor38receives information, it checks whether the information is from more than two devices30, block44, i.e., whether the radioactive signal has been “tracked” or “detected” by two or more wireless transmission towers12. If more than two towers12receive the radioactive signal, they are paired and indexed, block46. The towers12are paired because the calculation process, which uses a triangulation method, requires information from two towers. The towers are paired between them in such a way that three towers, A, B, and C will yield to three pairs of towers, AB, BC, and AC.

After the towers12are paired and indexed, the location processor38selects one pair for calculation, block50. The geographical parameters of each tower are stored in a database accessible to the location processor38. The geographical parameters include, but not limited to, longitude and latitude of each tower and the distance between the towers. The geographical parameters are used for the triangulation calculation, block52.

After the calculation, the result is stored, block54, and the location processor38checks whether there are more tower pairs to be calculated, block56. If there are additional pairs, then blocks50,52, and54are repeated until all pairs are used for the calculation. The result of the triangulation calculation is a pair of geographical coordinates of the source of the radioactive signal, i.e., the source's longitude and latitude.

After all pairs have been used for the calculation and all results stored, the location processor38proceeds to select the “best fit” of geographical coordinates, block58. The best fit of geographical coordinates may be determined by a simple average of coordinates or by a weighted average taking into account any obvious anomalies in location information. If one coordinate is far afield from the others, it may be due to an equipment malfunction and this should be considered and compensated. Other statistical models may also be used to determine the best fit.

The best fit is recorded, presumed to be accurate, and used to determine the street address. The best fit of geographical latitude and longitude is translated into street or highway addresses that are meaningful to the authorities at the PSAP, block60. This translation may be performed employing commercially available software and database, such as MAPINFO.

Finally, the street address is transmitted back to the PSAP, block62, together with other information associated with this data.

Back to block44, if the information on the radioactive signal is not received by more than two towers, it is checked whether only one tower received the information, block64. If only one tower received the information, then the triangulation method cannot be used and the location of the origin of the radioactive signal cannot be determined.

If two towers receive the information, then the triangulation method applies only to this pair of tower, block68. The result of the triangulation calculation is used to determine the street address, block60, and the street address is transmitted to the PSAP, block62.

FIG. 4illustrates the triangulation calculation process80. The process starts when the geographical parameters and information are received, block82. The triangulation process calculates the angle between the source and the towers, block84. A check is made to determine whether the angle calculated is less than one degree, block86. If the angle is less than one degree, it means that the source lies on the line between two towers and the triangulation method will not give accurate results. If the angle is one degree or more, then the location processor38can determine the distance from one tower to the emitter source, block88. Using the distance between a tower and the source, the location processor38can determine the geographical coordinates for the source, block90.

FIG. 5illustrates the triangulation method. The triangulation method assumes that the position of two points and the distance between them are known. The angular information about the third point is also known. The angular information is derived from the angle of arrival information provided by each device.

Equation 1 uses the distance between the two towers and the angular information from two devices to calculate distance v1, which is the distance from a first tower to point d1. d1is a point demarked by a perpendicular line between the emitter source and the line connecting the two towers.

Equation 2 uses v1to calculate the distance between the first tower and the emitter source.

After the distance between the first tower and the emitter source is calculated, the source's latitude and longitude can be easily determined using Equations 3 and 4.

In operation, when a radioactive signal is received from an emitter source,22, the radiation is received by a wireless transmission tower12, which is connected to a base station14. The base station14forwards the information to a MSC16, which attempts to route the data.

The MSC16routes the data to the PSAP20and sends a request to locate the emitter source to a location processor38. The MSC also sends radioactive signal information to the location processor38.

The location processor38sends the radioactive signal information to all devices30. Generally, one device30is attached to each wireless transmission tower12. The processor36of the device30sets-up the sensors32to tune-in to the radioactive signal and samples sequentially all the sensors32. Each device30will return information on the angle of arrival of the radioactive signal, if it is successful in locating the radioactive signal. The device30sends the results back to the location processor38.

The location processor38can determine the location of an emitter source if the location processor38receives the angle of arrival information from at least two devices30. If the location processor38receives the information from more than two devices30, then the location results can be analyzed and a “best fit” result selected.

The location processor38can easily translate the location information, which is expressed as longitude and latitude, into a street address through use of a commercial software or database. The street address is then transmitted to the MSC16, which in turn sends it to the PSAP20.

The foregoing description of preferred embodiments of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to explain the principles of the invention and their practical application to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated.