Patent Publication Number: US-2007124824-A1

Title: System and method for geolocation by a distributed network of geolocation equipment

Description:
FIELD OF THE INVENTION  
      This invention generally relates to geolocation equipment, and relates more particularly to a system and method for distributed networking of geolocation equipment.  
     BACKGROUND  
      Geolocation involves the process of identifying the location of an unknown radio transmitter on Earth using space-based satellites and Earth-based receiving stations. Geolocation is frequently used to locate emergency signals transmitted by ships or airplanes. Geolocation has also been employed to identify the location of unknown transmitters on Earth emitting signals interfering with satellite communications. The signal from the unknown transmitter is detected by at least two geostationary satellites. The satellites retransmit the unknown signal to a receiver at a known location. Since the unknown signal travels along different paths to the satellites, the retransmitted unknown signals arrive at the known receiver at different times. Geolocation uses this time delay and other measurements to determine the location of the unknown transmitter.  
      A prior art system for geolocation is shown in  FIG. 1 . Geostationary satellites  132  and  134  receive signal from an unknown transmitter  122  on the Earth  100  via signals paths  124  and  126 . Satellites  132  and  134  retransmit the received signals. The retransmitted signals are received at antennas  142   a  and  142   b . Antenna  142   a  is aimed at satellite  132  and thus receives the signal retransmitted by satellite  132  via signal path  144 . Antenna  142   b  is aimed at satellite  134  and thus receives the signal retransmitted by satellite  134  via signal path  146 . Thus antenna  142   a  and antenna  142   b  receive the signal transmitted by unknown transmitter  122  via two different paths. Antennas  142   a  and  142   b  thus receive the signal from the unknown transmitter at two different times. Antennas  142   a  and  142   b  are coupled to geolocation equipment  148 , which uses the time difference of the signals received by antennas  142   a  and  142   b  and other measurements to determine the location of unknown transmitter  122 . Examples of systems and methods for geolocation using a single installation of geolocation equipment are disclosed in U.S. Pat. No. 5,008,679 to Effland et al. and  Geolocation of a Known Altitude Object from TDOA and FDOA Measurements,  by K. C. Ho et al., IEEE Transactions on Aerospace and Electronic Systems, Vol. 33, No. 3, July 1997, pp. 770-783.  
      The satellite communications industry is experiencing a surge in demand for accurate, reliable, inexpensive, and flexible geolocation services. A number of factors are causing this increase in demand. First, the global demand for satellite-based communications is growing at a rapid pace. Coupled with the increase in the demand for satellite-based communications is the increase in the various ancillary services supporting satellite communications, including geolocation. Second, due to numerous technological advancements, the price for powerful ground-based transmitters has decreased markedly in recent years. As a result, the number and distribution of such ground-based transmitters has increased dramatically. Each ground-based transmitter has the capability and potential to transmit an interfering signal that needs to be geolocated. The global war on terror is also playing a role in the demand for geolocation services.  
      The prohibitive cost of geolocation equipment is a significant issue and weighs heavily against the growing demand for geolocation services. Geolocation equipment is highly complex and difficult to manufacture. As a result, each installation of geolocation equipment is extremely expensive, sometimes running as high as a million dollars per installation.  
      A customer in need of geolocation services gains access to such services typically in one of two ways. The customer may decide that its need for geolocation services is sufficiently great to warrant paying the substantial cost of the geolocation equipment. In this instance, the customer will purchase one or more installations of an entire geolocation system from a geolocation equipment manufacturer. At that point, as the owner of the geolocation system, the customer can geolocate with its purchased geolocation system without restriction. The obvious downside to this scenario is the substantial cost of the geolocation system.  
      Alternatively, the customer for geolocation services may determine that its need for geolocation services does not warrant purchasing an entire geolocation system. In this case, the customer will seek out the services of a geolocation service provider. A geolocation service provider typically owns and operates a geolocation system. The geolocation service provider sells geolocation services on an as-needed basis to any customer in need of geolocation services. There is a number of disadvantages associated with the use of a conventional geolocation service provider. First, the cost of purchasing geolocation services from a conventional geolocation service provider is still extremely expensive when considered in context. In addition, geolocation service providers typically charge the customer whether or not the attempt to geolocate was successful. Thus, a customer can make a significant expenditure on geolocation services and walk away without the geolocation information sought. Finally, because the geolocation service provider relies on its own installations of geolocation equipment, its ability to effectively geolocate is limited by the quality and location of its geolocation systems.  
      Therefore, there is a need for a system and method for geolocation that provides accurate, reliable, inexpensive, and flexible geolocation services.  
     SUMMARY  
      It is an advantage of the present invention to widely distribute and interconnect a plurality of individual installations of geolocation equipment so that geolocation services can be provided accurately on a global basis.  
      It is another advantage of the present invention to allow a geolocation service provider access to a plurality of individual installations of geolocation equipment over a network.  
      It is another advantage of the present invention to allow dynamic assignment of geolocation equipment over a network to perform specific geolocation services.  
      It is another advantage of the present invention to lower the cost of providing geolocation services to customers without degrading the quality of the provided services.  
      It is another advantage of the present invention to decrease the failure rate of any specific geolocation to allow the geolocation service provider to charge for geolocation services only when a search has been successful and not charge when the search is unsuccessful.  
      These and other advantages are achieved by the present invention. In accordance with one embodiment of the invention, a system for geolocation using a distributed network of geolocation equipment is provided, including a plurality of sites having geolocation equipment, each instance of geolocation equipment being coupled to a network, and a geolocation network controller operated by a service provider coupled to the network. Each instance of geolocation equipment is configured to both operate independently and operate as part of the network of geolocation equipment. In exchange for ownership and use of geolocation equipment provided by the service provider, a customer allows the service provider to access the geolocation equipment over the network for use in locating unknown transmitters. The service provider uses the distributed network of geolocation equipment to provide geolocation services to customers that do not have their own geolocation equipment, or to customers who have their own geolocation equipment but elect to engage the service provider to locate an unknown transmitter.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagram of a prior art system for geolocation;  
       FIG. 2  is a block diagram of one embodiment of a distributed network of geolocation equipment, in accordance with the invention;  
       FIG. 3  is a block diagram of a preferred embodiment of a distributed network of geolocation equipment, in accordance with the invention; and  
       FIG. 4  is a flowchart of method steps for providing geolocation services using a distributed network of geolocation equipment, in accordance with one embodiment of the invention.  
    
    
     DETAILED DESCRIPTION  
      The present invention will now be described with reference to  FIGS. 2-4  which in embodiments relate to a system and method for geolocation using a distributed network of geolocation equipment. It is understood that the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art. Indeed, the invention is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to those of ordinary skill in the art that the present invention may be practiced without such specific details.  
      The present invention contemplates establishing a large number of interconnected installations of geolocation equipment widely dispersed throughout the globe. The plurality of installations of geolocation equipment would be interconnected over a wide area network and accessible remotely by a geolocation service provider. To achieve this system in a cost effective manner, the present invention changes the manner in which geolocation equipment is provided to customers of geolocation services. Rather than selling geolocation equipment to the customers of geolocation services at the fair market value of the geolocation equipment, the geolocation equipment is provided to customers at a significantly reduced cost or even for free. At such a reduced cost, it is felt that the demand for geolocation equipment will increase significantly, thereby causing increased sales of geolocation equipment throughout the globe.  
      In exchange for providing the geolocation equipment at the significantly reduced cost, the equipment manufacturer or its agent would negotiate with the customers of the geolocation equipment the right to connect to the geolocation equipment through a network and the right to use the geolocation equipment over the network. Thus would be established the large number of interconnected installations of geolocation equipment widely dispersed throughout the globe. The equipment manufacturer or its agent can then use its access to the globally dispersed network of geolocation equipment to sell highly accurate, reliable, inexpensive, and flexible geolocation services.  
       FIG. 2  is a diagram of one embodiment of a distributed network of geolocation equipment according to the present invention. The distributed network includes, but is not limited to, a geolocation service provider  210 , a communication network  214 , and geolocation sites  220 ,  222 , and  224 . Geolocation service provider  210  includes, but is not limited to, a geolocation network controller  212 . Each geolocation site  220 ,  222 , and  224  includes, but is not limited to, geolocation equipment  234 . Each instance of geolocation equipment  234  is coupled to network  214  and is configured to communicate with geolocation network controller  212 . Network  214  may be implemented as any type of electronic network, for example a local area network, a wide area network, a wireless network, a virtual private network, the Internet, or a combination of any of these types of networks. Geolocation equipment  234  is coupled to at least two antennas for receiving signals from geostationary satellites, and includes hardware and software to perform geolocation methods to locate an unknown transmitter. Each instance of geolocation equipment  234  is configured to operate independently and to operate as part of a distributed network of geolocation equipment  234  to locate unknown transmitters. Although only three geolocation sites are shown in  FIG. 2 , any number of geolocation sites including geolocation equipment  234  is within the scope of the invention.  
      Geolocation service provider  210  can provide geolocation services by accessing geolocation equipment  234  via network  214  using geolocation network controller  212 . Geolocation network controller  212  is configured to access and operate geolocation equipment  234  over network  214 . Geolocation network controller  212  is able to select one or more of geolocation sites  220 ,  222 , or  224  that will provide the best performance for the requested geolocation service, and to control the operation of the selected geolocation equipment  234  via network  214 .  
      Each instance of geolocation equipment  234  is controlled by an operator (an individual or legal entity) other than geolocation service provider  210 . In one embodiment, the operators of geolocation sites  220 ,  222 , and  224  purchase, lease, or otherwise obtain control over an instance of geolocation equipment  234  from a vendor of geolocation equipment. The vendor of geolocation equipment may be geolocation service provider  210  or some other party. Each operator of geolocation sites  220 ,  222 , and  224  enters into an access agreement with geolocation service provider  210  in which geolocation service provider  210  is allowed to access and operate geolocation equipment  234  via network  214  while the operator maintains some control over operating geolocation equipment  234 .  
      In one embodiment, geolocation service provider  210  provides geolocation equipment  234  to the operators of geolocation sites  220 ,  222 , and  224  at a less than fair market price. For example, geolocation service provider  210  may provide geolocation equipment  234  to the operators of geolocation sites  220 ,  222 , and  224  at 100%, 50%, or 25% of the cost of geolocation equipment  234  or for free. In consideration of receiving geolocation equipment  234  at a less than fair market price, each of the operators of geolocation sites  220 ,  222 , and  224  enters into an access agreement with geolocation service provider  210  that allows geolocation network controller  212  to access and operate geolocation equipment  234  via network  214  for little or no cost, while each operator maintains some control over geolocation equipment  234 .  
      In one embodiment, the access agreement between geolocation service provider  210  and each of the operators of geolocation sites  220 ,  222 , and  224  allows geolocation network controller  212  to access and operate geolocation equipment  234  at specified times for a specified duration. For example, an access agreement between geolocation service provider  210  and the operator of geolocation site  220  allows geolocation network controller  212  to access and operate geolocation equipment  234  every day at 6:00 am and 6:00 pm for a period of 1 hour.  
      In another embodiment, the access agreement between geolocation service provider  210  and each of the operators of geolocation sites  220 ,  222 , and  224  allows geolocation network controller  212  to access and operate geolocation equipment  234  for a specified amount of time over a certain number of days. For example, an access agreement between geolocation service provider  210  and the operator of geolocation site  222  allows geolocation network controller  212  to access and operate geolocation equipment  234  at any time for a total of  12  hours every month.. Alternatively, geolocation network controller  212  may be allowed to access and operate geolocation equipment  234  for a total of  5  hours every week.  
      In another embodiment, the access agreement between geolocation service provider  210  and each of the operators of geolocation sites  220 ,  222 , and  224  allows geolocation network controller  212  to access and operate geolocation equipment  234  only after approval of a request for access. For example, the access agreement between geolocation service provider  210  and the operator of geolocation site  224  requires geolocation network controller  212  to send a request for access to geolocation site  224  and the request to be approved by geolocation site  224  before geolocation network controller  212  is allowed to access and operate geolocation equipment  234 . The request for access may be sent via network  214  to geolocation equipment  234 , which is configured to determine whether to approve or reject the request based on a set of criteria. In one embodiment, this set of criteria includes a current load on geolocation equipment  234  and network congestion.  
      Geolocation service provider  210  may have a different type of access agreement with each of the operators of geolocation sites  220 ,  222 , and  224  or may have a standard access agreement that it enters into with all operators of geolocation sites  220 ,  222 ,  224 . The type of access agreement may depend on whether the operators of geolocation sites  220 ,  222 , and  224  obtained geolocation equipment  234  from geolocation service provider  210  or some other vendor.  
       FIG. 3  is a block diagram of a preferred embodiment of the distributed network of geolocation equipment, in accordance with the invention. Geolocation service provider  310  is a vendor of satellite monitoring equipment  332  and geolocation equipment  234 . Each instance of satellite monitoring equipment  332  is configured to monitor satellites affiliated with each of geolocation sites  220 ,  222 , and  224 . Geolocation service provider  310  sells satellite monitoring equipment  332  to the operators of geolocation sites  220 ,  222 , and  224  for a fair market price. Geolocation service provider  310  also provides geolocation equipment  234  to the operators of geolocation sites  220 ,  222 , and  224 , but at a less than fair market price. For example, geolocation service provider  310  may provide geolocation equipment  234  to purchasers of satellite monitoring equipment  332  at 100%, 50%, or 25% of the cost of geolocation equipment  234  or for free. In consideration of receiving geolocation equipment  234  for less than the fair market price, each of the operators of geolocation sites  220 ,  222 , and  224  enters into an access agreement with geolocation service provider  310  that allows geolocation network controller  212  to access and operate geolocation equipment  234  via network  214 , while each operator maintains some control over geolocation equipment  234 . Geolocation service provider  310  can utilize the distributed network of geolocation equipment  234  to provide geolocation services to other customers, particularly customers that do not have their own geolocation equipment. Geolocation network controller  212  can access and operate any one or more of instances of geolocation equipment  234  to provide geolocation services to other customers, who may or may not have their own geolocation equipment. Geolocation network controller can select the geolocation equipment  234  that will provide the best results for geolocation of an unknown transmitter.  
       FIG. 4  is a flowchart of method steps for providing geolocation services using a distributed network of geolocation equipment, in accordance with one embodiment of the invention. In step  410 , geolocation service provider  210  receives a geolocation service request to locate an unknown transmitter somewhere on the Earth. In one embodiment, the service requestor is an entity that does not have its own geolocation equipment. In step  412 , geolocation network controller  212  performs a procedure to select one or more geolocation sites in a distributed network of geolocation equipment that provide the best fit for the service request. In step  414 , geolocation network controller  212  sends a request for access to each of the selected geolocation sites. In step  416 , geolocation network controller  212  determines if each geolocation site accepts or rejects the request for access. If the geolocation site accepts the request for access, the method continues with step  418 . If the geolocation site refuses the request for access, the method returns to step  412  where geolocation network controller  212  notes that the refusing geolocation site is not available, and re-selects one or more geolocation sites.  
      In step  418 , geolocation network controller  212  gains operational control over the one or more geolocation sites that accepted the request for access, and performs the requested geolocation service. In step  420 , geolocation network controller  212  determines whether the unknown transmitter (TX) has been located. If the unknown transmitter has been located, then in step  422  geolocation service provider  210  provides the location of the unknown transmitter to the service requester. If the unknown transmitter has not been located, then the method returns to step  412  where geolocation network controller  212  notes that the previously selected geolocation sites did not provide the requested location, and re-selects one or more geolocation sites.  
      Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically-disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed system and method. Thus, it is intended that the scope of the present invention should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.