Methods for detecting, computing and disseminating location information associated with emergency 911 wireless transmissions

• US 6,934,548 B1
• Filed: 08/10/2001
• Issued: 08/23/2005
• Est. Priority Date: 08/10/2001
• Status: Expired due to Fees

• Current Assignee: Tarsus Trust Company Limited
• Original Assignee: Tarsus Trust Company Limited
• Inventors: Gould, Lawrence A., Stangle, John A.
• Primary Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US09/927,992
• Time in Patent Office: 1,474 Days
• Field of Search: 455/404.1, 455/404.2, 455/414.2, 455/439, 4554561-457, 455/521, 370/310.2, 370/331, 342/357.01, 342/357.07, 342/357.08, 342/367, 701/207, 701/213, 701/214
• US Class Current: 455/456.1
• CPC Class Codes: G01S 2205/006 for emergency situations
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

Systems and methods to determine the location information of an emergency call made from a radiotelephone. The system employs multiple radio direction finding (RDF) devices, which is capable of determining the angle of arrival of a radio signal. The MSC sends a request along with radio information to a location processor, which controls RDF devices. The location processor sets up each RDF device to track the radio signal. If at least two RDF devices are successful in tracking the radio signals and returning information about the radio signal, then the location processor can determine the location of the radiotelephone by using a triangulation method.

Claims

1. A method for determining the location of a radio telephone device, said method comprising the steps of:

uniquely assigning a certain destination telephone number to a particular predetermined public safety answering point;

receiving a telephone call from said radiotelephone, said telephone call being directed to and uniquely identifying said destination telephone number;

identifying said destination telephone number from said received telephone call;

providing a first and a second radio finding device;

only after identifying said destination telephone number, causing said first and second radio finding devices to attempt to respectively determine the location of said radiotelephone device by use of signal angle information and, upon respectively determining said location, respectively providing location information;

determining whether both said first and said second radio finding devices respectively provided location information;

determining said location of said radiotelephone device only if said first and said second radio finding devices each respectively generate location information; and

communicating said determined location to said public safety answering point.

2. A method for determining the location of a radiotelephone device, said method comprising the steps of:

uniquely assigning a certain destination telephone number to a particular predefined public safety answering point;

receiving a telephone call from said radio telephone, said telephone call being directed to said destination telephone number;

identifying said destination telephone number from said received telephone call;

providing at least three radio finding devices;

only after identifying said destination telephone number, causing said at least three radio finding devices to attempt to respectively determine the location of said radiotelephone device by use of angle information and, upon respectively determining said location, respectively providing location information;

determining whether at least two of said radio finding devices have respectively provided location information;

determining said location of said radio telephone device only if at least two of said at least there radio finding devices have respectively provided location information;

identifying each of said radio finding devices which have respectively provided location information;

creating unique pairs of said radio finding devices which have respectively provided location information;

using a triangulation process on the respectively generated location information from each of said created unique pairs of said radio finding devices, thereby creating a single location for each of said unique pairs of said radio finding devices;

fitting each single location for each of said unique pairs of said radio finding devices, thereby calculating said location of said radio telephone device; and

communicating said calculated location to said particular predefined public safety answering point.

3. A method for determining the location of a radiotelephone device, said method comprising the steps of:

uniquely assigning a certain destination telephone member to a particular predefined public safety answering point;

receiving a telephone call from said radio telephone, said telephone call being directed to said destination telephone number,

identifying said destination telephone number from said received telephone call;

providing at least three radio funding devices;

only after identifying said destination telephone member, causing said at least three radio finding devices to attempt to respectively determinate the location of said radiotelephone device by use of angle information and, upon respectively determining said location, respectively providing location information only if the respective signal angle information is greater than zero degrees;

determining whether at least two of said three radio finding devices have respectively provided location information;

determining said location of said radio telephone device only if at least two of said at least three radio finding devices have respectively provided location information;

creating unique pairs of said radio finding devices which have respectively provided location information;

for each of said unique pairs of radio finding devices, using a triangulation process to create a single location for each of said unique pairs of radio frequency devices, wherein said triangulation process uses the distance between said unique pair of radio frequency devices and the distance between one of said pair of radiofrequency devices and the particular predefined public safety answering point to provide the single location for said unique pair of radio frequency devices;

determining whether one of said single locations is far from the other locations;

discarding said one of said single locations only of said one of said single locations is for from the other locations;

fitting all remaining locations to calculate a location of said radiotelephone device; and

communicating said calculated location of said radiotelephone device to said particular predefined public safety answering point.