1. A method for locating a source of a radio frequency emission, the method comprising the steps of:
receiving the radio frequency emission with at least two receivers;
recording data from the received radio frequency emission from at least two receiving points during at least one time interval;
recording positional data for at least one receiver;
tagging the recorded data of the radio frequency emission and the positional data whereby a proximate position of the at least one receiver at the time the radio frequency signal was recorded is determinable;
transmitting the tagged data to a processing unit;
defining a search grid within which to search for the source of the radio frequency emission, wherein the search grid comprises a plurality of grid points;
motion compensating the tagged data, thereby creating motion compensated data;
assigning a value to each grid point based on a relative phase coherence of the motion compensated data for each time interval; and
determining a location within the search grid having a highest assigned value, thereby determining the source of the radio frequency emission.
2. The method of claim 1, wherein the step of motion compensating further comprises modifying a phase of the tagged data based on the positional data of the receiver relative to each grid point, wherein the step of motion compensating is separately performed for each grid point, thereby creating motion compensated data;
3. The method of claim 1, wherein the step of recording data further comprises recording data from a plurality of time intervals, wherein the step of motion compensating the recorded data further comprises motion compensating the recorded data for each time interval and summing the relative phase coherence for each grid point to create the value assigned to each grid point.
4. The method of claim 1, further comprising filtering out a portion of the received radio frequency emission.
5. The method of claim 4, wherein the step of filtering further comprises filtering out specific radio frequencies from the received radio frequency emission.
6. The method of claim 4, wherein the step of filtering further comprises filtering out at least a portion of at least one time interval, thereby limiting the received data to be motion processed.
7. The method of claim 1, wherein the time interval is approximately two seconds.
8. The method of claim 1, wherein the step of determining the location further comprises identifying a grouping of grid points that have the highest assigned values, thereby determining the source of the radio frequency emission.
9. The method of claim 1, wherein the step of motion compensating further comprises:
identifying a first data signal from a stationary receiver of the at least two receivers and a second data signal from a moving receiver of the at least two receivers;
multiplying the first data signal and the second data signal to create an intermediate product signal; and
multiplying the intermediate product signal by a set of quantized complex chirp waveforms to create de-chirped product signals;
calculating the Fourier coefficients of the de-chirped product signals to create coherent integration interval magnitudes.
10. The method of claim 9, wherein the step of assigning a value to each grid point further comprises assigning coherent integration interval magnitudes to each grid point.
11. The method of claim 9, wherein the step of defining a search grid further comprises mapping the search grid to a new coordinate system defined by motion of the moving receiver.
12. The method of claim 9, wherein the step of motion compensating is performed for at least a first time interval and a second time interval wherein a first motion of the moving receiver during the first time interval is non-colinear with respect to a second motion of the moving receiver during the second time interval.
13. A system for locating a source of a radio frequency emission, the system comprising:
means for receiving the radio frequency emission from at least two separate locations at least partially contemporaneously;
means for recording data from the received radio frequency emission during at least one time interval;
means for defining a plurality of grid points within which to search for the source of the radio frequency emission;
means for motion compensating the data relative to each grid point, thereby creating motion compensated data;
means for assigning a value to each grid point based on the motion compensated data for each time interval; and
means for identifying a grouping of grid points that have the highest assigned values, thereby determining the source of the radio frequency emission.
14. The system of claim 13, further comprising means for filtering out a portion of the received radio frequency emission.
15. The system of claim 13, wherein the means for recording data further comprises means for recording data from a plurality of time intervals, wherein the means for motion compensating the recorded data further comprises means for motion compensating the recorded data for each time interval and means for summing the motion compensated data to create the value assigned to each grid point.
16. The system of claim 13, wherein the means for defining a plurality of grid points further comprises means for confining the plurality of grid points substantially to a plane approximately coincident with the Earth’s surface.
17. A radio frequency emission source locator, comprising:
at least two receiver sets, each receiver set comprising:
an antenna capable of receiving radio frequency emissions;
a radio frequency downconverter;
an analogdigital signal converter; and
a position-indicating unit;
a data processor in communication with the receiver sets wherein the data processor receives down converted radio frequency data from at least one signal received by each of the antennas and position-indicating unit data from each receiver set and wherein the data processor combines the down converted radio frequency data and the position-indicating unit data to create tagged data;
a data storage unit in communication with the data processor, the data storage unit capable of at least storing tagged data; and
a processing unit capable of processing the tagged data, the processing unit capable of:
defining a search grid within which to search for the source of the radio frequency emission, wherein the search grid comprises a plurality of grid points;
motion compensating the tagged data relative to each grid point, wherein motion compensation is performed to achieve a separate value for each grid point;
assigning the value to each grid point based on a phase coherence of the motion compensated data; and
determining a location within the search grid having a highest assigned value, thereby determining the source of the radio frequency emission.
18. The locator of claim 17, wherein the processing unit is further capable of filtering the tagged data.
19. The locator of claim 17, wherein the tagged data further comprises time data associated with a time the signal is received by the antenna.
20. The locator of claim 17, wherein the two receiver sets further comprise at least one mobile receiver set and at least one stationary receiver set.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method, comprising maintaining a continuous connection for the transmission of audiovisual content on demand between at least two end points on a packet-based network.
2. The method of claim 1, further comprising:
setting up at least one communication link between a plurality of end points connected to the network;
maintaining the communication link on a continuous basis for the transmission of content instantly on demand between end points.
3. The method of claim 1, wherein the content is selected from at least one of audio data and video data.
4. The method of claim 1, wherein the content is selected from at least one of voice, video, and other audiovisual data.
5. The method of claim 1, further comprising transmitting a data packet containing information to maintain the connection between the two or more end points.
6. The method of claim 2, wherein the content is speech data, the method further comprising establishing a Voice over Internet Protocol (VoIP) communication link.
7. The method of claim 1, further comprising maintaining the continuous communication link by transmitting signaling information between the end points that signifies that the communication link should be maintained.
8. The method of claim 7, wherein the signaling information comprises low bandwidth data packets transmitted between the end points.
9. The method of claim 7, wherein the continuous communication link is maintaining by disconnecting and reconnecting the communication link between the end points independently of the transmission on of content demand.
10. The method of claim 1, further comprising establishing a communication link across the Internet.
11. The method of claim 1, further comprising transmitting content between the end points over the continuous communication link with substantially no delay when a content transmission is desired.
12. The method of claim 13, further comprising transmitting content from a first of the two endpoints to a second of the end points with substantially no noticeable delay to the first end point.
13. The method of claim 2, further comprising a plurality of end points connected to the network, the method further comprising setting up and maintaining a plurality of established communication links between one of the end points and a plurality of other respective end points.
14. A method for enabling the instant transmission of audiovisual content between end points on a packet-based network, comprising:
maintaining an established communication link between two end points connected to the network on a continuous basis;
allowing audiovisual content to be transmitted on demand between the end points over the continuous communication link with substantially no delay.
15. The method of claim 14, wherein the audiovisual content is selected from at least one of audio data and video data.
16. The method of claim 15, wherein the content is speech data, the method further comprising establishing a Voice over Internet Protocol (VoIP) communication link.
17. The method of claim 14, further comprising maintaining the continuous communication link by transmitting signaling information between the end points that signifies that the communication link should be maintained.
18. The method of claim 14, further comprising establishing a communication link across the Internet.
19. The method of claim 14, further comprising a plurality of end points connected to the network, the method further comprising maintaining a plurality of established communication links between one of the end points and a plurality of other respective end points.
20. A system of maintaining a continuous connection for the transmission of content between two or more end points on a packet-based network, comprising:
a first audiovisual device located at a first end point connected to the network for sending and receiving audiovisual content;
a second audiovisual device located at a second end point connected to the network for sending and receiving audiovisual content;
a connection device for setting up a communication link over the network between the first and second end points and for maintaining the communication link on a continuous basis for the transmission of content on demand with substantially no delay between the first and second audiovisual devices.
21. The system of claim 20, wherein the audiovisual content is selected from at least one of audio data and video data.
22. The system of claim 21, wherein the audiovisual content is voice data, further wherein the connection device establishes a Voice over Internet Protocol (VoIP) communication link.
23. The system of claim 20, wherein the connection device maintains the continuous communication link by transmitting signaling information between the first and second end points that signifies that the communication link should be maintained.
24. The system of claim 20, wherein the connection device maintains the continuous communication link by transmitting low bandwidth data packets between the end points.
25. The system of claim 20, wherein the network is the Internet.
26. The system of claim 20, wherein the first and second audiovisual devices include transmission modules that allow content to be transmitted with substantially no delay between the first and second audiovisual devices over the continuous communication link when a content transmission is desired.
27. The system of claim 20, further comprising at least one additional audiovisual device connected to the network for sending and receiving audiovisual content; where the connection device establishes and maintains at least one additional communication link over the network between one of the first and second end points and the at least one additional audiovisual device a continuous basis for the transmission of content between one of the first and second audiovisual devices and the at least one additional audiovisual device.