HARMONIC BLOCK TECHNIQUE FOR COMPUTING SPACE-TIME SOLUTIONS FOR COMMUNICATION SYSTEM NETWORK NODES

• US 20100045531A1
• Filed: 01/16/2009
• Published: 02/25/2010
• Est. Priority Date: 12/07/2006
• Status: Active Grant

• Current Assignee: Digimarc Corporation
• Original Assignee: ZuluTime LLC
• Inventors: Rhoads, Geoffrey
• Granted Patent: US 7,876,266 B2
• Time in Patent Office: Days
• US Class Current: 342/464
• CPC Class Codes: G01S 5/18 using ultrasonic, sonic, or infrasonic waves
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence

Abstract

A space-time calibration system and method implement space-time solutions, in which, in one preferred embodiment, a single node determines its own space-time solutions based on other network nodes with which the single node communicates. In other preferred embodiments, space-time solutions for the node can be generated using other resources in the network. The disclosed system and method enable reliable, precise object positioning particularly for environments where the Global Positioning System (GPS) is blocked or subject to interference such as within the urban core.

Claims

1. A method of solving for unknown location values and clock rate values of one or more nodes of a network of nodes communicating with one another, comprising:

providing multiple nodes including transmitting nodes and receiving nodes, the transmitting nodes producing ping transmit events and the receiving nodes producing ping receive events by receiving and associating receive count stamps to the ping transmit events, the ping transmit events taking place at transmission times corresponding to a transmit clock count of a node transmit clock and the ping receive events taking place at receive times corresponding to a receive clock count of a node receive clock;

generating ping event values corresponding to ping events relating to associated ones of the ping transmit events and the ping receive events;

accumulating the ping event values produced by the multiple nodes;

grouping the accumulated ping event values corresponding to multiple ones of the ping events that occur within a harmonic block time interval; and

generating from the grouped, accumulated ping event values solutions for transmit and receive node clock rate values and node location values relating to the transmission and receive events at arbitrary times within the harmonic block time interval.

2. The method of claim 1, in which the harmonic block time interval has predetermined time boundaries, and further comprising performing, for the harmonic block time interval, node location interpolation weighting between successive solutions for node location values relative to the predetermined time boundaries.

3. The method of claim 1, in which the harmonic block time interval has predetermined time boundaries, and further comprising representing the node location of each of the multiple nodes at a transmit time or a receive time as a linear combination of the solutions for node location values at a predetermined time within the predetermined time boundaries of the harmonic block time interval.

4. The method of claim 1, in which the harmonic block time interval has predetermined time boundaries, and further comprising performing, for the harmonic block time interval, clock rate interpolation weighting between successive solutions for transmit and receive node clock rate values relative to the predetermined time boundaries.

5. The method of claim 1, in which the harmonic block time interval has predetermined time boundaries, and further comprising representing the transmit and receive node clock rates of the multiple nodes at a transmit time or a receive time as a linear combination of the solutions for the transmit and receive node clock rate values at a predetermined time within the predetermined time boundaries of the harmonic block time interval.

6. The method of claim 1, in which the nodes of the network include a set of the transmitting nodes and a set of the receiving nodes and multiple ones in the set of transmitting nodes are members of the set of receiving nodes.

7. The method of claim 1, in which the nodes of the network include a set of the transmitting nodes and a set of the receiving nodes and at least one in the set of transmitting nodes is not a member of the set of receiving nodes.

8. The method of claim 1, in which the accumulating of ping event values takes place in one of the transmitting nodes of the network and is transmitted to other ones of the multiple nodes of the network.

9. The method of claim 1, in which two of the multiple nodes are at different locations separated by a distance and include one of the transmitting nodes and one of the receiving nodes, and the grouped, accumulated ping event values correspond to a change in the distance separating the two nodes and changes in the transmit and receive clock rates, and in which movement of each of the two nodes causes changes in their respective node locations and corresponding changes in the distance separating the node locations.

10. The method of claim 1, further comprising associating with transmit count stamps the ping transmit events produced by the transmitting nodes, and in which the ping event values include differential count stamp values corresponding to differences between the receive count stamps and the associated transmit count stamps.

11. The method of claim 1, further comprising grouping the accumulated ping event values corresponding to multiple ones of the ping events that occur within multiple harmonic block time intervals such that some of the ping event values occur within multiple harmonic block time intervals.