Sensor web

• US 7,925,469 B2
• Filed: 09/01/2006
• Issued: 04/12/2011
• Est. Priority Date: 10/09/2002
• Status: Expired due to Term

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Delin, Kevin A., Jackson, Shannon P.
• Primary Examiner(s): Barbee; Manuel L
• Application Number:
  US11/514,458
• Publication Number:
  US 20070061098A1
• Time in Patent Office: 1,684 Days
• Field of Search: 702/127, 702176-179, 702/188, 702/187, 375/355, 375/356, 709/248, 370/464, 370/508, 370/512, 710/58, 710/61
• US Class Current: 702/178
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: H04J 3/0641 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A Sensor Web formed of a number of different sensor pods. Each of the sensor pods include a clock which is synchronized with a master clock so that all of the sensor pods in the Web have a synchronized clock. The synchronization is carried out by first using a coarse synchronization which takes less power, and subsequently carrying out a fine synchronization to make a fine sync of all the pods on the Web. After the synchronization, the pods ping their neighbors to determine which pods are listening and responded, and then only listen during time slots corresponding to those pods which respond.

Claims

1. A method, comprising:

deploying a plurality of sensor pods to a plurality of separated locations, and wherein each of said sensor pods have an internal time base, to measure a specified parameter;

synchronizing said time bases among said plurality of sensor pods by wirelessly transmitting a synchronization pattern that includes a data sync header, followed by actual real time clock information from a master clock, wherein said synchronizing comprises synchronizing to said synchronization pattern in order to sync each said sensor pod coarsely to the real time clock information from the master clock, and subsequently carrying out a second, fine synchronization, and where said fine synchronization provides the actual real time clock information;

using the synchronized time bases in each of said plurality of sensor pods to measure said specified parameter in each of said plurality of separate location sensor pods, at a synchronized first time in each of said sensor pods, and to report said specified parameter, where there are first and second sensor pods, and neither of said first and second sensor pods report said specified parameter at non-synchronized times; and

communicating between said sensor pods by communicating from a first sensor pod to a second sensor pod, and from said second sensor pod to a third sensor pod.

2. A method as in claim 1, wherein said synchronized time is precisely the same moment in each of said sensor pods.

3. A method as in claim 1, further comprising using said synchronized time base to carry out a main processing loop in each of said plurality of sensor pods which both starts and ends at substantially the same time.

4. A method as in claim 1, wherein said first and second sensor pods are each assigned a time slot within a time base, and each communicate with other sensor pods during said time slot within said time base.

5. A method as in claim 1, each of said spaced sensor pods transmit each item of information only a single time to another sensor pod.

6. A method as in claim 5, wherein each of said sensor pods has an identifier, and each of said sensor pods communicates during a parameter sensing routine at a specified time slot.

7. A method as in claim 5, further comprising a ping routine, during which each of the sensor pods determine which other sensor pods exist, and time slots during the existing sensors communicate, and listening only during times of the existing sensors and causing said sensor pods to enter a power reduced state at power reduced times between said first time and a second time, such that each of said first and second sensor pods maintain a power reduced state at said power reduced times, and each of said first and second sensor pods receive data at said first time.

8. A method as in claim 1, further comprising sharing data between the plurality of sensor pods, such that each of the sensor pods receives data from each other sensor pod.

9. A method as in claim 8, further comprising processing the data from the plurality of sensor pods, to determine information from the data and processing the data from each of the plurality of sensor pods, to determine information indicative of the first parameter that was measured by multiple different sensor pods.

10. A method as in claim 9, wherein the information from the data is vector information including both scalar and direction information related to a value of parameters sensed at different locations.

11. A method as in claim 1, further comprising adding another sensor pod to the sensor web during operation of the sensor web.

12. A method as in claim 11, wherein said another sensor pod is a sensor pod with a different hardware configuration then at least one other sensor pod in the web.

13. A method as in claim 11, further comprising, after adding said another sensor pod, resynchronizing a clock within said another sensor pod with said synchronized time base.

14. A method, comprising:

first, coarsely synchronizing a sensor pod to a master clock, using a coarse synchronization operation which looks for a wirelessly transmitted synchronization pattern that includes actual data real time clock information, where said synchronization pattern includes a data synchronization header, followed by the actual real time clock information from the master clock, and wherein said coarse synchronization information synchronizes to said synchronization pattern in order to sync the sensor pod coarsely to the actual real time clock information to provide the same real time clock information as in said master clock;

second, after said coarsely synchronizing, finely synchronizing said sensor pod to said master clock using a fine synchronization operation, where said fine synchronization takes more power then said coarse synchronization, and where said fine synchronization provides further synchronization to said actual real time clock information than said coarse synchronization.