Post data-collection synchronization for approximation of simultaneous data
First Claim
1. A method for post data-collection synchronization of data of at least one sensor unit in a distributed sensor system, comprising:
- (a) reading an initial local-clock time of a sensor unit, having a local clock, by a data processor before a data-collection session;
(b) reading an initial reference local-clock time of said data processor, having a reference local clock, by said data processor before the data-collection session;
(c) reading a final local-clock time of said sensor unit by said data processor after the data-collection session;
(d) reading a final reference local-clock time of said data processor by said data processor after the data-collection session;
(e) computing a time-scaling factor by said data processor as the ratio of the difference between the final and initial reference local-clock times and the difference between the final and initial local-clock times;
(f) converting at least two local-clock sampling times of said sensor unit'"'"'s collected data from the data-collection session by said data processor to their corresponding reference local-clock sampling times using the time-scaling factor; and
(g) interpolating said sensor unit'"'"'s collected data from the data-collection session by said data processor to approximate a data value of said sensor unit at a reference local-clock time between said reference local-clock sampling times.
1 Assignment
0 Petitions
Accused Products
Abstract
A system for synchronizing data after they are collected and stored locally in sensor units in a distributed sensor system, so that wired or wireless communication is not required during a data-collection session. Each sensor unit has a local clock providing local-clock times before and after a data-collection session, and a data processor uses its local clock or a sensor unit'"'"'s local clock as the reference to compute each sensor unit'"'"'s time-scaling factor, which is the ratio of the elapsed reference local-clock time and the elapsed local-clock time. The data processor uses the time-scaling factor to convert each sensor unit'"'"'s local-clock data-sampling times to the reference local-clock data-sampling times, and the data processor subsequently interpolates sensor data to approximate simultaneous sensor-data values at desired reference local-clock times. A physical-activity monitoring system can use this synchronization method to reduce the size, power consumption, and cost of the sensor units.
62 Citations
20 Claims
-
1. A method for post data-collection synchronization of data of at least one sensor unit in a distributed sensor system, comprising:
-
(a) reading an initial local-clock time of a sensor unit, having a local clock, by a data processor before a data-collection session; (b) reading an initial reference local-clock time of said data processor, having a reference local clock, by said data processor before the data-collection session; (c) reading a final local-clock time of said sensor unit by said data processor after the data-collection session; (d) reading a final reference local-clock time of said data processor by said data processor after the data-collection session; (e) computing a time-scaling factor by said data processor as the ratio of the difference between the final and initial reference local-clock times and the difference between the final and initial local-clock times; (f) converting at least two local-clock sampling times of said sensor unit'"'"'s collected data from the data-collection session by said data processor to their corresponding reference local-clock sampling times using the time-scaling factor; and (g) interpolating said sensor unit'"'"'s collected data from the data-collection session by said data processor to approximate a data value of said sensor unit at a reference local-clock time between said reference local-clock sampling times. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A method for post data-collection synchronization of data of a plurality of sensor units in a distributed sensor system, comprising:
-
(a) reading an initial local-clock time of each sensor unit, having a local clock, of a plurality of sensor units by a data processor before a data-collection session; (b) reading a final local-clock time of each sensor unit of said plurality of sensor units by said data processor after the data-collection session; (c) computing a time-scaling factor for each sensor unit of said plurality of sensor unit sensor units by said data processor as the ratio of the difference between the final and initial local-clock times of a selected sensor unit of said plurality of sensor units and the difference between the final and initial local-clock times of said sensor unit; (d) converting at least two local-clock sampling times of collected sensor data from the data-collection session of each sensor unit of said plurality of sensor units by said data processor to their corresponding local-clock sampling times of said selected sensor unit using the time-scaling factor; and (e) interpolating the collected sensor data from the data-collection session of each sensor unit of said plurality of sensor unit by said data processor to approximate simultaneous sensor-data values of said plurality of sensor units at a time between said local-clock sampling times of said selected sensor unit. - View Dependent Claims (7, 8, 9, 10, 11)
-
-
12. A post data-collection synchronization system, comprising:
-
(a) a plurality of sensor units, each sensor unit having a local clock, a synchronization-signal receiver for receiving synchronization signals, a sensor, a sensor-data controller for data acquisition from said sensor, a sensor-data memory for storing said sensor'"'"'s data and said local clock'"'"'s times, a communication port for sending said sensor'"'"'s data and said local clock'"'"'s times to a data processor, and a data-interpolating means for approximation of simultaneous sensor-data values of said plurality of sensor units after a data-collection session; and (b) a synchronization-signal transmitter for transmitting an initial synchronization signal to said synchronization-signal receiver of each sensor unit of said plurality of sensor units simultaneously before the data-collection session and a final synchronization signal to said synchronization-signal receiver of each sensor unit of said plurality of sensor units simultaneously after the data-collection session, so that said local clock'"'"'s time of each sensor unit of said plurality of sensor units is stored in said sensor-data memory when one of said initial synchronization signal and said final synchronization signal is received by said synchronization-signal receiver. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
-
Specification