Communications: directive radio wave systems and devices (e.g. – Directive – Position indicating
Reexamination Certificate
2006-07-06
2009-02-17
Tarcza, Thomas H (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Position indicating
C342S463000
Reexamination Certificate
active
07492316
ABSTRACT:
Instead of normalizing time reference of independent spatially-located clocks using a reference tag transmission from known location, the present invention uses an interarrival time interval between a pulse pair of UWB pulses as a timing metric. Thus, a method of synchronizing spatially-located clock or normalizing time indications thereof comprises transmitting a UWB pulse pair, determining at first and second monitoring stations a respective count value indicative of a locally measured time interval between received pulse pairs, determining a ratio between clock counts of first and second monitoring stations, and utilizing the ratio to determine clock skew, e.g., a timing correction to be applied to respective local clocks of the monitoring stations. A corresponding system comprises a reference tag transmitter that transmits a pulse pair of UWB pulses to define a time reference interval, a first independent receiver that receives the pulse pair to generate a first count value indicative an interarrival interval between the pulse pair, a second independent receiver that receives the pulse pair to similarly generate a second count value, and a processor hub responsive to the count values to determine a ratio corresponding to the ratio of respective clock frequencies of the first and second receiver clocks. Once the correction is applied, time-of-arrival information from object tag transmissions may be used to determine object location with sub-foot position accuracies.
REFERENCES:
patent: 5469409 (1995-11-01), Anderson
patent: 6882315 (2005-04-01), Richley
patent: 2002/0135511 (2002-09-01), Zhao et al.
patent: 2004/0108954 (2004-06-01), Richley et al.
patent: 2005/0148346 (2005-07-01), Maloney et al.
Ameti Aitan
Chen Keming
Fontana Robert J.
Richley Edward A.
Turner Belinda
McIntyre Harbin & King
Multispectral Solutions, Inc.
Nguyen Nga X
Tarcza Thomas H
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