06731908 is referenced by 60 patents and cites 2 patents.

A system, apparatus, and method for determining the distance between two objects using an indirect propagation delay measurement is disclosed. A frequency hopping scheme (such as the Bluetoothâ„¢ technology) is used to measure the relative phase offset of the received signal between the various frequencies. For a given distance between the objects, the phase offset vs. frequency curve is a straight line with the slope dependent upon the measured distance. After the phase of the received signals is detected, the data is plotted on a curve and the slope is calculated.

A wireless slave device remains phase locked with another device in a half-duplex communication mode by employing a low-drift phase locked loop employing a voltage controlled crystal oscillator. The phase locked loop further employs a mechanism that provides immunity from transitory phase slip at a time when the loop is opened.

Title
Distance measurement using half-duplex RF techniques
Application Number
9/759602
Publication Number
6731908 (B2)
Application Date
January 16, 2001
Publication Date
May 4, 2004
Inventor
Edward Mirodin
Rehovot
US
Uri Holzkaner
Rehovot
US
Shlomo Berliner
Rehovot
US
Agent
Weiss Moy & Harris P C
US
Agent
Harry M Weiss
US
Andrew M Harris
US
Assignee
Bluesoft
CA, US
IPC
H04B 17/00
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