Patent Number: 6,310,576

Title: Method of identifying location using a master clock to synchronize time of arrival signals

Abstract: A method is provided of identifying position location of a transmitter device, such as a mobile or portable, in an inbound system. The inbound system includes free receivers all coupled, over appropriate radio frequency (RF) links, to a common reference receiver, the latter equipped with a high precision timebase master clock for receiver synchronization purposes. Rather than requiring each and every receiver to maintain a separate high-precision timebase to record position related timing signals for position location determination, in accordance with a preferred embodiment, the free receivers are configured to detect timing signals from the transmitter device, and without timestamping them, quickly forward them (in the form of a signal-received indication) after a fixed or otherwise known time delay to the reference receiver. The reference receiver, in turn, timestamps all signals from all free receivers according to its own master clock high precision timebase. In this way, it is possible to synchronize the forwarded signal-received indications to the reference receiver master clock and to use the results to derive useful position location information. This is achieved without equipping high precision timebase clocks in the free receivers, which in most instances is prohibitively expensive.

Inventors: Johnson; Mark J. (Cary, IL)

Assignee: Motorola, Inc.

International Classification: H04B 7/26 (20060101); H04Q 7/38 (20060101); G01S 003/02 (); H04Q 007/20 ()

Expiration Date: 10/30/2018