Locator system with innovative time and frequency synchronization of locator transponders and related localization methods and services

摘要

The present invention relates to a localization method for locating a target associated with a locator transponder (24) associated with a permanent identification code permanently assigned to the locator transponder (24). The localization method comprises: a) upon receiving a user request to locate a target, transmits a spread spectrum paging signal carrying the permanent identification code and a temporary identification code temporarily assigned to a locator transponder (24) in a wireless communication system transmitting by (22), wherein the temporary identification code is shorter than the permanent identification code; b) a locator transponder (24) receiving a spread spectrum paging signal and extracting the temporary identification code carried by the received spread spectrum paging signal; c) transmit radar signals by the radar-based system 23 towards one or more regions of the earth''s surface or sky, and receive echo signals from the one or more regions of the earth''s surface or sky by the radar-based system 23 to do; d) when the locator transponder 24 receives one or more radar signals transmitted by the radar-based system 23, a spread spectrum watermarking signal is embedded in the sequence of watermarked radar echo signals to the locator transponder ( 24) generating and transmitting, wherein the spread spectrum watermarking signal carries the extracted temporary identification code; and e) performing localization operations by the radar-based system (23), the localization operations comprising: in the received echo signals, the water transmitted by the locator transponder (24). detecting a sequence of marked radar echo signals; extracting a temporary identification code carried by the spread spectrum watermarking signal embedded within the detected sequence of watermarked radar echo signals; and determining a location of the locator transponder based on the detected sequence of watermarked radar echo signals; f) transmitting one or more frequency-synchronization-support signals by the wireless communication system (22); g) receiving the frequency-synchronization-support signal(s) by a locator transponder 24 and avoiding frequency drift affecting a reference frequency provided by a local oscillator 86 of the locator transponder 24 estimating by the locator transponder (24) based on the received frequency-synchronization-support signal(s); wherein the locator transponder 24 transmits the sequence of watermarked radar echo signals using a reference frequency provided by the local oscillator 86 and a transmit carrier frequency obtained based on the estimated frequency drift. do.