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LOCATOR SYSTEM AND RELATED LOCALIZATION METHOD AND SERVICE WITH INNOVATIVE TIME AND FREQUENCY SINCHRONIZATION OF LOCALIZATOR TRANSPONDERS
LOCATOR SYSTEM AND RELATED LOCALIZATION METHOD AND SERVICE WITH INNOVATIVE TIME AND FREQUENCY SINCHRONIZATION OF LOCALIZATOR TRANSPONDERS
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机译：定位器收发器具有创新的时间和频率同步的定位器系统及相关的定位方法和服务
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摘要
The invention concerns a localization method for locating a target that is coupled with a locator transponder (24) associated with a permanent identification code permanently assigned to said locator transponder (24). The localization method comprises: a) upon reception of a user request for locating the target, transmitting, by a radio communications system (22), a spread spectrum paging signal carrying the permanent identification code and a temporary identification code temporarily assigned to the locator transponder (24), wherein said temporary identification code is shorter than said permanent identification code; b) receiving, by the locator transponder (24), the spread spectrum paging signal and extracting, by said locator transponder (24), the temporary identification code carried by the received spread spectrum paging signal; c) transmitting, by a radar-based system (23), radar signals towards one or more areas of earth's surface or sky and receiving, by said radar-based system (23), echo signals from said one or more areas of the earth's surface or sky; d) upon reception by the locator transponder (24) of one or more radar signals transmitted by the radar-based system (23), generating and transmitting, by said locator transponder (24), a sequence of watermarked radar echo signals in which a spread spectrum watermarking signal is embedded, wherein said spread spectrum watermarking signal carries the temporary identification code extracted; and e) carrying out, by the radar-based system (23), localization operations that include: detecting, in the received echo signals, the sequence of watermarked radar echo signals transmitted by the locator transponder (24); extracting the temporary identification code carried by the spread spectrum watermarking signal embedded in the detected sequence of watermarked radar echo signals; and determining a location of the locator transponder on the basis of the detected sequence of watermarked radar echo signals; f) transmitting, by the radio communications system (22), one or more frequency-synchronization-aid signals; g) receiving, by the locator transponder (24), the frequency-synchronization-aid signal(s) and estimating, by said locator transponder (24), based on the received frequency-synchronization-aid signal(s), a frequency drift affecting a reference frequency provided by a local oscillator (86) of said locator transponder (24); wherein the locator transponder (24) transmits the sequence of watermarked radar echo signals by using a transmission carrier frequency obtained based on the reference frequency provided by the local oscillator (86) and on the estimated frequency drift.
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