| 摘要 |
To enable a transponder in a radio identification system, such as a secondary surveillance radar system, to remain responsive to a new interrogating signal received while it is processing a previously received interrogating signal, the transponder is provided with storage means arranged to store the new interrogating signal until the previously received interrogating signal has been processed. In a preferred arrangement, the transponder also includes variable delay means arranged to delay the transmission of a reply signal to each received interrogation by a variable amount inversely dependent upon the length of any delay introduced by the storage means so that the aggregate of the variable delay and the storage delay is constant for all received interrogating signals. With a knowledge of the fixed overall delay between the reception of an interrogating signal by the transponder, and the transmission of a reply signal in response thereto, the conventional practice of determining the identity and position of a target carrying the transponder, by associating the reply signal with primary radar returns received from the target, can still be used.
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