Radio identification systems
First Claim
1. A transponder for use in a radio identification system comprising:
- a receiver for receiving interrogating signals transmitted from an interrogating station;
processing means for processing the received interrogating signals to produce reply signals in response thereto;
a transmitter for transmitting said reply signals;
storage means for temporarily storing a new interrogating signal received while the processing means is occupied in processing a previously received interrogating signal, at least until the processing means is capable of independently processing the new interrogating signal; and
variable delay means arranged to delay the transmission of the reply signal to each received interrogating signal by an amount inversely dependent upon the length of any delay introduced by storage of the interrogating signal in the said storage means, so that the overall delay between the reception of an interrogating signal and the transmission of a reply signal thereto is substantially constant for any interrogating signal.
0 Assignments
0 Petitions
Accused Products
Abstract
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.
-
Citations
8 Claims
-
1. A transponder for use in a radio identification system comprising:
-
a receiver for receiving interrogating signals transmitted from an interrogating station; processing means for processing the received interrogating signals to produce reply signals in response thereto; a transmitter for transmitting said reply signals; storage means for temporarily storing a new interrogating signal received while the processing means is occupied in processing a previously received interrogating signal, at least until the processing means is capable of independently processing the new interrogating signal; and variable delay means arranged to delay the transmission of the reply signal to each received interrogating signal by an amount inversely dependent upon the length of any delay introduced by storage of the interrogating signal in the said storage means, so that the overall delay between the reception of an interrogating signal and the transmission of a reply signal thereto is substantially constant for any interrogating signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
Specification