Communications: directive radio wave systems and devices (e.g. – Radar transponder system
Patent
1994-02-24
1996-06-11
Lobo, Ian J.
Communications: directive radio wave systems and devices (e.g.,
Radar transponder system
34082554, 34082555, 235384, G01S 1375, H04B 159
Patent
active
055259910
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a mobile object identification system for identifying a responder mounted on a mobile object in a communication area by transmitting interrogatory signals from an interrogator to the responder and receiving responding signals from the responder.
BACKGROUND OF THE INVENTION
A mobile object identification system transmits interrogatory signals from an interrogator to a responder attached to a mobile object and receives responding signals from the responder, thereby identifying the responder. Recently, there has been demand for mobile object identification systems that can assure accurate communication between interrogator and responder.
BRIEF SUMMARY OF THE INVENTION
To meet this demand, the first object of the invention (first invention) is to provide a responder for a mobile object identification system that, in the communication area of a writing interrogator, can write data upon receipt of a write signal and that, in the communication range of a reading interrogator, can read and transmit necessary data upon receipt of a read signal as it moves with the mobile object. The responder according to this invention comprises: data storage means for writing or reading necessary data; control means for controlling the processing for writing data to or reading data from the data storage means; and status storage means for storing the write completion status when necessary data has been written to the data storage means under control of the control means, so as to respond to a write signal received from the writing interrogator. The control means invalidates the processing for writing data when, with the write completion status retained in the status storage means, it receives a write signal from the writing interrogator.
According to the first invention, when the responder of the mobile object identification system receives a first write signal in the communication area of the writing interrogator, the control means writes the necessary data to data storage, and the status storage means ensures storage of the write completion status data. In this state, if the responder receives a second write signal from the writing interrogator, the control means invalidates the signal, since the write completion status data is already stored.
For various reasons, the mobile object may move slowly or stop in the communication area of the writing interrogator. In such a case, the responder attached to the mobile object receives the write signal repetitively from the writing interrogator. With the responder of the first invention, since the control means invalidates processing for writing the second and subsequent write signals, it allows a write signal to be written only once. Even if a plurality of responders are positioned in the same communication area, each responder operates as described above so that a write signal is written only once in each responder.
The second object of the invention (second invention) is to provide a mobile object identification system communication complex comprising: a responder for transmitting/receiving signals through the mobile antenna mounted on a mobile object; an interrogator for transmitting/receiving signal through a plurality of stationary antennas installed along the moving area of the mobile object; and a control device for controlling operation of the interrogator. The interrogator includes a level judging circuit to identify the highest-level responding signal of those received by the stationary antennas, and a signal selection circuit to selectively output to the control device the responding signal identified by the level judging circuit.
According to the communication complex of the second invention, the interrogator transmits interrogatory signals through the antennas. When the mobile object enters the communication area, the responder mounted on the mobile object transmits a responding signal in response to the interrogatory signal received.
Since the interrogator has the plurality of antennas installed along the movi
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patent: 5144553 (1992-09-01), Hassett et al.
patent: 5150114 (1992-09-01), Johansson
patent: 5289183 (1994-02-01), Hassett et al.
Ando Toshihide
Kago Yoshiyuki
Katoh Taisei
Matsumoto Manabu
Nagura Michinaga
Lobo Ian J.
Nippondenso Co. Ltd.
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