| 摘要 |
A transponder monitoring system includes a fixed location interrogation station and transponder units carried by vehicles, with the transponder units being placed in an activated transmit mode in response to interrogation pulses transmitted by the interrogation station. The messages received at the interrogation station are verified by the transmission of verification pulses on a bit by bit basis, with failure of verification causing a vehicle transponder unit to be reset to begin transmission over again. This permits an orderly response from the vehicle units to be obtained even though several units may be within the interrogation field at the same time and may be simultaneously attempting to transmit information to the interrogation station. Upon completion of transmission of an error free (verified) message from a transponder, the transponder is disabled from further transmission until the vehicle leaves the interrogation field.
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