Transaction accounting of toll transactions in transponder systems

摘要

This invention allows a toll authority to monitor transaction numbers which are sent from a transponder (14) to an interrogator (12). By incrementing the transaction counter stored in the transponder with successful transactions the toll authority can ascertain whether accounting of a transaction has been missed (i.e., a transaction number missing from the sequence), or double-counted (i.e., two transactions with the same transaction number). <IMAGE>