Importance

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Abstract

A system for detecting the presence in a compartment of a rack of a portable transmission unit of a number of portable transmission units, each being capable for transmitting or for receiving a signal containing an identification number assigned to the unit. All compartments of the rack or only compartments receiving or having received the units therein are scanned. The presence of a unit in a compartment is acknowledged by the unit after it has received a scanning signal, being identical for each scanned compartment, by providing a response signal comprising the identification number assigned to the unit. For each unit which is present, or until the actual scanning thereof was present, in a compartment a control circuit updates a datum, indicating the presence of the unit in a compartment, in a memory. Updating of the datum for absence can be carried out if a response signal is not received within a predetermined time or if a detection means, assigned individually to each compartment, detects a removement from a compartment for which a presence datum was set before.

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First Claim