US 5,194,856 AGranted

System for detecting the presence in a rack of a portable unit suitable for transmitting or receiving a signal containing an identification number assigned thereto

AssigneeEricsson Radio Systems B.V.

InventorGauke K. Zijlstra

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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.

A portable transmission unit detection system comprising:

a rack having a plurality of compartments;
a plurality of portable transmission units (PTU), each portable unit having:
a PTU control circuit;
communication means connected to the control circuit for performing at least one of wireless transmission and wireless reception of a signal containing an identification number assigned to the unit;
a register for storing the assigned identification number;
a PTU reception means for receiving a scanning signal from outside the unit;
and
a PTU transmission means for transmitting a response signal containing the identification number of the portable unit in response to a received scanning signal;
and
a detection unit associated with said rack and having;
a plurality of individual detection unit transmission means each assigned to one of said compartments and paired, when one of said portable units is placed in said one of said compartments, with said PTU reception means of said one of said portable units so that the PTU reception means of the pair is only sensitive to a scanning signal transmitted by the individual detection unit transmission means of the pair, all of said individual detection unit transmission means transmitting a scanning signal identical for all of said compartments;
a detection unit reception means for receiving a response signal;
a memory having a location for each portable unit for storing therein a datum which indicates the presence of the portable unit in the rack;
and
a rack control circuit connected to said plurality of individual detection unit transmission means, said detection unit reception means for receiving a response signal, and said memory, for selectively choosing an individual detection unit transmission means to transmit said scanning signal and for monitoring whether or not a response signal is received, said rack control circuit altering the contents of a memory location associated with the identification number of the response signal to indicate presence of the associated portable unit in the rack when a response signal is received, and, when no response signal is received in response to a last scanning signal transmitted via a particular individual detection unit transmission means but a response signal has been received in response to a next-to-last scanning signal transmitted via said particular detection unit individual transmission means, said rack control circuit altering the contents of an associated memory location to indicate the absence of the portable unit in the rack.

12 more elements

Abstract

Claims15