RADIO COMMUNICATION SYSTEM

• US 3,808,538 A
• Filed: 12/05/1972
• Issued: 04/30/1974
• Est. Priority Date: 12/06/1971
• Status: Expired due to Term

• Current Assignee: Kjell Goransson, Per Waerner
• Original Assignee: Kjell Goransson, Per Waerner
• Inventors: Waerner, Per, Goransson, Kjell
• Primary Examiner(s): Mayer, Albert J.
• Application Number:
  US05/312,370
• Time in Patent Office: 511 Days
• Field of Search: 320/30,48 325/16,55,64,119,169,185,186,352,356,361,492-496
• US Class Current: 340/7.21
• CPC Class Codes: G08B 3/1008 Personal calling arrangements or devices, i.e. paging systems selective calling systems and call receivers H04W84/00, H04W68/00
• CPC Class Codes: G08B 3/1075 Paging racks

Abstract

A wireless staff calling or paging system comprises a central transmitter station and a plurality of portable receivers, which can be called selectively and individually from the transmitter station by use of individual call signals, for instance in the form of tone codes, assigned to the receivers, and at least one storing rack with a plurality of storage compartments for the storing of temporarily non-used receivers belonging to persons who have left the area covered by the paging system and can no more be reached over the system. The paging system is provided with means for automatic absentee-indication to the transmitter station, when a receiver inserted in a storage compartment is called from the transmitter station. The absentee-indication does not require that the non-used receivers are deposited in individually assigned storage compartments, but a temporarily non-used receiver can be deposited in any convenient storage compartment. Only a single signal conductor is required from each storage compartment rack to the central transmitter station for the absentee-indication. The receivers inserted in the storage compartments are automatically '"'"''"'"''"'"''"'"'silenced'"'"''"'"''"'"''"'"' so that they can not emit any sound even if called-up from the transmitter station.

Claims

1. A radio communication system, in particular a wireless paging system, comprising a central transmitter unit and several portable receivers, which can be called selectively from said transmitter unit by use of individual call signals assinged to the receivers, each of said receivers including a call detector for receiving and detecting call signals transmitted from said transmitter unit and for generating upon detection of the individual call signal assigned to said receivers and internal call detection signal on its output and an audio frequency amplifier and a loudspeaker for amplifying and acoustically reproducing audio frequency signals transmitted from said transmitter unit to said receiver subsequent to said call signal, at least one rack including several storage compartments for the storing of temporarily non-used receivers, each such compartment being provided with a first electric contact and each receiver being provided with a corresponding first external electric contact on its casing adapted upon insertion of the receiver in a storage compartment to be connected to said first electric contact in the storage compartment, a common signal conductor connecting said first electric contacts in all said storage compartments to said transmitter unit, the output of said call detector in each receiver being connected to said first external electric contact on the casing of the receiver so that said call detection signal from said call detectoR is supplied to said first electric contact on the casing of the receiver and, if the receiver is inserted in a storage compartment, through said first electric contact in said storage compartment and said common signal conductor to said transmitter unit to be used therein as an absentee-indication, and each storage compartment being provided with a second electric contact connected to a predetermined potential and said audio frequency amplifier in each receiver being provided with a cut-off biasing input connected to a second external electric contact on the casing of the receiver adapted upon insertion of the receiver in a storage compartment to be connected to said second electric contact in the storage compartment, whereby the audio frequency amplifier is cut-off under influence of said predetermined potential then being connected from said second electric contact in the storage compartment to said cut-off biasing input of the audio amplifier.

2. A system as claimed in claim 1, wherein each receiver includes a rechargable power supply battery having one pole connected to said second external electric contact on the casing of the receiver, and said rack is provided with a charging current source having one pole connected to said second electric contact in each of said storage compartments in said rack, whereby the power supply battery of the receiver is recharged from said charging current source when the receiver is inserted in one of said storage compartments and the voltage potential of said one pole of said charging current source is applied to said cut-off biasing input of said audio frequency amplifier in the receiver so as to effect the cut-off of said audio amplifier.