APPARATUS FOR ESTABLISHING A TELEPHONE TO RADIO-TELEPHONE COMMUNICATION

• US 3,692,952 A
• Filed: 02/19/1970
• Issued: 09/19/1972
• Est. Priority Date: 02/19/1969
• Status: Expired due to Term

• Current Assignee: Didier Leonard
• Original Assignee: Didier Leonard
• Inventors: Leonard, Didier
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Kundert, Thomas L.
• Application Number:
  US05/012,576
• Time in Patent Office: 943 Days
• Field of Search: 179/41A 325/53,64
• US Class Current: 455/554.2
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 84/04 Large scale networks; Deep hierarchical networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The invention concerns duplex radiocommunications at variablyselected carrier frequencies. It describes a concentrator ensuring the duplex connection at variably-selected carrier frequencies between a system of mobile transmitters and a telephone exchange comprising several unattended transmitter-receiver sets, in which the transmitter contains an individual call coder and a general call coder, the latter being used to establish the connection with a mobile set wanting to call up a telephone set. The invention is applied to connecting an ordinary telephone system and a group of mobile radio electric transmitter receivers.

Claims

1. In a system for establishing communications between a telephone network having an exchange connected to a connection apparatus by ingoing and outgoing telephone lines and a group of radio-telephones, each having its own individual call-code and operating in duplex connection with common carrier frequencies, the connection apparatus comprising at least two transmitter-receivers each having a first variable coder capable of being set to a selected individual call-code to call the corresponding radio-telephone and a second fixed coder for transmitting a general call-code available to any radio-telephone wishing to establish communication with the telephone network;

selection means connected to the transmitter-receivers to enable only one transmitter-receiver at a time to transmit the general call-code; and

cut-off means in each transmitter-receiver to cut-off transmission of the general call-code when the transmitter transmitting it enters into a communication, wherein each transmitter-receiver of the connection apparatus includes means for actUating said cut-off means to cut-off transmission of the general call code in response to receipt of an engaged tone from a radio-telephone establishing a communication with a telephone subscriber and generator means for transmitting the engaged tone simultaneously with the general call code.

2. Apparatus as claimed in claim 1, wherein each transmitter-receiver includes enabling means for enabling said generator means to the engaged tone in response to the reception of the engaged tone from a radio-telephone establishing a communication with a telephone subscriber.

3. Apparatus as claimed in claim 2, wherein said enabling means includes means to cut-off transmission of the engaged tone when the communication is broken.

4. Apparatus as claimed in claim 3, wherein N lines are available for carrying traffic between the radio-telephones and between a radio-telephone and the telephone network on duplex radio links, and including means to transmit the general call code on a free channel for a period of at the most N times the decoding period of an individual call and to locate a different free channel at the end of this period.

5. Apparatus as claimed in claim 1, wherein said selection means includes a stepping means selectively connecting an acquisition signal in sequence to said transmitter-receivers for initiating generation of said general call code therein and a drive unit for advancing said stepping means.

6. Apparatus as claimed in claim 5, wherein said selection means includes first means in each transmitter-receiver for connecting said acquisition signal from said stepping means to said drive unit to advance said stepping means to another transmitter-receiver in response to receipt of an engaged tone from a radio-telephone.

7. Apparatus as claimed in claim 6, wherein said first means includes an engaged tone detector providing an output in response to detection of said engaged tone and a first relay actuated in response to the output of said tone detector to connect the acquisition signal received from said stepping means to said drive unit.

8. Apparatus as claimed in claim 6, wherein said selection means includes second means in each transmitter-receiver for connecting said acquisition signal from said stepping means to said drive unit to advance said stepping means to another transmitter-receiver in response to receipt of a signal from said exchange.

9. Apparatus as claimed in claim 8, wherein said second means includes a second relay actuated in response to receipt of a signal from said exchange to connect the acquisition signal received from said stepping means to said drive unit.

10. Apparatus as claimed in claim 5, wherein said cut-off means includes control means responsive to receipt of said acquisition signal for effecting transmission of said general call code by said second fixed coder and inhibiting means for inhibiting said control means in response to receipt in said transmitter-receiver of an engaged tone.

11. Apparatus as claimed in claim 10, wherein said selection means includes first means in each transmitter-receiver for connecting said acquisition signal from said stepping means to said drive unit to advance said stepping means to another transmitter-receiver in response to receipt of an engaged tone from a radio-telephone.

12. Apparatus as claimed in claim 11, wherein said first means includes an engaged tone detector providing an output in response to detection of said engaged tone and a first relay actuated in response to the output of said tone detector to connect the acquisition signal received from said stepping means to said drive unit.

13. Apparatus as claimed in claim 12, wherein said inhibiting means includes a first AND gate whose output is connected in operation of said control means, said acquisition signal being connected to one input of said first AND gate and the output of said engaged tone detector being connected to a second input of said first AND gate through an inverter.

14. ApparatuS as claimed in claim 13, wherein said control means includes a third relay actuated by the output of said first AND gate and having contacts for normally connecting said first variable coder to an output for transmission and connecting said second fixed coder to said output for transmission upon actuation of said third relay.

15. Apparatus as claimed in claim 14, wherein said third relay includes additional contacts for connecting said generator means to said output for transmission upon actuation thereof.

16. Apparatus as claimed in claim 15, wherein each transmitter-receiver includes enabling means for enabling said generator means to transmit the engaged tone in response to the reception of the engaged tone from a radio-telephone establishing a communication with a telephone subscriber.

17. Apparatus as claimed in claim 16, wherein said enabling means includes a second AND gate whose output is connected to said output for transmission, said generator means being connected to one input of said second AND gate and said output of said engaged tone detector being connected to a second input of said second AND gate.

18. In a receiver for a radio-telephone operating with a telephone network including a plurality of transmitter-receivers operating one at a time in duplex connection with common carrier frequencies to generate a general call code, an individual address code decoder and a general call code decoder, operating means for selectively energizing temporarily the general call code decoder when a connection must be established from the radio-telephone to said telephone network, means for scanning the duplex frequencies of said network, and means for stopping said scanning means in response to detection of the general call code by said general call code decoder, wherein said operating means includes a bistable flip-flop triggered by the discharge of a condenser selectively connectable thereto and arranged to be recharged in the non-connected condition.

19. A receiver as claimed in claim 18, wherein said operating means includes a bistable flip-flop triggered by the discharge of a condenser selectively connectable thereto and arranged to be recharged in the non-connected condition.

20. A receiver as claimed in claim 19, wherein said condenser is connected to a charging supply by a spring-loaded switch and is discharged by momentary operation of the switch.