DUPLEX RADIOCOMMUNICATION EQUIPMENT

• US 3,631,497 A
• Filed: 08/07/1968
• Issued: 12/28/1971
• Est. Priority Date: 08/11/1967
• Status: Expired due to Term

• Current Assignee: Leonard Didier
• Original Assignee: Leonard Didier
• Inventors: Didier, Leonard
• Application Number:
  US04/750,986
• Time in Patent Office: 1,238 Days
• US Class Current: 370/281
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

A duplex radiocommunication transceiver with carrier frequencies that are made available to all parties of a network comprises a generator providing a plurality of pairs of frequencies and which is equipped with a stepping switch, a coder for coding the address of a correspondent, means for transmitting an occupation frequency in a channel which is occupied, means for decoding an address code being received, means for interpreting the presence of the occupation frequency, and means for stopping said stepping switch if both frequencies of the concerned pair are free for both parties.

Claims

1. A transceiver for use in a network in which individual transceivers are identified by unique codes and in which N-lines are available for carrying traffic between the transceivers on duplex radio links, the transceiver comprising a transmitter portion and a receiver portion, a variable coder selectively connectable to said transmitter portion for producing a code of a selected transceiver with which a duplex link is to be established;

a fixed decoder connected to the output of said receiver portion for recognizing on an incoming signal a code representative of the transceiver identity;

a frequency generator providing N/2 frequency pairs spaced by N/2 frequency ranges, the two frequency ranges of each pair characterizing two lines available to one duplex connection;

a scanning device connecting the output of said frequency generator to the input of said receiver portion for conducting a step-by-step exploration of the frequency pairs, first means connected to the output of said receiver portion for checking the utilization of the two frequencies of a pair at each step of the exploration; and

second means responsive to said first means for stopping the exploration if both of the two frequencies of a pair are available to establish a new duplex link.

2. A transceiver as claimed in claim 1, including line-engaged means selectively connected to the input of said transmitter portion for modulating outgoing transmission with a characteristic signal signifying that the frequency of transmission is in use.

3. A transceiver as claimed in claim 2, in which said line-engaged means modulates the transmission with a continuous audio frequency signal above the normal range of speech frequencies.

4. A transceiver as claimed in claim 3, wherein said first means includes circuitry responsive to the absence of said continuous audio frequency signal on a particular frequency to signify the availability of that frequency for duplex connection.

5. A transceiver as claimed in claim 1 wherein said transmitter portion includes a code modulator operated by the variable coder to impress on an outgoing transmission a code signal representative of the identity of a transceiver with which communication is to be established, the code modulator modulating the transmission in a different manner to the modulation employed for transmitting information through the established duplex connection.

6. A transceiver as claimed in claim 3, including comparator means connected to the receiver portion and to the variable coder for comparing an incoming reply code imprEssed on an incoming transmission with a code impressed by the coder on an outgoing transmission and representative of the identity of a transceiver with which communication is to be established.

7. A transceiver as claimed in claim 6, including means for connecting said line-engaged means to the transmitter portion for modulating the outgoing transmission with the characteristic signal in response to the detection of said characteristic signal on an incoming transmission at the other frequency of the frequency of the frequency pair selected.

8. A transceiver as claimed in claim 7, including a switching circuit which reverts the transceiver to its watching quiescent condition upon the disappearance of said characteristic signal modulating the incoming transmission.

9. A transceiver as claimed in claim 7 further including detecting means for detecting the presence of said characteristic signal on an incoming transmission including a narrow band filter selective to the frequency of the characteristic signal, an integrator responsive to the duration during which the characteristic signal is sustained, and a threshold amplifier responsive to the amplitude of the characteristic signal.

10. A transceiver as claimed in claim 9, in which said detecting means is connected to first memory means for storing values signifying that a pair of frequencies are free for establishing duplex connections, such values controlling operation of a timing signal generator, and a logic circuit influencing operation of the stepping device.

11. A transceiver as claimed in claim 9 including means for accelerating the charging of a charging circuit forming part of the integrator, such accelerated charging taking place at the commencement of reception and after a frequency pair for the establishment of duplex connections have been found.

12. A transceiver as claimed in claim 1, having a telephone handset provided with a rest position at which a member is operated to revert the transceiver to its quiescent watching state.

13. A transceiver as claimed in claim 12, including means for speeding the operation of the scanning device during periods that the handset is not in its rest position.

14. A transceiver as claimed in claim 1, including means for continuously impressing the code of the variable coder on the radiated transmission at a particular frequency for a duration not less than the time necessary for the scanning device to conduct a complete exploration of the frequency pairs.

15. A transceiver as claimed in claim 1 wherein said scanning device includes a prepositioned counter set to a finite number of occupied lines corresponding to saturation of the network, and adapted to prevent further transmission after the exploration of the frequency pairs available signifies the network to be saturated.

16. A transceiver as claimed in claim 15, in which the counter includes means for releasing the stepping device for a fresh exploration of the frequency pairs a finite time after saturation has occurred.

17. A transceiver as claimed in claim 2 wherein said reciever portion includes a majority decision device inserted between a comparator receiving an incoming code, a local code and a memory.