TDM and FDM telephone communication

• US 4,013,840 A
• Filed: 07/11/1975
• Issued: 03/22/1977
• Est. Priority Date: 05/15/1972
• Status: Expired due to Term

• Current Assignee: Teleplex Incorporated
• Original Assignee: Teleplex Incorporated
• Inventors: Anderson, Scott K.
• Primary Examiner(s): Stewart, David L.
• Application Number:
  US05/595,100
• Time in Patent Office: 620 Days
• Field of Search: 179/15 FD, 179/2.5 R, 179/15 FS, 179/15 AT, 179/15 AL
• US Class Current: 370/261
• CPC Class Codes: H03L 7/199 with reset of the frequency divider or the counter, e.g. for assuring initial synchronisation
• CPC Class Codes: H04J 4/00 Combined time-division and frequency-division multiplex systems H04J13/00 takes precedence ; data transmission H04L5/26; telemetry G08C15/00
• CPC Class Codes: H04Q 11/00 Selecting arrangements for multiplex systems multiplex systems H04J

Abstract

A plurality of communicating stations have transmitters, receivers and control means. The transmitters are tunable across a broad radio frequency spectrum and transmit an amplitude modulated selected carrier frequency. Each receiver is set to receive only one preselected amplitude modulated carrier frequency fixed and identified with each particular station. Stations may be regarded as telephones having signaling means and a chassis. The control means includes means to receive TDM control signals from and to supply TDM control signals to a remote common equipment unit. The control signals and amplitude modulated carriers are sent and received over common cabling. The common equipment unit includes processor means to process and generate control signals and means to interface with an external telephone system.

Claims

1. A random access communication system for a plurality of telephone sets comprising:

a data processor;

common cabling for communicating frequency multiplexed amplitude modulated signals between said telephone sets and control signals between said telephone sets and said data processor;

means for coupling said processor and said sets to said cabling;

a plurality of said telephone sets, each of said telephone sets comprising;

a transmitter for transmitting a carrier signal over said cabling to other telephone sets, each said transmitter comprising an adjustable source of said carrier signals to transmit selected carrier signals and means to amplitude modulate the carrier signal transmitted by said transmitter,

a receiver for receiving a carrier signal over said cabling from other telephone sets, each said receiver being pre-tuned to receive only one carrier signal which differs for each telephone set and is dedicated thereto and means to amplitude demodulate the carrier signal received by said receiver, and

means for initiating a call to a called telephone set comprising means responsive to pulse code groups which are included in said control signals for digitally adjusting the frequency of the carrier signal of the transmitter associated with a calling telephone set to the dedicated carrier signal associated with the receiver of the called telephone set and adjusting the frequency of the carrier signal of the transmitter associated with the called set to the dedicated carrier signal associated with the receiver of the calling set; and

wherein said data processor responds to said means for initiating a call by transmitting pulse code groups which are included in said control signals indentifying the called and calling telephone sets to said calling and called sets respectively, and wherein said control signals are transmitted in time division multiplex format.

2. A random access communication system for a plurality of telephone sets comprising:

a data processor;

common cabling for communicating signals and frequency multiplexed amplitude modulated signals between said telephone sets and control signals between said telephone sets and said data processor and said telephone sets;

means for coupling said processor and said sets to said cabling;

a plurality of said telephone sets, each of said telephone sets comprising;

a transmitter for transmitting a carrier signal over said cabling to other telephone sets, each said transmitter comprising an adjustable source of said carrier signals to transmit selected carrier signals and means to amplitude modulate said selected carrier signal,

a receiver for receiving an amplitude modulated carrier signal over said cabling from other telephone sets, each said receiver being pretuned to receive only one said amplitude modulated carrier signal which differs for each telephone set and is dedicated thereto, said receiver having means to demodulate the received amplitude modulated carrier signal, and

means for transmitting over and receiving from said cabling control signals for executing feature oriented functions at called and calling telephone sets, said control signals comprising a recurrent pulse stream divided into time frames wherein each frame is dedicated to a respective set, said processor being responsive to control signals received from any set during its time frame for providing reply signals to said any set during its dedicated time frame and for providing control signals to at least one other telephone set during its respective dedicated time frame, said control and reply signals comprising pulse code groups representative of the functions associated with said control or reply signals; and

wherein said processor includes means responsive to a first control signal transmitted over said cabling from a calling telephone set representing the address of a called telephone set which transmits a first reply signal over said cabling to said calling set, said calling set comprising means responsive to said first reply signal to digitally adjust the carrier frequency of its transmitter to the dedicated carrier of the receiver of said called set, said means being further responsive to said first control signal by generating, providing and transmitting a second reply signal over said cabling during the dedicated time frame of said called set, said called set comprising means responsive to said second reply signal to digitally adjust the carrier frequency of its transmitter to the dedicated carrier of the receiver of said calling station.

3. An arrangement according to claim 2 wherein said processor comprises a memory and means responsive to the control signals transmitted over said cabling for examining the operating conditions of each set and storing pulse code groups representative of the updated conditions in said memory.

4. An arrangement according to claim 3 wherein each calling set includes a source of a normally-disabled local busy tone, said processor being responsive to a control signal received from a calling set representing the address of a called set to examine the operating conditions of said called set stored in memory and generate and transmit a reply control signal to said calling set representative of a busy condition, said calling set including means responsive to said last named reply signal to enable said source which provides said local busy tone.

5. An arrangement according to claim 3 wherein said cabling includes conference conductor means at at least one calling telephone set for initiating a conference call to include a second called set in a communication with a first called set which includes means for generating and transmitting over said common cabling a control signal representative of a hold condition, and further, control signals representative of the address of the second called set, said processor being responsive to the hold control signal and second set address control signal to store in memory the hold condition of the first called set and to establish audio communication between said calling set and said second called set over said common cabling, means at said calling set to provide and transmit a conference signal over said common cabling, said processor responsive to said transmitted conference signal for providing and transmitting a conference switching signal over said common cabling to said calling set and said first and second called sets during their respective dedicated time frames, said calling set and said first and second called sets being responsive to said transmitted conference switching signal for providing and transmitting audio signals associated with said calling and first and second called sets as audio signals over said conference conductor.

6. An arrangement for establishing further conference calls as provided in claim 5 comprising means for time division multiplexing said different conference calls on said conference conductor.

7. A random access multiple station telephone system comprising:

a plurality of stations interconnected by conductors having;

transmitter means to transmit across a broad radio frequency spectrum in selected frequency bands over said conductors,

receiver means to receive transmissions from other stations only in one preassigned frequency band identified with said receiver and dedicated thereto and different from the pre-assigned frequency bands of all other receivers,

signaling means to signal operator input signals, and

logic and audio control means to receive the operator input signals and cause the generation of system control signals reflective of said operator input, to cause system control signals to be impressed and extracted from a data frame, and to cause the generation of internal station operating signals reflective of incoming control signals extracted from said data frame;

system control means having;

means to generate and transmit a intervaled data frame for each station of said plurality of stations over said conductors,

means to impress on and extract from said data frame outgoing and incoming system control signals respectively,

means to process said system control signals in accordance with a preselected program,

memory means with input-output means to receive and store selected system control signals, and

interfacing and logic means to receive said incoming system control signals and to generate said outgoing system control signals, said processing means operating in accordance with a preselected program to selectively store system control signals and to selectively generate system control signals to control said system and each station thereof.

8. The system of claim 7 wherein said system control means includes a system synchronizer to transmit synchronizing signals to each of said stations and each said station control means includes a station synchronizer to receive said synchronizing signals and to synchronize said logic and audio control means with said system synchronizer.

9. The system of claim 8 wherein each said transmitter means includes a carrier generator circuit conductively connected to a modulator circuit to supply an amplitude modulated carrier signal, said carrier generator circuit being comprised of:

a voltage tuned oscillator (VTO) having a tuning input and an output;

a variable modulus counter (VMC) having a first input connected to receive the output of said VTO, a second input connected to receive an integer from said interfacing and logic means reflective of the desired carrier to be transmitted by said transmitter, and an output;

a frequency and phase locking tuning circuit having a first input to receive a reference frequency from an external source, a second input connected to receive said VMC output and an output connected to said VTO tuning input; and

wherein

said VMC output is the quotient of said VTO output divided by said integer which is compared with and locked in frequency and phase with said reference frequency by sending tuning signals to said VTO to tune said VTO output as necessary to effect said frequency and phase lock.

10. The system of claim 8 including a common equipment unit which includes said system control means, public address means and a trunk line unit having a plurality of trunk line cards and corresponding plurality of interface circuits connected to an external telephone system.

11. The system of claim 10 including an operator'"'"'s console having means to intercept and extend calls incoming from said external telephone system.

12. The system of claim 11 wherein said operator'"'"'s console has night service switching means activating said system control means to selectively divert incoming calls to a selected station and to hold said incoming call while announcing its existence by said public address means.

13. The system of claim 12 wherein said stations in cooperation with said system control means have means to hold incoming calls, transfer calls, divert calls, busy out the station and dial intercept calls incoming to another station.

14. The system of claim 13 wherein said operator'"'"'s console has means in cooperation with said system control means to camp incoming calls on an internal station that is busy and means to extend one incoming call serially.

15. The system of claim 14 wherein said operator'"'"'s console has digital number display means to display the identifying phone number of a first station in communication with a second station and the identity of stations to which incoming calls are to be diverted when in night service.

16. The system of claim 15 wherein said conductors are comprised of a control data coaxial cable, a R.F. coaxial cable and a power conductor.

17. The system of claim 16 wherein said cable includes conference conductors, and said stations include means to connect to said conference to effect conference calls.

18. The system of claim 17 wherein said stations include means to conduct a plurality of said conference calls over said conference conductors in accordance with a time division multiplex scheme.