Broadband and baseband LAN

• US 4,885,747 A
• Filed: 02/17/1988
• Issued: 12/05/1989
• Est. Priority Date: 02/17/1988
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Foglia, Henry R.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/156,763
• Time in Patent Office: 657 Days
• Field of Search: 370/124, 370/123, 370/76, 370/71, 370/72, 358/86, 455/3, 455/5, 455/6, 381/81
• US Class Current: 370/490
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay
• CPC Class Codes: H04N 7/108 the cable being constituted by a pair of wires

Abstract

Described is a communications system for transmitting baseband and broadband signals simultaneously. The system is ideally suited for interconnecting different types of data terminal equipment (DTE) within a building or limited geographical area. The system includes a backbone communications network formed from a plurality of independent communications systems. Each of the plurality of independent communications systems is dedicated to transmit either the baseband signals or the broadband signals. A Filter Coupler (FC) network combines and separates the two different type of signals at the distribution level. One embodiment of the FC includes a filter network coupled in tandem with a high frequency transformer. In an alternate embodiment the FC includes a balun transformer coupled to a directional coupler transformer.

Claims

1. An improved communications system for transmitting and receiving broadband and baseband information comprising:

a backbone communications network, said backbone communications network having a first sub-assembly network dedicated to transmit broadband signals representative of broadband information, a second sub-assembly network dedicated to transmit baseband signals representative of baseband information;

a distribution communications network for simultaneously transmitting and/or receiving broadband signals and baseband signals; and

a circuit arrangement coupling the backbone communications network and the distribution communications network, said circuit arrangement having a filter circuit means connected in tandem with a broadband transformer with the windings of said transformer causing the baseband signals to be transmitted in a balanced mode and the broadband signals to be transmitted in an equally unbalanced mode.

2. The improved communications system of claim 1 further including a broadband connector connected to the broadband transformer and operable for connecting high frequency devices.

3. The improved communications system of claim 2 further including an RF splitter circuit connected to the broadband connector.

4. The improved communications system of claim 1 further including a baseband connector connected to the filter circuit means and operable for attaching devices which operate within the baseband frequency range.

5. The improved communications system of claim 1 wherein the first subassembly network includes a coaxial cable;

a head end circuit arrangement for multiplexing signals from high frequency devices onto said coaxial cable, and a Tap/Combiner circuit arrangement coupled to said coaxial cable.

6. The communications system of claim 1 wherein the second subassembly includes a shielded twisted pair communications media, at least one multi-access unit connected to the media for distributing signals propagating on said media.

7. The communications system of claim 1 wherein the distribution communications network including at least one length of twisted pair communications media dedicated to provide communications services to an office;

and a first circuit arrangement connected to the end of the communications media entering said office;

said first circuit arrangement having a filter circuit means coupled in tandem with a broadband transformer with the winding of said transformer and the filter poled so that baseband signals are distributed in a balanced mode and broadband signals are distributed in an unbalanced mode.

8. In a communications system having a broadband network for transmitting high frequency electrical signals and a baseband network for transmitting relatively low frequency electrical signals an improved distribution communications network system for distributing the electrical signal comprising:

at least a length of communications media interconnecting an office with a wiring closet;

a pair of F-coupler modules one of each connected to opposite ends of the communications media, with each F-coupler module including a filter circuit connected in tandem with a broadband transformer with windings of said broadband transformer causing the high frequency electrical signals to be transmitted in an unbalanced mode and the relatively low frequency signals are transmitted in a balanced mode on said length of communications media.

9. An improved circuit arrangement for transmitting and receiving baseband and/or broadband electrical signals from a common communications media comprising:

a filter circuit configured to form a first input port for the baseband electrical signals;

a broadband transformer connected in tandem with the filter circuit, said broadband transformer having a plurality of windings arranged on a supporting corre with one of said windings forming a second port for receiving the broadband signals and the other windings forming an output port and causing the baseband electrical signals to be transmitted and delivered as balanced signals at the output port and the broadband electrical signals to be transmitted and delivered as unbalanced signals at said output port.

10. The improved circuit arrangement of claim 9 wherein the filter circuit includes a first coil having one end connected to the first input port and an opposite end connected to a series connected RC circuit;

and

a second coil disposed in spaced relationship to the first coil and having one end connected to the first input port and an opposite end connected to a series connected RC circuit.

26. The circuit arrangement of claim 9 wherein the broadband transformer includes three windings symmetrically arranged on the supporting core.

11. In a communications system having independent backbone networks for transmitting and/or receiving baseband signals and/or broadband signals and a distribution network for distributing the broadband and/or baseband signals into offices, a circuit module for multiplexing and/or demultiplexing broadband and/or baseband signals on the distribution network comprising:

a first means coupled to said distribution network, said means receiving broadband signals and causing the broadband signals to propagate in an unbalanced mode on said distribution network; and

a second means coupled to the first means and operable for receiving the baseband signals and for propagating said baseband signals in a balanced mode over said distribution network whereby the first and second means cause the broadband signals and the baseband signals to propagate simultaneously on said distribution network.

12. The circuit module of claim 11 wherein the first means includes a balun transformer.

13. The circuit module of claim 12 wherein the balun transformer includes a magnetic core and two coils tightly wound on said magnetic core with the coils and core providing a characteristic impedance of ##EQU4## where Z_OB is the characteristic impedance of a distribution link within the distribution network, L₁ represents the net mutual inductance and C_M represents the mutual capacitance.

14. The circuit module of claim 13 wherein Z_OB is approximately 150 ohms.

15. The circuit module of claim 11 wherein the second means includes a directional transformer.

16. The circuit module of claim 15 wherein the directional coupler transformer includes a magnetic core and three windings (N1, N2 and N3) positioned on said magnetic core with one of said windings N3 having a single ended output for connecting to an external device and spaced from N1 and N2 so that the windings are characterized by an impedance of ##EQU5## and the other two windings N1 and N2 being connected to the distribution network and characterized by an impedance of ##EQU6## where Z_OB represents a characteristic impedance for balanced signals on the distribution link within the distribution network,

Z_OU represents characteristic impedance for unbalanced signals on the distribution link of said distribution networks,

L_B represents mutual inductance between windings N1 and N2.

L_U represents the net mutual inductance between windings N1 and N2 together and that of winding N3.

C₁ 2, 3 represents mutual capacitance between N1 N2, and N3.

C₁,2 represents mutual capacitance between N1 and N2 in the presence of winding N3.

17. The circuit module of claim 16 wherein Z_OB is approximately 150 ohms and Z_OU is approximately 50 ohms.

18. An improved communications system for transmitting and receiving broadband and baseband information comprising:

a backbone communications network, said backbone communications network having a first sub-assembly network dedicated to transmit broadband signals representative of broadband information, a second sub-assembly network coupled to the first sub-assembly network and dedicated to tranamit baseband signals representative of baseband information;

a distribution communications network for simultaneously transmitting and/or receiving a broadband signals and baseband signals; and

a circuit arrangement interconnecting the backbone communications network and the distribution communications network, said circuit arrangement having a first circuit means coupled in tandem with a second circuit means with the first and second circuit means coacting so that baseband signals are propagated on the distribution communications network in a balanced mode and the broadband signals are propagated in an unbalanced mode.

19. In a communications system having a broadband network for transmitting high frequency electrical signals and a baseband network for transmitting relatively low frequency electrical signals an improved distribution communications network for distributing the electrical signals comprising:

at least a length of communications media interconnecting an office with a wiring closet;

a pair of F-coupler modules one of each connected to opposite ends of the communications media, with each F-coupler module including a balun transformer connected in tandem with a directional transformer with selected windings of said transformers causing the high frequency electrical signals to be transmitted in an unbalanced mode and the relatively low frequency signals to be transmitted in a balanced mode on said length of communications media.

20. An improved circuit arrangement for transmitting and receiving baseband and/or broadband electrical signals from a common communications media comprising:

a balun transformer configured to form a first input port for the baseband electrical signals;

a directional transformer connected in tandem with the balun transformer, said balun transformer having a supporting core, three windings N1, N2 and N3 arranged thereon with one of said windings forming a second single ended port for the broadband signals and the other two windings forming an output port and coacting with windings of the balun transformer so that baseband electrical signals are propagates as balanced signals at the output port and the broadband electrical signals are propagated as unbalanced signals at said second port.

21. An improved communicatins system for transmitting and receiving broadband and baseband information comprising:

a backbone communications network, said backbone communications network having a first sub-assembly network dedicated to transmit broadband signals representative of broadband information, a second sub-assembly network coupled to the first sub-assembly network and dedicated to transmit baseband signals representative of baseband information;

a distribution communications network for simultaneously transmitting and/or receiving broadband signals and baseband signals; and

a circuit arrangement coupled the backbone communications network and the distribution communications network, said circuit arrangement having a balun transformer connected in tandem with a directional transformer with windings of said transformers coacting so that baseband signals are distributed in a balanced mode and the broadband signals are distributed in an equally unbalanced mode.

24. The improved communications system of claim 21 wherein the backbone communications network is formed with a plurality of different media types including optical fiber, twisted pair cable and coax.

22. In a communications system having a first network for transmitting high frequency electrical signals and a second network for transmitting high frequency electrical signals an improved distribution communications network system for distributing the electrical signals comprising:

at least a length of communications media;

a pair of F-coupler modules one of each connected to opposite ends of the communications media, with each F-coupler module including a balun transformer connected in tandem with a directional coupler transformer with windings of said directional coupler transformer and said balun transformer poled and arranged in the path of the communications media so that high frequency electrical signals from said first and second networks are transmitted in an unbalanced mode and balanced mode with said high frequency electrical signals propagating simultaneously and occupying the same frequency bands on said communications media.

23. The improved distribution network system of claim 22 wherein the communications media includes twisted pair electrical conductors.

25. An improved communicatons system for transmitting and receiving broadband and baseband information comprising:

a backbone communications network, said backbone communications network having a first sub-assembly network dedicated to transmit broadband electrical signals representative of broadband information, a second sub-assembly network coupled to the first sub-assembly network and dedicated to transmit baseband electrical signals representative of baseband information;

means associated with the backbone communications network and operable for partitioning and distributing the broadband signals;

a distribution communications network for simultaneously transmitting and/or receiving broadband signals and baseband signals; and

a circuit arrangement coupling the backbone communications network and the distribution communications network, said circuit arrangement having a balun transformer connected in tandem with a directional coupler transformer with windings of said transformers coacting so that the circuit arrangement exercises its filtering characteristics on base band electrical signals and exercises its directivity characteristics on broad band electrical signals.