Transmission equipment with an optical transmission line

• US 5,319,486 A
• Filed: 07/24/1991
• Issued: 06/07/1994
• Est. Priority Date: 12/12/1989
• Status: Expired due to Term

• Current Assignee: Keymile AG (DZS, Inc.)
• Original Assignee: Ascom Tech AG
• Inventors: Vogel, Paul, Martinson, Thomas
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/730,784
• Time in Patent Office: 1,049 Days
• Field of Search: 359/118-120, 359/125, 359/127-128, 359/137-139, 359/165, 359/177, 359/157, 359/173
• US Class Current: 398/100
• CPC Class Codes: G02B 6/125 Bends, branchings or intersections

Abstract

The transmission equipment includes a plurality of subscriber nodes which are connected serially to an optical fiber. Every node comprises an access unit with at least one directional coupler, an address detection unit, a receiver, a synchronization unit, as well as a control unit with a switching transmitter. Addressed packets continuously reach the nodes and pass through the latter via the fiber in the form of modulated light. In a first switching position, the directional coupler branches off a part of the light power of the packets from the fiber, converts the light in the optoelectrical transducer into electrical signals and reads the respective packet address in the detection unit. If this packet address matches the address of the node the control unit switches the directional coupler into a second switching position. The coupler branches off another part of the light power of the packet in this second switching position and, in so doing, feeds the occurring electrical useful signals to the receiver. The first and second switching positions differ in that a considerably greater proportion of the respective light power is branched off from the fiber in the second position than in the first switching position.

Claims

1. In transmission equipment with an optical transmission line to which a plurality of subscriber nodes are connected in series and a clock and packet generation unit which determines at least one rigid bit clock and packets for the transmission line, the packets each including a header and infopart, the header having a target addresses, each of the plurality of subscriber nodes having an assigned address, at least one transmitter for continuously transmitting packets on the transmission line, a synchronization unit which is adjusted to the bit clock so as to be in correct phase, an address detection unit, and a receiver for receiving information contained in the infopart of the packet, the improvement comprising that the transmission line is constructed so as to be purely optical without electronic regenerators interrupting the line, and in that an access unit and a control unit are provided in each of the plurality of subscriber nodes, the control unit comprises the address detection unit and is connected to the access unit and the receiver in such a way that the access unit is incorporated in the transmission line and can be switched into at least a first (a) and a second switching position (b), wherein the light power (i_a) which can be branched off from the transmission line in the first switching position (a) is less than the light power (i_n) which can be branched off in the second switching position, and wherein the light power (i_a) branched off in the first switching position (a) is fed at least to the address detection unit and the light power (i_n) branched off in the second switching position (b) is fed to the receiver.

2. The transmission equipment according to claim 1, wherein the light power (i_a) branched off in the first switching position (a) is considerably less than the light power (i_n) branched off in the second switching position (b).

3. The transmission equipment according to claim 1, wherein the transmission line is constructed as a waveguide for guiding light.

4. The transmission equipment according to claim 3, wherein the access unit comprises at least one controllable directional coupler having a transit path and a branch, the transit path being a component part of the waveguide and the branch being connected with the receiver.

5. The transmission equipment according to claim 4, wherein the access unit comprises a single controllable directional coupler, the branch being connected with the address detection unit.

6. The transmission equipment according to claim 4, wherein the access unit comprises first and second controllable directional couplers which are serial components of the waveguide, the branch of the first directional coupler being connected with the address detection unit and the branch of the second directional coupler being connected with the receiver.

7. The transmission equipment according to claim 4, wherein the access unit comprises a controllable and a non-controllable directional coupler which are serial components of the waveguide, in that the branch of the non-controllable directional coupler is connected with the address detection unit and the branch of the controllable directional coupler is connected with the receiver.

8. A method for operating transmission equipment corresponding to claim 1, wherein each of said plurality of subscriber nodes switches the access unit into the first switching position (a) for every passing packet using the control unit for the duration of the header of the packet, determining during the first switching position (a) whether the target address of the packet matches an address of the respective subscriber node, when the target address matches the address, the access unit switches into the second switching position (b) for the duration of the infopart of the packet, information contained in the infopart being fed to the receiver during the second switching position (b).

9. The method of operation according to claim 8, wherein the access unit remains in the first switching position (a) when the target address does not match the address of the subscriber node.

10. The method for operation according to claim 8, wherein the access unit is switched into a third switching position (c), said third switching position causing the light power (I_a, i_n) branched off form the transmission line to be substantially zero when the target address does not match the address of the subscriber node.

11. A method for shutting down at least a part of the transmission equipment corresponding to claim 1, wherein at least one subscriber node switches the access unit into a third switching position (c) in which the light power (i_a, i_n) branched off from the transmission line is substantially zero.

12. The method for shutting down according to claim 11, wherein the third switching position (c) is achieved when the access unit receives no control voltage from the control unit.