Single master clock control of ethernet data transfer over both a cable TV return path and an ethernet forward path

• US 20050273837A1
• Filed: 08/02/2004
• Published: 12/08/2005
• Est. Priority Date: 05/12/2004
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Oyadomari, Randy Ichiro, Gordy, Stephen Charles, Lawson, Arthur Michael
• Granted Patent: US 8,032,916 B2
• Time in Patent Office: Days
• US Class Current: 725/119
• CPC Class Codes: H04H 60/13 Arrangements for device control affected by the broadcast information
• CPC Class Codes: H04H 60/97 using uplink of the CATV systems
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04N 21/437 Interfacing the upstream path of the transmission network, e.g. for transmitting client requests to a VOD server flow control in data networks H04L47/10; streaming protocols, e.g. RTP or RTCP, H04L65/65; scheduling or organising the servicing of application requests in data packet switching networks H04L67/60
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission

Abstract

An optical signal return path system analog RF signals are sampled using a master clock frequency, and combined with digital data such as Ethernet data at a cable node. The cable node sends the combined signals on a return path over a fiber optic medium to the cable hub. The cable hub extracts an approximate in-frequency replicate of a master clock signal, and can use the replicate master clock signal to desample the digitized RF signals back to analog. The cable hub can further use the replicate of the master clock signal to serialize Ethernet data, and send the Ethernet data back to the cable node via an optical cable in the forward direction. Accordingly, a single master clock signal can be used on a CATV network for encoding/decoding, and transmitting a variety of data signals, which enhances the integrity and reliability of the data signals.

Claims

1. In a cable distribution network environment that includes a cable hub and a cable node, the cable node capable of transmitting RF data and Ethernet data over a return path to the cable hub, the cable hub further being capable of transmitting Ethernet data over a forward path to the cable node, a method for synchronizing data transfers over both the return path and the forward path using a single master clock, the method comprising the following:

an act of the cable node using a master clock to sample the RF data and combine the RF data with the Ethernet data;

an act of the cable node transmitting the combined RF data and Ethernet data along with master clock information to the cable hub in a data stream;

an act of the cable hub recovering the master clock information from the data stream to acquire an approximate in-frequency replicate signal of the master clock;

an act of the cable hub using the replicated master clock signal to desample the RF data; and

an act of the cable hub using the replicated master clock signal to serialize Ethernet data transmitted along the forward path.

2. The method as recited in claim 1, wherein replicated master clock signal is sent with the Ethernet data along the forward path, and wherein the replicated master clock signal is used to deserialize the serialized Ethernet data at the cable node.

3. The method as recited in claim 1, wherein the master clock has a first clock rate, wherein the combined RF data, Ethernet data, and clock information are serialized at a second clock rate prior to being transmitted to the cable hub.

4. The method as recited in claim 3, further comprising an act of recovering the second clock rate from the transmitted data stream.

5. The method as recited in claim 4, further comprising an act of deserializing the combined RF data, Ethernet data, and clock information at the recovered second clock rate after arriving at the cable hub.

6. The method as recited in claim 1, wherein the recovered replicate signal is used to serialize the Ethernet data prior to transmitting the Ethernet data to the cable node.

7. The method as recited in claim 6, wherein the replicate signal is used to deserialize the serialized Ethernet data at the cable node, the serialized Ethernet data being received from the cable hub.

8. In a cable distribution network environment in which RF data and Ethernet data are transmitted between two points of return and forward optical cables, a cable node including one or more components having executable instructions stored thereon, that, when executed, perform a method comprising the following:

an act of using a master clock to sample RF data and combine the RF data with Ethernet data;

an act of transmitting the combined RF data and Ethernet data along with master clock information to the cable hub in a data stream;

an act of receiving Ethernet data from the cable hub along a forward optical cable, wherein the Ethernet data has been serialized into an Ethernet data stream using the master clock signal; and

an act of recovering an approximate replicate of the master clock signal from the received Ethernet data stream.

9. The cable node as recited in claim 8, wherein at least one of the one or more components having executable instructions stored thereon is a field programmable gate array.

10. The cable node as recited in claim 8, wherein the act of recovering an approximate in-frequency replicate of a master clock signal from the Ethernet data stream further comprises an act of comparing the recovered replicate of the master clock signal to a reference clock.

11. The cable node as recited in claim 8, wherein the cable node comprises one or more digital interface ports, such that the cable node can be accessed through the one or more digital interface ports by a connection that is different from the cable node connection to the forward optical cable.

12. The cable node as recited in claim 8, wherein the method further comprises an act of serializing the combined RF data and Ethernet data along with master clock information as a data stream at a second clock rate prior to transmitting the combined data to the cable hub.

13. The cable node as recited in claim 8, wherein the method further comprises an act of deserializing the Ethernet data stream using the approximate replicate of the master clock signal.

14. In a cable distribution network environment in which RF data and Ethernet data are transmitted between two points separated by return and forward optical cables, a cable hub including one or more components having executable instructions stored thereon, that, when executed, perform a method comprising the following:

an act of receiving a combined data stream sent from a cable node over a return optical cable, wherein the combined data stream includes one or more digitized RF data signals, and one or more non-RF data signals;

an act of recovering an approximate in-frequency replicate of a master clock signal from the combined data stream;

an act of desampling the RF data based on the recovered replicate of the master clock signal; and

an act of the using the recovered replicate of the master clock signal to serialize at least a portion of the non-RF data signals extracted from the combined data stream.

15. The cable hub as recited in claim 14, wherein at least one of the one or more components having executable instructions stored thereon is a field programmable gate array.

16. The cable hub as recited in claim 14, further comprising an act of including the recovered master clock signal in the serialized non-RF data stream and transmit the serialized non-RF data signals to the cable node on the forward optical cable.

17. The cable hub as recited in claim 14, wherein the act of recovering an approximate in-frequency replicate of a master clock signal further comprises an act of comparing the recovered replicate of the master clock signal to a reference clock.

18. The cable hub as recited in claim 14, wherein the non-RF data signals comprise Ethernet data signals received by virtue of one or more data transmissions through one or more corresponding digital interface ports at the cable node.

19. The cable hub as recited in claim 14, wherein the non-RF data signals comprise Ethernet data signals received from one or more Ethernet ports at the cable hub.

20. The cable hub as recited in claim 19, wherein the method further comprises an act of combining one or more Ethernet data signals received from one or more Ethernet ports at the cable hub with at least a portion of the extracted non-RF data signals.