System and method for transmitting data on return path of a cable television system

• US 7,529,487 B2
• Filed: 08/13/2007
• Issued: 05/05/2009
• Est. Priority Date: 12/13/1999
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Levinson, Frank H., Sage, Gerald F., Lawson, Arthur Michael, Mostert, Willem A.
• Primary Examiner(s): WANG, QUAN ZHEN
• Application Number:
  US11/838,167
• Publication Number:
  US 20070277213A1
• Time in Patent Office: 631 Days
• Field of Search: 398/135, 725/121
• US Class Current: 398/135
• CPC Class Codes: H04N 21/615 Signal processing at physical level signal processing in analog two-way television systems H04N7/173
• CPC Class Codes: H04N 21/6168 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

A return path transmitter includes an optical signal receiver configured to receive a digital optical signal and generate therefrom a first digitized RF data stream and a sample clock. The return path transmitter further includes an RF signal receiver, coupled to the optical signal receiver, configured to receive and convert the analog RF data signal into a second digitized RF data stream of digitized RF data samples at a rate determined by the sample clock. The return path transmitter further includes a summing circuit configured to mathematically sum the first and second digitized RF data streams so as to generate a third digitized RF data stream. The return path transmitter further includes an optical transmitter configured to convert an output data stream into a serialized optical data signal for transmission over an optical fiber, the output data stream including the third digitized RF data stream.

Claims

1. A return path transmitter for use in conjunction with a local system that generates an analog RF data signal to be conveyed to a head end system, the return path transmitter comprising:

an optical signal receiver configured to receive a digital optical signal and generate therefrom a first digitized RF data stream and a sample clock, wherein the optical signal receiver is further configured to demultiplex data within the received digital optical signal into a first digitized RF data stream and a first non-RF data stream;

an RF signal receiver, coupled to the optical signal receiver, configured to receive and convert the analog RF data signal into a second digitized RF data stream of digitized RF data samples at a rate determined by the sample clock;

a summing circuit configured to mathematically sum the first and second digitized RF data streams so as to generate a third digitized RF data stream;

an optical transmitter configured to convert an output data stream into a serialized optical data signal for transmission over an optical fiber, the output data stream including the third digitized RF data stream;

a data port for receiving a second non-RF data stream from a digital data source external to the return path transmitter, the second non-RF data stream having a data rate of at least 5 Mb/s;

a full duplex drop and add circuit for extracting a portion of the first non-RF data stream and for replacing the extracted portion of the first non-RF data stream with the second non-RF data stream so as to generate a third non-RF data stream;

a multiplexor coupled to the summing circuit and the full duplex drop and add circuit to receive the third digitized RF data stream and the third non-RF data stream and to output a combined data stream; and

the output data stream converted by the optical transmitter includes the combined data stream.

2. A method for transmitting data representing an analog RF signal generated at a local system, the method comprising:

receiving a digital optical signal and generating therefrom a first digitized RF data stream and a sample clock having an associated sample rate;

receiving and converting the analog RF signal into a second digitized RF data stream of digitized RF data samples at a rate determined by the sample clock;

mathematically summing the first and second digitized RF data streams so as to generate a third digitized RF data stream;

converting an output data stream into a serialized optical data signal for transmission over an optical fiber, the output data stream including the third digitized RF data stream;

demultiplexing data within the received digital optical signal into a first digitized RF data stream and a first non-RF data stream;

receiving a second non-RF data stream from a digital data source external to the return path transmitter, the second non-RF data stream having a data rate of at least 5 Mb/s;

extracting a portion of the first non-RF data stream and replacing the extracted portion of the first non-RF data stream with the second non-RF data stream so as to generate a third non-RF data stream; and

combining the third digitized RF data stream and the third non-RF data stream and generate a combined data stream;

wherein the output data stream includes the combined data stream.