Method and apparatus for a digitized CATV network for bundled services

• US 20050114903A1
• Filed: 12/09/2002
• Published: 05/26/2005
• Est. Priority Date: 02/08/2000
• Status: Active Grant

• Current Assignee: Quartics Incorporated
• Original Assignee: Quartics Incorporated
• Inventors: Elahi, Imtinana, Ahmed, Sherjil
• Granted Patent: US 7,984,474 B2
• Time in Patent Office: Days
• US Class Current: 725/114
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams

Abstract

A cost-efficient digital CATV network to improve signal quality, provide reliability, and offer the ability to meet demands for interactive services is described. Analog or digital video downstream channels are converted to a digital format by a digital headend transmitter. Relatively costly error-encoding for digital video channels is also part of the digital headend transmitter. Downstream analog and digital video channels in the digital format are transmitted using time-division multiplex technology from a headend to nodes using standard network protocols, such as SONET. Standard network protocols provide error-monitoring and status indication of transmit data, thus ensuring high signal quality and reliability. Time-division multiplexing facilitates easy adding or dropping of information to a transmit path. Flexibility to add or drop information is critical in providing interactive services. Data from interactive services can be added or dropped at points of presence throughout the digital CATV network. Subscribers to the digital CATV network can communicate with each other. A digital node transmitter receives the analog or digital video channels in digital format and converts the analog or digital video channels into an analog format. The digital node transmitter also frequency-division multiplexes multiple analog or digital video channels into one analog broadband signal for broadcast to subscribers'"'"' homes.

Claims

1. A digital cable television network comprising:

a headend transmitter comprising;

a digitzer configured to receive an analog video signal and convert said analog video signal to corresponding digital values; and

a framer configured to receive said digital values of said analog video signal and produce an output in a digital format, said digital format configured to include digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said analog video signal in said digital format; and

a node transmitter located at a node closest to a subscriber and comprising;

a deframer configured to receive said digital format of said analog video signal and recover said digital values; and

a converter configured to receive outputs from said deframer and produce an analog signal suitable for a subscriber type receiver.

2. The digital cable television network of claim 1, wherein said digital format is a Synchronous Optical Network standard and said analog video signal is represented by a level 3 bit-rate.

3. A digital cable television network comprising:

a formatter located at a headend and configured to receive a digital video signal, provide forward error-correction for said digital video signal, and produce an output in a digital format, wherein said digital format is configured to include digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said digital video signal in said digital format; and

a node transmitter located at a node closest to subscribers and comprising;

a deformatter configured to receive said digital format of said digital video signal, recover said digital video signal with said forward error-correction, and provide digital modulation; and

a converter configured to receive outputs from said deformatter and produce an analog signal suitable for a subscriber type receiver.

4. The digital cable television network of claim 3 wherein:

said digital format is a Synchronous Optical Network standard;

said digital video signal is represented by a level 1 bit-rate in said Synchronous Optical Network standard; and

said formatter combines a plurality of said digital video signals to achieve a standardized bit-rate.

5. The digital cable television network of claim 4 wherein said standardized bit-rate is a level 3 bit-rate.

6. A digital cable television network comprising:

a headend transmitter located at a headend and configured to receive a signal and produce a digital signal in a digital format, wherein said digital format is configured to include digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said signal in said digital format; and

a node transmitter located at a node closest to subscribers and configured to receive said signal in said digital format and produce an output in an analog format suitable for a subscriber type receiver.

7. The digital cable television network of claim 6 wherein a plurality of said signals in said respective digital formats comprises a set of downstream data, said set of downstream data is transmitted to said node using time division multiplexing technology, an external network signal in said digital format is added to said set of downstream data by a standard network element, and content of said set of downstream data is modified by said standard network element.

8. The digital cable television network of claim 7, wherein said standard network element is a SONET Add/Drop Multiplexer.

9. The digital cable television network of claim 6 wherein a bank of modems is configured to transmit information between an external network and said digital cable television network.

10. The digital cable television network of claim 9 wherein said information is Internet protocol data.

11. The digital cable television network of claim 6 wherein a bank of modems is configured to transmit information between subscribers of said digital cable cable television network.

12. The digital cable television network of claim 6 wherein said headend is a point of presence.

13. The digital cable television network of claim 6 wherein said node is a point of presence.

14. The digital cable television network of claim 6, further comprising a hub and wherein said hub is a point of presence.

15. The digital cable television network of claim 6, wherein said digital format is a Synchronous Optical Network standard.

16. The digital cable television network of claim 6, wherein said digital format is a Fiber Channel standard and said signal is represented in said Fiber Channel standard by segmented SONET frame.

17. A digital cable television network comprising:

a headend transmitter comprising;

an analog-to-digital converter configured to receive an analog video signal and produce corresponding digital values at fixed time intervals;

a digital mixer configured to receive an output of said analog-to-digital converter and frequency shift to a desired baseband frequency;

an anti-aliasing digital filter configured to receive an output of said digital mixer,

a sample rate compressor configured to receive an output of said digital filter;

a framer configured to receive a digital signal from said sample rate compressor, said framer configured to arrange digital signal to achieve a digital format configured to include additional digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said digital signal in said digital format; and

a node transmitter located at a node closest to subscribers and comprising;

a deframer configured to recover said digital signal embedded in said digital format;

a sample rate expander configured to receive an output of said deframer;

an anti-imaging filter configured to receive an output of said sample rate expander;

a digital frequency modulator block configured to frequency-division multiplex two or more digital signals from outputs of respective anti-imaging filters;

a digital-to-analog converter configured to receive an output of said digital frequency modulator block;

a lowpass filter configured to receive an output of said digital-to-analog converter, said lowpass filter configured to pass a baseband frequency;

an upconverter configured to receive an output of said lowpass filter and frequency shift to a desired transmit frequency; and

a transmit bandpass filter configured to receive an output of said upconverter, said transmit bandpass filter configured to pass said desired transmit frequency.

18. The digital cable television network of claim 17 wherein said digital frequency modulator block comprises an Inverse Fast Fourier Transform block.

19. A digital network system comprising:

a headend transmitter comprising;

a forward error-correction encoder configured to receive a digital video signal;

a framer configured to receive digital signals from two or more forward error-correction encoders, said framer configured to arrange said digital signals to achieve a digital format configured to include additional digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said digital signal in said digital format; and

a node transmitter located at a node closest to subscribers and comprising;

a deframer configured to recover said digital signals embedded in said digital format;

a digital modulator configured to receive an output of said deframer;

a sample rate expander configured to receive an output of said digital modulator;

an anti-imaging filter configured to receive an output of said sample rate expander;

a digital frequency modulator block configured to frequency-division multiplex two or more outputs of respective anti-imaging filters;

a digital-to-analog converter configured to receive an output of said digital frequency modulator block;

a lowpass filter configured to receive an output of said digital-to-analog converter, said lowpass filter configured to pass a baseband frequency;

an upconverter configured to receive an output of said lowpass filter and frequency shift to a desired transmit frequency; and

a transmit bandpass filter configured to receive an output of said upconverter, said transmit bandpass filter configured to pass the desired transmit frequency.

20. The digital cable television network of claim 19 wherein said digital frequency modulator block comprises an Inverse Fast Fourier Transform block.

21. A digital cable television network comprising:

means for converting a signal to a digital format at a headend, wherein said digital format is configured to include digital bits to facilitate a monitoring of errors and an indication of status in a transmission of said signal in said digital format; and

means for converting said signal in said digital format to an analog format at a node closest to a subscriber, wherein said analog format is suitable for a subscriber type receiver.

22. The digital cable television network of claim 21, further comprising:

means for providing forward error-correction to said signal at said headend; and

means for providing digital modulation to said signal with forward error-correction at said node.

23. The digital cable television network of claim 21, further comprising means for combining a plurality of said signals in said digital format to achieve a standardized bit-rate.

24. The digital cable television network of claim 21 wherein a plurality of said signals in said digital format comprises a set of downstream data and said set of downstream data is transmitted to said node using time division multiplexing technology.

25. The digital cable television network of claim 24, further comprising means for adding a signal from an external network to said set of downstream data.

26. The digital cable television network of claim 21, further comprising means for transmitting information between subscribers of said digital cable television network.

27. A method of cable television transmission comprising the acts of:

converting a signal to a digital format at a headend, wherein said digital format is configured to include digital bits to facilitate error-monitoring and status indication in a transmission of said video channel in said digital format;

transmitting a first plurality of signals in said digital format using time division multiplexing technology;

converting said signal in said digital format to an analog format at a node closest to a subscriber, wherein said analog format is suitable for a subscriber type receiver, and

transmitting a second plurality of signals in said analog format to a subscriber using frequency division multiplexing technology.

28. The method of cable television transmission of claim 27, further comprising the acts of:

providing forward error-correction to said signal at said headend; and

providing digital modulation to said signal with forward error-correction at said node.

29. The method of cable television transmission of claim 27, wherein said first plurality of signals in said digital format includes a signal from an external network and said second plurality of signals in said analog format is a subset of said first plurality of signals.