REVERSE PATH OPTICAL LINK USING FREQUENCY MODULATION

• US 20080220731A1
• Filed: 03/08/2007
• Published: 09/11/2008
• Est. Priority Date: 03/08/2007
• Status: Abandoned Application

• Current Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Inventors: WEST, LAMAR E.
• Application Number:
  US11/683,640
• Publication Number:
  US 20080220731A1
• Time in Patent Office: Days
• US Class Current: 455/113
• CPC Class Codes: H04B 10/25759 Details of the reception of RF signal or the optical conversion before the optical fibre

Abstract

Systems and methods of upstream communications using frequency modulation are disclosed. An exemplary method embodiment, among others, includes frequency modulating a communications signal, intensity modulating the frequency modulated signal, and applying that intensity modulated signal to a transmission medium. Also disclosed is a method of receiving the upstream signal including intensity demodulating the signal received from the transmission medium and frequency demodulating the resultant signal.

Claims

1. A communication system comprising:

a transmitter in a reverse path of a communication system comprising;

a first modulator configured to frequency modulate a radio frequency (RF) electrical signal; and

a second modulator configured to intensity modulate an optical signal with the radio frequency (RF) electrical signal.

2. The communication system of claim 1, wherein the first modulator comprises a wideband frequency modulation modulator.

3. The communication system of claim 1, wherein the second modulator comprises at least one of a laser and an intensity modulator.

4. The communication system of claim 1, further comprising a transmission medium communicatively coupled to the second modulator, the second modulator configured to transmit the intensity modulated frequency modulated RF electrical signal.

5. The communication system of claim 4, wherein the transmission medium comprises optical fiber.

6. The communication system of claim 1, further comprising an optical receiver configured to demodulate the intensity modulated frequency modulated RF electrical signal to produce a frequency modulated RF electrical signal.

7. The communication system of claim 6, wherein the optical receiver comprises a photodiode.

8. The communication system of claim 3, further comprising a frequency modulation demodulator communicatively coupled to an optical receiver configured to frequency modulation demodulate the frequency modulated RF electrical signal to produce an RF electrical signal.

9. The communication system of claim 1, wherein the transmitter is further configured to transmit upstream in a cable television system from a node to a headend or hub.

10. A method comprising:

frequency modulating a communications signal;

intensity modulating an optical signal with the frequency modulated (FM) communications signal; and

applying the intensity modulated optical signal to a transmission medium.

11. The method of claim 10, wherein frequency modulating comprises frequency modulating with a wideband FM modulator.

12. The method of claim 10, wherein intensity modulating comprises intensity modulating with at least one of a laser and an intensity modulator.

13. The method of claim 10, wherein the transmission medium comprises optical fiber.

14. The method of claim 10, further comprising:

receiving the intensity modulated frequency modulated communications signal from the transmission medium;

intensity demodulating the intensity modulated frequency modulated communications signal; and

frequency demodulating the frequency modulated communications signal.

15. The method of claim 14, wherein intensity demodulating comprises intensity demodulating with a photodiode.

16. A computer readable storage medium comprising:

logic configured to frequency modulate a communications signal;

logic configured to intensity modulate an optical signal with the frequency modulated (FM) communications signal; and

logic configured to apply the intensity modulated optical signal to a transmission medium.

17. The computer readable storage medium of claim 16, wherein the logic configured to frequency modulate comprises logic configured to modulate on a digital signal processor.

18. The computer readable storage medium of claim 16, further comprising:

logic configured to receive the intensity modulated frequency modulated communications signal from the transmission medium;

logic configured to intensity demodulate the intensity modulated frequency modulated communications signal; and

logic configured to frequency demodulate the frequency modulated communications signal.

19. The computer readable storage medium of claim 18, wherein the logic configured to frequency demodulate comprises logic configured to demodulate on a digital signal processor.