Method and apparatus for high-speed data transfer employing self-synchronizing quadrature amplitude modulation

Patent metadata

Field	Value
Publication number	US-10027526-B2
Application number	US-201715425785-A
Country	US
Kind code	B2
Filing date	Feb 6, 2017
Priority date	Mar 5, 2009
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

Methods and apparatus for wired communications are disclosed. A method for transmitting a data stream through a wired communications channel includes encoding the data stream to produce a first baseband modulating signal I(t) and a second baseband modulating signal Q(t) whose amplitudes together represent a time series of complex symbols (I, Q) each selected from a two-dimensional (2-D) constellation of symbols distributed on the phase plane about the origin such that at least one of the baseband modulating signals has a substantially non-zero mean amplitude, modulating the baseband signals I(t) and Q(t) to produce a modulated signal, wherein the I(t) and Q(t) components of the modulated signals are generally fixed in quadrature, and providing the modulated signal to a wired communications channel.

First claim

The invention claimed is:

1. A method for transmitting a data stream through a wired communications channel, comprising:
encoding the data stream to produce a first baseband modulating signal I(t) and a second baseband modulating signal Q(t) whose amplitudes together represent a time series of complex symbols (I, Q) each selected from a two-dimensional (2-D) constellation of symbols distributed on the phase plane about the origin such that at least one of the baseband modulating signals has a substantially non-zero mean amplitude;
modulating the baseband signals I(t) and Q(t) to produce a modulated signal, wherein the I(t) and Q(t) components of the modulated signals are generally fixed in quadrature; and
providing the modulated signal to a wired communications channel.

2. The method of claim 1 , wherein the 2-D symbol constellation is square and disposed asymmetrically about one of the two phase plane axes.

3. The method of claim 1 , wherein the 2-D symbol constellation is rectangular and disposed asymmetrically about one of the two phase plane axes.

4. The method of claim 1 , wherein the 2-D symbol constellation is square and disposed asymmetrically about both of the two phase plane axes.

5. The method of claim 1 , wherein the 2-D symbol constellation is rectangular and disposed asymmetrically about both of the two phase plane axes.

6. The method of claim 1 , wherein the signal channel comprises an electrical conductor.

7. The method of claim 1 , wherein the signal channel comprises an optical fiber.

8. The method of claim 1 , further comprising:
receiving the modulated signal from the wired communications channel;
recovering a clock signal from the modulated signal;
demodulating the received modulated signal; and
providing an output data stream corresponding to the encoded data stream.

9. The method of claim 8 , wherein the signal channel comprises an electrical conductor.

10. The method of claim 8 , wherein the signal channel comprises an optical fiber.

11. The method of claim 1 , further comprising:
receiving, from the wired communications channel, the modulated signal; and
generating a baseband symbol clock from the received modulated signal.

12. The method of claim 1 , further comprising:
receiving the modulated signal from the wired communications channel;
recovering a clock signal from the modulated signal;
demodulating the received modulated signal; and
providing an output data stream corresponding to the encoded data stream;
wherein:
the 2-D symbol constellation is square and disposed asymmetrically about one or both of the two phase plane axes; and
the signal channel comprises an electrical conductor.

13. The method of claim 12 , wherein the modulated signal is generated in a digital pipe inspection camera, the wired communications channel is disposed in a push-cable, and the output data stream is provided in a camera control unit (CCU).

14. The method of claim 1 , wherein the modulated signal is generated in a digital pipe inspection camera, the wired communications channel is disposed in a push-cable.

15. The method of claim 14 , wherein the video data stream is provided as video on a visual display.

16. The method of claim 1 , wherein the data stream comprises a video data stream.

17. The method of claim 1 , wherein the data stream comprises a digital image.

18. The method of claim 1 , wherein the data stream comprises control data.

Assignees

• Seescan Inc
• Seescan Inc

Inventors

• Bench Stephanie M
• Shaffer Roger B

Classifications

• H04L27/3455

  in order to facilitate carrier recovery at the receiver end, e.g. by transmitting a pilot or by using additional signal points to allow the detection of rotations · CPC title

• H04L27/362 Primary

  Modulation using more than one carrier, e.g. with quadrature carriers, separately amplitude modulated (H04L27/366 takes precedence) · CPC title

• H04L27/3818

  using coherent demodulation, i.e. using one or more nominally phase synchronous carriers (H04L27/227 and H04L27/389 take precedence) · CPC title