MODULATION ANALYSIS AND DISTORTION IDENTIFICATION

• US 20140241409A1
• Filed: 02/24/2014
• Published: 08/28/2014
• Est. Priority Date: 02/05/2010
• Status: Active Grant

• Current Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Original Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Inventors: Wolcott, Lawrence D., Chang, Phillip F.
• Granted Patent: US 9,602,518 B2
• Time in Patent Office: Days
• US Class Current: 375/224
• CPC Class Codes: H04L 2025/0342 QAM
• CPC Class Codes: H04L 2025/03808 Transmission of equaliser coefficients
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/03 Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
• CPC Class Codes: H04L 25/03019 adaptive, i.e. capable of adjustment during data reception
• CPC Class Codes: H04L 43/0823 Errors, e.g. transmission errors
• CPC Class Codes: H04L 63/107 wherein the security policies are location-dependent, e.g. entities privileges depend on current location or allowing specific operations only from locally connected terminals
• CPC Class Codes: H04L 67/52 specially adapted for the location of the user terminal

Abstract

An apparatus, method, computer readable medium, and system are provided to generate a symbol placement associated with a transmission scheme by transforming a retrieved set of equalization coefficients. Symbols included in the symbol placement may be analyzed and quantified in terms of their distance from a decision boundary. Symbols may be synthesized on an iterative basis in order to obtain visibility into the underlying performance of the transmission scheme over time. If equalization is unable to reduce a signal impairment below a threshold value within a predetermined amount of time, then a determination may be made that a non-linear distortion source is present in a network or communication system. Signals received from a plurality of user terminals may be compared with one another in order to determine a probable location or cause of the non-linear distortion.

Claims

1-20. -20. (canceled)

21. A method comprising:

generating, by a computer device, a symbol placement associated with a transmission scheme based on a set of pre-equalization coefficients; and

updating the symbol placement associated with the transmission scheme responsive to retrieving a second set of equalization coefficients.

22. The method of claim 21, further comprising:

generating a constellation pattern based on the symbol placement.

23. The method of claim 22, further comprising:

displaying the generated constellation pattern on a display device.

24. The method of claim 21, further comprising:

transmitting to a user terminal, based on the generated symbol placement, a status message comprising information about one or more symbols likely to be subject of demodulation error at a receiver.

25. The method of claim 21, further comprising:

calculating at least one of a modulation error ratio (MER) and an error vector based on the symbol placement.

26. The method of claim 21, further comprising:

quantifying a distortion present in a communication channel in terms of at least one of amplitude over an operating frequency range and phase over the operating frequency range.

27. The method of claim 21, further comprising:

calculating, by the computer device for at least one of a plurality of generated symbols included in the symbol placement, a position relative to at least one of a plurality of corresponding ideal symbols; and

communicating, by the computer device, the at least one calculated position.

28. A method comprising:

determining, by the computer device, that a non-linear distortion source is present in a communication channel connected to at least one user terminal after a determination that equalization is unable to reduce a signal impairment associated with a signal received from the user terminal below a threshold value within a predetermined amount of time.

29. The method of claim 28, further comprising:

determining that equalization is unable to reduce, within the predetermined amount of time, at least one signal impairment associated with at least one signal received from the at least one user terminal below the threshold value; and

determining a probable location of the non-linear distortion source by identifying a relationship between a user terminal associated with the at least one signal impairment and at least one other terminal not associated with the at least one signal impairments.

30. The method of claim 29, further comprising:

generating at least one status message comprising a map identifying a geographic region where the at least one user terminal is located.

31. The method of claim 29, further comprising:

generating at least one status message comprising an identification of at least one device located at the probable location of the non-linear distortion source.

32. A method comprising:

transforming, by a computer device, a set of equalization coefficients into a symbol placement value associated with a transmission scheme.

33. The method of claim 32, comprising:

transforming the set of equalization coefficients into a plurality of symbol placement values associated with the transmission scheme; and

generating a status message specifying which of the plurality of symbol values is more likely to be subject to a demodulation error at a receiver.

34. The method of claim 32, comprising:

generating a symbol placement associated with the symbol placement value.

35. The method of claim 32, comprising:

transmitting, to a user terminal based on the symbol placement value, a request to schedule an appointment or guidance on how to alter the user terminal or a component associated with the user terminal.

36. The method of claim 32, comprising:

transmitting, to a user terminal based on the symbol placement value, a distance from the user terminal to a likely source of a demodulation error.

37. The method of claim 32, comprising:

generating, by the computer device, a constellation pattern based on the symbol placement value.

38. The method of claim 32, wherein transforming a set of equalization coefficients into a symbol placement value comprises calculating at least one of a modulation error ratio (MER) and an error vector corresponding to a symbol placement.

39. The method of claim 32, comprising:

quantifying a distortion present in a communication channel associated with the symbol placement value in terms of amplitude over an operating frequency range or phase over the operating frequency range.

40. The method of claim 32, comprising:

updating the symbol placement value associated with the transmission scheme responsive to retrieving a second set of equalization coefficients.