Time alignment of signals

• US 20040240585A1
• Filed: 07/02/2004
• Published: 12/02/2004
• Est. Priority Date: 06/15/2001
• Status: Abandoned Application

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Bishop, John, Smithson, Antony James, Bennett, Richard Michael
• Application Number:
  US10/480,892
• Publication Number:
  US 20040240585A1
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3288 to compensate phase shift as a function of the amplitude

Abstract

Envelope-type signals are detected for the input and output of a linearised amplifier (12). The variance of the signal obtained from the output is measured and a variable delay (24) between the detected signals is adjusted to minimise the variance. The value of the variable delay then gives the propagation delays through the linearised amplifier. Further envelope-type signal from the output and interpolation can be used to enhance the adjustment of the delay to minimise variance.

Claims

1-27. -27. (canceled)

28. A method for processing signals in a signal processing apparatus adapted to generate an output signal from an input signal, the method comprising:

generating, over multiple sampling times, a plurality of samples of the input signal;

generating, over multiple sampling times, a plurality of samples of the output signal;

adjusting a variable delay in the signal processing apparatus to reduce a variance measure based on the input and output samples.

29. The invention of claim 28, wherein the signal processing apparatus comprises:

an amplifier adapted to generate the output signal; and

a predistorter adapted to pre-distort the input signal prior to amplification by the amplifier to linearize the output signal.

30. The invention of claim 28, further comprising determining a propagation delay through the signal processing apparatus based on the adjustment of the variable delay.

31. The invention of claim 30, further comprising adjusting the propagation delay through the signal processing apparatus.

32. The invention of claim 31, wherein the propagation delay through the signal processing apparatus is adjusted to synchronize operation of the signal processing apparatus with operation of one or more other signal processing apparatuses.

33. The invention of claim 28, wherein:

each input signal sample comprises an I_in component and a Q_in component;

each output signal sample comprises an I_out component and a Q_out component;

at each sampling time, one or more assay signals are generated from the components of the input and output signal samples; and

the variance measure is generated using at least one of the one or more assay signals.

34. The invention of claim 33, wherein:

the one or more assay signals comprise an assay signal E_isense based on a sum of (i) a product of the I_in and I_out components and (ii) a product of the Q_in and Q_out components;

a first variance measure is generated using the assay signal E_isense; and

the variable delay is adjusted based on the first variance measure.

35. The invention of claim 34, wherein:

the one or more assay signals further comprise an assay signal E_qsense based on a difference between (i) a product of the I_in and Q_out components and (ii) a product of the Q_in and I_out components;

a second variance measure is generated using the assay signal E_qsense; and

the variable delay is adjusted based on the first and second variance measures.

36. The invention of claim 33, wherein:

the one or more assay signals comprise an assay signal E_qsense based on a difference between (i) a product of the I_in and Q_out components and (ii) a product of the Q_in and I_out components;

a first variance measure is generated using the assay signal E_qsense; and

the variable delay is adjusted based on the first variance measure.

37. The invention of claim 28, wherein:

each input signal sample comprises an envelope measure for the input signal;

each output signal sample comprises an envelope measure for the output signal; and

the variance measure is generated using the input and output envelope measures.

38. The invention of claim 28, wherein:

the input and output signals are each sampled at a plurality of frequency sub-ranges;

a sub-range variance measure is generated for each of the frequency sub-ranges; and

the variance measure is based on the plurality of sub-range variance measures.

39. The invention of claim 38, wherein the plurality of frequency sub-ranges excludes one or more frequency sub-ranges within the full frequency range of the signal processing apparatus.

40. The invention of claim 39, wherein each excluded frequency sub-range corresponds to a frequency range over which the signal processing apparatus operates in a relatively non-linear manner as compared to the non-excluded frequency sub-ranges.

41. The invention of claim 28, wherein the variance measure is determined by applying a graph-based technique to one or more assay signals generated from the input and output signal samples.

42. The invention of claim 41, wherein the graph-based technique involves interpolation based on an intersection of two straight lines generated from the one or more assay signals.

43. The invention of claim 28, wherein the signal processing apparatus applies (i) the variable delay to one of either the input samples or the output samples and (ii) a fixed delay to the other of either the input samples or the output samples.

44. The invention of claim 43, wherein the signal processing apparatus applies (i) the variable delay to the output samples and (ii) the fixed delay to the input samples.

45. A signal processing apparatus adapted to generate an output signal from an input signal, the signal processing apparatus comprising:

means for generating, over multiple sampling times, a plurality of samples of the input signal;

means for generating, over multiple sampling times, a plurality of samples of the output signal;

means for adjusting a variable delay in the signal processing apparatus to reduce a variance measure based on the input and output samples.

46. A signal processing apparatus adapted to generate an output signal from an input signal, the signal processing apparatus comprising:

an input signal preprocessor adapted to delay samples of the input signal generated over multiple sampling times;

an output signal preprocessor adapted to delay samples of the output signal generated over multiple sampling times;

a correlator adapted to generate one or more assay signals from the input and output samples; and

a delay assessor adapted to adjust a variable delay in at least one of the input and output signal preprocessors to reduce a variance measure based on the one or more assay signals.

47. The invention of claim 46, further comprising

an amplifier adapted to generate the output signal;

and

a predistorter adapted to pre-distort the input signal prior to amplification by the amplifier to linearize the output signal.

48. The invention of claim 46, wherein the delay assessor is further adapted to determine a propagation delay through the signal processing apparatus based on the adjustment of the variable delay.

49. The invention of claim 48, further comprising an adjustable calibration delay adapted to adjust the propagation delay through the signal processing apparatus.

50. The invention of claim 49, wherein the adjustable calibration delay is adapted to be adjusted to synchronize operation of the signal processing apparatus with operation of one or more other signal processing apparatuses.

51. The invention of claim 46, wherein:

each input signal sample comprises an I_in component and a Q_in component;

each output signal sample comprises an I_out component and a Q_out component;

at each sampling time, one or more assay signals are generated from the components of the input and output signal samples; and

the variance measure is generated using at least one of the one or more assay signals.

52. The invention of claim 46, wherein:

the input and output signals are each sampled at a plurality of frequency sub-ranges;

a sub-range variance measure is generated for each of the frequency sub-ranges; and

the variance measure is based on the plurality of sub-range variance measures.

53. The invention of claim 46, wherein:

the output signal preprocessor applies the variable delay to the output signal samples; and

the input signal preprocessor applies a fixed delay to the input signal samples.