Method for equalizing a digital signal through removal of data dependent jitter
First Claim
1. A method of removing data dependent jitter from a symbolic representation of a digital signal, the method comprising the steps of:
- (a) digitizing a digital signal of interest to create a sequence of sampled values;
(b) processing the sampled values of Step (a) to form an Acquisition Record that is a symbolic representation of the time variant behavior of digital signal of interest;
(c) identifying, for each bit in the waveform of the digital signal of interest whose time variant behavior is represented in the Acquisition Record of Step (b), a respectively associated amount of data dependent jitter that is known to be associated with such each bit;
(d) modifying the Acquisition Record of Step (b) to remove from the symbolic representation of each bit therein the respectively associated amount of data dependent jitter identified in Step (c); and
(e) supplying to a using environment the modified Acquisition Record of Step (d).
2 Assignments
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Accused Products
Abstract
Equalized Acquisition Record are prepared from Original Acquisition Records reflecting Total Jitter and from an existing description of DDJ. Removal of timing DDJ alters the locations of edges associated with data events. Voltage DDJ adjusts the asserted voltage in the central portion of a Unit Interval. One technique for equalizing timing jitter variably interpolates along the existing Original Acquisition Record to discover plausible new voltage values to assign to existing sample locations along the time axis. Another technique construes the desired amount of correction for each data event as an impulse that is applied to a Finite Impulse Response Filter whose output is a Voltage Correction Waveform having a smoothed voltage excursion. Time variant voltage values output from the Finite Impulse Response Filter are collected into a Voltage Correction Waveform Record having entry times found in the Original Acquisition Record. An entry by entry addition of these two Records produces the Equalized Acquisition Record.
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Citations
16 Claims
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1. A method of removing data dependent jitter from a symbolic representation of a digital signal, the method comprising the steps of:
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(a) digitizing a digital signal of interest to create a sequence of sampled values;
(b) processing the sampled values of Step (a) to form an Acquisition Record that is a symbolic representation of the time variant behavior of digital signal of interest;
(c) identifying, for each bit in the waveform of the digital signal of interest whose time variant behavior is represented in the Acquisition Record of Step (b), a respectively associated amount of data dependent jitter that is known to be associated with such each bit;
(d) modifying the Acquisition Record of Step (b) to remove from the symbolic representation of each bit therein the respectively associated amount of data dependent jitter identified in Step (c); and
(e) supplying to a using environment the modified Acquisition Record of Step (d). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of relocating in time by Δ
- t the position of a waveform feature contained in a symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced apart in time, the method comprising the steps of;
(a) for a selected number of consecutive sampled voltage values within which the waveform feature occurs;
(a1) selecting a sampled voltage value old_vk whose associated position in time is old_tk;
(a2) interpolating between sampled voltage values among the vi to find new_vk whose associated position in time new_tk is Δ
t different from old_tk;
(a3) replacing old_vk with new_vk to alter the symbolic description of the waveform;
(b) subsequent to Steps (a1-a3), using the altered description of the waveform in place of its original unaltered description. - View Dependent Claims (10, 11, 12)
- t the position of a waveform feature contained in a symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced apart in time, the method comprising the steps of;
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13. A method of relocating in time by Δ
- t the position of a waveform feature contained in an original symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced δ
t apart in time along a time axis, the method comprising the steps of;
(a) for a selected number of consecutive sampled voltage values within which the waveform feature occurs, filtering Δ
t with a filter whose transfer function produces a symbolic description of a compensatory time domain waveform of values filtered_Δ
v that are equally spaced δ
t apart in time along the time axis and coincident with the time values for the symbolic description of the waveform, maximal at the location in time describing the center of the waveform feature to be relocated and minimal at locations in time on either side of that waveform feature;
(b) subsequent to Step (a), adding each filtered_Δ
v in the symbolic description of the compensatory time domain waveform to a corresponding vi in the original symbolic description of the waveform to produce an altered symbolic description. - View Dependent Claims (14)
- t the position of a waveform feature contained in an original symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced δ
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15. A method of relocating in voltage by Δ
- v the position of a waveform feature contained in an original symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced δ
t apart in time along a time axis, the method comprising the steps of;
(a) for a selected number of consecutive sampled voltage values within which the waveform feature occurs, filtering Δ
v with a filter whose transfer function produces a symbolic description of a compensatory time domain waveform of values filtered_Δ
v that are equally spaced δ
t apart in time along the time axis and coincident with the time values for the symbolic description of the waveform, maximal at the location in time describing the center of the waveform feature to be relocated and minimal at locations in time on either side of that waveform feature;
(b) subsequent to Step (a), adding each filtered_Δ
v in the symbolic description of the compensatory time domain waveform to a corresponding vi in the original symbolic description of the waveform to produce an altered symbolic description. - View Dependent Claims (16)
- v the position of a waveform feature contained in an original symbolic description of a waveform that is a sequence of sampled voltage values vi equally spaced δ
Specification