Equalizer for limited intersymbol interference

Patent metadata

Field	Value
Publication number	US-10075286-B1
Application number	US-201715687364-A
Country	US
Kind code	B1
Filing date	Aug 25, 2017
Priority date	Mar 13, 2017
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

Disclosed is a mechanism for limiting Intersymbol Interference (ISI) when measuring uncorrelated jitter in a test and measurement system. A waveform is obtained that describes a signal. Such waveform may be obtained from memory. A processor then extracts a signal pulse from the waveform. The processor selects a window function based on a shape of the signal pulse. Further, the processor applies the window function to the signal pulse to remove ISI outside a window of the window function while measuring waveform jitter. The window function may be applied by applying the window function to the signal pulse to obtain a target pulse. A linear equalizer is then generated that results in the target pulse when convolved with the signal pulse. The linear equalizer is then applied to the waveform to limit ISI for jitter measurement.

First claim

I claim:

1. A test and measurement system comprising:
an input port for receiving an input signal;
a waveform memory for a waveform describing the input signal; and
a processor coupled to the waveform memory, the processor configured to:
extract a signal pulse from the waveform;
select a window function based on a shape of the signal pulse; and
apply the window function to the signal pulse to remove Intersymbol Interference (ISI) outside a window of the window function.

2. The test and measurement system of claim 1 , wherein the processor applies the window function to the signal pulse by:
applying the window function to the signal pulse to obtain a target pulse;
generating a linear equalizer that, when convolved with the signal pulse, results in the target pulse; and
applying the linear equalizer to the waveform.

3. The test and measurement system of claim 2 , wherein the window function is applied to the signal pulse by employing point by point multiplication.

4. The test and measurement system of claim 2 , wherein the linear equalizer is generated according to:
h original *h equalizer =h target ,

where h original denotes the signal pulse, h equalizer denotes the linear equalizer and h target denotes the target pulse.

5. The test and measurement system of claim 1 , wherein the signal pulse is extracted from the waveform by linear pulse extraction.

6. The test and measurement system of claim 1 , wherein the window function is assigned a length of three bit periods.

7. The test and measurement system of claim 1 , wherein the window function is selected as a Tukey window.

8. A method comprising:
obtaining a waveform describing a signal from a memory;
extracting, via a processor, a signal pulse from the waveform;
selecting, by the processor, a window function based on a shape of the signal pulse; and
applying, by the processor, the window function to the signal pulse to remove Intersymbol Interference (ISI) outside a window of the window function.

9. The method of claim 8 , wherein the window function is applied to the signal pulse by:
applying the window function to the signal pulse to obtain a target pulse;
generating a linear equalizer that, when convolved with the signal pulse, results in the target pulse; and
applying the linear equalizer to the waveform.

10. The method of claim 9 , wherein the window function is applied to the signal pulse by employing point by point multiplication.

11. The method of claim 9 , wherein the linear equalizer is generated according to:
h original *h equalizer =h target ,

where h original denotes the signal pulse, h equalizer denotes the linear equalizer and h target denotes the target pulse.

12. The method of claim 8 , wherein the signal pulse is extracted from the waveform by linear pulse extraction.

13. The method of claim 8 , wherein the window function is assigned a length of three bit periods.

14. The method of claim 8 , wherein the window function is selected as a Tukey window.

15. A non-transitory computer readable medium for storing a computer program product comprising instructions that, when executed by a processor of a test and measurement system, cause the test and measurement system to:
obtain a waveform describing a signal from a memory;
extract a signal pulse from the waveform;
select a window function based on a shape of the signal pulse; and
apply the window function to the signal pulse to remove Intersymbol Interference (ISI) outside a window of the window function.

16. The non-transitory computer readable medium of claim 15 , wherein the window function is applied to the signal pulse by:
applying the window function to the signal pulse to obtain a target pulse;
generating a linear equalizer that, when convolved with the signal pulse, results in the target pulse; and
applying the linear equalizer to the waveform.

17. The non-transitory computer readable medium of claim 16 , wherein the window function is applied to the signal pulse by employing point by point multiplication.

18. The non-transitory computer readable medium of claim 16 , wherein the linear equalizer is generated according to:
h original *h equalizer =h target ,

where h original denotes the signal pulse, h equalizer denotes the linear equalizer and h target denotes the target pulse.

19. The non-transitory computer readable medium of claim 15 , wherein the window function is assigned a length of three bit periods.

20. The non-transitory computer readable medium of claim 15 , wherein the window function is selected as a Tukey window.

Assignees

• Tektronix Inc

Inventors

• Tan Kan

Classifications

• H04L1/205

  jitter monitoring · CPC title

• G01R31/2822

  of microwave or radiofrequency circuits (of attenuation, gain, e.g. using network analyzers G01R27/28) · CPC title

• H04L7/0331 Primary

  with a digital phase-locked loop [PLL] processing binary samples, e.g. add/subtract logic for correction of receiver clock (H04L7/0337 takes precedence) · CPC title

• G01R13/02

  for displaying measured electric variables in digital form · CPC title

• H04L25/03019

  adaptive, i.e. capable of adjustment during data reception · CPC title