Method and system for signal emulation

• US 8,605,566 B2
• Filed: 08/25/2010
• Issued: 12/10/2013
• Est. Priority Date: 08/07/2003
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Schmukler, Bruce C., Raghavan, Arvind, Nami, Ziba, Peddi, Jyothi Emmanuel, Kim, Andrew Joo, Vrazel, Michael G., Summers, Charles E.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US12/868,190
• Publication Number:
  US 20110069604A1
• Time in Patent Office: 1,203 Days
• Field of Search: 370/201, 370/286, 370/290, 370/291, 370/292
• US Class Current: 370/201
• CPC Class Codes: H03H 11/265 with adjustable delay
• CPC Class Codes: H03H 15/00 Transversal filters electromechanical filters H03H9/46, H03H9/70
• CPC Class Codes: H03H 2015/007 Programmable filters
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04B 3/238 using initial training sequence
• CPC Class Codes: H04B 3/32 Reducing cross-talk, e.g. by compensating
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30

Abstract

A circuit can process a sample of a signal to emulate, simulate, or model an effect on the signal. Thus, an emulation circuit can produce a representation of a real-world signal transformation by processing the signal according to one or more signal processing parameters that are characteristic of the real-world signal transformation. The emulation circuit can apply analog signal processing and/or mixed signal processing to the signal. The signal processing can comprise feeding the signal through two signal paths, each having a different delay, and creating a weighted sum of the outputs of the two signal paths. The signal processing can also (or alternatively) comprise routing the signal through a network of delay elements, wherein a bank of switching or routing elements determines the route and thus the resulting delay.

Claims

1. A communication system comprising:

an aggressor communication channel;

a victim communication channel; and

a crosstalk cancellation system, coupled between the aggressor communication channel and the victim communication channel, comprising;

an emulation channel that comprises;

a tap connected to the aggressor communication channel;

a limiting amplifier electrically coupled to an output of the tap;

a crosstalk modeling filter that is coupled to an output of the limiting amplifier and that comprises an adjustable delay and a filter arranged in electrical series with one another; and

a port coupling an output of the crosstalk modeling filter towards the victim communication channel; and

a control module comprising;

an input electrically coupled to the victim communication channel;

a delay control output electrically coupled to the adjustable delay; and

a filter control output electrically coupled to the filter.

2. The communication system of claim 1, further comprising a backplane-to-line card connector that comprises the aggressor communication channel and the victim communication channel.

3. The communication system of claim 1, further comprising a backplane that comprises the aggressor communication channel and the victim communication channel.

4. The communication system of claim 1, wherein the communication system is rack-mounted and comprises a backplane, and wherein the crosstalk cancellation system is operable to suppress crosstalk in the rack-mounted communication system.

5. The communication system of claim 1, further comprising a first line card and a second line card, wherein the aggressor communication channel and the victim communication channel each extends between the first line card and the second line card.

6. The communication system of claim 1, wherein the aggressor communication channel and the victim communication channel are physically separated from one another.

7. The communication system of claim 1, wherein the communication system comprises a rack-mounted digital communication system that comprises a backplane and a plurality of line cards connected to the backplane,

wherein at least one of the aggressor communication channel and the victim communication channel extends to one of the line cards.

8. The communication system of claim 1, wherein the control module is operable to refine the emulation channel for crosstalk cancellation via feeding delay control signals to the adjustable delay over the delay control output and feeding filter control signals to control gains on variable coefficient amplifiers of the filter.

9. The communication system of claim 1, wherein the filter comprises a plurality of delay elements, each operative to compensate for roll-off by applying frequency-dependent gain.

10. A system for emulating a transformation of a digital signal, comprising:

a tap operable to obtain a sample of the digital signal from a signal channel;

a delay module, electrically coupled to an output of the tap, operable to receive the sample and to apply a selectable level of delay to the sample;

a programmable filter, electrically connected in series with the delay module, operable to shape the sample according to an adjustable filtering parameter; and

a port, electrically coupled to the programmable filter, operable to output an emulation of the transformation that comprises the shaped and delayed sample,

wherein the programmable filter comprises a plurality of delay elements.

11. The system of claim 10, further comprising a controller that is operable to adjust the filtering parameter to refine emulation of the transformation.

12. The system of claim 10, further comprising a control module that is operable to adjust delay of the delay module to refine emulation of the transformation.

13. The system of claim 10, wherein the signal channel comprises an aggressor communication channel and wherein the port is coupled to a victim communication channel disposed adjacent the aggressor communication channel.

14. The system of claim 13, comprising a rack-mounted digital communication system that comprises at least part of the victim communication channel and at least part of the aggressor communication channel.

15. The system of claim 10, wherein each delay element is operable to compensate for roll-off via applying frequency-dependent gain to the sample.

16. A system that emulates a transformation of a digital signal, the system comprising:

a tap operable to sample the digital signal from a communication channel;

a delay module connected to the tap to receive a sample of the digital signal from the tap, the delay module operable to delay the sample by a selectable amount of delay;

a programmable filter connected in electrical series with the delay module, the programmable filter operable to shape the sample according to an adjustable filtering parameter; and

a port electrically coupled to the programmable filter, the port operable to output an emulation of the transformation comprising the shaped and delayed sample.

17. The system of claim 16, further comprising a rack, a plurality of line cards mounted in the rack, and a backplane providing the line cards connectivity,

wherein the communication channel comprises an aggressor communication channel, and

wherein the backplane comprises at least a section of the aggressor communication channel.

18. The system of claim 17, further comprising a victim communication channel oriented with respect to the aggressor communication channel to receive crosstalk from the aggressor communication channel,

wherein the backplane comprises at least a section of the victim communication channel.

19. A method for shaping a digital signal that carries information by modulation between discrete signals levels, the method comprising the steps of:

reinforcing discrete signal levels of the digital signal;

shaping the reinforced digital signal according to an adjustable filtering parameter with an adjustable filter that comprises a plurality of delay elements; and

compensating for roll-off of the sampled digital signal.

20. The method of claim 19, further comprising the steps of:

applying a delay to the digital signal; and

dynamically adjusting the delay to refine suppression of crosstalk caused by the digital signal.

21. The method of claim 19, wherein the digital signal transmits in a rack-mounted digital communication system during the shaping step.

22. The method of claim 19, wherein the shaping step comprises transmitting the digital signal over a backplane.

23. The method of claim 19, further comprising the step of:

in response to adjusting the adjustable filtering parameter, refining crosstalk cancellation occurring at a line card.

24. A method for emulating a transformation of a digital signal transmitting on a communication system, the method comprising the steps of:

obtaining a sample of the digital signal from a first communication channel of the communication system;

buffering the communication channel from an emulation channel via processing the sample;

applying to the processed sample a level of delay that is dynamically refined;

shaping the processed sample according to at least one filtering parameter that is dynamically refined; and

applying to a second communication channel of the communication system an emulation of the transformation that comprises the shaped and delayed sample.

25. The method of claim 24, wherein the first communication channel comprises an aggressor communication channel disposed in a rack-mounted digital communication system, and

wherein the second communication channel comprises a victim communication channel disposed in the rack-mounted digital communication system.

26. The method of claim 24, wherein the first communication channel and the second communication channel extend through a back plane.

27. The method of claim 24, wherein a line card comprises at least a portion of the first communication channel and at least a portion of the second communication channel, and

wherein the first communication channel and the second communication channel are physically separated.

28. The method of claim 24, wherein a backplane-to-line card connector comprises the aggressor communication channel and the victim communication channel.