Method and system for reducing radiated emissions from a communications channel

• US 20070253495A1
• Filed: 04/26/2007
• Published: 11/01/2007
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Kim, Andrew Joo
• Granted Patent: US 9,252,983 B2
• Time in Patent Office: Days
• US Class Current: 375/259
• CPC Class Codes: H04L 25/02 Details ; arrangements for supplying electrical power along data transmission lines systems for transmitting signals via power distribution lines H04B3/54
• CPC Class Codes: H04L 25/0288 the shape being matched to the transmission line pre-equalisation per se H04L25/03343
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/03828 Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties partial response systems H04L25/497
• CPC Class Codes: H04L 25/03878 Line equalisers; line build-out devices

Abstract

A communications channel may radiate energy undesirably, for example in the form of electromagnetic radiation, when a communication signal transmits over the communications channel. Processing the signal before and after transmission on the communications channel can reduce the level of radiated energy. Signal processing in advance of transmission over the communications channel can transform the communication signal into a waveform that has a reduced propensity to emit radiated energy during transmission over the communications channel. Exemplary signal transformations can involve applying either frequency-selective or broadband attenuation to the communication signal. Following transmission of the waveform over the communications channel, the original communication signal can be restored via reversing the signal transformation. The reverse transformation can comprise applying frequency-selective gain or broadband gain to the transmitted waveform.

Claims

1. A method for reducing electromagnetic emissions associated with transmission of a signal from a first end of a communications channel to a second end of the communications channel, comprising the steps of:

attenuating components of the signal at the first end of the communications channel; and

restoring the attenuated components of the signal at the second end of the communications channel.

2. The method of claim 1, further comprising the step of transmitting the signal having the attenuated components from the first end to the second end,

wherein restoring the attenuated components comprises processing the transmitted signal at the second end of the communications channel.

3. The method of claim 1, wherein the step of attenuating components of the signal comprises applying broadband attenuation to the signal.

4. The method of claim 1, wherein the signal has a signal spectrum, and

wherein the step of attenuating components of the signal comprises attenuating a full range of the signal spectrum.

5. The method of claim 1, wherein the signal consists of signal frequencies, and

wherein the attenuating step comprises attenuating essentially all of the signal frequencies.

6. The method of claim 1, wherein the signal consists of signal frequencies, and wherein the attenuating step comprises applying essentially uniform attenuation across the signal frequencies.

7. The method of claim 1, wherein restoring the attenuated components of the signal comprises applying a broadband gain to the signal following transmission over the communications channel.

8. The method of claim 1, wherein restoring the attenuated components of the signal comprises applying limiting amplification to the signal following transmission over the communications channel.

9. The method of claim 1, wherein the step of attenuating components of the signal comprises passing signal components having a frequency below a frequency threshold and attenuating signal components having a frequency above the frequency threshold.

10. The method of claim 1, wherein attenuating components of the signal comprises processing the signal with a low-pass filter.

11. The method of claim 1, wherein attenuating components of the signal comprises generating a second signal that exhibits a significant level of intersymbol interference,

wherein the method further comprises the step of transmitting the second signal over the communications channel, and

wherein the restoring step comprises processing the transmitted second signal.

12. The method of claim 1, wherein the attenuating step comprises processing the signal with a low-pass filter, and

wherein the restoring step comprises countering signal distortion induced by the low-pass filter via processing the signal at the second end of the communications channel with a high-pass filter or an equalizer.

13. The method of claim 1, wherein the attenuating step comprises generating a second signal, having a significant level of intersymbol interference, in response to attenuating signal frequencies above a threshold frequency and passing signal frequencies below the threshold frequency, and

wherein the method further comprises the step of transmitting the second signal over the communications channel to the second end, and

wherein the restoring step comprises reducing the intersymbol interference in response to amplifying the attenuated signal frequencies above the threshold frequency.

14. The method of claim 1, wherein the communications channel comprises copper cabling.

15. The method of claim 1, wherein the communications channel comprises a conductive trace on a printed circuit board.

16. The method of claim 1, wherein the communications channel comprises a plurality of communication lines extending between the first end and the second end,

wherein the attenuating step comprises attenuating components of a respective signal for each of the communications lines at the first end, and

wherein the restoring step comprises restoring the attenuated components of the respective signal for each of the communications lines at the second end.

17. A method for upgrading a communications channel to provide a reduction in radiated emissions, comprising the steps of:

disposing a transmitter at a first end of the communications channel and a receiver at a second end of the communications channel;

coupling a signal attenuator between an output of the transmitter and the first end of the communications channel; and

coupling a signal amplifier between the second end of the communications channel and the receiver.

18. The method of claim 17, further comprising the steps of:

the transmitter feeding a communication signal to the signal attenuator;

the signal attenuator attenuating frequencies of the communication signal that are above a threshold frequency and passing frequencies of the communication signal that are below the threshold frequency;

coupling the attenuated and passed frequencies to the first end of the communications channel;

the communications channel carrying the attenuated and passed frequencies to the signal amplifier;

the signal amplifier amplifying the attenuated frequencies; and

the receiver decoding the communication signal in response to receiving the amplified frequencies and the passed frequencies.

19. The method of claim 17, wherein the communications channel comprises an open conductor.

20. The method of claim 17, further comprising the step of supporting an increased level of communication bandwidth on the communications channel,

wherein the communications channel has a physical state that remains essentially constant before and after the upgrade.

21. The method of claim 17, wherein the communications channel has a first physical state prior to the upgrade and a second physical state following the upgrade, and

wherein the first physical state and the second physical state are essentially uniform with respect to one another.

22. The method of claim 17, wherein the communications channel has essentially the same shielding configuration prior to and following the upgrade.

23. A communication method, comprising the steps of:

providing a first communication signal having a first eye diagram;

providing a second communication signal, having a second eye diagram, in response to attenuating a selected frequency of the first communication signal;

transmitting the second communication signal from a first end of a signal path to a second end of the signal path; and

providing a third communication signal, having a third eye diagram, in response to amplifying the selected frequency of the transmitted second communication signal.

24. The communication method of claim 23, wherein the first eye diagram is more open than the second eye diagram, and wherein the third eye diagram is more open than the second eye diagram.

25. The communication method of claim 23, wherein the second eye diagram is degraded relative to the first and the second eye diagrams.

26. The communication method of claim 23, wherein the first and third eye diagrams indicate acceptable levels of intersymbol interference and wherein the second eye diagram indicates a substantial level of intersymbol interference.

27. The communication method of claim 23, wherein the first, second, and third communication signals carry like data, and

wherein amplifying the selected frequency of the transmitted second communication signal comprises applying gain to the selected frequency at the second end of the signal path.

28. A communication system comprising:

a first signal processor for coupling between an output of a transmitter and an first end of a transmission line; and

a second signal processor for coupling between a second end of the transmission line and a receiver,

wherein the first signal processor is operative to;

receive a first signal from the transmitter; and

produce a second signal, in response to attenuating frequencies of the first signal, for transmission on the transmission line, and

wherein the second signal processor is operative to;

receive the second signal from the transmission line; and

reproduce the first signal, in response to amplifying the attenuated frequencies, for reception by the receiver.

29. The communication method of claim 28, wherein the first signal processor comprises a low-pass filter and wherein the second signal processor comprises an equalizer.

30. The communication method of claim 28, wherein the first signal processor comprises a frequency selective filter and wherein the second signal process comprises a limiting amplifier or a high-pass filter.

31. The communication method of claim 28, wherein each of the first signal processor and the second signal processor comprises an integrated circuit.

32. The communication method of claim 28, wherein the operability to reproduce the first signal comprises an operability to produce a likeness of the first signal.

33. The communication method of claim 28, wherein the first signal carries an information payload, and

wherein reproducing the first signal comprises generating a third signal that carries the information payload with acceptable signal integrity.

34. A communication method, comprising the steps of:

providing a digital signal having a propensity to emit electromagnetic radiation in connection with transmission on a communication path;

reducing the propensity to emit electromagnetic radiation in response to transforming the digital signal; and

following transmission of the transformed digital signal on the communication path, essentially restoring the digital signal in response to reversing the transformation.

35. The communication method of claim 34, wherein transforming the digital signal comprises suppressing selected frequency components of the digital signal, and wherein reversing the transformation comprises amplifying the selected frequency components.

36. The communication method of claim 34, wherein the transformed digital signal exhibits a degraded level of intersymbol interference relative to the digital signal and relative to the restored digital signal.

37. The communication method of claim 34, wherein the transformed digital signal exhibits a degraded eye diagram relative to the digital signal and relative to the restored digital signal.

38. A signal processing method, comprising the steps of:

receiving a first signal that conveys information and that has a propensity to emit radiation during transmission over a communications channel; and

in preparation for conveying the information over the communications channel, transforming the first signal into a second signal having a reduced propensity to emit radiation during transmission over the communications channel.

39. The signal processing method of claim 38, wherein transforming the first signal comprises applying a signal transformation, and

wherein the method further comprises the step of identifying the signal transformation to support reversing the signal transformation following transmission of the second signal over the communications channel.

40. The signal processing method of claim 38, wherein the transforming step comprises applying a signal transformation parameter, and

wherein the method further comprises the step of noting the signal processing parameter to facilitate transforming the second signal to a facsimile of the first signal following transmission of the second signal over the communications channel.

41. The signal processing method of claim 38, wherein the first signal comprises a digital signal encoded with the information.

42. The signal processing method of claim 38, wherein transforming the first signal into the second signal comprises reducing a rise time of a digital signal.

43. The signal processing method of claim 38, wherein the first signal comprises a first discrete signal level and a second discrete signal level, and

wherein transforming the first signal into the second signal comprises smoothing a transition between the first discrete signal level and the second discrete signal level.

44. A signal processing system comprising an operable to:

receive from a signal source a communication signal that has a tendency to produce emissions of electromagnetic radiation from a communications channel during transmission of the communication signal over the communications channel;

reduce the tendency in response to attenuating a selected frequency range of the received communication signal; and

output the attenuated communication signal for transmission over the communications channel.

45. The signal processing system of claim 44, wherein the selected frequency range spans essentially all frequencies of the communication signal.

47. The signal processing system of claim 44, wherein the communications signal comprises the selected frequency range and another frequency range, and

wherein the signal processing system further comprises an operability to pass the another frequency range.

48. The signal processing system of claim 44, wherein the communications signal comprises the selected frequency range and another frequency range that is below the selected frequency range, and

wherein the signal processing system is further operable to pass the another frequency range.

49. The signal processing system of claim 44, further comprising an operability to:

process the output communication signal; and

amplify the attenuated selected frequency range.

50. The signal processing system of claim 44, wherein the communications channel comprises a first end for receiving the output communication signal and a second end, and

wherein the signal processing system further comprises an operability to amplify the attenuated frequency range at the second end.

51. The signal processing system of claim 44, wherein the communications channel comprises a first end and a second end,

wherein outputting the attenuated communication signal for transmission over the communications channel comprises feeding the attenuated communications signal to the first end, and

wherein the signal processing system is further operable to receive a second communication signal arriving at the first end and to restore at least one attenuated frequency of the received second communication signal.

46. The signal processing system of claim 46, wherein the communication signal comprises the selected frequency range and another frequency range.

52. A method for reducing a radiated emission profile of a communication signal that comprises a first signal component and a second signal component, the method comprising the steps of:

determining that the first signal component contributes more to the radiated emission profile than does the second signal component; and

removing the first signal component from the communication signal in preparation for transmitting the communication signal along a signal path.

53. The method of claim 52, further comprising the step of transmitting the communication signal, with the first signal component removed, along the signal path towards a signal processor that is operative to insert the first signal component.

54. The method of claim 52, wherein the signal path comprises a first end and a second end, and

wherein the method further comprising the step of

in response to the removing step, feeding the communication signal onto the first end of the signal path towards a integrated circuit that is disposed at the second end of the signal path and that is operative to restore the removed first signal component.

55. The method of claim 52, wherein the removing step comprises removing the first signal component from the communication signal in preparation for transmission of the communication signal over the signal path, with an expectation that the first signal component will be added to the communication signal following the transmission to facilitate signal decoding.

56. The method of claim 52, wherein removing the first signal component from the communication signal comprises retaining at least some residual amount of the first signal component in the communication signal.

57. A signal processing method, comprising the steps of:

receiving a communication signal that has undergone a transformation to reduce radiated emissions during transmission over a communications channel; and

processing the received communication signal to reverse the transformation.

58. The signal processing method of claim 57, wherein the transformation comprises an attenuation of a selected component of the communication signal, and

wherein processing the received communication signal comprises amplifying the selected component.

59. The signal processing method of claim 57, wherein the transformation comprises an attenuation of a selected frequency band of the communication signal, and

wherein processing the received communication signal comprises amplifying the selected frequency band.

60. A communication method, comprising the steps of:

receiving a communication signal from which a signal component has been attenuated in advance of transmitting the communication signal over a communications channel; and

amplifying the attenuated signal component.

61. The communication method of claim 60, wherein amplifying the attenuated signal component comprises processing the received communication signal.

62. The communication method of claim 60, wherein the signal component is operative to increase radiated emissions during transmission over the communications channel and to promote extracting information from the communication signal.

63. The communication method of claim 60, wherein attenuating the signal component comprises reducing radiated emissions associated with transmitting the communication signal over the communications channel, and

wherein amplifying the attenuated signal component comprises enhancing sensitivity of a detector to the communication signal.

64. A communication system comprising an integrated circuit,

the integrated circuit operable to amplify a component of a communication signal that has been attenuated in advance of transmission of the communication signal over a communications channel,

wherein the component of the communication signal is operable to induce radiated emissions associated with transmission over the communications channel.

65. The communication system of claim 64, wherein the component of the communication signal is further operable to promote extracting information from the communication signal.

66. The communication system of claim 64, wherein the component of the communication signal is further operable to distinguish between digital states of the communication signal.

67. The communication system of claim 64, wherein the component of the communication signal is further operable to distinguish between discrete signal levels of the communication signal.