Systems and methods to adaptively mitigate electro-magnetic interference (EMI) in automotive and industrial communication systems

• US 9,716,529 B1
• Filed: 05/25/2016
• Issued: 07/25/2017
• Est. Priority Date: 06/24/2015
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Gu, Zhenzhong, Cheong, Kok-Wui, Sun, Junqing, Dai, Shaoan, Wu, Xing
• Primary Examiner(s): Tayong, Helene
• Application Number:
  US15/164,391
• Time in Patent Office: 426 Days
• Field of Search: 375232, 375229, 375230
• CPC Class Codes: H04B 3/04 Control of transmission; Equalising
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers
• CPC Class Codes: H04L 25/03885 adaptive
• CPC Class Codes: H04L 25/085 Arrangements for reducing interference in line transmission systems, e.g. by differential transmission

Abstract

A transceiver includes an equalizer, an adaptation module, an error detector, and a controller. The equalizer receives an input signal via the single twisted-pair Ethernet cable, including outputs of an analog front end of the receiver and an echo canceller, to cancel electromagnetic interference from the input signal. The adaptation module adapts parameters of one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on an error in an output of the equalizer due to the electromagnetic interference. The error detector detects when the error is greater than or equal to a predetermined threshold and in response sets an error indicator to indicate no error for a predetermined period of time. The controller controls adaptation of the parameters of the one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on the error indicator.

Claims

1. A transceiver to communicate in a vehicle via a single twisted-pair Ethernet cable, the transceiver including a transmitter to transmit signals via the single twisted-pair Ethernet cable and a receiver to receive signals via the single twisted-pair Ethernet cable, the transceiver comprising:

an equalizer to receive an input signal received by the transceiver via the single twisted-pair Ethernet cable and to cancel electromagnetic interference from the input signal, the input signal including outputs of i) an analog front end of the receiver and ii) an echo canceller, wherein the echo canceller is to cancel echo from the transmitter, and wherein the transmitter is collocated with the receiver;

an adaptation circuit to adapt parameters of one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on an error in an output of the equalizer due to the electromagnetic interference;

an error detector to detect when the error is greater than or equal to a predetermined threshold and in response to detecting that the error is greater than or equal to the predetermined threshold, the error detector is to set an error indicator to indicate no error for a predetermined period of time, wherein the error indicator set to zero for the predetermined period of time indicates that no error has occurred for the predetermined period of time; and

a controller to control adaptation of the parameters of the one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on the error indicator.

2. The transceiver of claim 1, wherein the controller does not adapt the parameters during the predetermined period of time in response to i) the error being greater than or equal to the predetermined threshold and ii) the error indicator indicating no error.

3. The transceiver of claim 1, wherein the parameters include i) a gain of the equalizer, ii) a timing of the analog front end, and iii) coefficients of the echo canceller.

4. The transceiver of claim 1, wherein:

the electromagnetic interference includes i) narrowband interference and ii) burst noise;

the error is greater than or equal to the predetermined threshold due to the burst noise;

the predetermined time period is based on a duration of the burst noise; and

the predetermined threshold is based on a strength of the burst noise.

5. The transceiver of claim 1, wherein the equalizer is further to generate a notch filter to cancel the electromagnetic interference, the electromagnetic interference including narrowband interference, the transceiver further comprising:

a signal-to-noise ratio estimator to estimate a signal-to-noise ratio based on the output of the equalizer,

wherein the controller is further to control a rate of generation of the notch filter by the equalizer based on the signal-to-noise ratio.

6. The transceiver of claim 5, wherein the rate of generating the notch filter is inversely related to the signal-to-noise ratio.

7. The transceiver of claim 5, wherein the controller is further to increase the rate of generation of the notch filter in response to the signal-to-noise ratio being less than or equal to a predetermined value.

8. The transceiver of claim 7, wherein the controller is further to decrease a rate of adaptation of the parameters to less than a predetermined rate.

9. The transceiver of claim 8, wherein the controller is further to i) increase the rate of generation of the notch filter and ii) decrease the rate of adaptation of the parameters in response to the error being less than the predetermined threshold after the predetermined time period.

10. The transceiver of claim 1, wherein the input signal is a combination of i) a first signal received by the receiver via the single twisted-pair Ethernet cable and ii) an echo cancellation signal from the echo canceller associated with the transmitter.

11. The transceiver of claim 1, wherein:

the equalizer is a feedforward equalizer including a notch filter;

the notch filter is a finite impulse response filter; and

a number of taps of the notch filter is based on a frequency of the electromagnetic interference to be mitigated.

12. The transceiver of claim 1, further comprising:

a decision feedback equalizer including an infinite impulse response filter to receive the output of the equalizer;

a slicer to slice an output of the decision feedback equalizer; and

a forward error correcting decoder to decode an output of the slicer.

13. A method for communicating in a vehicle using a transceiver, the transceiver including a transmitter and a receiver to respectively transmit and receive signals via a single twisted-pair Ethernet cable, the method comprising:

receiving, at an equalizer, an input signal received by the transceiver via the single twisted-pair Ethernet cable to cancel electromagnetic interference from the input signal, the input signal including outputs of i) an analog front end of the receiver and ii) an echo canceller, wherein the echo canceller is to cancel echo from the transmitter, and wherein the transmitter is collocated with the receiver;

adapting parameters of one or more of the i) equalizer, ii) the analog front end, and iii) the echo canceller based on an error in an output of the equalizer due to the electromagnetic interference;

detecting when the error is greater than or equal to a predetermined threshold;

setting, in response to detecting that the error is greater than or equal to the predetermined threshold, an error indicator to indicate no error for a predetermined period of time, wherein the error indicator set to zero for the predetermined period of time indicates that no error has occurred for the predetermined period of time; and

controlling adaptation of the parameters of the one or more of i) the equalizer, ii) the analog front end, and iii) the echo canceller based on the error indicator.

14. The method of claim 13, further comprising not adapting the parameters during the predetermined period of time in response to i) the error being greater than or equal to the predetermined threshold and ii) the error indicator indicating no error.

15. The method of claim 13, wherein the parameters include i) a gain of the equalizer, ii) a timing of the analog front end, and iii) coefficients of the echo canceller.

16. The method of claim 13, wherein the electromagnetic interference includes i) narrowband interference and ii) burst noise, and wherein the error is greater than or equal to the predetermined threshold due to the burst noise, the method further comprising:

selecting the predetermined time period based on a duration of the burst noise; and

selecting the predetermined threshold based on a strength of the burst noise.

17. The method of claim 13, further comprising:

generating a notch filter of the equalizer to cancel the electromagnetic interference, wherein the electromagnetic interference includes narrowband interference;

estimating a signal-to-noise ratio based on the output of the equalizer; and

controlling a rate of generation of the notch filter by the equalizer based on the signal-to-noise ratio.

18. The method of claim 17, wherein the rate of generating the notch filter is inversely related to the signal-to-noise ratio.

19. The method of claim 17, further comprising increasing the rate of generation of the notch filter in response to the signal-to-noise ratio being less than or equal to a predetermined value.

20. The method of claim 19, further comprising decreasing a rate of adaptation of the parameters to less than a predetermined rate.

21. The method of claim 20, further comprising i) increasing the rate of generation of the notch filter and ii) decrease the rate of adaptation of the parameters in response to the error being less than the predetermined threshold after the predetermined time period.

22. The method of claim 13, wherein the input signal is a combination of i) a first signal received by the receiver via the single twisted-pair Ethernet cable and ii) an echo cancellation signal from the echo canceller associated with the transmitter.

23. The method of claim 13, wherein the equalizer is a feedforward equalizer including a notch filter, and wherein the notch filter is a finite impulse response filter, the method further comprising selecting a number of taps of the notch filter based on a frequency of the electromagnetic interference to be mitigated.

24. The method of claim 13, further comprising:

processing the output of the equalizer using a decision feedback equalizer, the decision feedback equalizer including an infinite impulse response filter;

slicing an output of the decision feedback equalizer using a slicer; and

decoding an output of the slicer using a forward error correcting decoder.