Systems and methods to mitigate electro-magnetic interference in single twisted-pair-based communication systems

• US 9,838,072 B1
• Filed: 05/25/2016
• Issued: 12/05/2017
• 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: Dai, Shaoan, Cheong, Kok-Wui, Gu, Zhenzhong, Sun, Junqing, Zeng, Meng, Wu, Xing
• Primary Examiner(s): Lugo, David B.
• Application Number:
  US15/164,364
• Time in Patent Office: 559 Days
• 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 to communicate in a vehicle via a single twisted-pair Ethernet cable includes 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 includes an equalizer, a signal-to-noise ratio estimator, and a controller. The equalizer includes a notch filter and a slicer. The equalizer receives an input signal received by the transceiver via the single twisted-pair Ethernet cable. The notch filter cancels electromagnetic interference from the input signal and to output a filtered signal. The slicer slices the filtered signal. The signal-to-noise ratio estimator estimates a signal-to-noise ratio based on an output of the slicer. The controller controls a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the signal-to-noise ratio.

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, the equalizer including

a notch filter to cancel electromagnetic interference from the input signal and to output a filtered signal; and

a slicer to slice the filtered signal;

a signal-to-noise ratio estimator to estimate a signal-to-noise ratio based on an output of the slicer; and

a controller to

control a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the signal-to-noise ratio,

make a frequency response of the equalizer independent of the electromagnetic interference by controlling the tap values of the notch filter, and

control a gain of an analog front-end of the receiver based on the frequency response of the equalizer.

2. 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 transmitter transmitting signals via the single twisted-pair Ethernet cable.

3. The transceiver of claim 1, wherein the electromagnetic interference includes i) narrowband interference and ii) burst noise.

4. The transceiver of claim 1, wherein the equalizer is a feedforward equalizer, and wherein the notch filter is a finite impulse response filter.

5. The transceiver of claim 1, wherein the equalizer is a decision feedback equalizer, and wherein the notch filter is an infinite impulse response filter.

6. The transceiver of claim 1, wherein a number of taps of the notch filter is based on a frequency of the electromagnetic interference to be mitigated.

7. The transceiver of claim 1, further comprising a forward error correcting decoder to decode the output of the slicer.

8. 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, the equalizer including a notch filter to cancel electromagnetic interference from the input signal;

a power estimator to estimate a power of the notch filter based on tap values of the notch filter; and

a controller to

control a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the power of the notch filter,

make a frequency response of the equalizer independent of the electromagnetic interference by controlling the tap values of the notch filter, and

control a gain of an analog front-end of the receiver based on the frequency response of the equalizer.

9. The transceiver of claim 8, 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 transmitter transmitting signals via the single twisted-pair Ethernet cable.

10. The transceiver of claim 8, wherein the equalizer is a feedforward equalizer, and wherein the notch filter is a finite impulse response filter.

11. The transceiver of claim 8, wherein the equalizer is a decision feedback equalizer, and wherein the notch filter is an infinite impulse response filter.

12. The transceiver of claim 8, further comprising:

a slicer to slice an output of the notch filter; and

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

13. A method for communicating in a vehicle using a transceiver to 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;

filtering, using a notch filter, the input signal to cancel electromagnetic interference from the input signal;

slicing the filtered signal using a slicer;

estimating a signal-to-noise ratio based on an output of the slicer;

controlling a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the signal-to-noise ratio;

making a frequency response of the equalizer independent of the electromagnetic interference by controlling the tap values of the notch filter; and

controlling a gain of an analog front-end of the receiver based on the frequency response of the equalizer.

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

15. The method of claim 13, wherein the electromagnetic interference includes i) narrowband interference and ii) burst noise.

16. The method of claim 13, wherein the equalizer is a feedforward equalizer, and wherein the notch filter is a finite impulse response filter.

17. The method of claim 13, wherein the equalizer is a decision feedback equalizer, and wherein the notch filter is an infinite impulse response filter.

18. The method of claim 13, further comprising selecting a number of taps of the notch filter based on a frequency of the electromagnetic interference to be mitigated.

19. The method of claim 13, further comprising decoding the output of the slicer using a forward error correcting decoder.

20. A method for communicating in a vehicle using a transceiver to 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;

filtering, using a notch filter, the input signal to cancel electromagnetic interference from the input signal;

estimating a power of the notch filter based on tap values of the notch filter;

controlling a rate of adapting the equalizer by controlling a rate of change of tap values of the notch filter based on the power of the notch filter;

making a frequency response of the equalizer independent of the electromagnetic interference by controlling the tap values of the notch filter; and

controlling a gain of an analog front-end of the receiver based on the frequency response of the equalizer.

21. The method of claim 20, wherein the input signal is a combination of i) a first signal received by a receiver of the transceiver via the single twisted-pair Ethernet cable and ii) an echo cancellation signal from a transmitter of the transceiver transmitting signals via the single twisted-pair Ethernet cable.

22. The method of claim 20, wherein the equalizer is a feedforward equalizer, and wherein the notch filter is a finite impulse response filter.

23. The method of claim 20, wherein the equalizer is a decision feedback equalizer, and wherein the notch filter is an infinite impulse response filter.

24. The method of claim 20, further comprising:

slicing the filtered signal using a slicer; and

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