System and method for periodic noise avoidance in data transmission systems

• US 7,050,516 B2
• Filed: 03/20/2003
• Issued: 05/23/2006
• Est. Priority Date: 03/20/2003
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kolze, Thomas J., Currivan, Bruce J., Yousef, Nabil, Howard, Daniel H., Ngai, William
• Primary Examiner(s): Corrielus, Jean B.
• Application Number:
  US10/391,555
• Publication Number:
  US 20040184571A1
• Time in Patent Office: 1,160 Days
• Field of Search: 375/224, 375/227, 375/254, 375/285, 375/259, 375/342, 375/346, 375/350, 375/354, 375/355, 714/776, 370/252, 370/516
• US Class Current: 375/346
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A system for periodic noise avoidance including a timing discriminator receiving an input signal from a communications channel. The input signal includes data packets and empty slots with periodic noise. The timing discriminator outputs a first error measurement of periodic noise width and a second error measurement of periodic noise position. A first loop filter inputs the first error measurement and outputs a width of the empty slots. A second loop filter inputs the second error measurement and outputs a frequency of the periodic noise. An oscillator inputs the width of the empty slots and the frequency, and outputs an empty slot waveform to the timing discriminator.

Claims

1. A system for periodic noise avoidance comprising:

a timing discriminator that receives an input signal from a communications channel, the input signal including data packets and empty slots with periodic noise, and outputs a first error measurement of periodic noise width and a second error measurement of periodic noise position;

a first loop filter having as an input the first error measurement and outputting a width of the respective empty slots;

a second loop filter having as an input the second error measurement and outputting a repetition frequency of the periodic noise; and

an oscillator having as an input the width of the respective empty slots and the repetition frequency, and outputting an empty slot waveform to the timing discriminator.

2. The system of claim 1, further including an energy detection logic that determines whether periodic noise is present in the input signal.

3. The system of claim 1, wherein the oscillator is a numerically controlled oscillator.

4. The system of claim 1, wherein the oscillator is controlled by a media access controller (MAC), the MAC using the repetition frequency, the width of the respective empty slots, and a phase estimate from the oscillator to control the oscillator.

5. The system of claim 1, wherein the periodic noise is low pass filtered.

6. The system of claim 1, wherein the periodic noise width is determined using a center of gravity method.

7. The system of claim 1, wherein the periodic noise width is determined using a nonlinear threshold method.

8. The system of claim 1, wherein initial conditions for the timing discriminator are provided by slewing the timing discriminator, the first and second loop filters and the oscillator.

9. The system of claim 1, wherein initial conditions for the timing discriminator are provided by using a raster method on the input signal.

10. The system of claim 1, wherein a modulation scheme of the data packets is dynamically adjusted based on parameters of the periodic noise.

11. The system of claim 1, wherein data is transmitted in conjunction with the periodic noise.

12. The system of claim 1, wherein duration of the empty slots is adjusted based on the width of the periodic noise.

13. A method for periodic noise avoidance comprising:

inputting a signal from a communications channel, the input signal including data packets and empty slots with periodic noise;

outputting a first error measurement of periodic noise width and a second error measurement of periodic noise position;

determining a width of the respective empty slots based on the first error measurement;

determining a repetition frequency of the periodic noise based on the second error measurement; and

providing an empty slot waveform to a timing discriminator based on the width of the respective empty slots and the repetition frequency.

14. The method of claim 13, further including the step of determining whether periodic noise is present in the empty slot.

15. The method of claim 13, further including the step of low pass filtering the periodic noise.

16. The method of claim 13, further including the step of determining the periodic noise width using a center of gravity method.

17. The method of claim 13, further including the step of determining the periodic noise width using a nonlinear threshold method.

18. The method of claim 13, wherein initial conditions for the timing discriminator are provided by using a raster method on the input signal.

19. The method of claim 13, wherein a modulation scheme of the data packets is dynamically adjusted based on parameters of the periodic noise.

20. The method of claim 13, wherein data is transmitted when periodic noise is present.