Impulse noise mitigation under out-of-band interference conditions

• US 8,792,543 B2
• Filed: 07/15/2013
• Issued: 07/29/2014
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Maxlinear Incorporated
• Original Assignee: Maxlinear Incorporated
• Inventors: Lo, Andy, Kang, Sugbong
• Primary Examiner(s): Ahn, Sam K
• Assistant Examiner(s): Wong, Linda
• Application Number:
  US13/941,604
• Publication Number:
  US 20130301766A1
• Time in Patent Office: 379 Days
• Field of Search: 375229-236, 375/219, 375/211, 375/220, 375/221, 375/222, 37524026-24029, 375/254, 375/259, 375/284, 375/285, 375/295, 375/296, 375/299, 375/316, 375346-350, 375/269, 375272-277, 375/340, 375/343, 708322-400
• US Class Current: 375/229
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/1036 with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters H04B1/123 takes precedence; filter circuits H03H

Abstract

An impulse noise mitigation circuit (INMC) may set a cut-off frequency of each of two high pass filters to bound a frequency bandwidth of a desired signal, wherein a first of the two filters allows frequencies higher than the frequency bandwidth of the desired signal, and a second of the two filters allows frequencies lower than the frequency bandwidth of the desired signal. The INMC may compute and store a mean magnitude separately for a first signal response of the first filter and a second signal response of the second filter. The INMC may select the first filter for impulse noise mitigation when the mean magnitude of the second filter is greater than the mean magnitude of the first filter. The INMC may select the second filter for impulse noise mitigation when the mean magnitude of the first filter is greater than the second filter.

Claims

1. A method for impulse noise mitigation, comprising:

setting a cut-off frequency of each of a first high pass filter and a second high pass filter to bound a frequency bandwidth of a desired signal, wherein;

the first high pass filter allows frequencies higher than the frequency bandwidth of the desired signal; and

the second high pass filter allows frequencies lower than the frequency bandwidth of the desired signal;

determining a mean magnitude for a first signal response of the first high pass filter and for a second signal response of the second high pass filter;

selecting the first high pass filter for impulse noise mitigation when the mean magnitude for the second signal response of the second high pass filter is greater than the mean magnitude for the first signal response of the first high pass filter; and

selecting the second high pass filter for impulse noise mitigation when the mean magnitude for the first signal response of the first high pass filter is greater than the mean magnitude for the second signal response of the second high pass filter.

2. The method of claim 1, comprising measuring the first signal response of the first high pass filter and the second signal response of the second high pass filter over a predetermined time period.

3. The method of claim 1, comprising storing the mean magnitude for the first signal response of the first high pass filter and the second signal response of the second high pass filter, wherein:

the determining of the mean magnitude for the first signal response of the first high pass filter and the second signal response of the second high pass filter comprises computing the mean magnitude separately for the first signal response of the first high pass filter and the second signal response of the second high pass filter; and

the computing, the storing and the selecting are controlled by a state machine.

4. The method of claim 1, wherein impulse noise mitigation includes other noise interferers.

5. The method of claim 1, wherein the first high pass filter and the second high pass filter are integrated together into a single programmable filter.

6. The method of claim 5, comprising:

configuring the single programmable filter as the first high pass filter;

measuring the mean magnitude of the first high pass filter using the single programmable filter configured as the first high pass filter;

configuring the single programmable filter as the second high pass filter; and

measuring the mean magnitude of the second high pass filter using the single programmable filter configured as the second high pass filter.

7. The method of claim 6, comprising:

comparing the mean magnitude of the first high pass filter with the mean magnitude of the second high pass filter; and

selecting which configuration of said single programmable filter to use for mitigation of impulse noise based on a result of said comparing.

8. The method of claim 1, comprising detecting impulse noise via a selected one of the first high pass filter and the second high pass filter.

9. The method of claim 8, comprising clipping or nulling samples determined to be corrupted by the detected impulse noise.

10. A system for impulse noise mitigation, comprising:

an impulse noise mitigation circuit (INMC) that comprises a first high pass filter and a second high pass filter, the INMC being connected to an output of an analog to digital converter (ADC), wherein;

the first high pass filter bounds a bandwidth of a desired RF signal on a first side and the second high pass filter bounds the bandwidth of the desired RF signal on a second side;

the INMC is configured to determine, for each of the first and second high pass filters, a mean magnitude value corresponding to effects of impulse noise on the output of the ADC;

the first high pass filter is selected for processing the output of the ADC when the mean magnitude value of the second high pass filter is greater than the mean magnitude value of the first high pass filter; and

the second high pass filter is selected for processing the output of the ADC when the mean magnitude value of the first high pass filter is greater than the mean magnitude value of the second high pass filter.

11. The system of claim 10, wherein the first high pass filter operates on frequencies higher than frequencies of the desired RF signal to detect impulse noise.

12. The system of claim 10, wherein the first high pass filter operates on frequencies lower than frequencies of the desired RF signal to detect impulse noise.

13. The system of claim 10 wherein the ADC receives an input from an RF tuner.

14. The system of claim 13, wherein the INMC comprises a suppressor circuit that an output of the ADC as an input.

15. The system of claim 14, wherein the suppressor circuit clips samples determined to be corrupted.

16. The system of claim 14, wherein the suppressor circuit nulls out samples determined to be corrupted.

17. The system of claim 10, wherein the suppressor circuit delivers a digital signal with impulse noise mitigated to a demodulator circuit.

18. The system of claim 10, wherein the first high pass filter and the second high pass filter are integrated together into a single programmable high pass filter.

19. The system of claim 18 wherein the single programmable high pass filter is configured as the first high pass filter to measure the mean magnitude of the first high pass filter and configured as the second high pass filter to measure the mean magnitude of the second high pass filter.

20. The system of claim 19, wherein which of the first high pass filter and the second high pass filter is selected for mitigation of impulse noise is based on a comparison of the mean magnitudes of the first high pass filter and second high pass filter.