Method and system for FM interference detection and mitigation

• US 8,811,468 B2
• Filed: 11/22/2005
• Issued: 08/19/2014
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Ibrahim, Brima, Lettieri, Paul
• Primary Examiner(s): Dsouza, Adolf
• Application Number:
  US11/286,950
• Publication Number:
  US 20060269021A1
• Time in Patent Office: 3,192 Days
• Field of Search: 375/340, 375/281, 375/319, 375/322, 704/500, 330/51, 327/77, 327/100, 455/295, 455/303, 455/307, 607/5
• US Class Current: 375/240
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and systems for processing signals are provided and may include removing a DC component from a signal envelope comprising a combined signal within a range of allocated FM channels to generate a modified signal envelope. Fluctuation in power in the signal envelope may be detected based on a ratio of a magnitude of the signal envelope and a magnitude of the modified signal envelope. The removing may further include low-pass filtering the signal envelope to generate a low-pass filtered signal envelope. A square values of the low-pass filtered signal envelope may be determined to generate a squared signal envelope. The squared signal envelope may be high-pass filtered to generate a high-pass filtered signal envelope. The fluctuation in power in the signal envelope may be detected based on a ratio of a magnitude of the high-pass filtered signal envelope and a magnitude of the low-pass filtered signal envelope.

Claims

1. A method, comprising:

low-pass filtering a signal envelope to generate a low-pass filtered signal envelope;

modifying the low-pass filtered signal envelope to generate a modified signal envelope;

determining a magnitude of the low-pass filtered signal envelope and a magnitude of the modified signal envelope; and

detecting an interference signal based on a ratio of the magnitude of the low-pass filtered signal envelope and the magnitude of the modified signal envelope.

2. The method according to claim 1, wherein modifying the low-pass filtered signal envelope comprises high-pass filtering the low-pass filtered signal envelope.

3. The method according to claim 2, wherein modifying the low-pass filtered signal envelope further comprises, before the high-pass filtering, squaring the low-pass filtered signal envelope.

4. The method according to claim 1, wherein detecting the interference signal further comprises comparing the ratio to a predetermined threshold.

5. The method according to claim 1, further comprising:

low-pass filtering a second signal envelope to generate a second low-pass filtered signal envelope;

modifying the second low-pass filtered signal envelope to generate a second modified signal envelope;

determining a magnitude of the second low-pass filtered signal envelope and a magnitude of the second modified signal envelope; and

detecting a second interference signal based on a ratio of the magnitude of the second low-pass filtered signal envelope and the magnitude of the second modified signal envelope.

6. The method according to claim 5, further comprising selecting a frequency channel based on a difference between the interference signal and the second interference signal.

7. The method according to claim 6, wherein the frequency channel is selected from within a range of allocated frequency modulation (FM) channels.

8. The method according to claim 1, wherein:

the low-pass filtering comprises low pass filtering a plurality of signal envelopes within a range of allocated frequency modulation (FM) channels to generate a plurality of low-pass filtered signal envelopes;

the modifying comprises modifying the plurality of low-pass filtered signal envelopes to generate a plurality of modified signal envelopes; and

the detecting comprises detecting interference within the range of allocated FM channels based on ratios of magnitudes of the plurality of low-pass filtered signal envelopes and magnitudes of the plurality of modified signal envelopes.

9. A system, comprising:

a low-pass filter that filters a signal envelope to generate a low-pass filtered signal envelope;

a high-pass filter that filters the low-pass filtered signal envelope to generate a modified signal envelope;

a magnitude detector that determines a magnitude of the low-pass filtered signal envelope and a magnitude of the modified signal envelope; and

an interference detector that detects an interference signal based on a ratio of the magnitude of the low-pass filtered signal envelope and the magnitude of the modified signal envelope.

10. The system according to claim 9, further comprising a squared value determiner that squares the low-pass filtered signal envelope.

11. The system according to claim 9, wherein the interference detector further compares the ratio to a predetermined threshold.

12. The system according to claim 9, wherein:

the low-pass filter further filters a second signal envelope to generate a second low-pass filtered signal envelope;

the high-pass filter further filters the second low-pass filtered signal envelope to generate a second modified signal envelope;

the magnitude detector further determines a magnitude of the second low-pass filtered signal envelope and a magnitude of the second modified signal envelope; and

the interference detector further detects a second interference signal based on a ratio of the magnitude of the second low-pass filtered signal envelope and the magnitude of the second modified signal envelope.

13. The system according to claim 12, further comprising a radio that selects a frequency channel based on a difference between the interference signal and the second interference signal.

14. The system according to claim 13, wherein the frequency channel is selected from within a range of allocated frequency modulation (FM) channels.

15. The system according to claim 9, wherein:

the low-pass filter filters a plurality of signal envelopes within a range of allocated frequency modulation (FM) channels to generate a plurality of low-pass filtered signal envelopes;

the high-pass filter filters the plurality of low-pass filtered signal envelopes to generate a plurality of modified signal envelopes; and

the interference detector detects interference within the range of allocated FM channels based on ratios of magnitudes of the plurality of low-pass filtered signal envelopes and magnitudes of the plurality of modified signal envelopes.

16. A non-transitory machine-readable storage that stores a program thereon that, when executed by a processing circuit, directs the processing circuit to perform a method, comprising:

low-pass filtering a signal envelope to generate a low-pass filtered signal envelope;

modifying the low-pass filtered signal envelope to generate a modified signal envelope;

determining a magnitude of the low-pass filtered signal envelope and a magnitude of the modified signal envelope; and

detecting, by the processing circuit, an interference signal based on a ratio of the magnitude of the low-pass filtered signal envelope and the magnitude of the modified signal envelope.

17. The non-transitory machine-readable storage of claim 16, wherein modifying the low-pass filtered signal envelope comprises high-pass filtering the low-pass filtered signal envelope.

18. The non-transitory machine-readable storage of claim 17, wherein modifying the low-pass filtered signal envelope further comprises, before the high-pass filtering, squaring the low-pass filtered signal envelope.

19. The non-transitory machine-readable storage of claim 16, the method further comprising:

low-pass filtering a second signal envelope to generate a second low-pass filtered signal envelope;

modifying the second low-pass filtered signal envelope to generate a second modified signal envelope;

determining a magnitude of the second low-pass filtered signal envelope and a magnitude of the second modified signal envelope; and

detecting a second interference signal based on a ratio of the magnitude of the second low-pass filtered signal envelope and the magnitude of the second modified signal envelope.

20. The non-transitory machine-readable storage of claim 19, the method further comprising selecting a frequency channel based on a difference between the interference signal and the second interference signal.

21. A system, comprising:

a low-pass filter that filters a signal envelope to generate a low-pass filtered signal envelope;

a high-pass filter that filters the low-pass filtered signal envelope to generate a modified signal envelope;

a magnitude detector that determines a magnitude of the low-pass filtered signal envelope and a magnitude of the modified signal envelope; and

an interference detector that detects an interference signal based on the magnitude of the low-pass filtered signal envelope and the magnitude of the modified signal envelope.

22. The system according to claim 21, wherein:

the low-pass filter filters a plurality of signal envelopes within a range of allocated frequency modulation (FM) channels to generate a plurality of low-pass filtered signal envelopes;

the high-pass filter filters the plurality of low-pass filtered signal envelopes to generate a plurality of modified signal envelopes; and

the interference detector detects interference within the range of allocated FM channels based on magnitudes of the plurality of low-pass filtered signal envelopes and magnitudes of the plurality of modified signal envelopes.

23. A method, comprising:

low-pass filtering a signal envelope to generate a low-pass filtered signal envelope;

modifying the low-pass filtered signal envelope to generate a modified signal envelope;

determining a magnitude of the low-pass filtered signal envelope and a magnitude of the modified signal envelope; and

detecting an interference signal based on the magnitude of the low-pass filtered signal envelope and the magnitude of the modified signal envelope.

24. The method according to claim 23, wherein:

the low-pass filtering comprises low pass filtering a plurality of signal envelopes within a range of allocated frequency modulation (FM) channels to generate a plurality of low-pass filtered signal envelopes;

the modifying comprises modifying the plurality of low-pass filtered signal envelopes to generate a plurality of modified signal envelopes; and

the detecting comprises detecting interference within the range of allocated FM channels based on ratios of magnitudes of the plurality of low-pass filtered signal envelopes and magnitudes of the plurality of modified signal envelopes.

25. A system, comprising:

a low-pass filter that filters a signal envelope to generate a low-pass filtered signal envelope;

a high-pass filter that filters the low-pass filtered signal envelope to generate a modified signal envelope;

a received signal strength indicator that measures a strength of the low-pass filtered signal envelope and a strength of the modified signal envelope; and

an interference detector that detects an interference signal based on a difference between the strength of the low-pass filtered signal envelope and the strength of the modified signal envelope.

26. The system according to claim 25, wherein:

the low-pass filter further filters a second signal envelope to generate a second low-pass filtered signal envelope;

the high-pass filter further filters the second low-pass filtered signal envelope to generate a second modified signal envelope;

the received signal strength indicator further measures a strength of the second low-pass filtered signal envelope and a strength of the second modified signal envelope; and

the interference detector further detects a second interference signal based on a difference between the strength of the second low-pass filtered signal envelope and the strength of the second modified signal envelope.

27. The system according to claim 26, further comprising a radio that selects a frequency channel based on a difference between the interference signal and the second interference signal.