Radar detection and dynamic frequency selection

• US 20070126622A1
• Filed: 04/25/2006
• Published: 06/07/2007
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Hsu, Yungping, Yu, Tsunglun, Nallapureddy, Bhaskar, Neng, Sek
• Granted Patent: US 7,702,044 B2
• Time in Patent Office: Days
• US Class Current: 342/92
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0232 Avoidance by frequency multiplex

Abstract

A wireless network device includes a correlation module, an automatic gain control module, and a control module. The correlation module correlates a predetermined portion of a radio frequency (RF) signal and generates a correlation signal based thereon. The automatic gain control (AGC) module generates a gain control signal based on said RF signal. The control module selectively determines whether said RF signal is a radar signal based on said correlation signal and said gain control signal.

Claims

1. A wireless network device, comprising:

a correlation module that correlates a predetermined portion of a radio frequency (RF) signal and that generates a correlation signal based thereon;

an automatic gain control (AGC) module that generates a gain control signal based on said RF signal; and

a control module that selectively determines whether said RF signal is a radar signal based on said correlation signal and said gain control signal.

2. The wireless network device of claim 1 wherein said control module determines whether said RF signal is a radar signal when said correlation signal indicates that said RF signal is not a packet of wireless data.

3. The wireless network device of claim 1 wherein said control module determines whether said RF signal is a radar signal when said gain control signal indicates that a gain of said AGC module exceeds a predetermined threshold.

4. The wireless network device of claim 1 further comprising a converter module that converts said RF signal to a digital RF signal, wherein said control module generates a reset signal that resets said AGC module when an output of said converter module decreases to less than a predetermined value.

5. The wireless network device of claim 4 wherein said control module determines a pulse width of a pulse of said RF signal based on a time difference between said gain control signal and said reset signal that follows said gain control signal.

6. The wireless network device of claim 5 wherein said control module determines that said RF signal is a radar signal when said pulse width for a predetermined number of adjacent pulses of said RF signal is substantially equal to a pulse width of a predetermined radar pulse.

7. The wireless network device of claim 4 wherein said control module:

divides an output of said converter module into N equal segments during a period between said gain control signal and said reset signal that follows said gain control signal, where N is an integer greater than one;

counts a number of zero-crossings in each of said N segments; and

determines that said RF signal is one of a single tone radar signal and a chirp radar signal based on said number of zero-crossings in said N segments.

8. The wireless network device of claim 7 wherein said control module determines that said RF signal is a chirp radar signal when said number of zero-crossings in said N segments vary approximately linearly.

9. The wireless network device of claim 1 further comprising a channel changing module that changes a communication channel of said network device when said control module determines that said RF signal is a radar signal.

10. The wireless network device of claim 1 is an access point.

11. The wireless network device of claim 1 is a client station.

12. The wireless network device of claim 1 further comprising a radio frequency (RF) receiver that receives said RF signal.

13. The wireless network device of claim 1 complies with at least one of IEEE 802.11, 802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16, and 802.20 standards.

14. A method for detecting radar, comprising:

correlating a predetermined portion of a radio frequency (RF) signal;

generating a correlation signal based on said correlation;

generating a gain control signal based on said RF signal; and

selectively determining whether said RF signal is a radar signal based on said correlation signal and said gain control signal.

15. The method of claim 14 further comprising determining whether said RF signal is a radar signal when said correlation signal indicates that said RF signal is not a packet of wireless data.

16. The method of claim 14 further comprising determining whether said RF signal is a radar signal when said gain control signal indicates that a gain of an automatic gain-control (AGC) module exceeds a predetermined threshold.

17. The method of claim 14 further comprising converting said RF signal to a digital RF signal and generating a reset signal that resets an automatic gain control (AGC) module when said digital RF signal decreases to less than a predetermined value.

18. The method of claim 17 further comprising determining a pulse width of a pulse of said RF signal based on a time difference between said gain control signal and said reset signal that follows said gain control signal.

19. The method of claim 18 further comprising determining that said RF signal is a radar signal when said pulse width for a predetermined number of adjacent pulses of said RF signal is substantially equal to a pulse width of a predetermined radar pulse.

20. The method of claim 17 further comprising:

dividing said digital RF signal into N equal segments during a period between said gain control signal and said reset signal that follows said gain control signal, where N is an integer greater than one;

counting a number of zero-crossings in each of said N segments; and

determining that said RF signal is one of a single tone radar signal and a chirp radar signal based on said number of zero-crossings in said N segments.

21. The method of claim 20 further comprising determining that said RF signal is a chirp radar signal when said number of zero-crossings in said N segments vary approximately linearly.

22. The method of claim 14 further comprising changing a communication channel when said RF signal is determined to be a radar signal.

23. An access point comprising the method of claim 14.

24. A client station comprising the method of claim 14.

25. The method of claim 14 further comprising receiving said RF signal.

26. The method of claim 14 further comprising complying with at least one of IEEE 802.11, 802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16, and 802.20 standards.

27. A wireless network device, comprising:

correlation means for correlating a predetermined portion of a radio frequency (RF) signal and generating a correlation signal based thereon;

automatic gain control (AGC) means for generating a gain control signal based on said RF signal; and

control means for selectively determining whether said RF signal is a radar signal based on said correlation signal and said gain control signal.

28. The wireless network device of claim 27 wherein said control means determines whether said RF signal is a radar signal when said correlation signal indicates that said RF signal is not a packet of wireless data.

29. The wireless network device of claim 27 wherein said control means determines whether said RF signal is a radar signal when said gain control signal indicates that a gain of said AGC means exceeds a predetermined threshold.

30. The wireless network device of claim 27 further comprising converter means for converting said RF signal to a digital RF signal, wherein said control means generates a reset signal that resets said AGC means when an output of said converter means decreases to less than a predetermined value.

31. The wireless network device of claim 30 wherein said control means determines a pulse width of a pulse of said RF signal based on a time difference between said gain control signal and said reset signal that follows said gain control signal.

32. The wireless network device of claim 31 wherein said control means determines that said RF signal is a radar signal when said pulse width for a predetermined number of adjacent pulses of said RF signal is substantially equal to a pulse width of a predetermined radar pulse.

33. The wireless network device of claim 30 wherein said control means:

divides an output of said converter means into N equal segments during a period between said gain control signal and said reset signal that follows said gain control signal, where N is an integer greater than one;

counts a number of zero-crossings in each of said N segments; and

determines that said RF signal is one of a single tone radar signal and a chirp radar signal based on said number of zero-crossings in said N segments.

34. The wireless network device of claim 33 wherein said control means determines that said RF signal is a chirp radar signal when said number of zero-crossings in said N segments vary approximately linearly.

35. The wireless network device of claim 27 further comprising channel changing means for changing a communication channel of said network device when said control means determines that said RF signal is a radar signal.

36. The wireless network device of claim 27 is an access point.

37. The wireless network device of claim 27 is a client station.

38. The wireless network device of claim 27 further comprising radio frequency (RF) receiver means for receiving said RF signal.

39. The wireless network device of claim 27 complies with at least one of IEEE 802.11, 802.11a, 802.11b, 802.11g, 802.11h, 802.11n, 802.16, and 802.20 standards.