Radar detection circuit for a WLAN transceiver

• US 7,701,382 B2
• Filed: 12/01/2006
• Issued: 04/20/2010
• Est. Priority Date: 09/15/2003
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Hansen, Christopher J.
• Primary Examiner(s): Lobo; Ian J
• Application Number:
  US11/607,488
• Publication Number:
  US 20070281638A1
• Time in Patent Office: 1,236 Days
• Field of Search: 375/340, 455/63.1, 342/137, 342/52, 342/57
• US Class Current: 342/52
• 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: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus
• CPC Class Codes: H04K 2203/18 for wireless local area networks or WLAN
• CPC Class Codes: H04K 3/226 Selection of non-jammed channel for communication spectrum sharing arrangements H04W16/14; selection of wireless resources by user or terminal H04W72/02
• CPC Class Codes: H04K 3/822 by detecting the presence of a surveillance, interception or detection
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A single chip radio transceiver includes circuitry that enables detection of radar signals to enable the radio transceiver to halt communications in overlapping communication bands to avoid interference with the radar transmitting the radar pulses. The radio transceiver is operable to evaluate a number of most and second most common pulse interval values to determine whether a traditional radar signal is present. The radio transceiver also is operable to FM demodulate an incoming signal to determine whether a non-traditional radar signal, such as a bin-5 radar signal, is present. After. FM demodulation, the signal is averaged wherein a substantially large value is produced for non-traditional radar signals and a value approximately equal to zero is produced for a communication signal that is not FM modulated with a continuously increasing frequency signal. Gain control is used to limit incoming signal magnitude to a specified range of magnitudes.

Claims

1. A method for detecting radar performed within a wireless communication transceiver, comprising:

reading pulse information from each of a plurality of radio frequency transceiver receive path first in first out buffers (FIFOs) into groups of arrays, wherein each group of arrays includes a start time array, a pulse width array, and an FM value array wherein the FM values represent an absolute value of a difference of an estimate of a frequency at a start of the pulse and an estimate of a frequency at an end of the pulse as determined by an FM demodulator;

combining adjacent pulses in each array wherein, if the difference in start times between two adjacent pulses is less than a specified minimum spacing value, the method includes deleting the 2nd pulse and setting the pulse width for the first pulse equal to the combined pulse width of the two original pulse widths; and

setting an FM value equal to the sum of the FM values of the two original pulse widths of the adjacent pulses.

2. The method of claim 1 wherein the process is repeated for all pulses in the arrays of pulse information.

3. The method of claim 2 wherein the method is performed for each FIFO for each antenna.

4. The method of claim 1 further including combining each group of arrays into a single group.

5. The method of claim 4 further including sorting the pulses within the single group according to start time.

6. The method of claim 5 further including combining pulses again and, if the start time between two adjacent pulses is less than a minimum spacing value, deleting the second pulse and keeping the first pulse without adding the pulse widths.

7. The method of claim 6 further including repeating the step of deleting the second pulse and keeping the first pulse without adding the pulse widths until no more pulses may be deleted.

8. The method of claim 7 further including determining whether a remaining number of pulses exceeds a specified value to determine that a long non-traditional radar has been detected.

9. The method of claim 7 further including determining whether a remaining number of pulses does not exceed a specified value to determine that a long non-traditional radar has not been detected.

10. The method of claim 9 further including performing traditional radar analysis to determine a traditional radar signal is present.

11. A method for detecting a radar signal, comprising:

receiving, in at least one receive path of a radio transceiver, a radar signal;

adding pulse start times to a long pulse buffer for each pulse having a pulse width that is greater than a minimum width value and less than a maximum width value wherein the minimum width value is greater than a maximum pulse width of a traditional radar pulse to detect a non-traditional radar pulse having a pulse width that is substantially greater than a traditional radar signal pulse width;

if a difference in start times between the newest pulse in the long pulse buffer and the oldest pulse is greater than a maximum window value, removing the oldest pulse;

repeating previous step until no more pulses are removed; and

if a number of pulses greater than a specified number of long pulses remain in the long pulse buffer, determining that a radar signal has been detected.

12. The method of claim 11 further including, if a radar signal is not detected because the number of pulses was not greater than the specified number of long pulses, performing radar pulse detection for traditional radar signals.

13. The method of claim 11 wherein the method is operable to detect non-standard radar pulses having non-traditional long pulse lengths.

14. The method of claim 11 wherein the method is operable to detect bin-5 category radar signals.

15. A method in an integrated circuit radio transceiver, comprising:

detecting traditional short pulse radar signals;

detecting non-traditional long pulse radar signals;

inhibiting wireless transmissions from a radio transceiver upon detection of either a short pulse or a long pulse radar signal; and

reading pulse information from each receive path first in first out buffer (FIFO) into groups of arrays, wherein each group of arrays includes a start time array, a pulse width array, and an FM value array;

combining adjacent pulses in each array wherein, if the difference in start times between two adjacent pulses is less than a specified minimum spacing value, deleting the 2nd pulse and making the pulse width for the first pulse equal to the combined pulse width of the two original pulse widths; and

setting an FM value equal to the sum of the FM values of the two original pulse widths of the adjacent pulses.

16. The method of claim 15 further including combining each group of arrays into a single group and for sorting the pulses within the single group according to start time.

17. The method of claim 15 further including combining pulses again and, if the start time between two adjacent pulses is less than the specified minimum spacing value, deleting the second pulse and keeping the first pulse without adding the pulse widths.

18. The method of claim 15 further including adding pulse start times to a long pulse buffer for each pulse having a pulse width that is greater than a specified minimum width value and less than a specified maximum width value.

19. The method of claim 15 further including, if a difference in start times between the newest pulse in the long pulse buffer and the oldest pulse is greater than a maximum window value, removing the oldest pulse and for repeating this step until no more pulses are removed.

20. The method of claim 19 further including determining that a radar has been detected if a number of pulses greater than a specified number of long pulses remain in the long pulse buffer.

21. The method of claim 19 further including, if a radar signal is not detected because the number of pulses was not greater than the specified number of long pulses, performing radar pulse detection for traditional radar signals.

22. The method of claim 19 further including detecting bin-5 category radar signals.