Near-far sensing using frequency swept RSSI

• US 8,270,905 B1
• Filed: 10/02/2007
• Issued: 09/18/2012
• Est. Priority Date: 10/02/2007
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Plantroncis, Inc.
• Inventors: Cahill, Stephen V., Rosener, Douglas K
• Primary Examiner(s): Anderson, Matthew D
• Assistant Examiner(s): Tsvey, Gennadiy
• Application Number:
  US11/906,670
• Time in Patent Office: 1,813 Days
• Field of Search: None
• US Class Current: 455/67.11
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A method and apparatus for determining proximity of a headset relative to its base. A plurality of frequency swept RSSI signals are measured and processed to determine a near status or a far status of the headset relative to its base. In one example, a peak RSSI signal is identified in the plurality of frequency swept RSSI signals. The peak RSSI signal is compared to a near/far threshold RSSI value to generate a near status or far status indication.

Claims

1. A method for determining a near status or a far status of a headset in relation to a base unit comprising:

measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different carrier frequency;

identifying a peak RSSI signal in the plurality of RSSI signals;

comparing the peak RSSI signal to a near/far threshold RSSI value; and

generating a near status or far status indication responsive to comparing the peak RSSI signal to the near/far threshold RSSI value.

2. The method of claim 1, wherein measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different carrier frequency, comprises measuring RSSI signals at a plurality of hop frequencies in a Bluetooth system.

3. The method of claim 1, wherein measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different carrier frequency, comprises measuring RSSI signals at a plurality of selected frequencies in a non-frequency hopped system.

4. The method of claim 3, wherein the non-frequency hopped system comprises a DECT system.

5. The method of claim 3, wherein measuring RSSI signals at a plurality of selected frequencies in a non-frequency hopped system is performed at a time or frequency not normally used for data communication.

6. The method of claim 1, wherein measuring a plurality of RSSI signals is performed at either a headset or a headset base station.

7. The method of claim 1, wherein the near/far threshold RSSI value is a value above which a headset is in a near status and below which the headset is in a far status.

8. The method of claim 1, wherein generating a near status or far status indication responsive to comparing the peak RSSI signal to the near/far threshold RSSI value comprises employing a hysteresis to prevent rapid toggling between near status and far status.

9. A method for determining a near status or a far status of a headset in relation to a base unit comprising:

measuring a plurality of headset RSSI signals at a headset, wherein each headset RSSI signal of the plurality of headset RSSI signals is measured at a different carrier frequency;

identifying a peak headset RSSI signal in the plurality of headset RSSI signals;

comparing the peak headset RSSI signal to a headset near/far threshold RSSI value;

generating a first near status or far status indication responsive to comparing the peak headset RSSI signal to a headset near/far threshold RSSI value;

measuring a plurality of base station RSSI signals at a base station, wherein each base station RSSI signal of the plurality of base station RSSI signals is measured at a different carrier frequency;

identifying a peak base station RSSI signal in the plurality of base station RSSI signals;

comparing the peak base station RSSI signal to a base station near/far threshold RSSI value;

generating a second near status or far status indication responsive to comparing the peak base station RSSI signal to a base station near/far threshold RSSI value;

comparing the first near status or far status indication and the second near status or far status indication and responsively outputting a third near status or far status indication.

10. The method of claim 9, wherein measuring a plurality of headset RSSI signals, wherein each headset RSSI signal of the plurality of headset RSSI signals is measured at a different carrier frequency, comprises measuring headset RSSI signals at a plurality of hop frequencies in a Bluetooth system.

11. The method of claim 9, wherein measuring a plurality of headset RSSI signals, wherein each headset RSSI signal of the plurality of headset RSSI signals is measured at a different carrier frequency, comprises measuring headset RSSI signals at a plurality of selected frequencies in a non-frequency hopped system.

12. A method for determining a near status or a far status of a DECT headset in relation to a base unit comprising:

selecting a plurality of frequency beacons within a DECT frequency bandwidth;

measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different frequency beacon;

identifying a peak RSSI signal in the plurality of RSSI signals;

comparing the peak RSSI signal to a near/far threshold RSSI value; and

generating a near status or far status indication.

13. The method of claim 12, wherein measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different frequency beacon is performed at a time or frequency not normally used for data communication.

14. A wireless headset comprising:

a wireless transceiver for sending and receiving signals;

a memory storing a near/far application program for determining a near status or a far status of the headset relative to a base station; and

a processor for executing the near/far application program to process a plurality of RSSI signals measured at different carrier frequencies, wherein a peak RSSI signal in the plurality of RSSI signals is identified and compared to a near/far threshold RSSI value to generate a near status or far status indication.

15. The wireless headset of claim 14, further comprising a sensor.

16. The wireless headset of claim 15, wherein the sensor comprises a motion detector.

17. The wireless headset of claim 15, wherein the sensor comprises one selected from the group consisting of an infra-red detector, a pyroelectric sensor, a capacitance circuit, a micro-switch, an inductive proximity switch, a skin resistance sensor, and at least two pyroelectric sensors for determining a difference in temperature readings from the two pyroelectric sensors.

18. The wireless headset of claim 14, wherein the wireless transceiver comprises a DECT transceiver, Bluetooth transceiver, or IEEE 802.11 transceiver.

19. A wireless headset comprising:

a measuring means for measuring a plurality of RSSI signals, wherein each RSSI signal of the plurality of RSSI signals is measured at a different carrier frequency;

an identifying means for identifying a peak RSSI signal in the plurality of RSSI signals;

a comparison means for comparing the peak RSSI signal to a near/far threshold RSSI value and responsively generating a near status or far status indication.

20. The wireless headset of claim 19, wherein the detector means comprises a motion detecting means for detecting headset movement.

21. A wireless headset base station comprising:

a network interface;

a wireless transceiver for sending and receiving signals;

a memory storing a near/far application program for determining a near status or a far status of the headset relative to a base station; and

a processor for executing the near/far application program to process a plurality of RSSI signals measured at different carrier frequencies, wherein a peak RSSI signal in the plurality of RSSI signals is identified and compared to a near/far threshold RSSI value to generate a near status or far status indication.

22. The wireless headset base station of claim 21, further comprising an IEEE 802.11 access point.

23. The wireless headset base station of claim 21, wherein the network interface comprises an interface to a public switched telephone network, integrated services digital network, local area network, or wireless local area network.

24. The wireless headset base station of claim 21, wherein the wireless transceiver comprises a DECT transceiver, Bluetooth transceiver, or IEEE 802.11 transceiver.