APPARATUS AND METHOD FOR RANGING OF A WIRELESS TRANSCEIVER WITH A SWITCHING ANTENNA

• US 20090195365A1
• Filed: 02/04/2008
• Published: 08/06/2009
• Est. Priority Date: 02/04/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Nusseibeh, Fouad, Peczalski, Andy
• Granted Patent: US 7,884,753 B2
• Time in Patent Office: Days
• US Class Current: 340/10.5
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A sensor includes a transceiver configured to receive a wireless signal from an interrogator and to reflect the wireless signal back. The sensor also includes an antenna-switching modulator configured to modulate a radar cross-section of the sensor by repeatedly switching an antenna between, for example, a short-circuit position and an operational circuit position. The operational circuit position could be associated with an impedance matched receiver, and the short-circuit position could be associated with ground. Also, the sensor could be further configured to transmit the wireless signal to a second sensor and to receive a reflected wireless signal from the second sensor, and the sensor could further include a phase comparator configured to compute a phase difference between the transmitted wireless signal and the reflected wireless signal. The phase comparator could be further configured to compute a distance between the sensor and the second sensor based on the phase difference.

Claims

1. A sensor comprising:

a transceiver configured to receive a wireless signal from an interrogator and to reflect the wireless signal back; and

an antenna-switching modulator configured to modulate a radar cross-section of the sensor by repeatedly switching an antenna between two of a short-circuit position, an open-circuit position, and an operational circuit position.

2. The sensor of claim 1, wherein the transceiver is further configured to transmit the wireless signal to a second sensor and to receive a reflected wireless signal from the second sensor.

3. The sensor of claim 2, further comprising a phase comparator configured to compute a phase difference between the transmitted wireless signal and the reflected wireless signal.

4. The sensor of claim 3, wherein the phase comparator is further configured to compute a distance between the sensor and the second sensor based on the phase difference.

5. The sensor of claim 4, wherein the antenna-switching modulator is configured to provide for a third signal at a different frequency than a carrier frequency for measurements of the phase difference between the wireless signal and the reflected wireless signal in the second sensor and using it for range calculations.

6. The sensor of claim 1, wherein the antenna-switching modulator is configured to provide for a signal gain for the reflected wireless signal.

7. The sensor of claim 1, wherein the operational circuit position is associated with an impedance matched receiver and the short-circuit position is associated with ground.

8. The sensor of claim 1, wherein the sensor is further configured to reject a radar reflection coming from an interfering object whose radar cross-section is stationary in time or changes with a low frequency.

9. The sensor of claim 8, wherein the sensor is configured to distinguish the reflected wireless signal from the radar reflection using at least one of:

a bandpass filtering routine and a correlation routine.

10. The sensor of claim 1, further comprising a subject matter sensing module configured to detect a presence of a subject matter and the subject matter is one of:

heat, smoke, carbon monoxide, and a biochemical material.

11. The sensor of claim 1, wherein the sensor comprises a passive sensor.

12. A method comprising:

receiving a wireless signal from an interrogator at a sensor;

modulating a radar cross-section of the sensor by repeatedly switching an antenna between two of a short circuit position, an open-circuit position, and an operational circuit position; and

returning a reflected wireless signal back to the interrogator.

13. The method of claim 12, wherein modulating the radar cross-section further comprises modulating the radar cross-section of the sensor by repeatedly switching the antenna between the short-circuit position and the open-circuit position with a chip pattern.

14. The method of claim 13, further comprising

detecting a phase difference between the wireless signal and the reflected wireless signal at the interrogator;

and

calculating a distance between the sensor and the interrogator based on the phase difference.

15. The method of claim 14, further comprising rejecting an interfering radar reflection from an interfering object whose radar cross-section is stationary or changes at a low frequency using at least one of:

a bandpass filtering process and a correlation process.

16. The method of claim 14, wherein detecting the phase difference further comprises minimizing the interference between the wireless signal and the reflected wireless signal in the interrogator.

17. The method of claim 14, further comprising

correlating the chip pattern in a receiving channel of the interrogator to reject an interference of the wireless signal due to a crosstalk in the interrogator;

receiving the reflected wireless signal at the interrogator when the interrogator is not transmitting to avoid the crosstalk; and

turning the reflected wireless signal on and off with a time interval shorter than a shortest round trip flight time.

18. A system comprising:

a sensor configured to receive a wireless signal, modulate a radar cross-section of the sensor by repeatedly switching an antenna between a short circuit position and an operational circuit position, and reflect the wireless signal back; and

an interrogator configured to send the wireless signal to the sensor, receive the reflected wireless signal from the sensor, determine a phase difference between the wireless signal and the reflected wireless signal, and compute a distance between the sensor and the interrogator.

19. The system of claim 18, wherein the phase difference is proportional to a distance of a two-way signal trip between the sensor and the interrogator.

20. The system of claim 18, wherein the interrogator comprises a sensor.