METHOD AND APPARATUS FOR DETERMINING LOCATION OF A COMMUNICATION DEVICE

• US 20100151886A1
• Filed: 12/15/2008
• Published: 06/17/2010
• Est. Priority Date: 12/15/2008
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: GONZALEZ, ARMANDO J., SWOPE, CHARLES B., RUELKE, CHARLES R.
• Granted Patent: US 8,131,215 B2
• Time in Patent Office: Days
• US Class Current: 455/456.500
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A reference device determines its distance from a communication device by first using a training process to determine a calibrated time delay for the communication device when the communication device is at a known distance from the reference device, wherein the calibrated time delay comprises a steady state internal processing delay for the communication device. Subsequently, when the reference device is at an unknown distance from the communication device, the reference device determines the unknown distance using the previously determined calibrated time delay.

Claims

1. A method for determining a distance of a communication device from a reference device, the method comprising:

measuring a first time delay corresponding to a known distance between the communication device and the reference device;

determining, using a training process, a calibrated time delay based on the first time delay, wherein the calibrated time delay comprises a steady state internal processing delay for the communication device;

measuring a second time delay corresponding to a second distance between the communication device and the reference device;

calculating a delay difference between the second time delay and the calibrated time delay; and

translating the delay difference into the second distance.

2. The method of claim 1, wherein the training process comprises:

at the reference device;

sending an initial request to the communication device on a first data channel to initiate an inbound location pulse sequence;

receiving, on a second data channel in response to the initial request, at least one pulse of the inbound location pulse sequence, wherein the first time delay is a time difference between sending the initial request and receiving the at least one pulse;

determining an intermediate time delay based on the first time delay, wherein the intermediate time delay comprises an intermediate internal processing delay for the communication device;

for at least one iteration;

sending a subsequent request to the communication device on the first data channel;

receiving, on the second data channel in response to the subsequent request, at least one subsequent pulse of the inbound location pulse sequence;

determining a subsequent time delay that is a time difference between sending the subsequent request and receiving the at least one subsequent pulse; and

determining a subsequent intermediate time delay based on the subsequent time delay,

until the calibrated time delay is reached that comprises the steady state internal processing delay for the communication device.

3. The method of claim 2, wherein each internal processing delay for the communication device comprises a delay between the communication device receiving a request from the reference device and the communication device responsively transmitting a corresponding pulse of the inbound location pulse sequence.

4. The method of claim 2 further comprising transmitting each intermediate time delay on the first data channel to the communication device to use in managing its internal processes to reach the steady state internal processing delay.

5. The method of claim 4, wherein the communication device suspends at least one voice or non-voice internal process while managing its internal processes.

6. The method of claim 2 further comprising transmitting, to the communication device on the first data channel, the calibrated time delay that comprises the steady state internal processing delay for the communication device.

7. The method of claim 2, wherein the first data channel comprises a narrowband channel, and the second data channel comprises a wideband channel.

8. The method of claim 7, wherein the narrowband channel comprises an Association of Public Safety Communications Officials Project 25 (APCO 25) data channel.

9. The method of claim 2, wherein the inbound location pulse sequence comprises a plurality of chirp signals.

10. The method of claim 1, wherein measuring the second time delay comprises:

at the reference device;

sending a request to the communication device on a narrowband channel to transmit an inbound location chirp signal; and

receiving the inbound location chirp signal on a wideband channel, wherein the second time delay is a time difference between sending the request and receiving the inbound location chirp signal.

11. A method for enabling a distance determination of a communication device from a reference device, the method comprising:

at the communication device;

sending at least one pulse of an inbound location pulse sequence in response to a request from the reference device;

receiving an intermediate time delay from the reference device, wherein the intermediate time delay is derived from a time difference between the reference device sending the request to the communication device and the reference device receiving the at least one pulse;

configuring internal processes based on the intermediate time delay to enable the reference device to calculate a calibrated time delay that comprises a steady state internal processing delay for the communication device;

receiving and storing the calibrated time delay; and

sending the calibrated time delay to the reference device, wherein the calibrated time delay enables the reference device to determine a distance of the communication device to the reference device.

12. The method of claim 11, wherein configuring the internal processes comprises suspending at least one voice or non-voice process at the communication device.

13. The method of claim 11 further comprising associating the calibrated time delay to pre-programmed and predictable timing functions at the communication device.

14. The method of claim 11, wherein the inbound location pulse sequence comprises a plurality of chirp signals.

15. The method of claim 14 further comprising selecting a slope polarity and magnitude for a chirp signal prior to sending the chirp signal to the reference device, wherein the slope polarity and magnitude indicates to the reference device data associated with the communication device.

16. An apparatus for determining a distance of a communication device from a reference device, the apparatus comprising:

a first radio interface to transmit and receive, on a narrowband channel, control information related to an inbound location pulse sequence;

a second radio interface to receive, on a wideband channel, the inbound location pulse sequence from the communication device; and

a processor coupled to the first radio interface and the second radio interface, wherein the processor is programmed to perform the steps of;

sending, via the first radio interface, a request to the communication device to initiate the inbound location pulse sequence;

receiving, via the second radio interface, at least one pulse of the inbound location pulse sequence from the communication device;

iteratively determining a reference time delay, wherein the reference time delay is a time difference between sending the request and receiving the at least one pulse of the inbound location pulse sequence;

calibrating, to each reference time delay, to determine a calibrated time delay, wherein the calibrated time delay measures a steady state internal processing delay for the communication device; and

determining the distance between the reference device and the communication device based on the calibrated time delay.

17. The apparatus of claim 16, wherein the first radio interface is a radio interface in accordance with Association of Public Safety Communication Officials Project 25 (APCO-25) protocols.

18. The apparatus of claim 16, further comprising a timer coupled to the processor and used to measure the reference time delay, the second time delay, and the calibrated time delay.

19. The apparatus of claim 16 further comprising a memory element coupled to the processor to store the reference time delay, the second time delay, and the calibrated time delay.