DIGITAL DELAY MEASUREMENT

• US 20130106439A1
• Filed: 10/29/2012
• Published: 05/02/2013
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Digi International Inc.
• Original Assignee: Digi International Inc.
• Inventors: Dahl, Paul A.
• Granted Patent: US 9,013,190 B2
• Time in Patent Office: Days
• US Class Current: 324/617
• CPC Class Codes: G01S 13/46 Indirect determination of position data
• 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: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Distance between two devices is determined by sending a digital signal from a first device to a second device, and receiving a repeated signal from the second device in the first device. The repeated signal comprises the digital signal sent from the first device resent by the second device. A time difference between the sent digital signal and the received repeated signal is determined by providing both the sent digital signal and the received repeated signal to a logic gate, the output of the logic gate indicating whether the digital signal and the received repeated signal are at same or different states. The output of the logic gate is evaluated to determine an approximate distance between the first device and the second device.

Claims

1. A method of determining distance between two devices, comprising:

sending a digital signal from a first device to a second device;

receiving a repeated signal from the second device in the first device, the repeated signal comprising the digital signal sent from the first device resent by the second device;

determining a time difference between the sent digital signal and the received repeated signal by providing both the sent digital signal and the received repeated signal to a logic gate, the output of the logic gate indicating whether the digital signal and the received repeated signal are at same or different states; and

evaluating the output of the logic gate to determine an approximate distance between the first device and the second device.

2. The method of determining distance between two devices of claim 1, wherein the logic gate is an XOR or XNOR logic gate.

3. The method of determining distance between two devices of claim 1, wherein the output of the logic gate is averaged over time to determine the approximate distance.

4. The method of determining distance between two devices of claim 1, further comprising providing the output of the logic gate to a lowpass filter operable to average the output level of the logic gate over time.

5. The method of determining distance between two devices of claim 4, further comprising converting an output of the lowpass filter to a digital signal representing the approximate distance between the first device and the second device.

6. The method of determining distance between two devices of claim 1, wherein the sent digital signal is encoded to have frequent state transitions.

7. The method of determining distance between two devices of claim 1, further comprising determining a position of a mobile one of the first and second devices using a known location of the other of the first and second devices and the approximate distance between the first device and the second device.

8. The method of determining distance between two devices of claim 1, wherein the sent digital signal and the received repeated digital signal are wireless radio frequency signals.

9. An electronic device, comprising:

a communication module operable to send a digital signal to a second device and to receive a repeated signal from the second device, the repeated signal comprising the sent digital signal resent by the second device; and

a processing module comprising a logic gate coupled to receive the sent digital signal and the repeated digital signal, the processing module operable to determine a time difference between the sent digital signal and the received repeated signal by indicating whether the digital signal and the received repeated signal are at same or different states, the output of the logic gate indicating an approximate distance between the first device and the second device.

10. The electronic device of claim 9, wherein the communication module further comprises a wireless RF transceiver, and the sent digital signal and received repeated digital signal comprise wireless radio frequency signals.

11. The electronic device of claim 9, wherein the logic gate is an XOR or XNOR logic gate.

12. The electronic device of claim 9, further comprising a lowpass filter coupled to receive the output of the logic gate, the lowpass filter operable to average the output of the logic gate over time.

13. The electronic device of claim 12, further comprising an analog-to-digital converter coupled to an output of the lowpass filter, operable to provide a digital signal representing the approximate distance between the first device and the second device.

14. The electronic device of claim 9, wherein the sent digital signal is encoded to have frequent state transitions.

15. The electronic device of claim 9, further comprising a position determination module operable to determine a position of a mobile one of the first and second devices using a known location of the other of the first and second devices and the indicated approximate distance between the first device and the second device.

16. The electronic device of claim 9, wherein the device comprises a cellular telephone.

17. The electronic device of claim 9, wherein the device comprises a mesh network node.