Digital delay measurement

• US 9,013,190 B2
• Filed: 10/29/2012
• Issued: 04/21/2015
• Est. Priority Date: 10/28/2011
• Status: Active Grant

• Current Assignee: Digi International Inc.
• Original Assignee: Digi International Inc.
• Inventors: Dahl, Paul A.
• Primary Examiner(s): Nguyen, Vincent Q
• Application Number:
  US13/663,183
• Publication Number:
  US 20130106439A1
• Time in Patent Office: 904 Days
• Field of Search: 324/76.11, 324/617
• 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 includes 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. An electronic device, comprising:

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

a processing module comprising a logic gate, the logic gate coupled to the communication module to receive the digital signal as sent to the second device 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;

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; and

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.

2. The electronic device of claim 1, wherein the communication module further comprises a wireless RF transceiver, and the digital signal and received repeated digital signal comprise wireless radio frequency signals.

3. The electronic device of claim 1, wherein the logic gate is an XOR or XNOR logic gate.

4. The electronic device of claim 1, wherein the digital signal is encoded to have frequent state transitions.

5. The electronic device of claim 1, 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.

6. The electronic device of claim 1, wherein the device comprises a cellular telephone.

7. The electronic device of claim 1, wherein the device comprises a mesh network node.