Reverse locator

• US RE43,740 E1
• Filed: 08/05/2011
• Issued: 10/16/2012
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: Mann Group, LLC
• Original Assignee: RoundTrip, LLC
• Inventors: Karr, Lawrence J.
• Primary Examiner(s): Swarthout, Brent
• Application Number:
  US13/204,033
• Time in Patent Office: 438 Days
• Field of Search: 3405391-53932, 3405681-5721, 34042613-42622, 340/425.5, 340/988, 340/457, 340/989, 340/932.2, 455/456.1, 701/2, 701207-213
• US Class Current: 340/539.13
• CPC Class Codes: G01S 13/589 measuring the velocity vector
• CPC Class Codes: G01S 13/765 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 3/52 using a receiving antenna moving, or appearing to move, in a cyclic path to produce a Doppler variation of frequency of the received signal

Abstract

A remote locator (RL) continuously transmits multi-frame pings in a slow ping mode. The user activates a transponder/micro-transponder (MT) to receive at least a portion of the multi-frame ping and transmits a reply to the RL. The RL calculates a distance between the RL and the MT using the time-of-flight between the transmission of the ping and the receipt of the corresponding reply. The RL continues to send pings to the MT, where the ping includes distance measurements encoded therein. The user initiates sending a message from the MT to the RL to change to a fast ping mode, where the RL transmits pings at an increased rate. The MT includes a compass to capture readings while receiving and replying to pings. The MT determines a directional location for the RL with the collected measurements and received information and can provide a distance and directional readout to the user.

Claims

1. A remote locator device that is tagged to an object, wherein the remote locator device is arranged to communicate with a portable transponder device that is operated by a user such that the user can determine a relative direction and at least a distance to the object from the portable transponder device, the remote locator device comprising:

a time control circuit that is arranged to provide timing control signals according to an internal clock of the remote locator device;

a transmitter means that is arranged to transmit a structured multi-frame transmission to the portable transponder device when activated such that the structured multi-frame transmission has a transmit cadence and frequency that is determined by the internal clock of the remote locator device, wherein the structured multi-frame transmission is coded with an identifier recognized by the portable transponder device;

a receiver means that is arranged to capture samples when activated with an array of capture buffers;

a circular correlator that is arranged to identify a correlation and a correlation phase in response to captured samples from the receiver means;

a processor means that is arranged in cooperation with the time control circuit, the transmitter means, the receiver means and the circular correlator, wherein the processor means is arranged to initialize the remote locator device in a slow ping mode, wherein in the slow ping mode the processor means is arranged for;

initiating the transmission of a first structured multi-frame transmission to the portable transponder device at a first time;

capturing samples with the array of capture buffers and the receiver means over a first predetermined time interval that is sufficient to accumulate values for multiple transmissions of a first sequence from the portable transponder device;

detecting a first reply from the portable transponder device at a second time when the captured samples in the array of capture buffers correlates with an expected first reply transmission for the first sequence from the portable transponder device;

calculating a distance between the remote locator device and the portable transponder device based on a difference between the second time and the first time;

encoding the calculated distance between the remote locator device and the portable transponder device in a second structured multi-frame transmission; and

initiating the transmission of the second structured multi-frame transmission to the portable transponder device at a third time such that the portable transponder device can extract the encoded calculated distance from the second structured multi-frame transmission upon receipt.

2. The remote locator device of claim 1, wherein in the slow ping mode the processor means is further arranged for:

capturing samples with the array of capture buffers and the receiver means over a second predetermined time interval that is sufficient to accumulate values for multiple transmissions of a second sequence from the portable transponder device;

detecting a second reply from the portable transponder device at a fourth time when the captured samples in the array of capture buffers correlates with an expected second reply transmission for the second sequence from the portable transponder device;

identifying a message to change to a fast ping mode from second reply from the portable transponder device; and

initiating a change to the fast ping mode in response to the identified message.

3. The remote locator device of claim 2, wherein in the fast ping mode the processor means is arranged for repeatedly:

capturing samples with the array of capture buffers and the receiver means over a third predetermined time interval that is sufficient to accumulate values for multiple transmissions of a third sequence from the portable transponder device;

detecting a third reply from the portable transponder device at a fifth time when the captured samples in the array of capture buffers correlates to an expected third reply transmission for the third sequence from the portable transponder device;

calculating a second distance between the remote locator device and the portable transponder device based on a difference between the second time and the first time;

encoding the calculated second distance between the remote locator device and the portable transponder device in a third structured multi-frame transmissions; and

initiateinitiating the transmission of the third structured multi-frame transmission to the portable transponder device at a sixth time such that the portable transponder device can extract the encoded calculated distance from the third structured multi-frame transmissionstransmission upon receipt.

4. The remote locator device of claim 3, wherein in the fast ping mode the processor means is further arranged for:

extracting compass measurements from the portable transponder device that is encoded in each third reply;

pairing each compass measurement with an associated calculated distance;

determining the relative direction of the remote locator device from the portable transponder device from at least the compass measurements and the calculated distances;

encoding the relative direction in a fourth structured multi-frame transmission; and

initiating the transmission of the fourth structured multi-frame transmission to the portable transponder device at a seventh time such that the portable transponder can extract the relative direction from the fourth structured multi-frame transmission upon receipt.

5. The remote locator device of claim 3, further comprising:

a first antenna located in a first region of the remote locator device;

a second antenna that is located in a second region of the remote locator device;

wherein the receiver means comprises a first receiver means configuration withcoupled to the first antenna;

, and a second receiver means coupled to the second antenna

a second receiver means configuration with the second antenna, wherein in the fast ping mode the processor means is further arranged for;

evaluating captured samples associated with the first receiver configuration and the second receiver configuration;

and

determining the relative direction of the remote locator device from the portable transponder device based on the evaluated captured samples from the first receiver configuration and the second receiver configuration;

encoding the relative direction in a fourth structured multi-frame transmission; and

initiating the transmission of the fourth structured multi-frame transmission to the portable transponder device at a seventh time such that the portable transponder can extract the relative direction from the fourth structured multi-frame transmissions transmission upon receipt.

6. The remote locator device of claim 3, wherein in the fast ping mode the processor means if is further arranged for:

identifying correlator phase information associated with detected replies, and encoding correlator phase information in the third structured multi-frame transmission for receipt by the portable transponder device.

7. The remote locator device of claim 2, wherein the fast ping mode is terminated and the slow ping mode activated when the processor determines that a timeout condition is satisfied without detecting replies from the portable transponder device.

8. The remote locator device of claim 1, wherein the processor means comprises at least one of:

a micro-processor, a micro-controller, a complex instruction set computer (CISC) processor, a reduced instruction set computer (RISC) processor, an application specific integrated circuit (ASIC), a programmable logic device (PLD), a mode control logic, a firmware, a software, a storage circuit, a memory circuit, a non-volatile memory (NVM), and a read-only memory (ROM).

9. The remote locator device of claim 1, wherein the receiver means is arranged to accumulate captured signals to form an integrated captured sequence as the captured samples such that the circular correlator can identify the correlation when the captured samples from the integrated captured sequence correlates with a structured reply transmission from the portable transponder device.

10. A portable transponder device that is operated by a user and arranged to communicate with a remote locator device that is tagged to an object such that the user can determine at least a relative direction and distance to the object from the portable transponder device, the portable transponder device comprising:

an input device that is arranged to accept user initiated input;

a time control circuit that is arranged to provide timing control signals from a high speed internal clock, wherein the time control circuit is arranged to deactivate the high speed internal clock when the portable transponder device is in a low power sleep mode, and enable the high speed internal clock when a wake-up is initiated;

an indication means that is arranged to report information to the user;

a transmitter means that is arranged to transmit a structured multi-frame reply transmission to the remote locator device when activated such that the structured multi-frame transmission has a transmit cadence and frequency that is determined by the internal clock and the structured multi-frame transmission is coded with an identifier recognized as from the portable transponder device;

a receiver means that is arranged to capture samples when activated;

a correlator that is arranged to identify a correlation and a correlation phase in response to captured samples from the receiver means;

a processor means that is arranged in cooperation with the input device, the time control circuit, the indication means, the transmitter means, the receiver means and the correlator, wherein the processor means is arranged for;

initializing the portable transponder device in a low power sleep mode;

detecting user initiated inputs;

activating a slow ping mode when the user initiates a wake-up, wherein in the slow ping mode the processor is arranged for;

capturing samples with the receiver means over a first predetermined time interval sufficient to capture a first expected transmission of a first sequence from the remote locator device;

detecting a first ping from the remote locator device at a first time when the captured samples correlate with the expected first transmission from the remote locator device;

initiating the transmission of a first structured multi-frame reply transmission to the remote locator device at a second time,

capturing samples with the receiver means over a second predetermined time interval sufficient to capture a second expected transmission of a second sequence from the remote locator device;

detecting a second ping from the remote locator device at a third time when the captured samples from the second predetermined time interval correlate to the second expected transmission from the remote locator device; and

extracting the distance to the object from the detected second ping.

11. The portable transponder device of claim 10, wherein in the slow ping mode the processor means is further arranged for:

encoding a first message to the remote locator device in a second structured multi-frame reply transmission, wherein the message includes a request to change to a fast ping mode; and

initiating the transmission of the second structured multi-frame reply transmission in response to user initiated input at a fourth time.

12. The portable transponder device of claim 11, wherein in the fast ping mode the processor means is arranged for repeatedly:

capturing samples with the receiver means over a third predetermined time interval sufficient to capture a third expected transmission of a third sequence from the remote locator device;

detecting a third ping from the remote locator device at a fourth time when the captured samples correlate to the third expected transmission from the remote locator device; and

extracting the distance to the object from each detected third ping.

13. The portable transponder device of claim 12, wherein in the fast ping mode the processor means is arranged for repeatedly:

monitoring a rotational position of the portable transponder device for each detected third ping;

initiating the transmission of a third structured multi-frame reply transmission to the remote locator device at a fifth time; and

determining the relative distance and direction to the object.

14. The portable transponder device of claim 12, wherein in the fast ping mode the processor means is arranged for repeatedly:

capturing samples with the receiver means over a fourth predetermined time interval sufficient to capture a fourth expected transmission of a fourth sequence from the remote locator device;

detecting a fourth ping from the remote locator device at a fifth time when the captured samples correlate to the fourth expected transmission from the remote locator device; and

extracting the relative direction of the object from the detected fourth ping.

15. The portable transponder device of claim 10, further comprising a means for determining a rotational position associated with the portable transponder device about an axis that is approximately centered about the user of the portable transponder device.

16. The portable transponder device of claim 15 wherein the means for determining the rotational position comprises at least one of:

an analog compass sensor device, a digital compass sensor device, and an analog-to-digital converter that is arranged to work with the analog compass sensor device.

17. The portable transponder device of claim 12, wherein in the fast ping mode the processor means is further arranged for:

extracting correlator phase information associated with the remote locator from the detected third ping, and utilizing the correlator phase information to synthesize the a high frequency clock for the transmitter means.

18. The portable transponder device of claim 12 13, wherein the fast ping mode is terminated and the slow ping mode is initiated after the relative distance and direction to the object is determined.

19. The portable transponder device of claim 10, wherein the processor means comprises at least one of:

a micro-processor, a micro-controller, a complex instruction set computer (CISC) processor, a reduced instruction set computer (RISC) processor, an application specific integrated circuit (ASIC), a programmable logic device (PLD), a mode control logic, a firmware, a software, a storage circuit, a memory circuit, a non-volatile memory (NVM), and a read-only memory (ROM).

20. The portable transponder device of claim 10, wherein the processor means is further arranged to initiate a user notification via the indication means when the direction associated with the location of the remote locator relative to the portable transponder device is determined.

21. The portable transponder device of claim 10, wherein the indication means is arranged to provide a visual indicator of the determined direction.

22. The portable transponder device of claim 10, wherein the visual indicator comprises at least one of:

a graphical distance indication, an alphanumeric distance indication, a graphical direction indication, and an alphanumeric direction indication.

23. The portable transponder device of claim 10, the input device comprising an interrupt signal, a wake-up timer, a keyboard device, a keypad device, a button, a key, a touch-screen, a touch-panel, a joystick device, a joy-pad device, a mouse device, a pointing device, a touch-pad device, a pressure sensitive input device, another processor, or an input generated by a software program.

24. The portable transponder device of claim 10, the input device comprising an audio input processor that is arranged to process sound as the user input.

25. The portable transponder device of claim 24, the audio input processor comprising either an analog to digital-converter (ADC) circuit or a coder-decoder (CODEC) circuit.

26. The portable transponder device of claim 24, the audio input processor comprising a voice input means.

27. The portable transponder device of claim 10, the indication means comprising an audio output circuit that is configured to provide an audible alert to the user, wherein the audio output circuit includes an audio output processor that is combined in function with the audio input processor.

28. The portable transponder device of claim 10, the indication means comprising an audio output circuit that is configured to provide audible information to the user.

29. The portable transponder device of claim 28, wherein the audio output circuit comprises either:

an audio output device, an audio output processor, or a combination of the audio output device and the audio output processor.

30. The portable transponder device of claim 28, wherein the audio output circuit comprises either a speaker device, a piezo device, or an audio output port that is accessible by the user.

31. The portable transponder device of claim 28, wherein the audio output circuit comprising either an analog to digital-converter (ADC) circuit or a coder-decoder (CODEC) circuit.

32. The portable transponder device of claim 28, the audio output circuit is arranged to playback sounds from either a previously recorded sound or a user recorded sound.

33. The portable transponder device of claim 28, wherein the audio output circuit is arranged to synthesize previously selected sounds.

34. The portable transponder device of claim 10, the indication means comprising a visual output circuit that is configured to provide visual information to the user.

35. The portable transponder device of claim 34, wherein the visual information comprises at least one of:

a graphical distance indication, an alphanumeric distance indication, a graphical direction indication, and an alphanumeric direction indication.

36. The portable transponder device of claim 34, the visual output circuit comprising at least one of:

an LED type display, an LCD type display, an active display, a passive display, a black and white display, a monochromatic display, a color display, a discrete arrangement of LEDs, a seven segment display, and a light emitting device.

37. The portable transponder device of claim 34, wherein the visual output circuit and the input device are combined in a touch screen device.

38. The portable transponder device of claim 10, wherein the processor means is further arranged for determining an elapsed time since the last successful communication and computing an approximation of a time uncertainty associated with the portable transponder device based on the elapsed time.

39. The portable transponder device of claim 38, wherein the portable transponder device is arranged to re-establish communications with the remote locator device by evaluating the approximation of the time uncertainty associated with the portable transponder device and scanning the relevant time range such that communication are re-established with minimal impact on power consumption.