Electronic tether for portable objects

1. An electronic tether for an animal comprising:

an animal worn monitoring module comprising a portable transmitter adapted for transmitting a signal, wherein monitoring module further comprises a first clock and the audio signal comprising a first clock time T 1 as measured by the first clock at the time of transmission of the signal; and

an alert module comprising a receiver wirelessly connected to the portable transmitter and a second clock, wherein the receiver is adapted to receive the signal from the transmitter, wherein the first clock and the second clock are referenced to a common time T 0 and wherein the alert module is adapted to:

receive the signal from the monitoring module, wherein the signal is received at time T 2 ;

determine a signal propagation time indicative of the time for the signal to reach the alert module from the monitoring module, wherein the signal propagation time is equal to T 2 =T 1 ;

determine a separation distance between the animal worn monitoring module and the alert module based on the propagation time and a propagation speed of the signal, and

issue an alert when the separation distance exceeds a predetermined threshold.

2. The electronic tether for an animal of claim 1 , wherein the portable transmitter is an RF transmitter.

3. The electronic tether for an animal of claim 1 , wherein the portable transmitter is an audio transmitter.

4. A method for monitoring an animal using electronic tether comprising:

sending a signal from an animal worn monitoring module, wherein the signal comprises a first clock time T 1 as measured by a first clock in the monitoring module at the time of transmission of the signal;

receiving the signal from the animal worn monitoring module at an alert module;

determining an arrival time T 2 of the signal at the alert module as measured by a second clock in the alert module, wherein the first clock and the second clock are referenced to a common time T 0 ;

determining a signal propagation time indicative of the time for the signal to reach the alert module from the monitoring module, wherein the signal propagation time is equal to T 2 −T 1 ;

determining a separation distance between the animal worn monitoring module and the alert module based on the propagation time and a propagation speed of the signal; and

issuing an alert when the separation distance exceeds a predetermined threshold.

5. The method of claim 4 , wherein the signal is generated by an audio transmitter.

6. The method of claim 4 , wherein the signal is generated by a RF transmitter.

7. A method for monitoring object location using an electronic tether comprising:

sending a signal from a monitoring module, wherein the signal comprises a first clock time T 1 as measured by a first clock in the monitoring module at the time of transmission of the signal;

receiving the signal from the monitoring module at an alert module;

determining an arrival time T 2 of the signal at the alert module as measured by a second clock in the alert module, wherein the first clock and the second clock are referenced to a common time T 0 ;

determining a signal propagation time indicative of the time for the signal to reach the alert module from the monitoring module, wherein the signal propagation time is equal to T 2 −T 1 ;

determining a separation distance between the monitoring module and the alert module based on the propagation time and a propagation speed of the signal; and

issuing an alert when the separation distance exceeds a predetermined threshold.

8. The method of claim 7 , wherein issuing an alert when the separation distance exceeds a predetermined threshold level comprises issuing a visual alarm.

9. The method of claim 7 , wherein issuing an alert when the separation distance exceeds a predetermined threshold level comprises displaying a text message.

10. The method of claim 7 , wherein issuing an alert when the separation distance exceeds a predetermined threshold level comprises issuing a tactile alert.

11. The method of claim 7 , wherein the signal is an RF signal.

12. The method of claim 7 , wherein the signal is an audio signal.

13. The method of claim 7 , wherein the monitoring device is used to monitored an object selected from the list consisting of a human, a non-human animal, an article of luggage, a computer, a package, and a container.

14. The method of claim 7 , wherein issuing an alert when the separation distance exceeds a predetermined threshold level comprises issuing an audible alarm.

15. The method of claim 14 , wherein issuing an audible alarm when the separation distance exceeds a predetermined threshold level comprises issuing a synthesized voice.

16. An electronic tether comprising:

a monitoring module comprising a first clock, wherein the monitoring module is adapted to send a signal comprising a first clock time T 1 as measured by the first clock at the time of transmission of the signal; and

an alert module comprising a second clock, wherein the first clock and the second clock are referenced to a common time T 0 and the alert module is adapted to:

receive the signal from the monitoring module, wherein the signal is received at time T 2 ;

determine a signal propagation time indicative of the time for the signal to reach the alert module from the monitoring module, wherein the signal propagation time is equal to T 2 −T 1 ;

determine a separation distance between the monitoring module and the alert module based on the propagation time and a propagation speed of the signal; and

issue an alert when the separation distance exceeds a predetermined threshold.

17. The electronic tether of claim 16 , wherein the signal is an RF signal.

18. The electronic tether of claim 16 , wherein the signal is an audio signal.

19. The electronic tether of claim 16 , wherein the monitoring device is used to monitored an object selected from the list consisting of a human, a non-human animal, an article of luggage, a computer, a package, and a container.

20. The electronic tether of claim 16 , wherein the alert is an audible alarm.

21. The electronic tether of claim 20 , wherein the audible alarm is a synthesized voice.

22. The electronic tether of claim 16 , wherein the alert is a visual alarm.

23. The electronic tether of claim 22 , wherein the visual alarm is a text.

24. An anti-theft alert device comprising:

a monitoring module comprising a portable transmitter adapted for transmitting an audio signal, wherein the monitoring module further comprises a first clock and the audio signal comprising a first clock time T 1 as measured by the first clock at the time of transmission of the signal; and

an alert module comprising a receiver wirelessly connected to the portable transmitter and a second clock, wherein the receiver is adapted to receive the signal from the transmitter, wherein the first clock and the second clock are referenced to a common time T 0 and wherein the alert module is adapted to:

receive the signal from the monitoring module, wherein the signal is received at time T 2 ;

determine a signal propagation time indicative of the time for the signal to reach the alert module from the monitoring module, wherein the signal propagation time is equal to T 2 −T 1 ;

determine a separation distance between the monitoring module and the alert module based on the propagation time and a propagation speed of the signal, and

issue an alert when the separation distance exceeds a predetermined threshold.

25. The electronic tether of claim 24 , wherein the portable transmitter is an RF transmitter.

26. The electronic tether of claim 25 , wherein the transmitter is a audio transmitter.

27. The electronic tether of claim 24 , wherein the alert is an audible alarm.

28. The electronic tether of claim 27 , wherein the audible alarm is a synthesized voice.

29. The electronic tether of claim 24 , wherein the alert is a visual alarm.

30. The electronic tether of claim 29 , wherein the visual alarm is a text message.