Patent ID: 7064669

Claim:
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.