Abstract: Methods and systems for determining the distance between two objects and optionally activating an alarm when the distance exceeds a predetermined threshold. The detection system includes a base unit and a remote unit. The base unit includes a first transmitter for transmitting at least one locator pulse; a first receiver for receiving at least one return pulse, the first receiver including a pulse detector for detecting the leading edge of the at least one return pulse; and a distance measurement unit. The remote unit includes a second receiver for receiving the at least one locator pulse; and a second transmitter for transmitting the at least one return pulse in response to the at least one locator pulse. The distance measurement unit is adapted for determining the distance between the base unit and the remote unit based on the leading edge of the at least one return pulse.