Embodiments are described for securing a vehicle or location. One embodiment of a method comprises: periodically transmitting a ping packet from a vehicle or location in a locked or inactive state; resetting a timer or recording a time at which the ping packet was transmitted; receiving a response packet to the ping packet; determining a time between transmitting the ping packet and receiving the response packet based on a current value in the timer when the response packet is received or based on a difference between the time at which the ping packet was transmitted and the time at which the response packet was received; determining whether the time is above a specified threshold; unlocking and/or activating the vehicle or location if the time is below the specified threshold; and maintaining the locked or inactive state if the time is above the specified threshold.