System and method for saving energy in a locator apparatus

A method for saving energy in a locator apparatus, wherein the locator apparatus comprises a movement detector, a satellite positioning device, a group of communication channels comprising at least two communication channels, a battery, means for harvesting energy and a processor comprising a memory, said memory storing allowed position of the locator apparatus as a function of time and a set of instructions for performing a location update, the method comprising

• calculating an update threshold as a function of energy available in the locator apparatus, movement detection and location detection,
• performing a location update when the update threshold is exceeded, and
• transmitting the location update to a server, using a selected communication channel, the selection being based on energy efficiency of the communication channel at the time of the transmission, wherein the energy efficiency is determined by
• measuring received signal strength from each communication channel,
• adding a predefined protocol overhead to an amount of data of the location update to be transmitted, to obtain an actual amount of data of the location update to be transmitted, for each communication channel,
• performing a conversion from the actual amount of data of the location update to energy required for transmission using each communication channel, and
• selecting the communication channel having the lowest requirement of energy for transmission.