Wireless sensor time synchronization

A computer readable storage device having instructions for causing electronics to perform a method, the method comprising:

• running a local low frequency clock in a node in a network during a battery conserving sleep mode;
• waking from the sleep mode at a time boundary determined by the low frequency clock;
• updating a representation of a master time based on a calculation and the time boundary;
• advancing the representation of master time based on a local high frequency clock while the node is awake;
• receiving a time synchronization signal from a node in the network;
• and
• updating the calculation based on a difference between the representation of master time and a time provided in the time synchronization signal;
• setting a new time boundary;
• returning to the sleep mode.

A system comprising:

• a local high frequency clock;
• a local low frequency clock;
• a receiver to receive a time synchronization signal from a node in the network;
• and
• a controller coupled to the local high frequency clock, the low frequency clock, and the receiver to wake the system responsive to a time boundary determined by the low frequency clock, update a representation of master time based on a calculation and the time boundary, advance the representation of master time based on the local high frequency clock while the system is awake, receive a time synchronization signal from a node in the network, and update the calculation based on a difference between the representation of master time and a time provided in the time synchronization signal.