Method and apparatus for conserving energy in a battery powered tag which
comprises a battery, one or more sensors, and a transmitter. The tag may be used
in a pneumatic tire monitoring system which senses and transmits tire pressure
and temperature readings. The method fundamentally comprises: hibernating between
transmissions by the transmitter; and reading at least one of the sensors after
each of a plurality of sleep periods while hibernating. A hibernation period may
be ended if one of the sensor readings, preferably tire temperature, is very low,
and at least one of a plurality of qualification criteria is met.
