An active tag (Figure 3-8) has an on-board power source, usually a battery, and an
active transmitter. The IC of this tag may contain more processing power to implement
additional functionalities such as data manipulation. This tag uses the
battery to power its IC and transmitter. It does not need emitted power or radio
signals from the interrogator to transmit its data. Actually, it does not even need
an interrogator.An active tagmay be set to broadcast its data at a preset time,periodically,
or on occurrence of a certain event. Its typical read range is 300 to 750
feet. The read range depends on the battery power and type of transmitter on the
tag. An active tag, like a semi-passive tag, may have on-board sensors or external
sensors connected to it. With more processing power, the tag may collect data
from the sensors and locally process the data before broadcasting. Active tags are
often used by real time location systems(RTLSs).(RTLS is discussed inChapter 5.)