A transceiver includes a receiver, a signal strength determiner, and a controller. The receiver receives a trigger signal transmitted by a triggering device; the trigger signal indicates both a signal strength range and a command. The signal strength determiner determines the strength of the trigger signal received by the receiver. The controller is configured to: 1) determine whether the strength of the trigger signal determined by the signal strength determiner is within the signal strength range indicated by the trigger signal; 2) and perform a task in accordance with the command indicated by the trigger signal only when the strength of the trigger signal is within the signal strength range.