Patent ID: 7443287

Claim:
A portable device for performing wireless communication with a controller, which controls a predetermined controlled subject, and remotely controlling the controller, the portable device comprising: a receiver for receiving a transmission signal from the controller in a plurality of predetermined areas, the receiver having an adjustable signal receiving sensitivity enabling receipt of the transmission signal and being selectively operable in a normal mode and a sensitivity adjustment mode; a control unit, connected to the receiver, for lowering or raising the signal receiving sensitivity of the receiver by a predetermined level in the sensitivity adjustment mode in cooperation with the transmission signal when the portable device is located in a designated one of the predetermined areas to which the transmission signal is transmitted, wherein when in the sensitivity adjustment mode, the control unit finds a limit for the signal receiving sensitivity of the receiver in the designated one of the predetermined areas to set a signal receivable area for the receiver in accordance with the limit of the signal receiving sensitivity; and an operation unit connected to the control unit and operable by a person holding the portable device, the operation unit being operated to switch the receiver between the normal mode and the sensitivity adjustment mode, wherein the operation unit is operated during the sensitivity adjustment mode to designate one of the predetermined areas to which the transmission signal is transmitted.