A wireless keyboard has a transmitting and receiving portion 12 for
transmitting an input data D to an information processing device 2 and
receiving a reception level from the information processing device 2, a
transmission level setting portion 14 for storing the transmission level
of the input data D, setting a new transmission level referring to the
transmission level setting table in response to the combination of the
stored transmission level and the reception level on receiving the
reception level and detecting a distance information with respect to the
information processing device 2 referring to a distance information table,
a transmission level switching portion 15 for switching the transmission
level of the input data D to a new transmission level, an LCD indicating
portion 16 for receiving and indicating the distance information, a timer
13 for output a time-out signal in the event the reception level is not
transmitted even a fixed period of time passed after the input data D is
transmitted and an indication LED 17 for indicating the communications
failure by receiving the above-mentioned time-out signal.
