A communication channel selecting circuit which can select and use a channel
that
does not disturb or interfere with another radio apparatus, avoiding a channel
occupied by other similar radio apparatus nearby, is provided. The communication
channel selecting circuit selects a communication channel in accordance with radio
signal intensity, the selecting circuit transmitting and receiving radio signals
in a plurality of channels. A radio unit outputs a signal indicating radio signal
intensity of a radio signal received through an antenna in a receiving status and
transmitting a radio signal to the antenna in a transmission status. A control
circuit sets the radio unit to the receiving status even at a transmission timing.
The communication channel selecting circuit further includes a timing control circuit
which outputs a timing signal for each of the plurality of channels at the transmission
timing, a register which stores a signal level outputted from the radio unit in
the receiving status corresponding to the timing signal and a transmission receiving
control circuit which compares the signal level stored in the register and selects
one of the plurality of channels to transmit/receive.
