An antenna switching apparatus which detects an antenna of good reception with
high precision and suppresses control errors in antenna switching. A comparator
compares a noise component obtained from a selected antenna with a threshold for
noise detection. When noise detection occurs a predetermined number of times within
a predetermined time, an antenna switching control unit outputs an antenna switching
control signal to switch to another antenna. If all antennas are switched within
a predetermined time, a noise switching count analyzing unit outputs a sensitivity
control signal, deciding that the threshold should be changed. A noise detection
sensitivity setting unit, when supplied with the sensitivity control signal within
a predetermined time, increases the threshold to lower the noise detection sensitivity
of the comparator. When the predetermined time elapses without the sensitivity
control signal being supplied, the noise detection sensitivity setting unit decreases
the threshold to lower the noise detection sensitivity of the comparator. The noise
detection sensitivity is thus varied and adjusted to the actual reception quality,
whereby an antenna of good reception is detected with high precision and control
errors in antenna switching are suppressed.