In FIG. 1, transceiver apparatus 100 comprises signal transmitting and receiving means such as signal transmitting and receiving switching means such as switch 12, attenuating means such as attenuator 14, low noise amplifying means such as low noise amplifier (LNA) 16, first variable amplifying means such as variable gain amplifier (VGA) 18, demodulating means such as demodulator 20, first low pas