Panasonic KX-TG7731S Service Manual page 9

4.2.3. Signal Flowchart in the Radio Parts
Reception
Base unit:
A voice signal from TEL line is encoded to digital data and converted into a 1.9GHz modulated radio signal by BBIC(IC501).
The RF signal, after which is amplified in BBIC, is fed to selected antenna.
Handset:
As for a handset RF, RF signal is received in one antenna.
BBIC down-converts to 864 kHz IF signal from RX signal and demodulates it to digital data "RXDATA".
BBIC (IC1) converts RXDATA into a voice signal and outputs it to speaker.
Transmission
Handset:
A voice signal from microphone is encoded to digital data and converted into a 1.9GHz modulated radio signal by BBIC(IC1).
The RF signal, after which is amplified in BBIC, is fed to an antenna.
Base unit:
As for a base unit RF, RF signal is received in two antennas.
BBIC (IC501) compares RF signal levels and selects the antenna to be used. Then BBIC down-converts to 864 kHz IF signal
from RX signal in the selected antenna, and demodulates it to digital data "RXDATA".
BBIC (IC501) converts RXDATA into a voice signal and outputs it to TEL line.
KX-TG7731S/KX-TG7732S/KX-TG7733S/KX-TGA470S
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