Circuit Operation (Cordless Handset) - Panasonic KX-TCD540NZM Service Manual

The voice signal input from the TEL LINE interface goes to RF Module (RFM1)
through DECT BBIC (IC2) as shown in BLOCK DIAGRAM (BASE UNIT) (
)
The voice signal passes through the analog part of IC2 where it is amplified and
converted to a digital audio stream signal. The burst switch controller processes
this stream performing encryption and scrambling, adding the various other fields
to produce the GAP (Generic Access Profile) standard DECT frame, assigning to a
time slot and channel etc.
In RFM1, the carrier frequency is changing, and frequency modulated RF signal is
generated and amplified, and radiated from antenna. Cordless Handset detects the
voice signal or data signal in the circuit same as the following explanation of
Receiver Block.
21.4.2. Receiver Block
The signal of 19.2 MHz band (18.81792 MHz ~ 18.97344 MHz) which is input from
antenna is input to RFM1 as shown in BLOCK DIAGRAM (BASE UNIT) (
).
In RFM1, the signal of 19.2 MHz band is downconverted to 864 kHz signal and
demoduleted, and goes to IC2 as GAP (Generic Access Profile) standard DECT
frames. It passes through the decoding section burst switch controller where it
separates out the frame information and performs de-encryption and de-scrambling
as required. It then goes to the DSP section where it is turned back into analog
audio. This is amplified by the analog front end, and goes to the TEL LINE Interface.
22. BLOCK DIAGRAM (CORDLESS HANDSET)

23. CIRCUIT OPERATION (CORDLESS HANDSET)

23.1. Outline
118