Panasonic KX-TCD455GM Service Manual

21.4. Transmitter/ReceiverBase Unit and Handset mainly consist of RF Module and DECT BBIC.Base Unit and Handset transmit/receive voice signal and data signal through the antenna oncarrier frequency.Signal Pass:*Refer to SIGNAL ROUTE ().21.4.1. Transmitter BlockThe voice signal input from the TEL LINE interface goes to RF Module (IC3) 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 adigital audio stream signal. The burst switch controller processes this stream performingencryption and scrambling, adding the various other fields to produce the GAP (Generic AccessProfile) standard DECT frame, assigning to a time slot and channel etc.In IC3, the carrier frequency is changing, and frequency modulated RF signal is generated andamplified, and radiated from antenna. Handset detects the voice signal or data signal in thecircuit same as the following explanation of Receiver Block.21.4.2. Receiver BlockThe signal of 19.2 MHz band (18.81792 MHz ~ 18.97344 MHz) which is input from antenna isinput to IC3 as shown in BLOCK DIAGRAM (BASE UNIT) ().In IC3, the signal of 19.2 MHz band is downconverted to 864 kHz signal and demoduleted, andgoes to IC2 as GAP (Generic Access Profile) standard DECT frames. It passes through thedecoding section burst switch controller where it separates out the frame information andperforms de-encryption and de-scrambling as required. It then goes to the DSP section where itis turned back into analog audio. This is amplified by the analog front end, and goes to the TELLINE Interface.22. BLOCK DIAGRAM (HANDSET)23. CIRCUIT OPERATION (HANDSET)23.1. OutlineHandset consists of the following ICs as shown in BLOCK DIAGRAM (HANDSET) ().- DECT BBIC (Base Band IC): IC1- All data signals (forming/analyzing ACK or CMD signal)- All interfaces (ex: Key, Detector Circuit, Charge, DC/DC Converter,67