PANASONIC KX-A142AXM
Manual de Servicio

20.4. Transmitter/Receiver
Base 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 on carrier frequency.

Signal Pass: *Refer to SIGNAL ROUTE ().

20.4.1. Transmitter Block
The 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 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 IC3, the carrier frequency is changing, and frequency modulated RF signal is generated and amplified, and radiated from antenna. Handset detects the voice signal or data signal in the circuit same as the following explanation of Receiver Block.

20.4.2. Receiver Block
The signal of 19.2 MHz band (18.81792 MHz ~ 18.97344 MHz) which is input from antenna is input to 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, 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.

20.5. Pulse Dialing
During pulse dialing the hookswitch (Q2, Q3) is used to generate the pulses using the HOOK control signal, which is set high during pulses. To force the line impedance low during the �pause� intervals between dial pulses, the PULSE_DIAL signal turns on Q7.

21. BLOCK DIAGRAM (HANDSET) 22. CIRCUIT OPERATION (HANDSET)
22.1. Outline
Handset consists of the following ICs as shown in BLOCK DIAGRAM (HANDSET) ().

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