Panasonic KX-A143EXC, Service Manual

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- A R77 D2 Q2 R8 Q3 D2 B [OFF HOOK]
Earth Recall Service Option
The circuit can be configured for connection to signalling earth by a service engineer as an
optional feature. In order to facilitate this the components listed below are to be fitted by a
Service Engineer/Technician.
This modification connects the "E" and "A" contacts of the pulg when the relay is switched on.
The relay is controlled by the "EARTH" signal from IC2 pin58.
It can be programmed to operate in Earth Recall or Timed Break mode.
The factory preset is Timed Break mode.
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.
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