Panasonic KX-TG7120FXT Service Manual

Also see for KX-TGA711FXS: Service manual Service manual

Contents

10KX-TG7120BXS/KX-TG7120BXT/KX-TGA711CXS/KX-TGA711CXT4.2.4. Transmitter/Receiver• Audio Circuits and DTMF tone signal circuits.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 Path:*Refer to Signal Route (P.14).4.2.4.1. Transmitter BlockThe voice signal input from the TEL LINE interface goes to RF Module (IC10) through DECT BBIC (IC7) as shown in Block Dia-gram (Base Unit) (P.7)The voice signal passes through the analog part of IC7 where it is amplified and converted to a digital audio stream signal. Theburst switch controller processes this stream performing encryption and scrambling, adding the various other fields to producethe GAP (Generic Access Profile) standard DECT frame, assigning to a time slot and channel etc.In IC10, the carrier frequency is changing, and frequency modulated RF signal is generated and amplified, and radiated fromantenna. Handset detects the voice signal or data signal in the circuit same as the following explanation of Receiver Block.4.2.4.2. Receiver BlockThe signal of 1900 MHz band (1881.792 MHz ~ 1897.344 MHz) which is input from antenna is input to IC10 as shown in BlockDiagram (Base Unit) (P.7).In IC10, the signal of 1900 MHz band is downconverted to 864 kHz signal and demodulated, and goes to IC7 as GAP (GenericAccess Profile) standard DECT frames. It passes through the decoding section burst switch controller where it separates out theframe information and performs de-encryption and de-scrambling as required. It then goes to the DSP section where it is turnedback into analog audio. This is amplified by the analog front end, and goes to the TEL LINE Interface.4.2.5. Pulse DialingDuring pulse dialing the hookswitch (Q3,Q4) is used to generate the pulses using the HOOK control signal, which is set highduring pulses. To force the line impedance low during the “pause” intervals between dial pulses, the PULSE_DIAL signal turnson Q2.