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Model
KX-TG6811UAB KX-TG6811UAM KX-TG6812UAB KX-TG6821UAB KX-TGA681RUB KX-TGA681RUM
Pages
95
Size
6.8 MB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS ANSWERING SYSTEM
File
kx-tg6811uab-kx-tg6811uam-kx-tg6812uab-kx-tg6821ua.pdf
Date

Panasonic KX-TG6811UAB / KX-TG6811UAM / KX-TG6812UAB / KX-TG6821UAB / KX-TGA681RUB / KX-TGA681RUM Service Manual ▷ View online

9
KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.2.
Circuit Operation (Base Unit)
4.2.1.
Outline
Base Unit consists of the following ICs as shown in Block Diagram (Base Unit) (P.8).
• DECT BBIC (Base Band IC): IC501
- Handling all the audio, signal and data processing needed in a DECT base unit
- Controlling the DECT specific physical layer and radio section (Burst Module Controller section)
- ADPCM code filter for speech encoding and speech decoding (DSP section)
- Echo-cancellation and Echo-suppression (DSP section)
- Any tones (tone, sidetone, ringing tone, etc.) generation (DSP section)
- DTMF receiver (DSP section)
- Clock Generation for RF Module
- ADC, DAC, timer, and power control circuitry
- PLL Oscillator
- Detector 
- Compress/Expander
- First Mixer
- All interfaces (ex: QSPI FLASH MEMORY, EEPROM, LED, Analog Front End, etc.)
- Integrated 1.9GHz PA for DECT
• EEPROM: IC611
- Temporary operating parameters (for RF, etc.)
• FLASH MEMORY: IC601 (for KX-TG6821 only)
- Voice Prompt (TAM) D/L Area
- ICM/OGM Recording Area
• Additionally,
- Power Supply Circuit (+3.0 V output)
- Crystal Circuit (13.824 MHz)
- Charge Circuit
- Telephone Line Interface Circuit
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KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.3.
Block Diagram (Base Unit RF Part)
DA802
ANT2
ANT1
RXp
RXn
ANT2
ANT1
TXp
TXn
KX-TG6811/6821 BLOCK DIAGRAM (Base Unit_RF Part)
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KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.4.
Circuit Operation (Base Unit)
General Description:
(BBIC, Flash Memory, EERROM) is a digital speech/signal processing system that implements all the functions of 
speechcompression, record and playback, and memory management required in a digital telephone answering machine.The
BBIC system is fully controlled by a host processor. The host processor provides activation and control of all that functionsas 
follows.
4.4.1.
BBIC (Base Band IC: IC501)
• Voice Message Recording/Play back
The BBIC system uses a proprietary speech compression technique to record and store voice message in Flash Memory.An
error correction algorithm is used to enable playback of these messages from the Flash Memory.
• DTMF Generator
When the DTMF data from the handset is received, the DTMF signal is output.
• Synthesized Voice (Pre-recorded message)
The BBIC implements synthesized Voice, utilizing the built in speech detector and a Flash Memory, which stored the vocabulary.
• Caller ID demodulation
The BBIC implements monitor and demodulate the FSK/DTMF signals that provide CID information from the Central Office.
• Digital Switching
The voice signal from telephone line is transmitted to the handset or the voice signal from the handset is transmitted to the 
Telephone line, etc. They are determined by the signal path route operation of voice signal.
• Block Interface Circuit
RF part, LED, Key scan, Speaker, Telephone line.
4.4.2.
Flash Memory (IC601) (for KX-TG6821 only)
Following information data is stored.
• Voice signal
ex: Pre-recorded Greeting message, Incoming message
4.4.3.
EEPROM (IC611)
Following information data is stored.
• Settings
ex: message numbers, ID code, Flash Time, Tone/Pulse
RF part
ADPCM
Analog
Front
End
&
  
Multi-
plexer
TEL
Line
Interface
Digital
Speech
Processor
Caller ID
Modem
Digital TAM  System
*1
Flash Memory  IC601
*1
 Host CPU
BBIC (IC501)
DECT RF system
 TDMA/TDD
 Mod/Demod
 PA/LNA
ADPCM
Keys/ LEDs/ Charge
*1
EEPROM IC611
*1 for KX-TG6821 only
Speaker
*1
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KX-TG6811UAB/KX-TG6811UAM/KX-TG6812UAB/KX-TG6821UAB/KX-TGA681RUB/KX-TGA681RUM
4.4.4.
Telephone Line Interface
Telephone Line Interface Circuit:
Function
• Bell signal detection
• ON/OFF hook and pulse dial circuit
• Side tone circuit
Bell signal detection and OFF HOOK circuit:
In the idle mode, Q141 is open to cut the DC loop current and decrease the ring load. When ring voltage appears at the Tip (T)
and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows:
→ P101 → R111 → C111 → Q111 → BBIC pin 5
When the CPU (BBIC) detects a ring signal, Q141 turns on, thus providing an off-hook condition (active DC current flow
throughthe circuit). Following signal flow is the DC current flow.
→ D101 → Q141 → Q161 → R163 → D101 → P101 → R
ON HOOK Circuit:
Q141 is open, Q141 is connected as to cut the DC loop current and to cut the voice signal. The unit is consequently in an on-
hook condition.
Pulse Dial Circuit:
Pin 6 of BBIC turns Q141 ON/OFF to make the pulse dialing.
Side Tone Circuit:
Basically this circuit prevents the TX signal from feeding back to RX signal. As for this unit, TX signal feed back from Q161 is
canceled by the canceller circuit of BBIC.
4.4.4.1.
Pulse Dialling
During pulse dialling the hookswitch (Q141, Q142) 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 Q140.
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