Panasonic KX-TG6811CAB / KX-TG6811CAM / KX-TG6812CAB / KX-TG6821CAB / KX-TG6821CAM / KX-TG6822CAB / KX-TGA681RUB / KX-TGA681RUM Service Manual ▷ View online
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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
- 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
- ICM/OGM Recording Area
• Additionally,
- Power Supply Circuit (+3.0 V output)
- Crystal Circuit (13.824 MHz)
- Charge Circuit
- Crystal Circuit (13.824 MHz)
- Charge Circuit
- Telephone Line Interface Circuit
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KX-TG6811CAB/KX-TG6811CAM/KX-TG6812CAB/KX-TG6821CAB/KX-TG6821CAM/KX-TG6822CAB/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-TG6811CAB/KX-TG6811CAM/KX-TG6812CAB/KX-TG6821CAB/KX-TG6821CAM/KX-TG6822CAB/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 speechcom-
pression, 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.
pression, 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.
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 theTele-
phone line, etc. They are determined by the signal path route operation of voice signal.
phone 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
Front
End
&
Multi-
plexer
Multi-
plexer
TEL
Line
Interface
Line
Interface
Digital
Speech
Processor
Speech
Processor
Caller ID
Modem
Modem
Digital TAM System
*1
Flash Memory IC601
*1
Host CPU
BBIC (IC501)
DECT RF system
TDMA/TDD
Mod/Demod
PA/LNA
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-TG6811CAB/KX-TG6811CAM/KX-TG6812CAB/KX-TG6821CAB/KX-TG6821CAM/KX-TG6822CAB/KX-TGA681RUB/KX-TGA681RUM
4.4.4.
Telephone Line Interface
Telephone Line Interface Circuit:
Function
Function
• Bell signal detection
• ON/OFF hook and pulse dial circuit
• Side tone circuit
• 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:
R
and Ring (R) leads (When the telephone rings), the AC ring voltage is transferred as follows:
R
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.
T
throughthe circuit). Following signal flow is the DC current flow.
T
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.
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.
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.
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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