DOWNLOAD Panasonic KX-TG8551CAB / KX-TG8561CAB / KX-TGA855RUB Service Manual ↓ Size: 8.49 MB | Pages: 103 in PDF or view online for FREE

Model
KX-TG8551CAB KX-TG8561CAB KX-TGA855RUB
Pages
103
Size
8.49 MB
Type
PDF
Document
Service Manual
Brand
Device
Telephone / DIGITAL CORDLESS PHONE
File
kx-tg8551cab-kx-tg8561cab-kx-tga855rub.pdf
Date

Panasonic KX-TG8551CAB / KX-TG8561CAB / KX-TGA855RUB Service Manual ▷ View online

10
KX-TG8551CAB/KXTG8561CAB/KX-TGA855RUB
4.3.
Block Diagram (Base Unit RF Part)
KX-TG8551/8561 BLOCK DIAGRAM (Base Unit_RF Part)
DA801
ANT2
ANT1
TXON
RXON
RXp
RXn
ANT2
ANT1
TXp
TXn
11
KX-TG8551CAB/KXTG8561CAB/KX-TGA855RUB
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.
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 theTele-
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-TG8561 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
Flash Memory  IC601
 Host CPU
BBIC (IC501)
DECT RF system
 TDMA/TDD
 Mod/Demod
 PA/LNA
ADPCM
Keys/ LEDs/ Charge
EEPROM IC611
12
KX-TG8551CAB/KXTG8561CAB/KX-TGA855RUB
4.4.4.
Power Supply Circuit
The power is supplied to the DECT BBIC, QSPI FLASH MEMORY, FLASH MEMORY, EEPROM and Charge Contact from AC
Adaptor (+5.5 V) as shown in Fig.101. The power supply is as follows;
• DECT BBIC (IC501): 
DC Jack (+5.5 V) 
→ IC302 → IC501
DC Jack (+5.5 V) 
→ IC302 → Q302 → IC501
DC Jack (+5.5 V) 
→ IC302 → Q301 → IC501
• EEPROM (IC611): 
DC Jack (+5.5 V) 
→ IC302 → IC501→ IC611
• FLASH MEMORY (IC601) (for KX-TG8561 only): 
DC Jack (+5.5 V) 
→ IC302→ IC501→ IC601
• Charge Contact (CHARGE+): 
DC Jack (+5.5 V) 
→ R371 → R372 → D362→ CHARGE+
• QSPI FLASH MEMORY (IC502): 
DC Jack (+5.5 V) 
→ IC302 → IC501 → IC502 
<Fig.101>
AC Adaptor 
* for KX-TG8561 only
DCP
IC302
Q302
IC501 
IC502
IC601*
IC611
+5.5 V 
1.8 V 
3.0 V 
3.0 V 
Q301
2.4 V 
CHARGE+
D362
R372
R371
DC
Jack
2.85 V 
DCM
1
2
3
On
DC
S
1.8 V
Reset
(IC501(RSTN))
Off
13
KX-TG8551CAB/KXTG8561CAB/KX-TGA855RUB
4.4.5.
Telephone Line Interface
<Function>
• Bell signal detection
• Clip signal detection
• ON/OFF hook circuit
Bell & Clip (: Calling Line Identification Presentation: Caller ID) signal detection:
In the standby mode, Q141 is open to cut the DC loop current and decrease the ring load.
When ring voltage appears at the L1T (A) and L1R (B) leads (when the telephone rings), the AC ring voltage is transferred as
follows;
• B 
→ P101 → C106 → R106 → R107 → IC501 (CID INp) 
• A 
→ C105 → R105 → R108 → IC501 (CID INn)
ON/OFF hook circuit:
In the standby mode, Q104 is open, and connected as to cut the DC loop current and to cut the voice signal. The unit is
consequently in an on-hook condition
When IC501 detects a ring signal or press the TALK Key onto the handset, Q142 turns on and then Q141 turns on, thus
providing an off-hook condition (DC current flows through the circuit) and the following signal flow makes the loop current.
• B 
→ P101 →D101 → Q141 → Q161 → R163 → R167 → D101 → A
4.4.6.
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.17).
4.4.6.1.
Transmitter Block
The voice signal input from the TEL LINE interface goes to DECT BBIC (IC501) as shown in Block Diagram (Base Unit) (P.8)
The voice signal passes through the analog part of IC501 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 IC501, the carrier frequency is changing, and frequency modulated RF signal is generated.In IC501,RF signal is amplified,
and radiated from antenna. Handset detects the voice signal or data signal in the circuit same as the following explanation of
Receiver Block.
4.4.6.2.
Receiver Block
The signal of 1900 MHz band (1881.792 MHz ~ 1897.344 MHz) which is input from antenna is input to IC501 as shown in Block
Diagram (Base Unit)
 (P.8).
In IC501, the signal of 1900 MHz band is downconverted to 864 kHz signal and demodulated, 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.
4.4.6.3.
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 Q144.
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