14
KX-PRW130W/KX-PRWA13W
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
C104
R102
IC501 (CID INp)
C106
R104
• A
C103
R101
IC501 (CID INn)
C105
R103
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
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.19).
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.10)
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 (
G
eneric
A
ccess
P
rofile) 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 (1921.536 MHz ~ 1928.448 MHz) which is input from antenna is input to IC501 as shown in
Block
Diagram (Base Unit)
(P.10).
In IC501, the signal of 1900 MHz band is downconverted to 864 kHz signal and demodulated, as GAP (
G
eneric
A
ccess
P
rofile)
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.
4.4.7.
WiFi Module
BBIC and WiFi module are connected with 3group signals as shown in
Block Diagram (Base Unit)
(P.10).
SPI (Serial Peripheral Interface) Control --- Control the data (except Audio data) between BBIC and Wi-Fi module
Interrupt Control --- Control the timing of sending/receiving of BBIC and Wi-Fi module
PCM (Pulse Code Modulation) Control --- Control the Audiol data between BBIC and Wi-Fi module.
When turning ON, it start to communicate between BBIC and WiFi module by SPI Control with Interrupt control to set various
data into the register of WiFi module and then it becomes Stand-by status.
WiFi network data, such as MAC address is transferred to Memory of WiFi module from BBIC's one.
For talk with Smartphone via WiFi, audio signal is modified to PCM signal then communicated.
4.4.8.
Parallel Connection Detect Circuit/Auto Disconnect Circuit
Function:
In order to disable call waiting and stutter tone functions when using telephones connected in parallel, it is necessary to have a
circuit that judges whether a telephone connected in parallel is in use or not. This circuit determines whether the telephone
connected in parallel is on hook or off hook by detecting changes in the T/R voltage.
Circuit Operation:
Parallel connection detection when on hook:
When on hook, the voltage is monitored at pin (N1), (N2) of IC501. There is no parallel connection if the voltage is
0.54 V or higher, while a parallel connection is deemed to exist if the voltage is lower.
