Panasonic KX-TG2216LAS, Service Manual

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Circuit Operation:
Parallel connection detection when on hook:
When the set is on hook, the voltage is monitored at DSP (DCIN0). There is no parallel
connection if the voltage is 2.50 V or higher, while a parallel connection is deemed to exist if the
voltage is lower.
Parallel connection detection when off hook:
When the set is off hook, the voltage is monitored at DSP (DCIN1); the presence/absence of a
parallel connection is determined when the voltage changes by 0.2 V or more.
16.9. Calling Line Identification (Caller ID)
Function:
The caller ID is a chargeable ID which the user of a telephone circuit obtains by entering a
contract with the telephone company to utilize a caller ID service. For this reason, the operation
of this circuit assumes that a caller ID service contract has been entered for the circuit being
used.
The Caller-ID data from exchange is supplied to the telephone using either method of FSK. The
method is chosen according to the exchange of telephone office. This unit is available to
receive the data with both methods and displays the received data on LCD.
- FSK (Frequency Shift Keying) format
- DTMF format
It is the method to send the telephone number of calling party with
DTMF to the telephone. DTMF is sent before the first bell signal.
The data is sent in turn; first the start code, secondly the
telephone number of calling party, lastly end code.
The DTMF is chosen from A (1633Hz and 697Hz), B (1633Hz and
770Hz), C (1633Hz and 852Hz) and D (1633Hz and 941Hz) as the
start code and end code according to the exchange.
17. BLOCK DIAGRAM (HANDSET)
18. CIRCUIT OPERATION (HANDSET)
18.1. Construction
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