Panasonic KX-TC1811B Service Manual ▷ View online
11.8. Calling Line Identification Circuit (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 data for the caller ID from the telephone exchange is sent during the interval between the first and second rings of the bell
signal. The data from the telephone exchange is a modem signal which is modulated in an FSK (Frequency Shift Keying) format.
Data "0" is a 1200 Hz sine wave, and data 1 a 2200 Hz sine wave.
There are two type of the message format which can be received: i.e. the single message format and plural message format. The
plural message format allows to transmit the name and data code information in addition to the time and telephone number data.
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 data for the caller ID from the telephone exchange is sent during the interval between the first and second rings of the bell
signal. The data from the telephone exchange is a modem signal which is modulated in an FSK (Frequency Shift Keying) format.
Data "0" is a 1200 Hz sine wave, and data 1 a 2200 Hz sine wave.
There are two type of the message format which can be received: i.e. the single message format and plural message format. The
plural message format allows to transmit the name and data code information in addition to the time and telephone number data.
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l
Call Waiting
Calling Identity Delivery on Call Waiting (CIDCW) is a CLASS service that allows a customer, while off-hook on an existing call, to
receive information about a calling party on a waited call. The transmission of the calling information takes place almost
immediately after the customer is alerted to the new call so he/she can use this information to decide whether to take the new call.
receive information about a calling party on a waited call. The transmission of the calling information takes place almost
immediately after the customer is alerted to the new call so he/she can use this information to decide whether to take the new call.
Function:
The CAS signal flows from T/R
The CAS signal flows from T/R
→
R111, R112 collector
→
C111, C112
→
IC501 pins 41~43 and the ACK (DTMF signal) is
returned to the telephone exchange. The telephone exchange that received the ACK can send the data in the same manner as the
caller ID. If the unit deems that a telephone connected in parallel is in use, ACK is not returned even if CAS is received, and the
information for the second and subsequent callers is not displayed on the portable handset display.
caller ID. If the unit deems that a telephone connected in parallel is in use, ACK is not returned even if CAS is received, and the
information for the second and subsequent callers is not displayed on the portable handset display.
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KX-TC1811B
11.9. Parallel Connection Detection 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.
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 Q115 is ON, the voltage is monitored pin 40 of IC501. There is no parallel connection if the voltage is 1.65 V or
higher, while a parallel connection is deemed to exist if the voltage is lower.
Parallel connection detection when on hook:
When on hook Q115 is ON, the voltage is monitored pin 40 of IC501. There is no parallel connection if the voltage is 1.65 V or
higher, while a parallel connection is deemed to exist if the voltage is lower.
Parallel connection detection when off hook:
When off hook Q115 is OFF, the voltage is monitored pin 40 of IC501; the presence/absence of a parallel connection is determined
when the voltage changes by 0.2 V or more.
When off hook Q115 is OFF, the voltage is monitored pin 40 of IC501; the presence/absence of a parallel connection is determined
when the voltage changes by 0.2 V or more.
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KX-TC1811B
11.10. DSP (Digital Speech/Signal Processing) Circuit
General Description:
(IC501, IC551) is a digital speakerphone/signal processing system that implements all the functions of memory management
required in a digital telephone.
The DSP system is fully controlled by a host processor IC501. The host processor provides activation and control of all that
functions, such as Tone detecting and Line monitoring.
(IC501, IC551) is a digital speakerphone/signal processing system that implements all the functions of memory management
required in a digital telephone.
The DSP system is fully controlled by a host processor IC501. The host processor provides activation and control of all that
functions, such as Tone detecting and Line monitoring.
The DSP system comprises of following.
— a Host Processor.
— a Host Processor.
— a Digital Signal Processor which includes the firmware implemented functions.
— a EEPROM (IC551), which is used for stored system data.
•
DTMF Detection
The DTMF detection is implemented by the DSP system in software. The DTMF detection is performed during Record,
Playback, and Line Monitoring modes of operation.
The DTMF detection is implemented by the DSP system in software. The DTMF detection is performed during Record,
Playback, and Line Monitoring modes of operation.
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KX-TC1811B
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