Analog Circuit - Panasonic KX-NT265X Service Manual

8.6.

ANALOG CIRCUIT

This circuit performs the setting of the call path/vol. adjustment in each call mode by a built-in DSP of VoIP (IC1).The audio gain
of each call is determined by download data from PBX or by internal data from flash memory (IC3).
See 17.3. ANALOG/KEY/LED block
1. Handset Call
Transmitting signal is inputted from handset microphone, and amplified by IC14 and IC18 → inputted to IC1-pin112 →A/D
conversion and Gain adjustment by a built-in DSP of IC1 → then sent to PBX.
Transmitting signal inputted from handset microphone is controlled by transmission switching SW IC16 as follows;
IC16-pin5 L: Handset Call
(IC16-pin5 H: Headset Call)
Transmitting signal inputted from handset microphone is controlled by transmission switching SW IC16 as follows;
Receiving signal inputted from PBX → Gain adjustment by a built-in DSP of IC1 → D/A conversion and outputted from IC1-
pin115. → Amplified by IC17 and IC19, and outputted to handset.
2. Headset Call
Transmitting signal is inputted from headset microphone, and amplified by IC14 and IC18 → inputted to IC1-pin112 →A/D
conversion and Gain adjustment by a built-in DSP of IC1 → then sent to PBX.
Transmitting signal inputted from headset microphone is controlled by transmission switching SW IC16 as follows;
IC16-pin5 H: Headset Call
(IC16-pin5 L: Handset Call)
Receiving signal inputted from PBX → Gain adjustment by a built-in DSP of IC1 → D/A conversion and outputted from IC1-
pin115. → Amplified by IC17 and IC19, and outputted to headset.
3. Speakerphone Call
Speakerphone call realizes all double-call by a built-in DSP (echo canceller) of IC1. For a call in the most appropriate condition,
DSP checks voice level of the calling party, acoustics in a room, voice level of the other party and state of the line of contact,
and cancels echo in transmitting and receiving at the start of calling. It operates in a half double-call state in a few seconds for
the check.
Transmitting signal is inputted from microphone and amplified by IC15 → A/D conversion and Gain adjustment by a built-in DSP
of IC1, then sent to PBX through echo canceller.
Receiving signal inputted from PBX → Gain adjustment by DSP through a built-in echo canceller of IC1 → D/A conversion and
outputted from IC1-pin116 → Amplified by IC14 and outputted from IC11 (Amp) to speaker.
Power Amp IC11 is controlled as follows;
IC11-pin1 L → ON
IC11-pin1 H → OFF
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KX-NT265X / KX-NT265X-B