Samsung SF11OT Servise Manual page 26

This circuitry controls transmission of analog
signals from the MODEM. Output voltage from
the MODEM is buffered through the LIU board
and OP amp after signal smoothing and filtering,
and finally output to the line.
TAD circuit consists of a voice coprocessor to record and play voice messages in voice memory.
Voice signal from the microphone is passed
through active filter U15, R117 and C96, R82, C58
to clear aliasing noise occuring while sampling
and amplifying the signal. Q5 and Q2 compose
converts the digital signal from voice coprocessor
into analog for line output.
Transmit path functions as MIC input path.
Outgoing messages and memo messages from
DRAM) through the DSPG DRAM controller.
In receive mode, analog signals from the LIU
board are transferred to RX IN through the BPF
and smoothing filter.
Incoming signals from line are stored in the voice
memory (4 M DRAM) through CODEC and DSPG
DRAM controller. When played, DSPG processes
the data stored in voice memory and sends it out
to LIU through CODEC and R108. To playback
through the speaker, DSPG sends the signal to
speaker through R108, MUX (U12, U14), and op
amp.
This circuit consists of Host Interface, Memory
Interface, CODEC Interface, and DSP core. Host
Interface sends and receives data to and from IFC.
Memory Interface sends and receives the
compressed voice data to and from DRAM to play
back and record voice data. DSP core
communicates with host IFC through Host
Interface.
when power is on. When power is off, +5V is
supplied from the 9V backup battery.
Circuit Description