Service Manual

Ringer
FLASH
Memory
&
SRAM
EEPROM
Receptacle
Power Supply
AUDIO
Processor
M
S
M
3
0
0
0
Earpiece
Mic
[Figure 3-1] Block Diagram of Digital/Voice Processing Part
3.3.2 Audio Processing Part
MIC signals are amplified through the audio codec which is U401 (TWL1103), and converted into digital signals.
Then, they are inputted into MSM3000. In addition, digital audio signals outputted from MSM3000 are converted
into analog signals after going through the audio codec to be amplified. and then transferred to the ear piece.
3.3.3 MSM Part
MSM3000, which is U301, is the core element of CDMA system terminal that includes ARM7TDMI
microprocessor core. It is made up of a CPU, encoder, interleaver, deinterleaver, Viterbi decoder, MOD/DEM, and
vocoder. MSM3000, when operated in the CDMA mode, utilizes CHIPX8 (9.8304MHz) as the reference clock that
is received from IFR3000, and uses TCXO (19.68MHz) that is received from U174. CPU controls the terminal
operation. Digital voice data that have been inputted are voice-encoded and variable-rated. Then, they are
convolutionally encoded so that error detection and correction are possible. Coded symbols are interleaved in order
to cope with multi-path fading. Each data channel is scrambled by the long code PN sequence of the user in order to
ensure the confidentiality of calls.
Moreover, binary quadrature codes are used based on Walsh functions in order to discern each channel
.