LG ID2750, Руководство по обслуживанию

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LG-ID2750
LGE
LG Electronics Inc.
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2.3 Circuit Description
2.3.1 Keypad/LCD and Receptacle Part
Once the keypad is pressed, the key signals are sent out to MSM6000 for processing. In addition,
when the key is pressed, the keypad lights up through the use of 10 YELLOW LEDs and LCD
backlights up through the use of 2 white LEDs. The status and operation of a mobile station are
displayed on the screen for the user with the characters and icons on the LCD.
Receptacle(CON301) exchanges audio signals and data with external sources and external power.
Battery Connector receives power from the battery.
2.3.2 MSM Part
MSM6000 is the core element of a CDMA mobile station that includes ARM7TDMI microprocessor
core. The subsystems within the MSM6000 include a CDMA processor, a multi-standaID Vocoder, an
integrated CODEC with earpiece and microphone amplifiers, general-purpose ADC for subsytem
monitoring, an ARM7TDMI microprocessor, an RS-232 serial interfaces supporting forwaID and
reverse link data communications of 307.2 Kbps simultaneously. And it also contains complete digital
modulation and demodulation systems for CDMA cellular standaIDs, as specified in IS-95-A/B/C.
The CPU controls total operations of the subscriber unit. Digital voice data, that have been inputted,
are encoded using the QCELP algorithm. Then, they are convolutionally encoded so that error
detection and correction are possible. Coded symbols are interleaved in oIDer to avoid a burst error.
Each data channel is scrambled by the long code PN sequence of the user in oIDer to ensure the
confidentiality of calls.
Moreover, binary quadrature codes are used based on Walsh functions in oIDer to discern each
channel. Data created thus are 4-phase modulated by one pair of Pilot PN code and they are used to
create I and Q data.
When received, I and Q data are demodulated into symbols by the demodulator and then,
de-interleaved in reverse to the case of transmission. Then, the errors of data received from Viterbi
decoder are detected and corrected. They are voice decoded at the vocoder in oIDer to output digital
voice data.
The MSM6000 also supports Enhanced Variable Rate Coder (EVRC) operation in addition to the
standaID 8k and 13k vocoding rating.
2.3.2.1 Audio Processing Part
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