LGC-340/345W
28
LGIC
LG Information & Communications, Ltd.
2.3.3 MSM Part
MSM3000 is the core element of a CDMA mobile station. Subsystems within the MSM3000 include a CDMA
processor,a QCELP(qualcomm Code Excited Linear Predication) vocoder,an EVRC(Enhanced Variable Rate
Codec) vocoder, an ARM7TDMI microprocessor ,and assorted peripheral interfaces that are used to support
other functions. MSM3000, when operated in the CDMA mode, utilizes CHIP
×
8 (9.8304MHz) received from the
IFR3000 as the reference clock primarily for CDMA and vocoder processing.MSM3000 also uses TCXO/4
(4.92MHz) received from IFR3000.
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 order to avoid a burst error. 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. 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 order to output digital voice data.
The MSM3000 also supports Enhanced Variable Rate Coder (EVRC) operation in addition to the standard 8k
and 13k vocoding rating.
2.3.4 Memory Part
The memory part consists of a 16Mbits Flash Memory, a 4Mbits SRAM(Static Random Access Memory), and a
256kbits EEPROM(Electrically Erasable and Programmable Read Only Memory). In the Flash Memory, there
are programs used for the operation of a mobile station. The programs can be changed through down loading
after the assembling of mobile stations. On the SRAM, data generated during the operation of a mobile station
are stored temporarily. On the EEPROM, the non-volatile data of the mobile station such as a ESN(Electronic
Serial Number) are stored.
2.3.5 Power Supply Part
turn ON
When the battery voltage (4.2V ~ 3.0V) is fed and the PWR key of keypad is pressed, Q8 is activated by the
+VPWR and ON_SW signal and then, ON/ is generated. Based on this ON/, regurator U3 is operated and
+3.0V_MSM is generated.
operating
During the phone is on operating state,
LDO for MSM is always enable and gives the power MSM and memory part
LDO for IFT_IFR are always enable and gives the power IFT, IFR and VC-TCXO.