Subsystem (Msm7227) - LG GT540 Service Manual

3.9 Subsystem (MSM7227)

3.9.1. ARM Microprocessor Subsystem
The MSM7227 device uses an embedded ARM1136JF-S, ARM926EJ-S microprocessor. This microprocessor, through
the system software, controls most of the functionality for the MSM, including control of the external peripherals
such as the keypad, LCD, SDRAM, and NANDFlash devices. Through a QUALCOMM proprietary single-wire SBI (SSBI)
the ARM926EJ-S configures and controls the functionality of the RTR6285 and PM7540 devices.
3.9.2. WCDMA Subsystem
The WCDMA subsystem performs the data conversions and signal processing necessary to maintain the WCDMA air
interface between the handset and the base station (and also the WCDMA network). The subsystem components
include:
Searcher engine
Demodulating fingers
Combining block
Frame deinterleaver
Viterbi decoder
Reverse link subsystem
Turbo decoder
On the forward link traffic channel, the WCDMA subsystem searches, demodulates, and decodes incoming pilot,
sync, paging, and traffic channel information. It extracts low bit-rate packet data from the forward link traffic
channel and sends the packet data to the vocoder for processing. On the reverse link, the WCDMA subsystem
processes the packet data from the vocoder and modulates the reverse traffic channel.
3.9.3. GSM Subsystem
The GSM subsystem performs the data conversions and signal processing necessary to maintain the GSM air
interface, including PA gain control for GPRS support. For GSM, the power profile ramps up before the burst and
ramps down afterward. For GPRS, transmit bursts can occur in as many as four sequential slots and the PA must be
ramped up and down smoothly between each slot, holding the desired output power level during each burst. GSM
support includes:
GSM release '99 (circuit switching)
GPRS (packet switching)
EDGE E2 power class for 8 PSK
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Only for training and service purposes
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3. TECHNICAL BRIEF
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