LG LG-TM250 User manual

Features of LG-TM250
1. Wave Type
•CELLULAR : G7W
•PCS : G7W
2. Frequency Scope
Transmit Frequency (MHz) Receive Frequency (MHz)
CELLULAR PCS CELLULAR PCS GPS
824.82 ~ 848.19 1850~1910 869.82~893.19 1930~1990 1575.42
3. Rated Output Power : CELLULAR = 0.20W
PCS = 0.20W
4. Output Conversion Method : This is possible by correcting the key board channel.
5. Voltage and Current Value of Termination Part Amplifier (Catalogue included)
MODE Part Name Voltage Current Power
CELLULAR CX77105 4.0V 600mA 0.20W
PCS CX77107 4.0V 700mA 0.20W
6. Functions of Major Semi-Conductors
Classification Function
MSM6050-FBGA Terminal operation control and digital signal processing
MCP (TH50VPF5585ADSB) Flash Memory (32Mbit) + SRAM (32Mbit)
Storing of terminal operation program
RFR6000 Converts Rx RF signal to baseband signal
RFT6100 Converts baseband signal to Tx RF signal
7. Frequency Stability
•CELLULAR : ±0.5PPM
•PCS : ±0.1PPM
LG Electronics Inc.

LG-TM250
CDMA Mobile Subscriber Unit
LG-TM250
SERVICE MANUAL
Tri-Band, Tri-Mode
[PCS/GPS/Cellular]
CDMA Mobile Phone
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LG-TM250
Table of Contents
General Introduction
............................................................................................................................................................. 4
CHAPTER 1. System Introduction
1. System Introduction......................................................................................................................4
2. Features and Advantages of CDMA Mobile Phone ...................................................................6
3. Structure and Functions of Tri-band CDMA Mobile Phone ....................................................9
4. Specification.................................................................................................................................10
5. Installation ..................................................................................................................... 18
CHPATER 2. NAM Input Method
1. NAM Program Method and Telephone Number Inputting Method ................................. 20
CHAPTER 3. Circuit Description
1. RF Transmit/Receive Part..........................................................................................................24
2. Digital/Voice Processing Part.....................................................................................................29
CHAPTER 4. Trouble Shooting…………………………………………………………………….38
CHAPTER 5. Safety……………………………………………………………………………..…..44
CHAPTER 6. Glossary…………………………………………………………………………..…..47
CHAPTER 7. How to Download………………………………………………………………..…..??
APPENDIX……………………………………………………………………………………….…..60
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LG-TM250
General Introduction
The LG-TM250 phone has been designed to operate on the latest digital mobile communication technology,
Code Division Multiple Access (CDMA). This CDMA digital technology has greatly enhanced voice clarity and
can provide a variety of advanced features. Currently, CDMA mobile communication technology has been
commercially used in Cellular and Personal Communication Service (PCS). The difference between them is the
operating frequency spectrum. Cellular uses 800Mhz and PCS uses 1.9Ghz. The LG-TM250 support GPS Mode,
we usually call it tri-band phone.
The CDMA technology adopts DSSS (Direct Sequence Spread Spectrum). This feature of DSSS enables the
phone to keep communication from being crossed and to use one frequency channel by multiple users in the
same specific area, resulting that it increases the capacity 10 times more compared with that in the analog mode
currently used. Soft/Softer Handoff, Hard Handoff, and Dynamic RF power Control technologies are combined
into this phone to reduce the call being interrupted in a middle of talking over the phone.
Cellular and PCS CDMA network consists of MSO (Mobile Switching Office), BSC (Base Station Controller),
BTS (Base station Transmission System), and MS (Mobile Station). The following table lists some major
CDMA Standards.
CDMA Standard Designator Description
Basic air interface TIA/EIA/IS-95-A/B/C
ANSI J-STD-008
Protocol between MS and BTS for Cellular
Protocol between MS and BTS for PCS
Network TIA/EIA/IS-634
TIA/EIA/IS/651
TIA/EIA/IS-41-C
TIA/EIA/IS-124
MAS-BS
PCSC-RS
Intersystem operations
Nom-signaling data comm.
Service TIA/EIA/IS-96-B
TIA/EIA/IS-99
TIA/EIA/IS-637
TIA/EIA/IS-657
Speech CODEC
Assign data and fax
Short message service
Packet data
Performance TIA/EIA/IS-97
TIA/EIA/IS-98
ANSI J-STD-018
ANSI J-STD-019
TIA/EIA/IS-125
Cellular base station
Cellular mobile station
PCS personal station
PCS base station
Speech CODEC
* TSB –74: Protocol between an IS-95A system and ANSI J-STD-008
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LG-TM250
1. System Introduction
1.1 CDMA Abstract
The CDMA mobile communication system has a channel hand-off function that is used for collecting the
information on the locations and movements of mobile telephones from the cell site by automatically controlling
several cell site through the setup of data transmission routes, and then enabling one switching system to carry
out the automatic remote adjustment. This is to maintain continuously the call state through the automatic
location confirmation and automatic radio channel conversion when the busy subscriber moves from the service
area of one cell site to that of another by using automatic location confirmation and automatic radio channel
conversion functions. The call state can be maintained continuously by the information exchange between
switching systems when the busy subscriber moves from one cellular system area to the other cellular system
area.
In the cellular system, the cell site is a small-sized low output type and utilizes a frequency allocation system
that considers mutual interference, in an effort to enable the re-use of corresponding frequency from a cell site
separated more than a certain distance.
Unlike the time division multiple access (TDMA) or frequency division multiple access (FDMA) used in the
band limited environment, the Code Division Multiple Access (CDMA) system which is one of digital cellular
systems is a multi-access technology under the interference limited environment. It can process more number of
subscribers compared to other systems (TDMA system has the processing capacity three times greater than the
existing FDMA system whereas CDMA system, about 12~15 times of that of the existing system).
CDMA system can be explained as follows; TDMA or CDMA can be used to enable each person to talk
alternately or provide a separate room for each person when two persons desire to talk with each other at the
same time, whereas FDMA can be used to enable one person to talk in soprano, whereas the other in bass (one
of the two talkers can carry out synchronization for hearing in case there is a bandpass filter function in the area
of the hearer). Another available method is to make two persons to sing in different languages at the same time,
space, and frequency when wishing to let the audience hear the singing without being confused. This is the
characteristic of CDMA.
On the other hand, when employing the CDMA technology, each signal has a different pseudo-random binary
sequence used to spread the spectrum of carrier. A great number of CDMA signals share the same frequency
spectrum. In the perspective of frequency area or time area, several CDMA signals are overlapped. Among these
types of signals, only desired signal energy is selected and received through the use of pre-determined binary
sequence; desired signals can be separated, and then received with the correlator used for recovering the
spectrum into its original state. At this time, the spectrums of other signals that have different codes are not
recovered into its original state, and appears as the self-interference of the system.
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