LG LGC800W Service Manual

Features of Mobile Subscriber Radio Telephone Set
(LGC-800W Type)

1. Wave Type

• Digital : G7W

2. Frequency Scope

• Send Frequency : 824.820~848.190MHz

• Receive Frequency : 869.820~893.190MHz

3. Rated Output

• 0.2W

4. Output Conversion Method : This is possible by correcting the key board channel.

5. Voltage and Current Value of Termination Part Amplifier(Catalogue included)

Product Type Name Voltage Current Power

PWR AMP RF2132 5.0V 400mA 0.63W

6. Functions of Major Semi-Conductors

Classification Function

MSM3000-PBGA Terminal operation control and digital signal processing
FLASH MEMORY

& STATIC RAM

(MB84VA2103-10P8)

IFT3000/IFR3000 Converting IF signal into baseband signal and analog signal into digital signal

Flash Memory (16Mbit) Õ Storing of terminal operation program
SRAM (2Mbit) Õ Temporary storing of the data created while busy

7. Frequency Stability

• ¡¾0.5PPM

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CDMA PORTABLE CELLULAR PHONE

LGC-800W

SERVICE MANUAL

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LGC-800W

Table of Contents

General Introduction

.............................................................................................................................................................. 2

CHAPTER 1. System Introduction

1. System Introduction ................................................................................................................................... 3

2. Features and Advantages of CDMA Mobile Phone .................................................................................... 4

3. Structure and Functions of CDMA Mobile Phone ..................................................................................... 7

4. Specification ............................................................................................................................................... 8

5. Installation ................................................................................................................................................ 13

CHAPTER 2. NAM Input Method(Inputting of telephone numbers included)

1. Telephone Number Input Method ............................................................................................................ 13

2. NAM Program Method ............................................................................................................................ 16

CHAPTER 3. Circuit Description

1. RF Transmitter and Receiver ................................................................................................................ 17

2. Digital/Voice Processor .......................................................................................................... 24

CHAPTER 4. Trouble Shooting

............................................................................................................................................ 28

CHAPTER 5. Test Proceduce

............................................................................................................................................ 34

Appendix

............................................................................................................................................ 35

1. Assembly and Disassembly Diagram

2. Block & Circuit Diagram

3. Part List

4. Component Layout

5. Accessories

- Desktop Charger

- Travel Charger

- Cigar Lighter Charger

- Hands Free Kit

- Data Cable

6. WLPST ( LGIC Product Support Tool For Win95 )

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LGC-800W

General Introduction

The LGC-800W cellular phone is a digital cellular phone working in CDMA (Code Division Multiple Access)
mode. DSSS (Direct Sequence Spread Spectrum) mode which is used in military is applied to CDMA type digital
mode.

This feature enables the phone to keep communication from being crossed and one frequency channel to be used
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 drop in a middle of talking over phone.

CDMA digital cellular network consists of MSC (Mobile Switching Office), BSC (Base Station Controller), BTS
(Base station Transmission System), and MS (Mobile Station). Communication between MS and BTS is
designed to meet the specification of IS-95A (Common Air Interface). MS meets the specifications of the below :

- IS-95A ( Common Air Interface ) : Protocol between MS and BTS

- IS-96A ( Vocoder ) : Voice signal coding

- IS-98 : Basic MS functions

- IS-126 : Voice loopback

- IS-99 : Short Message Service, Async Data Service, and G3 Fax Service

LGC-800W is composed of transceiver, desktop charger, two Li-Ion Battery (900mAh), h
charger, Data Cable. Hands-free kit in digital mode is designed to be operated in full duplex.

ands-free kit, travel

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LGc-320/330W

CHAPTER 1. System Introduction

1. System Introduction

1.1 CDMA Abstract

The cellular system has a channel hand-off function that is used for collecting the information on the locations
and movements of radio mobile telephones from the cell site by automatically controlling several cell site through
the setup of data transmission routes and thus, 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 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 reuse corresponding frequency from a cell site separated more than
a certain distance. The analog cellular systems are classified further into an AMPS system, E-AMPS System,
NMT system, ETACS system, and JTACS system depending on technologies used.

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 the capacity of CDMA system is about 12~15 times that of the existing system).
CDMA system can be explained as follows: TDMA or SDMA 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 method available 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 song without being confused. This is the characteristics 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 instead, processed as noise and appears as the self-interference of the system.

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LGC-800W

2. Features and Advantages of CDMA Mobile Phone

2.1 Various Types of Diversities

When employing the narrow band modulation (30kHz band) that is the same as the analog FM modulation
system used in the existing cellular system, the multi-paths of radio waves create a serious fading. However, in
the CDMA broadband modulation(1.25MHz band), three types of diversities (time, frequency, and space) are
used to reduce serious fading problems generated from radio channels in order to obtain high-quality calls.
Time diversity can be obtained through the use of code interleaving and error correction code whereas frequency
diversity can be obtained by spreading signal energy to more wider frequency band. The range of fading related
to normal frequency is normally 200~300kHz and accordingly, serious effect can be avoided. Moreover, space
diversity (also called path diversity) can be realized with the following three types of methods.
First, it can be obtained by the duplication of cell site receive antenna. Second, it can be obtained through the use
of multi-signal processing device that receives a transmit signal having each different transmission delay time and
then, combines them. Third, it can be obtained through the multiple cell site connection (Soft Handoff) that
connects the mobile station and more than two cell sites at the same time.

2.2 Power Control

The CDMA system utilizes the forward (from a base station to mobile stations) and backward (from the mobile
station to the base station) power control in order to increase the call processing capacity and obtain high-quality
calls. In case the originating signals of mobile stations are received by the cell site in the minimum call quality
level (signal to interference) through the use of transmit power control on all the mobile stations, the system
capacity can be maximized.
If the signal of mobile station is received too strong, the performance of that mobile station is improved.
However, because of this, the interference on other mobile stations using the same channel is increased and
accordingly, the call quality of other subscribers is reduced unless the maximum accommodation capacity is
reduced.
In the CDMA system, forward power control, backward open loop power control, and closed loop power control
methods are used. The forward power control is carried out in the cell site to reduce the transmit power on
mobile stations less affected by the multi-path fading and shadow phenomenon and the interference of other cell
sites when the mobile station is not engaged in the call or is relatively nearer to the corresponding cell site. This
is also used to provide additional power to mobile stations having high call error rates, located in bad reception
areas or far away from the cell site.
The backward open loop power control is carried out in a corresponding mobile station; the mobile station
measures power received from the cell site and then, reversely increases/decreases transmit power in order to
compensate channel changes caused by the forward link path loss and terrain characteristics in relation to the
mobile station in the cell site. By doing so, all the mobile office transmit signals in the cells are received by the
cell site in the same strength.
Moreover, the backward closed loop power control used by the mobile station to control power with the
commands issued out by the cell site. The cell site receives the signal of each corresponding mobile station and
compares this with the pre-set threshold value and then, issues out power increase/decrease commands to the

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LGC-800W

corresponding mobile station every 1.25 msec (800 times per second).
By doing so, the gain tolerance and the different radio propagation loss on the forward/backward link are
complemented.

2.3 Voice Encoder and Variable Data Speed

The bi-directional voice service having variable data speed provides voice communication which employs voice
encoder algorithm having power variable data rate between the mobile telephone cell site and mobile station. On
the other hand, the transmit voice encoder performs voice sampling and then, creates encoded voice packets to be
sent out to the receive voice encoder, whereas the receive voice encoder demodulates the received voice packets
into voice samples.
One of the two voice encoders described in the above is selected for use depending on inputted automatic
conditions and message/data; both of them utilize four-stage frames of 9600, 4800, 2400, and 1200 bits per
second. In addition, this type of variable voice encoder utilizes adaptive threshold values when selecting required
data rate. It is adjusted in accordance with the size of background noise and the data rate is increased to high rate
only when the voice of caller is inputted.
Therefore, background noise is suppressed and high-quality voice transmission is possible under the environment
experiencing serious noise. In addition, in case the caller does not talk, data transmission rate is reduced so that
the transmission is carried out in low energy. This will reduce the interference on other CDMA signals and as a
result, improve system performance (capacity, increased by about two times).

2.4 Protecting Call Confidentiality

CDMA signals have the function of effectively protecting call confidentiality by spreading and interleaving call
information in broad bandwidth. This makes the unauthorized use of crosstalk, search receiver, and radio very
hard substantially. Also included is the encryption function on various authentication and calls specified in IS-95
for the double protection of call confidentiality.

2.5 Soft Handoff

During the soft hand, the cell site already in the busy state and the cell site to be engaged in the call later
participate in the call conversion. The call conversion is carried out through the original call connection cell site,
both cell sites, and then, new cell site. This method can minimize call disconnection and prevent the user from
detecting the hand-off.

2.6 Frequency Re-Use and Sector Segmentation

Unlike the existing analog cellular system, the CDMA system can reuse the same frequency at the adjacent cell

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LGC-800W

and accordingly, there is no need to prepare a separate frequency plan. Total interference generated on mobile
station signals received from the cell site is the sum of interference generated from other mobile stations in the
same cell site and interference generated from the mobile station of adjacent cell site. That is, each mobile station
signal generates interference in relation to the signals of all the other mobile signals.
Total interference from all the adjacent cell sites is the ratio of interference from all the cell sites versus total
interference from other mobile stations in the same cell site (about 65%). In the case of directional cell site, one
cell normally uses a 120¡Æsector antenna in order to divide the sector into three. In this case, each antenna is
used only for 1/3 of mobile stations in the cell site and accordingly, interference is reduced by 1/3 on the average
and the capacity that can be supported by the entire system is increased by three times.

2.7 Soft Capacity

The subscriber capacity of CDMA system is flexible depending on the relation between the number of users and
service classes. For example, the system operator can increase the number of channels available for use during
the busy hour despite the drop in call quality. This type of function requires 40% of normal call channels in the
standby mode during the handoff support, in an effort to avoid call disconnection resulting from the lack of
channels.
In addition, in the CDMA system, services and service charges are classified further into different classes so that
more transmit power can be allocated to high class service users for easier call set-up; they can also be given
higher priority of using hand-off function than the general users.

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LGC-800W

3. Structure and Functions of CDMA Mobile Phone

The mobile station of CDMA system is made up of a radio frequency part and logic/control (digital) part. The
mobile station is fully compatible with the existing analog FM system. The mobile station antenna is connected
with the transmitter/receiver via a duplexer filter so that it can carry out the transmit/receive function at the same
time.
The transmit frequency is the 25MHz band of 824~849MHz, whereas the receive frequency is the 25MHz band
of 869~894MHz. The transmit/receive frequency is separated by 45MHz. The RF signal from the antenna is
converted into intermediate frequency(IF) band by the frequency synthesizer and frequency down converter and
then, passes the bandpass SAW filter having the 1.25MHz band. IF output signals that have been filtered from
spurious signal are converted into digital signals via an analog-to-digital converters(ADC) and then, sent out
respectively to 5 correlators in each CDMA de-modulator. Of these, one is called a searcher whereas the
remaining 4 are called data receiver(finger). Digitalized IF signals include a great number of call signals that
have been sent out by the adjacent cells. These signals are detected with pseudo-noise sequence (PN Sequence).
Signal to interference ratio (C/I) on signals that match the desired PN sequence are increased through this type of
correlation detection process. Then, other signals obtain processing gain by not increasing the ratio. The carrier
wave of pilot channel from the cell site located most adjacently is demodulated in order to obtain the sequence of
encoded data symbols. During the operation with one cell site, the searcher searches out multi-paths in
accordance with terrain and building reflections. On three data receivers, the most powerful four paths are
allocated for the parallel tracing and receiving. Fading resistance can be improved a great deal by obtaining the
diversity combined output for de-modulation. Moreover, the searcher can be used to determine the most powerful
path from the cell sites even during the soft handoff during the two cell sites. Moreover, four data receivers are
allocated in order to carry out the de-modulation of these paths. Data output that has been demodulated change
the data string in the combined data row as in the case of original signals(deinterleaving), and then, are de­modulated by the forward error correction decoder which uses the Viterbi algorithm.
On the other hand, mobile station user information sent out from the mobile station to the cell site pass through
the digital voice encoder via a mike. Then, they are encoded and forward errors are corrected through the use of
convolution encoder. Then, the order of code rows is changed in accordance with a certain regulation in order to
remove any errors in the interleaver. Symbols made through the above process are spread after being loaded onto
PN carrier waves. At this time, PN sequence is selected by each address designated in each call.
Signals that have been code spread as above are digital modulated (QPSK) and then, power controlled at the
automatic gain control amplifier (AGC Amp). Then, they are converted into RF band by the frequency
synthesizer synchronizing these signals to proper output frequencies.
Transmit signals obtained pass through the duplexer filter and then, are sent out to the cell site via the antenna.

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LGC-800W

4. Specification

4.1 General Specification

4.1.1 Transmit/Receive Frequency Interval : 45 MHz

4.1.2 Number of Channels (Channel Bandwidth) : 20 CH

4.1.3 Operating Voltage : DC 3.0V

4.1.4 Battery Power Consumption : DC 3.5V

SLEEP IDLE MAX POWER

CDMA

2 mA 120 mA 800 mA (24 dBm)

4.1.5 Operating Temperature : -30° ~ +60

°

4.1.6 Frequency Stability : ¡¾0.5PPM

4.1.7 Antenna : Retractable Type (Herical+Whip), 50

4.1.8 Size and Weight

1) Size : 105545519.9

2) Weight : 104g (About)

§§

4.1.9 Channel Spacing : 1.25MHz

4.1.10 Battery Type, Capacity and Orerating Time.

State Retracted (900mAh)

Stand-By Time

Talk Time

Unit = Hours : Minutes

Ω

150

2:20

4.2 Receive Specification

4.2.1 Frequency Range : 869.82MHz ~ 893.190MHz

4.2.2 Local Oscillating Frequency Range : 966.88MHz¡¾12.5MHz

4.2.3 Intermediate Frequency : 85.38MHz

4.2.4 Sensitivity : -104dBm(C/N 12dB or more)

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