LG VN250 Service Manual
Features of LG-VN250
1. Wave Type
CELLULAR : G7W
x
PCS : G7W
x
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 = 0.263W
PCS = 0.282W
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 WS1102 4.2V 600mA 0.282W
PCS WS1403 TR1G 4.2V 600mA 0.282W
6. Functions of Major Semi-Conductors
Classification Function
QSC6055 Terminal operation control and digital signal processing
Converts RF signal to baseband signal
Converts baseband signal to RF signal
MCP (
{`hWhXXXXXWrj
7. Frequency Stability
CELLULAR : ധ0.5PPM
x
)
NAND (1Gbit) + DDR (512Mbit)
Storing of terminal operation program
PCS : ധ0.1PPM
x
LG Electronics Inc.
VN250
CDMA Mobile Subscriber Unit
LG-VN250
SERVICE MANUAL
TRIPLE BAND, TRIPLE MODE
[PCS/GPS/CELLULAR]
CDMA MOBILE PHONE
1 LG Electronics Inc.
VN250
Table of Contents
General Introduction .................................. 2
CHAPTER 1. System Introduction
1. System Introduction.........................................3
1.1 CDMA Abstract ..........................................3
2. Features and Advantages of CDMA Mobile
Phone ..............................................................5
2.1 Various Types of Diversities ......................5
2.2 Power Control ............................................5
2.3 Voice Encoder and Variable Data Speed ..6
2.4 Protecting Call Confidentiality....................6
2.5 Soft Handoff...............................................6
2.6 Frequency Re-Use and Sector
Segmentation.............................................7
2.7 Soft Capacity .............................................7
3. Structure and Functions of Tri-band CDMA
Mobile Phone...................................................8
4. Specification ....................................................9
4.1 General Specification.................................9
4.2 Receive Specification ..............................10
4.3 Transmit Specification .............................11
4.4 MS (Mobile Station) Transmitter
Frequency................................................12
4.5 MS (Mobile Station) Receiver Frequency 13
4.6 AC Adaptor : See Appendix.....................14
4.7 Cigar Lighter Charger : See Appendix.....14
5. Installation .....................................................14
5.1 Installing a Battery Pack ..........................14
5.2 For Adapter Use ......................................14
5.3 For Mobile Mount.....................................14
CHAPTER 2. NAM Input Method
1. NAM Programming Method and Telephone
Number Input Method ....................................16
CHAPTER 3. Circuit Description
1. RF Transmit/Receive Part .............................24
1.1 Overview..................................................24
1.2 Description of Rx Part Circuit...................24
1.3 Description of Transmit Part Circuit .........30
1.4 Description of Frequency Synthesizer
Circuit.......................................................33
2. Digital/Voice Processing Part ........................33
2.1 Overview..................................................33
2.2 Configuration ...........................................33
2.3 Circuit Description....................................34
Chapter 4. Trouble Shooting
1. Rx Part Trouble .............................................37
1.1 DCN & PCS Rx Trouble...........................37
2. Tx Part Trouble..............................................44
2.1 DCN & PCS Tx Trouble ...........................44
3. Power ............................................................52
3.1 Power On Trouble....................................52
3.2 Charging Trouble .....................................54
4. Logic Part Trouble .........................................56
4.1 LCD Trouble ............................................56
4.2 Camera Trouble.......................................60
4.3 Audio Trouble ..........................................62
4.4 Vibrator Trouble .......................................70
4.5 USB Trouble ............................................72
4.6 Qwerty Key Trouble .................................74
4.7 QWERTY KEY BACKLIGHT LED
TROUBLE................................................76
4.8 Sub Key Backlight LED Trouble ..............78
4.9 Bluetooth Trouble ....................................80
CHAPTER 5. Safety .................................. 83
CHAPTER 6. Glossary.............................. 86
Appendix ................................................... 99
1. Block and Circuit Diagram.............................99
2. BGA Pin Map...............................................109
2-1. U105 [BCM2046B1]..............................110
2-2. U200 [QSC6055] ..................................111
2-3. U301 [TY9A0A111110KC]....................112
3. Component Layout ......................................113
4. Assembly and Disassembly diagram...........120
5. Part List .......................................................123
6. Accessories .................................................141
6-1. AC Adaptor ...........................................142
6-2. Cigar Light Charger ..............................145
6-3. USB Cable............................................146
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General Introduction
General Introduction
The LG-VN250 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-VN250 support GPS
Mode, we usually call it tri-band phone. We call it tri-mode phone. If one of the Cellular and PCS base stations
is located nearby, Call fail rate of triple-mode phone is less than dual-mode phone or single-mode 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
Network TIA/EIA/IS-634
TIA/EIA/IS/651
TIA/EIA/IS-41-C
TIA/EIA/IS-124
Service TIA/EIA/IS-96-B
TIA/EIA/IS-99
TIA/EIA/IS-637
TIA/EIA/IS-657
Protocol between MS and BTS for Cellular & AMPS
Protocol between MS and BTS for PCS
MAS-BS
PCSC-RS
Intersystem operations
Nom-signaling data comm.
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
* TSB –74: Protocol between an IS-95A system and ANSI J-STD-008
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Cellular base station
Cellular mobile station
PCS personal station
PCS base station
Speech CODEC
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Chapter 1. System Introduction
Chapter 1. System Introduction
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. 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 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
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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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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 wider frequency band. The fading related to normal
frequency can affect the normal 200~300kHz among signal bands 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 with 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 power 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 transmit signals received by the base station have same
strength.
Moreover, the backward closed loop power control used by the mobile station is performed to control power
using the commands issued out by the cell site. The cell site receives the signal of each corresponding mobile
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station and compares this with the pre-set threshold value and then, issues out power increase/decrease
commands to the corresponding mobile station every 1.25msec (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 base station and the 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 for cellular and 14400,7200,3600,1800 bits per second for PCS, so PCS provide relatively better voice
quality (almost twice better than the existing celluar system). In addition, this type of variable voice encoder
utilizes adaptive threshold values on 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
Voice privercy is provided in the CDMA system by means of the private long code mask used for PN spreading.
Voice privacy can ve applied on the traffic channels only. All calls are initiated using the public long code mask
for PN spreading. The mobile station user may request voice privacy during call setup using the origination
message or page response message, and during traffic channel operation using the long code transition request
order.
The Transition to private long code mask will not be performed if authentication is not performed. To initiate a
transition to the private or public long code mask, either the base station or the mobile station sends a long code
transition request order on the traffic channel.
2.5 Soft Handoff
A handoff in which the mobile station commences communications with a new base station without interrupting
communications with the old base station. Soft handoff can only be used between CDMA channels having
identical freqeuncy assignments.
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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.
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 stations.
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¶sector 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 the 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, 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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3. Structure and Functions of tri-band CDMA Mobile Phone
The hardware structure of CDMA mobile phone is made up of radio frequency (RF) part and logic part. The
RF part is composed of Receiver part (Rx), Transmitter part (Tx) and Local part (LO). For the purpose of
operating on tri-band, It is necessary dual Tx path, tri Rx path, dual PLL and switching system for band
selection. The mobile phone antenna is connected with quintplexer which divides antenna input/output signals
between cellular frequency band (824~894 MHz) and PCS frequency band (1850~1990MHz). Quintplexer
carrys out seperating Rx band and Tx band. The Rx signals from the antenna are directly converted into
baseband signal by the frequency synthesizer and frequency down converter. And then, are converted into
digital signals via Analog-to-Digital Converter (ADC). In front of the ADC, switching system is required to
choose which band path should be open. The digital signals send to 5 correlators in each CDMA de-modulator.
Of these, one is called a searcher whereas the remaining 4 are called data receivers (fingers). Digitalized 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, but other signals obtain processing
gain by not increasing the ratio. The carrier wave of pilot channel from the cell site most adjacently located 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 3 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 between the two cell sites.
Moreover, 3 data receivers are allocated in order to carry out the de-modulation of these paths. Output data that
has been demodulated changes 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.
Mobile station user information send 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 quintplexer filter and then, are sent out to the cell site via the
antenna.
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4. Specification
4.1 General Specification
4.1.1 Transmit/Receive Frequency Interval
1) CELLULAR : 45 MHz
2) PCS : 80 MHz
4.1.2 Number of Channels (Channel Bandwidth)
1) CELLULAR : 20 Channels
2) PCS : 48 Channels
4.1.3 Operating Voltage
DC 3.3~4.2V
4.1.4 Battery Power Consumption
SLEEP IDLE MAX POWER
CELLULAR
PCS
1.0 mA 65~75 mA 600 mA (24.5 dBm)
1.0 mA 65~75 mA 600 mA (24.5 dBm)
4.1.5 Operating Temperature
-20qC ~ +60qC
4.1.6 Frequency Stability
1) CDMA : ധ0.5PPM
2) PCS : ധ0.1PPM
4.1.7 Antenna
Internal Antenna, 50 :
4.1.8 Size and Weight
DC 3.7V
1) Size : W x H x D : 52x112x16.9mm (2.05 x 4.41 x 0.67 inch)
2) Weight : 120g
4.1.9 Channel Spacing
1) CELLULAR : 1.25MHz
2) PCS: 1.25 MHz
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4.1.10 Battery Type, Capacity and Orerating Time
Unit = Hours, Minutes
Standard (950mAh)
PCS(Slot Cycle 2)
Stand-by Time
Celluar (Slot Cycle 2)
PCS(Slot Cycle 2)
Talk Time
Celluar (Slot Cycle 2)
4.2 Receive Specification
4.2.1 Frequency Range
1) CELLULAR : 869.820 MHz ~ 893.190 MHz
2) PCS : 1930 MHz ~ 1990 MHz
3) GPS : 1575.42 MHz
4.2.2 Local Oscillating Frequency Range
1) CELLULAR : 1738.08MHz ~ 1787.94MHz
About 300 Hrs (SCI=2)
About 300 Hrs (SCI=2)
About 330 Min.(typical quintplexer, -92dBm Input)
About 330 Min.(typical quintplexer, -92dBm Input)
2) PCS : 1715.56MHz a 1768.89MHz
3) GPS : 3150.84MHz
4.2.3 Sensitivity
1) CELLULAR : -104dBm (C/N 12dB or more)
2) PCS : -104dBm (C/N 12dB or more)
3) GPS : -148.5dBm
4.2.4 Selectivity
1) CELLULAR : 3dB C/N Degration (With Fchധ1.25 kHz : -30dBm)
2) PCS : 3dB C/N Degration (With Fchധ1.25 kHz : -30dBm)
4.2.5 Interference Rejection
1) Single Tone : -30dBm at 900 kHz (CELLULAR), -30dBm at 1.25MHz(PCS)
2) Two Tone : -43dBm at 900 kHz & 1700kHz(CELLULAR), -43dBm at 1.25 MHz & 2.05 MHz
4.2.6 Spurious Wave Suppression
Maximum of -80dB
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4.2.7 CDMA Input Signal Range
z Dynamic area of more than -104~ -25 dB: 79dB at the 1.23MHz band.
4.3 Transmit Specification
4.3.1 Frequency Range
1) CELLULAR : 824.820MHz ~ 848.190MHz
2) PCS : 1850 MHz ~ 1910 MHz
4.3.2 Local Oscillating Frequency Range
1) CELLULAR : 1738.08MHz ~ 1787.94MHz
2) PCS : 1715.56MHz a 1768.89MHz
4.3.3 Intermediate Frequency
Direct Conversion
4.3.4 Output Power
1) CELLULAR : 0.263W
2) PCS: 0.282W
4.3.5 CDMA TX Frequency Deviation
1) CELLULAR: +300Hz or less
2) PCS: r 150Hz
4.3.6 CDMA TX Conducted Spurious Emissions
1) CELLULAR : 900kHz : - 42 dBc/30kHz below
1.98MHz : - 54 dBc/30kHz below
2) PCS : -42 dBc / 30KHz below
4.3.7 CDMA Minimum TX Power Control
1) CELLULAR : - 50dBm below
2) PCS: -50dBm below
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4.4 MS (Mobile Station) Transmitter Frequency
4.4.1 CELLULAR mode
Ch # Center Freq. (MHz) Ch # Center Freq. (MHz)
1011
29
70
111
152
193
234
275
316
363
824.640
825.870
827.100
828.330
829.560
830.790
832.020
833.250
834.480
835.890
404
445
486
527
568
609
650
697
738
779
837.120
838.350
839.580
840.810
842.040
843.270
844.500
845.910
847.140
848.370
4.4.2 PCS mode
Ch # Center Freq (MHz) Ch # Center Freq (MHz) Ch # Center Freq (MHz)
25 1851.25 425 1871.25 825 1891.25
50 1852.50 450 1872.50 850 1892.50
75 1853.75 475 1873.75 875 1893.75
100 1855.00 500 1875.00 900 1895.00
125 1856.25 525 1876.25 925 1896.25
150 1857.50 550 1877.50 950 1897.50
175 1858.75 575 1878.75 975 1898.75
200 1860.00 600 1880.00 1000 1900.00
225 1861.25 625 1881.25 1025 1901.25
250 1862.50 650 1882.50 1050 1902.50
275 1863.75 675 1883.75 1075 1903.75
300 1865.00 700 1885.00 1100 1905.00
325 1866.25 725 1886.25 1125 1906.25
350 1867.50 750 1887.50 1150 1907.50
375 1868.75 775 1888.75 1175 1908.75
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4.5 MS (Mobile Station) Receiver Frequency
4.5.1 CELLULAR mode
Ch. # Center Freq. (MHz) Ch. # Center Freq. (MHz)
1011
29
70
111
152
193
234
275
316
363
869.640
870.870
872.100
873.330
874.560
875.790
877.020
878.250
879.480
880.890
404
445
486
527
568
609
650
697
738
779
882.120
883.350
884.580
885.810
887.040
888.270
889.500
890.910
892.140
893.370
4.5.2 PCS mode
Ch # Center Freq (MHz) Ch # Center Freq (MHz) Ch # Center Freq (MHz)
25 1931.25 425 1951.25 825 1971.25
50 1932.50 450 1952.50 850 1972.50
75 1933.75 475 1953.75 875 1973.75
100 1935.00 500 1955.00 900 1975.00
125 1936.25 525 1956.25 925 1976.25
150 1937.50 550 1957.50 950 1977.50
175 1938.75 575 1958.75 975 1978.75
200 1940.00 600 1960.00 1000 1980.00
225 1941.25 625 1961.25 1025 1981.25
250 1942.50 650 1962.50 1050 1982.50
275 1943.75 675 1963.75 1075 1983.75
300 1945.00 700 1965.00 1100 1985.00
325 1946.25 725 1966.25 1125 1986.25
350 1947.50 750 1967.50 1150 1987.50
375 1948.75 775 1968.75 1175 1988.75
4.5.3 GPS mode : 1575.42MHz
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4.6 AC Adaptor
See Appendix
4.7 Cigar Lighter Charger
See Appendix
5. Installation
5.1 Installing a Battery Pack
1) The Battery pack is keyed so it can only fit one way. Align the groove in the battery pack with the rail
on the back of the phone until the battery pack rests flush with the back of the phone.
2) Slide the battery pack forward until you hear a “click”, which locks the battery in place.
5.2 For Adapter Use
1) Plug the adapter into a wall outlet. The adapter can be operated from a 110V source.
When AC power is connected to the adapter.
2) Insert the adapter jack into the phone with the installed battery pack.
Red light indicates battery is being charged.. Green light indicates battry is fully charged.
5.3 For Mobile Mount
5.3.1 Installation Position
In order to reduce echo sound when using the Hands-Free Kit, make sure that the speaker and microphone are
not facing each other and keep microphone a generous distance from the speaker.
5.3.2 Cradle Installation
Choose an appropriate flat surface where the unit will not interface with driver’s movement or passenger’s
comfort. The driver/user should be able to access the phone with ease. Using the four self-tapping screws
provided, mount the supplied braket on the selected area. Then with the four machine screws provided, mount
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the counterpart on the reverse side of the reverse side of the cradle. Secure the two brackets firmly together by
using the two bracket joint screws provide.
The distance between the cradle and the interface box must not exceed the length of the main cable.
5.3.3 Interface Box
Choose an appropriate flat surface ( somewhere under the dash on the passenger side is preferred ) and mount
the IB bracket with the four self-tapping screws provided. Clip the IB into the IB bracket.
5.3.4. Microphone Installation
Install the microphone either by cliiping I onto the sunvisor (driver’s side) or by attaching it to door post
(driver’s side), using a velcno adhesive tape (not included).
5.3.5 Cable Connections
5.3.5.1 Power and Ignition Cables
Connect the red wire to the car battery positive terminal and the black wire to the car ground. Connect the green
wire to the car ignition sensor terminal. ( In order to operate HFK please make sure to connect green wire to
ignition sensor terminal.) Connect the kit’s power cable connector to the interface box power receptacle.
5.3.5.2 Antenna Cable Connection
Connect the antenna coupler cable connector from the cradle to the internal antenna connector.
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LG-VN250
Chapter 3. Circuit Description
Chapter 3. Circuit Description
1. RF Transmit/Receive Part
1.1 Overview
The Tx and Rx part employs the Direct Conversion system. The Tx and Rx frequencies are respectively
824.04~848.97MHz and 869.04~893.97MHz for cellular and 1850~1910MHz and 1930~1990MHz for PCS.
The block diagram is shown in Page 71. RF signals received through the antenna are seperated by quintplexer.
RF Signal fed into the low noise amplifier (in QSC6055) through the quintplexer. Then, they are combined with
the signals of local oscillator (VCO) at the down conversion mixer(in QSC6055) in order to create Base-band
frequency. Then, this signal is changed into digital signal by the analog to digital converter (ADC, A/D
Converter), and the digital circuit part of the QSC(Qualcomm Single Chip)6055 processes the data from ADC.
The digital processing part is a demodulator.
In the case of transmission, RF Transmitter(in QSC6055) receives QPSK-modulated anlog signal from the
QSC6055. In QSC6055, the baseband quadrature signals are upconverted to the Cellular or PCS frequency
bands and amplified to provide signal drive capability to the power amp.
After that, the RF signal is amplified by the Power Amp in order to have enough power for radiation.
Finally, the RF signal is sent out to the cell site via the antenna after going through the coupler and quintplexer.
1.2 Description of Rx Part Circuit
1.2.1 Quintplexer (DP100)
The ACFM-7103 is a quintplexer that combines a US PCS duplexer, a cellular band duplexer and a S-GPS band
filter into a single, miniature package with a single antenna port
The main function of quintplexer is to prohibit the other band signals from flowing into the one band circuit
and vice versa. RF designer can use common tri-band antenna regardless of frequency band (800, 1575 and
.
1900 MHz). The specification of LG-VN250 quintplexer is described below:
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LG-VN250
1.2.2 LNAs (U200)
The QSC6055 has cellular and PCS LNAs, respectively. The characteristics of Low Noise Amplifier (LNA)
are low noise figure, high gain, high intercept point and high reverse isolation.
The frequency selectivity characteristic of mobile phone is mostly determined by LNA.
The specification of VN250 LNAs is described below:
1.2.2.1 Cellular CDMA LNA performance specifications
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1.2.2.2 PCS CDMA LNA performance specifications
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