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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
Internal
www.huawei.com
Spectrum Test and
Instructions for YBT250
ISSUE1.0
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 1
The WCDMA system is a restricted
communication system by the interference.
The network quality, capacity and coverage
are all related to the background noise.
When design the radio network, we must
obtain the strength of the background noise in
the coverage area.
If strong interference exists within the band,spectrum test need to be performed, or the
operator have to apply for new frequency
spectrum.
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After studying this course, you should be
able to:
Know the sources of electromagneticbackground interference.
Master the methods for electromagnetic
background test.
Know how to use YBT250 for spectrum test.
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Chapter 1 Impact of Electromagnetic
Interference on the System
Chapter 2 Sources of ElectromagneticBackground Interference
Chapter 3 Introduction to Interference
Test Tools
Chapter 4 Methods for Electromagnetic
Background Test
Chapter 5 Instructions for YBT250
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Chapter 1 Impact of Electromagnetic Interference
on the System
1.1 Bands Used in the WCDMA System
1.2 Interference Requirements for UE Reception
1.3 Interference Requirements for NodeB
Reception
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Bands used in the WCDMA system
Operating
Band
UpLink Band
UE transmit, Node Breceive
DownLink Band
UE receive, Node Btransmit
I 1920 - 1980 MHz 2110 -2170 MHz
II 1850 -1910 MHz 1930 -1990 MHz
III 1710-1785 MHz 1805-1880 MHz
IV 1710-1755 MHz 2110-2155 MHz
V 824 - 849MHz 869-894MHz
VI 830-840 MHz 875-885 MHz
VII 2500 - 2570 MHz 2620 - 2690 MHz
VIII 880 - 915 MHz 925 - 960 MHz
IX 1749.9 - 1784.9 MHz 1844.9 - 1879.9 MHz
Band I, II, V and VII are most popular used in the world.
Band I is used in China.
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Impact of Electromagnetic Interference on the System
Determine the impact of interference on the system according to experience, as
shown in the following table (for UE).
Interference Band
Interference Level
Not AffectingReceiver Sensitivity
(With the Sensitivity
Worsened by 0.1 dB)
Acceptable
Interference Level(With the Sensitivity
Worsened by 3 dB)
Acceptable
Interference Level(With the Sensitivity
Worsened by 6 dB)
Interference That SeriouslyEffects Equipment Indexes
Instead of Equipment Running,Lower Than the Maximum Signal
Strength (-25 dBm) the UE Can
Receive by 10 dB
ProtocolRequirement
2110-2170 MHz (co-
frequency interference)-117 dBm/ 3.84 MHz
-101 dBm/ 3.84
MHz-96 dBm/ 3.84 MHz -35 dBm/ 3.84 MHz
The required
sensitivity is -107
dBm/ 3.84 MHz.
2095-2185 MHz (adjacent
channel interference,
deviated from the carrier
by 5 MHz)
-82 dBm/ 3.84 MHz -66 dBm/ 3.84 MHz -61 dBm/ 3.84 MHz -16 dBm/ 3.84 MHz
-66 dBm/ 3.84
MHz (with the
sensitivity
worsened by 3 dB)
2095-2185 MHz (in-band
blocking, deviated from
the carrier by 10 MHz)
-72 dBm/ 3.84 MHz -56 dBm/ 3.84 MHz -51 dBm/ 3.84 MHz -6 dBm/ 3.84 MHz
-56 dBm/ 3.84
MHz (with the
sensitivity
worsened by 3 dB)
2095-2185 MHz (in-band
blocking, deviated from
the carrier by 15 MHz)
-60 dBm/ 3.84 MHz -44 dBm/ 3.84 MHz -39 dBm/ 3.84 MHz 6 dBm/ 3.84 MHz
-44 dBm/ 3.84
MHz (with the
sensitivity
worsened by 3 dB)
Other bands (out-of-band
blocking and spurious
response)
-60 dBm/ 3.84 MHz -44 dBm/ 3.84 MHz -39 dBm/ 3.84 MHz 6 dBm/ 3.84 MHz
-44 dBm/ 3.84MHz (with the
sensitivity
worsened by 3 dB)
Note:
dBm/Hz refers to the level unit of single-tone signals.
The reference port for measurement is the reception port of the UE antenna.
The reference requirements are based on the protocol TSG25.101.
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Impact of Electromagnetic Interference on the System Determine the impact of interference on the system according to experience,
as shown in the following table (for NodeB).
Interference Band
Interference Level
Not AffectingReceiver Sensitivity
(With the SensitivityWorsened by 0.1 dB)
Acceptable
Interference Level(With the
SensitivityWorsened by 3 dB)
Acceptable
Interference Level(With the
SensitivityWorsened by 6 dB)
Interference That Seriously
Effects Equipment IndexesInstead of Equipment Running,
Lower Than the Maximum
Signal Strength (-70 dBm) the
UE Can Receive by 10 dB
Specification for NodeB
Indexes
1920-1980 MHz (co-
frequency interference)-121 dBm/ 3.84 MHz -105 dBm/ 3.84 MHz -100 dBm/ 3.84 MHz -80 dBm/ 3.8 4MHz
The sensitivity specification
is -123 dBm/3.84MHz.
1900-2000 MHz
(adjacent channel
interference, deviated
from the carrier by 5
MHz)
-63 dBm/ 3.84 MHz -47 dBm/ 3.84 MHz -42 dBm/ 3.84 MHz -22 dBm/ 3.84 MHz-42 dBm/ 3.84 MHz (with the
sensitivity worsened by 6 dB)
1900-2000 MHz (in-band
blocking)-51 dBm/ 3.84 MHz -35 dBm/ 3.84 MHz -30 dBm/ 3.84 MHz -10 dBm/ 3.84 MHz
-30 dBm/ 3.84 MHz (with the
sensitivity worsened by 6 dB)
1900-2000 MHz (out-of-
band blocking)-46 dBm/ 3.84 MHz -30 dBm/ 3.84 MHz -25 dBm/ 3.84 MHz -5 dBm/ 3.84 MHz
-25 dBm/ 3.84 MHz (with the
sensitivity worsened by 6 dB)
935-960 MHz
1805-1880 MHz (out-of-
band blocking)
-5 dBm/Hz 11 dBm/Hz 16 dBm/Hz 36 dBm/Hz16 dBm/Hz (with the
sensitivity worsened by 6 dB)
Other bands (out-of-
band blocking)-26 dBm/Hz -10 dBm/Hz -5 dBm/Hz 15 dBm/Hz
-5 dBm/Hz (with the
sensitivity worsened by 6 dB)
Note:
dBm/Hz refers to the level unit of single-tone signals.
The reference port for measurement is the reception port of the NodeB antenna.
The reference requirements are based on the protocol TSG25.101.
During analysis, the index for adjacent channel interference and in-band blocking is 10 dB better than that specified in the protocol. This is the RF index the NodeBcan ensure.
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Impact of Electromagnetic Interference on the System
Interference requirements for UE reception(taking the band 2110 -
2170 MHz as an example)
Interference band: 2110 - 2170 MHz
Interference level not affecting receiver sensitivity: -117 dBm/3.84 MHz, with
the sensitivity worsened by 0.1 dB
Acceptable interference: -101 dBm/3.84 MHz, with the sensitivity worsened
by 3 dB
Acceptable interference: -96 dBm/3.84 MHz, with the sensitivity worsened by
6 dB
Interference that seriously effects equipment indexes instead of equipment
running:
-35dBm/3.84MHz, lower than the maximum signal strength (-25 dBm) the UE
can receive by 10 dB
Sensitivity: at least -107 dBm/3.84 MHz as required in the protocol
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Impact of Electromagnetic Interference on the System
Interference requirements for NodeB reception (taking the band
1920 -1980 MHz as example)
Interference band: 1920 - 1980 MHz
Interference level not affecting receiver sensitivity: -121 dBm/3.84 MHz, with
the sensitivity worsened by 0.1 dB
Acceptable interference: - 105 dBm/3.84 MHz, with the sensitivity worsened
by 3 dB
Acceptable interference: - 100 dBm/3.84 MHz, with the sensitivity worsened
by 6 dB
Interference that seriously effects equipment indexes instead of equipment
running: -80 dBm/3.84MHz
Sensitivity: at least -123 dBm/3.84 MHz as required in the protocol
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Chapter 1 Impact of Electromagnetic
Interference on the System
Chapter 2 Sources of Electromagnetic
Background Interference
Chapter 3 Introduction to InterferenceTest Tools
Chapter 4 Methods for Electromagnetic
Background Test
Chapter 5 Instructions for YBT250
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Chapter 2 Sources of Electromagnetic
Background Interference
2.1 2G Band Allocation
2.2 Analysis on Interference Sources
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2G Band Allocation
In china, 2G bands are allocated as follows:
Band (MHz) Occupation
1710~1720/1805~1815 GSM1800 for China Mobile
1745~1755/1840~1850 GSM1800 for China Unicom
1800~1805 SCDMA (Beijing Xinwei)
1850~1865/1920~1945 Reserved
1865~1880/1954~1960 PCS1900 (not occupied)
1880~1900/1960~1980 FDD WIL (used by China Telecom and China
Unicom in some cities by the end of 2002)
1900~1920 TDD WLL (PHS/DECT)
Planning of Bands 1.8 GHz and 1.9 GHz in China
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Chapter 2 Sources of Electromagnetic
Background Interference
2.1 2G Band Allocation2.2 Analysis on Interference Sources
TDD WLL
FDD WLL
Microwave transmission
Repeater
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Analysis of Interference Sources
TDD WLL (PHS/DECT)
The system occupies the 1900 -1920 MHz band.
For the PHS system, the bandwidth occupied by the channel is
smaller than or equal to 288 KHz.
For the DECT system, the bandwidth occupied by the channel
is smaller than or equal to 1533 KHz.
FDD WLL
Uplink band: 1880 -1900 MHz
Downlink band: 1960 -1980 MHz
The bandwidth occupied by the system is 1.25 MHz.
The EiRP of a typical NodeB is about 25 dBm.
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Analysis of Interference Sources
Microwave transmission
Occupied bandwidth: usually over several MHz.
Normal reception level of microwave is about -60 dBm, imposing a great impact
on the WCDMA system.
Repeater
Nonstandard installation results in insufficient antenna isolation, thus self-
excitation. This affects normal running of the NodeB where the repeater is
installed.
The repeater is a wide-band non-linear amplifier. Its intermodulation index
exceeds the one specified in the protocol. The repeater easily causes
interference to nearby NodeBs when its power is too large.
Others
Some communication devices occupy WCDM bands. Unreasonable installation
and isolation result in high harmonic signals and thus cause interference to the
WCDMA system. In addition, radar is also a common interference source.
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Chapter 1 Impact of Electromagnetic
Interference on the System
Chapter 2 Sources of Electromagnetic
Background Interference
Chapter 3 Introduction to Interference
Test Tools
Chapter 4 Methods for Electromagnetic
Background Test
Chapter 5 Instructions for YBT250
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Chapter 3 Introduction to Interference Test Tools
1.1 Spectrum Analyzer
1.2 Antenna
1.3 Low Noise Amplifier
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Interference Test Tools
Spectrum analyzer
A spectrum analyzer is used to test frequency domain features of signals,covering spectrum, adjacent channel power, fast time domain scanning,
spurious radiation and intermodulation attenuation.
Key indexes
Resolution bandwidth (RBW)
Input frequency and central frequency (F0) Sensitivity
Span
Reference level (RefLvl)
Video filter bandwidth (VBW)
Input signal attenuation (ATT) Detection mode (RMS)
Sweep time
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Interference Test Tools
Main technical indexes of various spectrum analyzers
Model Working Band Sensitivity (1 Hz)Minimum Resolution
Bandwidth
HP8591E 30 - 1.8 GHz -145 dBm 30 Hz
HP8594E 30 - 2.9 GHz -142 dBm 30 Hz
HP8595E 30 - 6.5 GHz -142 dBm 30 Hz
HP8561E 30 - 6.5 GHz -145 dBm 1 Hz
YBT250 30 - 2500 MHz -132 dBm 1 KHz
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Interference Test Tools
Antenna
Omnidirectional antenna: It facilitates interference
measurement instead of interference location.
Directional antenna: It is used to search interference sources.
The more distinct the directivity is and the higher the gain is,
the stronger the searching capability is. Common directional antennas:
Panel antenna
Yagi antenna
Log periodic antenna
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Interference Test Tools
Low noise amplifier (LNA)
Used to improve the receiver sensitivity of the testing instrument.
During a test, we can select the LNA with 30 dB gain and 5 dB
noise coefficient.
Additional power supply needs to be considered for the LNA. Some
testing instruments (like YBT250 ) are configured a built-in LNA.
For a cascade network, the noise coefficient of the system depends
on level-1 noise coefficient when a high gain amplifier is configured
at the front end of the system.
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Chapter 1 Impact of Electromagnetic
Interference on the System
Chapter 2 Sources of Electromagnetic
Background Interference
Chapter 3 Introduction to Interference
Test Tools
Chapter 4 Methods for Electromagnetic
Background Test
Chapter 5 Instructions for YBT250
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Chapter 4 Methods for Electromagnetic Background Test
4.1 Preparations
4.2 Setting Basic Parameters
4.3 Measurement Procedure
4.4 Data Processing
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Preparations
Master local radio band planning and the usage of radio
equipment by enterprises
For pilot networks
No available frequency is determined and the testing frequency is allocated
temporarily. During a spectrum test, you need to scan the entire band or
select several 5 MHz bands for test according to the local frequency
resources for use at the later phase.
For commercial networks
Frequency resources are determined. The test focuses on the bands used
by the operator and is intended to eliminate interference at the bands in use.
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Preparations
Determine the test time and place
Uplink electromagnetic interference test
Test place: the place where the NodeB antenna is installed.
Conduct the test in three directions (0, 120 and 240).
Use a portable antenna or the NodeBs antenna.
Downlink electromagnetic interference test
Select a certain quantity of typical points within the cell coverage for test.
Conduct the test in three directions (0, 120 and 240).
Use a portable antenna.
Perform a drive test, drive the vehicle slowly along the main streets covered by acell and then stop the vehicle for further test when detecting the interference.
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Preparations
Prepare tools and make surethat they are available:
Spectrum analyzer
GPS receiver
Compass
Testing antenna
Vehicle
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Preparations
Prepare tools and make them available:
Connect an LNA to the spectrum
analyzer with low receiver sensitivity.
During system connection, check
whether connectors are matched and
ensure continuous power supply for
the instruments.
Device Connector Model
Yagi antenna N (female)
Bandpass filter N (female)
YBT250 spectrum
analyzerN (female)
LNA SMA (male)
Feeder N (male)
Feeder N (male)/SMA (male)
50 ohm matched
loadN (male)
YBT250spectrumanalyzer
Yaqi antenna
Filter
LNA
Cable
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Chapter 4 Methods for Electromagnetic Background Test
4.1 Preparations
4.2 Setting Basic Parameters
4.3 Measurement Procedure
4.4 Data Processing
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Setting Basic Parameters
Set the following basic parameters
Parameter Parameter Value Remarks
FoUplink: Fo=1950; downlink: Fo=2140
(MHz)
Central frequency of the
spectrum under test
SPAN For example, SPAN=100 MHzSpan of the testable
spectrum
MaxHold
/Average
Select MaxHoldor Averageaccording
to occurrent or continuous interference
respectively.
Display the maximum
value/the average value
RefLvl
Do notselect AutoLevel. Set the
reference level according to the testing
signal and try to display the signal in themiddle of the spectrum analyzer.
Reference level
Vertical
Scale10 dB/div (default) Vertical scale
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Chapter 4 Methods for Electromagnetic Background Test
4.1 Preparations
4.2 Setting Basic Parameters
4.3 Measurement Procedure
4.4 Data Processing
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Measurement Procedure
Determining the test azimuth Select the position where the NodeB antenna is installed for test. Usually, you
need to conduct the test in three directions. If the direction of the NodeB
antenna is determined, make the testing antenna be in the same direction as
the NodeB antenna.
Searching interference
Search interference within the uplink band and then within the downlink band.
Specific operations:
Enter the YBT250 spectrum test interface and set Fo and Span.
Fill in the record table, save data files, and check whether there is interference.
Judge rule: whether there is interference waveform higher than the noise floor.
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Measurement Procedure
Interference confirmation
During interference search, if there is interference, conduct a interference
confirmation test. Specific steps are as follows:
Enter the interface for measuring YBT250 NodeB test information, and set Foto a
central frequency point near interference,Spanto 3 interference bandwidth,
and Channel Bandwidthto 4 M.
Read the in-band interference power, fill in the record table, and save the data file.
In-band test
For the customer pilot, test the in-band power for all the candidate channels.
For commercial offices, focus on testing the in-band power for the available
channels. Specific steps are as follows:
Enter the interface for measuring YBT250 NodeB test information, and
set Foto a central frequency point of the testing channel, ChannelBandwidthto 5 M, and Spanto 3 interference bandwidth.
Read the in-band power, fill in the record table, and save the data file.
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Measurement Procedure
Downlink drive test
Downlink drive test means driving a vehicle slowly along the main
streets covered by a cell and conducting a point test after discovering
large interference.
Specific operations:
Enter the YBT250 spectrum test interface.
Set Foto 2140 MHzand Spanto 60 MHz. Search interference when the
vehicle moves at a speed lower than 15 km/h.
Point test items include:
Set Foto a central frequency point near the interference, Channel
Bandwidthto 4 MHz, and Spanto 3 interference bandwidth. Record the
in-band interference power.
Or set Foto a central frequency point of the testing channel, ChannelBandwidthto 5 MHz, and Spanto 3 channel bandwidth. Record the in-
band power.
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Chapter 4 Methods for Electromagnetic Background Test
4.1 Preparations
4.2 Setting Basic Parameters
4.3 Measurement Procedure
4.4 Data Processing
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Data Processing
After completing measurement, perform data
processing.
After completing measurement for the test area,
output
WCDMA Electromagnetic Interference Test Form
After completing measurement for the entire
local network, output
Report on WCDMA Electromagnetic Interference
Test
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Question
Is the interference level obtained
from the electromagnetic
interference test equal to the
level of the interference signals
at the top of the NodeB or at the
antenna port of the MS?
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Answer
The testing system and WCDMA
system adopt different antennas
and feeders. Therefore, you
need to calculate the level of the
interference signals at the top of
the NodeB or at the antenna port
of the MS according to the test
data during analysis.
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Answer
Testing system Antenna gain: 3 dBi
Feeder loss: 1 dB
Measured interference level: -90 dBm
WCDMA system
Gain of the NodeB antenna: 10 dBi
Feeder loss: 2 dB
Interference level at the NodeB: 90 - (3 -1) + (10 - 2)-84 dBm
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Question
How to estimate the power of the
interference level within the
channel bandwidth according to
the interference level within the
RBW?
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Answer
The WCDMA system is a broadband system.Therefore, you need to calculate theintegral
power of the interference level within the
channel bandwidth.
RBW of the testing system: 10 KHz
Interference level within the RBW: -80 dBm
Channel bandwidth: 3.84 MHz
Integral power within the channel:
P = -80 + 10LOG(3.84*106/10*103) = -54dBm
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Chapter 1 Impact of Electromagnetic
Interference on the System
Chapter 2 Sources of Electromagnetic
Background Interference
Chapter 3 Introduction to Interference
Test Tools
Chapter 4 Methods for Electromagnetic
Background TestChapter 5 Instructions for YBT250
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Chapter 5 Instructions for YBT250
System connection
Power-on
Measurement
Measurement setting
Measurement result
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Instructions for YBT250
Before site survey, you need to conduct a spectrum testand find proper frequency test instruments.
Tektronix YBT250 is recommended.
Features of YBT250
Portable, easy to carry
System integration, with a built-in LNA
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Instructions for YBT250
System connection
The matched antenna of YBT250 is Yagi
directional antenna.
A portable small antenna can be used for
electromagnetic background test.
YBT250 can use the battery deliveredtogether or can be externally connected to
the power supply.
Power-on
Press Powerand enter the Windows CE
operating system.
Enter the measurement interface through
the touch screen of YBT250.
YBT250spectrumanalyzer
Yaqi antenna
Filter
LNA
Cable
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Instructions for YBT250
Measurement
YBT250 supports the following three
measurement functions:
NodeB information measurement
Spectrum test
Interference source search
Spectrum test supports the following two
display modes:
Spectrum mode
Spectrogrum mode
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Instructions for YBT250
Measurement The spectrum mode is used for real-time measurement.
Determine the band to be tested and set Fo.
Modify the span.
Observe the spectrum diagram, adjust the Fo and span, and view whether there is
interference.
The Tracemenu includes the following options:
Normal, Max Hold, Min Hold and Max/Min Hold
Save the current spectrum diagram.
Note: You need to set RefLvlcorrectly to make the measured signal levelrange from RefLvl to (RefLvl-70dB). The difference of the maximum level and
minimum of level that the YBT250 can correctly display is 70 dB.
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Instructions for YBT250
Measurement
The spectrogrum mode is used to check
whether there is interference at a certain band
in a specified time. The horizontal axis stands
for the band and the vertical axis for the time.
Specific operations:
Set the automatic storage option and a file name.
Set the band (Fo and span).
Open the saved file and view interference.
To view the exact interference, you can export
the file as:
A picture
Data (.txt,.csv)
Export the data from YBT250 using the U disk or
network cable.
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Instructions for YBT250
Measurement setting
Fo: the central frequency of the testing signal (unit: MHz)
Span: It can be set to 100 MHz, 10 MHz or 5 MHz.
RBW: It is automatically set by the instrument according to the span.
MaxHold/Average: display the maximum value and the average value.
RefLvl: set according to the interference level.
Measurement result
WCDMA Electromagnetic Interference Test Formand Report on WCDMA
Electromagnetic Interference Test
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Instructions for YBT250
A spectrum trail in the interference windowInstance of displaying signal strength
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Conclusion
This course describes possible
interference sources at the WCDMA
band, methods for electromagnetic
background test, and instructions for
YBT250.
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Thank You!
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