Testing Radio Interference

Testing Radio Interference
Gustaaf Sutorius
Application Engineer
© 2012 Agilent Technologies
Agenda Fieldfox Workshop
10.30 – 11.00: Vector Network Analyzer Fundamentals
11.00 – 12.30: Making precise RF&uWave measurements in the field
12.30 – 13.30: Lunch
13.30 – 14.30: Making precise cable and antenna measurements
14.30 – 14.45: break
14.45 – 15.45: Techniques to troubleshoot interference in the field
15.45:
Drinks
© 2012 Agilent Technologies
Agilent Spectrum Analyzer Portfolio for Interference Test
© 2012 Agilent Technologies
Other tools for interference…
N6841A RF Sensor
GPS antenna
GPS
Power Data
RF Inputs
RF Sensor Key Benefits:
•
•
•
•
N6841A
20 MHz - 6 GHz, 20 MHz info BW
Sealed/ Weatherproof: IP 67!
Synchronization < 20 nS!
Proven Reliability
© 2012 Agilent Technologies
Testing Radio Interference Using Agilent
FieldFox Handheld Analyzers
5
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
6
© 2012 Agilent Technologies
What is Radio interference
•IEEE Interference event definition:
Interference Event = a Quantified threshold of
Interference has been exceeded
• Dynamic Spectrum Access:
White Space/Cognitive radio/Digital Dividend
• ISM band (ISM = Industrial, Scientific, Medical)
“Listen before talk” in WLAN 802.11
• Example: London Olympic games 2012
Olympics report.pdf page 25 and 31
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
8
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Spectrum Assignments: USA example
© 2012 Agilent Technologies
Licensed and Unlicensed Spectrum
(MHz)
Licensed : Protected against harmful interference
Unlicensed : Expected amount of interference
(Part 15 Rules)
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
11
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Intentional, Unintentional, Incidental Radiators
Intentional radiators
Active transmitters
• Broadcast radio and television
• Cellular
• Satellite
• Radar
• Mobile radio
• WLAN
• Cordless phones
Unintentional radiators
Use RF but not for
radio transmission
• Microwave ovens
• Radio receiver
• Industrial heaters
• MRI equipment
Incidental radiators
Do not use RF
• Switching power supplies
• Clock and control signals
• Ignition motors
• Fluorescent lighting
© 2012 Agilent Technologies
Ambient Man-Made Radio Noise
Median Noise above kTB (dB)
Antenna connected
Input terminated
Frequency (Hz)
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
14
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Interference Classifications
• In-band interference
• Co-channel interference
• Out-of-band interference
• Adjacent channel interference
• Uplink interference
• Downlink interference
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In-Band and Co-Channel Interference
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Out-of-Band Interference
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Adjacent Channel Interference
Channel power
Adjacent channel power
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Downlink and Uplink Interference
Interference
Interference
Downlink spectrogram
Uplink spectrogram
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Near-Far Conditions
f1
f2
Analyzer display
Potential overload of
analyzer’s front-end
f1
f2
All signals enter analyzer’s front-end
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Techniques to Avoid Analyzer Overload
Avoid saturation and overload of the
handheld analyzer
Filter
– Connect with bandpass filter to filter out
strong signals
– Do not point the directional antenna
towards the transmitter
– Turn off preamplifier and increase
attenuation (if the sensitivity allows)
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
22
© 2012 Agilent Technologies
Key Analyzer Specifications
Displayed Average
Noise Level (DANL)
Also,
• RBW filter
• Preamplifier
• Third order intercept
• Phase noise
• Spurious
Frequency range
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RBW and Preamplifier
Preamp ON
Lower RBW improves DANL
RBW=1 kHz
Narrowband
signal
Preamp OFF
RBW=1KHz
RBW=100 Hz
Wideband
signal
Preamp ON
Reducing RBW:
Narrow-band signals (BW < RBW)
Same signal level, lower DANL (improve SNR)
Wide-band signals (BW > RBW)
Lower signal level, lower DANL (same SNR)
© 2012 Agilent Technologies
FieldFox InstAlign
Total amplitude accuracy across frequency and temperature
•
•
•
•
Frequency
range
(23 °C ± 5 °C)
(–10 to +55 °C)
100 kHz to
18 GHz
± 0.35 dB
± 0.50 dB
>18 GHz to
26.5 GHz
± 0.50 dB
± 0.60 dB
Auto correction with 30 sec elapsed time
Auto correction with 1 oC instrument change
Accurate across -10 to +55 oC
No warm-up required
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
26
© 2012 Agilent Technologies
Antenna Configurations
Antenna connected directly
Antenna patterns
Antenna cabled to analyzer
Horizontal plane
Omni
Omnidirectional
High gain
Vertical plane
Horizontal plane
High gain
Vertical plane
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High Gain versus Omnidirectional Antenna Types
Yagi
Whip
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Amplitude Correction and Field Strength
Field strength units
FieldFox
Amplitude correction = antenna gain - cable loss
Correction factors editor
Corrections .csv
© 2012 Agilent Technologies
Testing Radio Interference
Agenda:
1. What is Radio Interference
2. Spectrum Assignments
3. Sources of Interference
4. Interference Classifications
5. Analyzer Specifications
6. Antenna Specifications
7. Measurement Modes
30
© 2012 Agilent Technologies
Clear/Write and Max Hold Display Modes
Max hold trace
Fixed carrier
Frequency hopping
carrier
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Amplitude scale
Spectrogram Display Mode
Fixed carrier
Frequency hopping
carrier
Time
Frequency
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Waterfall Display
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Lab TIME
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Zero Span Display Mode
Duration of Signal @ fcenter
Trigger Level
Time
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Measurement Configurations
N993xA spectrum analyzer
N991xA spec/VNA combo
© 2012 Agilent Technologies
Other Agilent Handheld Spectrum Analyzers
N9344C
SA 1 MHz to 20 GHz
N9340B/42C
SA 100 KHz to 3/7 GHz
N9343C
SA 1 MHz to 13.6 GHz
© 2012 Agilent Technologies
Channel Scanner
Top/Bottom horizontal listing to sort on frequency, power, or Carrier ID. Ideal for
coverage test, band clearance, and spectrum monitoring.
Time Chart
Top /Bottom list >20 channels
20 channels fast sweep time
Time Chart monitors signals in time (burst signal analysis) for power variations
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Data Mapping with Google Earth & MapInfo
Collect data and log it with the GPS Option and Channel Scanner &
Marker logging feature.
Generates data files to use with Google Earth & MapInfo
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Accessories
N9311X log periodic directional antenna
-504
700 MHz to 4 GHz
-508
680 MHz to 8 GHz
-518
680 MHz to 18 GHz
N9311X-500 whip antenna, 70 to 1000 MHz
N9311X-501 omnidirectional antenna, 700 to 2500 MHz
N9311X bandpass filter
-550
814 to 850 MHz
-553
1845 to 1915 MHz
-551
880 to 915 MHz
-554
1910 to 1990 MHz
-552
1707.5 to 1787.5 MHz
N9311X phase stable test cable, type N(m) to N(m)
© 2012 Agilent Technologies
Summary
• Reviewed radio interference classifications and spectrum use
• Discussed why interference analysis is important
• Discussed equipment and antenna requirements
• Reviewed spectrum analyzer settings for high accuracy
• Reviewed FieldFox display modes for identifying radio interference
• Introduced Handheld Spectrum Analyzer series for Drive tests – coverage
mapping
© 2012 Agilent Technologies
For More Information
Web: www.agilent.com/find/FieldFox
Literature:
- Techniques for Precise Interference Measurements in the Field, application note,
literature number 5991-0418EN
- FieldFox Handheld Analyzers, brochure, literature number 5990-9779EN
Thank you for your time
Questions?
© 2012 Agilent Technologies
Agenda Fieldfox Workshop
10.30 – 11.00: Vector Network Analyzer Fundamentals
11.00 – 12.30: Making precise RF&uWave measurements in the field
12.30 – 13.30: Lunch
13.30 – 14.30: Making precise cable and antenna measurements
14.30 – 14.45: break
14.45 – 15.45: Techniques to troubleshoot interference in the field
15.45:
Drinks
© 2012 Agilent Technologies
Appendix: Field Strength Calculations
S=
4π Pr
gλ2
S = power density, watt/m 2
Pr = received power, watts
g = gain of receiving antenna relative to isotropic
λ = wavelength
2
E
as the power density, S , in free space is equal to
E=
120π
68.8 Pr
λ
g
E = incident field strength in V/m
© 2012 Agilent Technologies
Appendix: Field Strength Calculations (continued)
The analyzer measures received power, Pr , in dBm.
Converting Pr to watts, the field strength, E (V/m), can be calculated using the
previous equation.
Convert E (V/m) to dBµV/m (dB relative to 1µV) using
[
dBµV/m = 20log10 (V/m)/10 -6
]
© 2012 Agilent Technologies