ETSI TR 103 151 V1.1.1 (2013-09)

Electromagnetic compatibility and Radio spectrum Matters (ERM); Tests on the immunity of Wind Profiler Radar to transmissions from RFID, ALDs and GSM

DTR/ERM-TG34-259

General Information

• Status: Published
• Publication Date: 05-Sep-2013
• Technical Committee: ERM TG34 - ERM RF Identification Devices
• Current Stage: 12 - Completion
• Due Date: 18-Sep-2013
• Completion Date: 06-Sep-2013

Standards Content (Sample)

Technical Report
Electromagnetic compatibility
and Radio spectrum Matters (ERM);
Tests on the immunity of Wind Profiler Radar
to transmissions from RFID, ALDs and GSM

2 ETSI TR 103 151 V1.1.1 (2013-09)

Reference
DTR/ERM-TG34-259
Keywords
radio, RFID, SRD
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© European Telecommunications Standards Institute 2013.
All rights reserved.
TM TM TM
DECT , PLUGTESTS , UMTS and the ETSI logo are Trade Marks of ETSI registered for the benefit of its Members.
TM TM
3GPP and LTE are Trade Marks of ETSI registered for the benefit of its Members and
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GSM® and the GSM logo are Trade Marks registered and owned by the GSM Association.
ETSI
3 ETSI TR 103 151 V1.1.1 (2013-09)
Contents
Intellectual Property Rights . 4
Foreword . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definitions, symbols and abbreviations . 5
3.1 Definitions . 5
3.2 Symbols . 6
3.3 Abbreviations . 6
4 Description of equipment . 7
4.1 Facilities at Camborne . 7
4.2 Description of Interferers . 8
4.2.1 RFID Interrogator . 8
4.2.2 ALD Prototype . 9
4.2.2.1 ALD Use . 9
4.2.3 GSM and UMTS emulation . 9
5 Description of Tests. 9
5.1 Tests with RFID . 9
5.2 Tests with ALDs . 12
5.2.1 Measurement Sequence . 12
5.2.2 Test sequence . 12
5.3 Tests with GSM and UMTS . 14
6 Analysis of Results . 14
6.1 Met Office Test Result and Interference Level Criteria . 15
6.2 Possible Mitigation for the WPR . 18
7 Conclusions . 18
Annex A: Details of Wind Profiler Radar . 19
A.1 Operational description . 19
A.2 Specifications for Wind Profiler Radar LAP-3000 . 20
Annex B: Spectrum masks . 23
B.1 ALDs . 23
B.2 RFID . 25
B.3 GSM and UMTS . 27
Annex C: Typical emissions from RFID systems . 29
th
Annex D: Camborne test results (14-15 February 2013) . 34
D.1 Annotated WPR interference screenshots - radial velocity dwell display . 34
Annex E: Bibliography . 53
History . 54

ETSI
4 ETSI TR 103 151 V1.1.1 (2013-09)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Electromagnetic compatibility and Radio
spectrum Matters (ERM).
The present document includes necessary information to support the co-operation under the MoU between ETSI and the
Electronic Communications Committee (ECC) of the European Conference of Postal and Telecommunications
Administrations (CEPT).
The present document was prepared with the assistance of the UK Met Office without whose support the present
document would not have been possible.
Introduction
Recently ETSI made a request to CEPT for use by SRDs and RFID of the band 915 MHz to 921 MHz. Since this band
was already allocated to the railways and to government services, SE24 was asked to investigate if sharing in these
bands by SRDs and RFID with the primary services would be possible. In the course of their compatibility studies SE24
has learnt that two sites exist in the UK where Wind Profiler Radar (WPR) are in use operating within the band
915 MHz to 917 MHz. It was decided that some practical tests should be made at one of these sites to find out if SRDs
and RFID caused unacceptable levels of interference.
Further technical information on the Wind Profiler Radar is provided in annex A.
The UK Met Office kindly agreed to make their site and facilities at Camborne available in order to perform practical
th th
tests. The tests took place on 14 and 15 February and involved personnel from the Met Office who operated the WPR
and recorded data and ETSI ERM TG 34/17 who operated the interferers. Two items of equipment were made available
as interferers for the tests. One of these was a prototype Assisted Listening Device (ALD) operating at 10 dBm and the
other was an RFID interrogator transmitting at levels up to 36 dBm in free space (It should be noted that this equipment
is normally mounted in a shielded portal, which contains the RF). The actual ERP at a distance of 10 m from a
distribution centre where RFID is installed is in the region of -36 dBm. See annex C for typical use cases. In addition it
was also possible to generate signals that emulated the transmissions from 3G and UMTS.
The Met Office had previously carried out testing on a similar WPR operating at 1 290 MHz and considered the results
would echo the testing on the 915 MHz unit.
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5 ETSI TR 103 151 V1.1.1 (2013-09)
1 Scope
The present document gives a report on compatibility tests between the Wind Profiler Radar at the Met Office site in
Camborne UK, a prototype ALD device and a RFID interrogator. In addition the report also provides results on the
compatibility between WPR and simulated transmissions of GSM and UMTS.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] OFCOM Report SES/10/12: "Wind Profiler Radar Measurements Camborne".
[i.2] ETSI TR 102 791: "Electromagnetic compatibility and Radio spectrum Matters (ERM); System
Reference Document; Short Range Devices; Technical characteristics of wireless aids for hearing
impaired people operating in the VHF and UHF frequency range".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply:
Assistive Listening Devices (ALD): systems utilizing electromagnetic, radio or light waves or a combination of these,
to transmit the acoustic signal from the sound source (a loudspeaker or a person talking) directly to the hearing impaired
person
interrogator: fixed or mobile data capture and identification device using a radio frequency electromagnetic field to
stimulate and affect a modulated data response from a transponder or group of transponders in its vicinity
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6 ETSI TR 103 151 V1.1.1 (2013-09)
Telecoil: Audio Induction Loop systems, also called audio-frequency induction loops (AFILs) or hearing loops are an
aid for the hard of hearing
NOTE: They is a loop of cable around a designated area, usually a room or a building, which generates a
magnetic field picked up by a hearing aid. The benefit is that it allows the sound source of interest -
whether a musical performance or a ticket taker's side of the conversation - to be transmitted to the
hearing-impaired listener clearly and free of other distracting noise in the environment. Typical
installation sites would include concert halls, ticket kiosks, high-traffic public buildings (for PA
announcements), auditoriums, places of worship, and homes. In the United Kingdom, as an aid for
disability, their provision where reasonably possible is required by the Disability Discrimination Act
1995, and they are available in the back seats of all London taxis, which have a little microphone
embedded in the dashboard in front of the driver; at 18 000 post offices in the U.K.; at most churches and
cathedrals.
Wind Profiler Radar (WPR): instrument that uses radar to measure the wind velocity at different altitudes
3.2 Symbols
For the purposes of the present document, the following symbols apply:
dB decibel
kHz kilohertz
km kilometre
s seconds
m metre
MHz Megahertz
min minute
ns nano second
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AFIL Audio-Frequency Induction Loops
ALD Assisted Listening Device
CW Carrier Wave
ECC Electronic Communications Committee
ERP Effective Radiated Power
GMSK Gaussian Minimum Shift Keying
GSM Global System for Mobile communication
HQ HeadQuarters
LTE Long Term Evolution
MFCN Mobile/Fixed Communications Networks
NE North East
NW North West
NWP Numerical Weather Prediction
PR ASK Phase Reversal Amplitude Shift Keying
PR Phase Reversal
PRF Pulse Repetition Frequency
QPSK Quadrature Phase Shift Keying
RF Radio Frequency
RFID Radio Frequency Identification
RMS Root Mean Square
SE South East
SRD Short Range Device
SW South West
TRS Telecoil Replacement System
UHF Ultra High Frequency
UMTS Universal Mobile Telecommunications System
VAC Volts Alternating Current
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7 ETSI TR 103 151 V1.1.1 (2013-09)
WCDMA Wideband Code Division Multiple Access
WPR Wind Profiler Radar
4 Description of equipment
4.1 Facilities at Camborne
The Met Office site at Camborne is located in a grass field of approximately 170 metres square surrounded by open
farmland. The wind profiler radar on site provides important information on the state of the atmosphere that is used to
drive NWP (Numerical Weather Prediction) models and inform forecasts - this particular location in the west of the UK
is notably important in respect of this being the prevailing direction from which weather approaches the UK.
The antennas for the Wind Profiler Radar have been installed inside a fibreglass container positioned approximately in
the centre of the site. The equipment was controlled from a building, adjacent to the antennas. The site is shown in
figure 1.
Figure 1: Camborne Meteorological Station
In December 2012 OFCOM made measurements at Camborne of the isolation provided by the container. (See [i.1].)
Their measurements showed that at a height of 1,5 m the sidewall attenuation varied between 7,3 dB and 10,6 dB. A
picture of the fibreglass container is shown in figure 2.
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8 ETSI TR 103 151 V1.1.1 (2013-09)

Figure 2: WPR Antenna housing
In normal operation the four antennas of the WPR are steered electronically to measure reflections from the atmosphere
in NE, SE, SW, and NW, directions. After processing, this information gives details of direction and wind-speed at
different altitudes, as well as reflectivity data (see annex A for full description of available parameters). Two different
pulse lengths and PRFs are used to measure the conditions at low (up to 2 km) and high (up to 8 km) altitudes. For the
higher altitudes a radar pulse length of 1 400 ns having a 3 dB bandwidth of 632 kHz is used (High mode). For low
altitudes a pulse length of 400 ns is transmitted with a 3 dB bandwidth of 2,5 MHz (Low mode). Each measurement is
made over a period of about one minute.
It was believed that the WPR equipment has been operational on the site for some 15 years. During this time it has
operated almost continuously to provide valuable information to the Met Office for their weather forecasts.
Further technical information on the Wind Profiler Radar is provided in annex A. However whilst the data sheet refers
to the transmitter bandwidth there is no information available on the receiver. From the testing carried out this appears
to be considerably wider than the 2,5 MHz shown.
4.2 Description of Interferers
4.2.1 RFID Interrogator
The RFID equipment was provided by a manufacturer and comprised a standard interrogator connected to its patch
antenna. The antenna, which had a gain of 7 dBi, was mounted vertically on a post 0,8 m above the ground so that it
transmitted in a horizontal direction. The transmission from the antenna was circularly polarized. The interrogator was
controlled from an application installed on a laptop. The interrogator was fitted with test firmware, which allowed it to
transmit on a fixed frequency with either continuous CW or a continuously modulated signal. The modulation used was
PR ASK. It should be noted that in a typical application, such as a distribution centre, an RFID interrogator would only
transmit for between 1,5 s and 2 s every 10 s over a period of about 10 min. This might be repeated up to 4 times during
a day.
For the purposes of the tests at Camborne, the interrogator was set initially to transmit at a level of 36 dBm at a fixed
frequency of 916,25 MHz. Subsequently measurements were also made with the interrogator set to output powers of
8,6 dBm and -2,6 dBm and at a transmit frequency of 917,25 MHz.
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9 ETSI TR 103 151 V1.1.1 (2013-09)
4.2.2 ALD Prototype
A prototype system was used providing an output of some 10 mW into a 0 dbi calibrated ½ wave dipole at 915 MHz
(see annex E for details) mounted on a wooden tripod some 1,5 m above the ground. The system was programmed with
the following parameters:
1) nominal 200 kHz bandwidth 124 kbit/s 4GFSK modulation (BT = 0,5) with 40 kHz deviation (outer symbols),
5 ms packets, 5 ms interval between packets (50 % duty cycle), 0 dBi antenna at 1,5 m above ground level;
2) nominal 600 kHz bandwidth, 360 kbit/s 4GFSK modulation (BT = 0,5) with 162 kHz deviation (outer
symbols), continuous PN9 data modulated transmission (100 % duty cycle), 0 dBi antenna at 1,5 m above
ground level.
Other system features not used in tests:
• The system is designed to spectrum sense and frequency hop to minimize interference to other spectrum users.
• Can be pre-programmed to the spectrum available at that site.
4.2.2.1 ALD Use
The ALD system under test is referred to as the Telecoil Replacement System (TRS) designed to take an input such as a
railway or airport information service normally provided by a public address system and provide hard of hearing
customers with a direct input to their hearing aids. The problem for the majority of hard of hearing is not volume but
clarity. The system is designed to replace the inductive telecoil system (see definitions for description) currently used in
some religious buildings, theatres and similar locations. TR 102 791 [i.2] provides full information on these issues but
briefly the telecoil only has one channel and cannot be used in large areas such as railway stations and airports and is
extremely difficult to retrofit to existing buildings whereas the TRS can provide multiple channels for translation
services, school and theatre use and is simple to install and run
The vast majority of systems will be indoor.
4.2.3 GSM and UMTS emulation
A Rhode and Schwarz SMIQ generator was fed into the 0 dBi cable-mounted ½ wave 915 MHz dipole mounted on a
wooden tripod some 1,5 m above the ground and set to the following configurations:
R&S SMIQ to transmit a standard GSM GMSK waveform, nominal 200 kHz bandwidth.
This transmission used 100 % duty cycle and a relatively low power level due to limitations of the test equipment. In
practice a single mobile device would typically transmit at 1/8 duty cycle (in speech) or less during signalling, but in
many locations can be expected to use significantly higher power (up to 2W for typical mobile devices).
Set up R&S SMIQ to transmit a standard WCDMA QPSK waveform, nominal 5 MHz bandwidth.
This transmission used 100 % duty cycle, representative of a phone with a connected channel. The relatively low power
level was due to limitations of the test equipment. Mobile devices in this band are understood to be able to transmit at
up to +24 dBm, though power control in the system means that this will usually occur only in the outer parts of a cell.
5 Description of Tests
5.1 Tests with RFID
Initially the RFID equipment was mounted on a table about 10 m from the WPR with the RFID antenna directed at the
centre of the fibreglass container. The antenna was approximately 1,2 m above the ground. A picture of the set-up is
shown at figure 3.
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10 ETSI TR 103 151 V1.1.1 (2013-09)

Figure 3: Initial RFID test setup
With the interrogator transmitting at 916,25 MHz and an output of 36 dBm, measurements were made at the monitor of
the WPR. For both CW and continuous modulated transmissions, significant levels of interference were evident in both
the high and low modes of the WPR. The measurements were made in all four orientations of the WPR. The results
together with a control measurement are shown at figures B.1 to B.9.
The RFID equipment was then moved to the perimeter of the site, which put it at a distance of 85 m from the fibreglass
container. Measurements were again made at 916,25 MHz and 36 dBm (see annex C for real site calculations where a
typical figure of -52 dBm e.r.p. would be experienced at this distance) with both CW and continuous modulation.
Examination of the results from the monitor of the WPR showed that in the low mode RFID was still causing levels of
interference. In the high mode interference from RFID was not immediately apparent. However any possible harmful
effects will need to be confirmed by the team in Exeter who interpret the output.
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11 ETSI TR 103 151 V1.1.1 (2013-09)

Figure 4: Setup of RFID and ALD at perimeter of site
The WPR can be seen at to the right of the building.
By the insertion of attenuators in the feeder cable to the RFID antenna, the transmitted power was reduced first to
-2,6 dBm and then 8,6 dBm. The interrogator was set to transmit a continuously modulated transmission (from previous
measurements this represented the worst case condition). The WPR monitor appeared to show no evidence of
interference in the low mode at a transmit level of -2,6 dBm but interference was just evident at 8,6 dBm.
The measurements were repeated with an output power of 8,6 dBm and the interrogator operating at a frequency of
917,25 MHz. In this configuration there was no obvious sign of any interference on the monitor of the WPR.
In a final test the RFID system was set-up in the conference room of the site office with its antenna directed at the
fibreglass container. Although the RFID equipment was probably no more than 20 m from the fibreglass container, the
transmission had to pass through at least three brick walls. With the interrogator again set to 916,25 MHz and 36 dBm
transmit power in continuous modulation; an inspection was made of the traces at the monitor. There was no immediate
evidence of interference in the high mode but there was clear evidence of interference from RFID in the low mode.
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12 ETSI TR 103 151 V1.1.1 (2013-09)

Figure 5: Tests carried out in left hand room of the building
5.2 Tests with ALDs
5.2.1 Measurement Sequence
Power levels for all of the following tests except for WCDMA were measured using the R&S ZVL using input
resolution bandwidth at least 3x the signal bandwidth, and the peak detector in max hold mode run for at least 10 s. For
WCDMA, because of the waveform's crest factor, power was measured with 10 MHz input bandwidth and the RMS
detector. All power levels quoted here are referred to the antenna connector.
The antenna for all of the ALD, GSM and WCDMA tests was a 0 dBi cable-mounted ½ wave 915 MHz dipole from
Taoglas (see note), with an omnidirectional response in the horizontal direction. (Datasheet in annex C). For the tests at
1,5 m height, this antenna was mounted on a non-metallic antenna stand via a cable. For the indoor tests the antenna
was fitted directly to the ALD prototype. Figures 3 and 4 provide an overview of the test setup.
NOTE: See
http://www.taoglas.com/images/product_images/original_images/TI.09.0111%20915MHz%200dBi%20T
eminal%20Antenna%20090409.pdf
This antenna has performance typical of professional-grade SRD, ALD and mobile devices - in many consumer
devices, antenna gain will be lower than this.
Antenna for RFID tests was a nominal +7 dBi directional patch antenna, Symbol branded. Input power is noted here. In
all RFID tests, the antenna centre was directed at the radar.
5.2.2 Test sequence
Thursday 14 February 2013 - measurements at 85 m from WPR:
• Set up ALD1, nominal 200 kHz bandwidth, 124 kbit/s 4GFSK modulation (BT = 0,5) with 40 kHz deviation
(outer symbols), 5 ms packets, 5 ms interval between packets (50 % duty cycle), 0 dBi antenna at 1,5 m above
ground level
• Baseline (no tx)
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13 ETSI TR 103 151 V1.1.1 (2013-09)
• ALD1 915,2 MHz, 9,92 dBm
• ALD1 915,2 MHz, -1,67 dBm
• Baseline
• ALD1 915,2 MHz, 10,40 dBm
• ALD1 916,2 MHz, 9,79 dBm
• ALD1 916,2 MHz, -1,72 dBm
• Baseline
• ALD1 918,0 MHz, 9,65 dBm
• ALD1 918,0 MHz, -1,76 dBm
• Baseline
• Set up ALD2, nominal 600 kHz bandwidth, 360 kbit/s 4GFSK modulation (BT = 0,5) with 162 kHz deviation
(outer symbols), continuous PN9 data modulated transmission (100 % duty cycle), 0 dBi antenna at 1,5 m
above ground level
• Power level 0x40 used for 10 mW, 0x12 used for 1 mW
• ALD2 915,6 MHz, 10,54 dBm
• ALD2 915,6 MHz, -0,42 dBm
• Baseline
• ALD2 916,2 MHz, -0,58 dBm
• ALD2 916,2 MHz, 10,63 dBm
• Baseline (some measurements were missed first time and were repeated)
Friday 15 February 2013 - measurements at 85 m from WPR:
• Baseline
• Set up ALD2 in the same configuration as before, 0 dBi antenna at 1,5 m above ground level
• ALD2 918,0 MHz, 11,17 dBm
• ALD2 918,0 MHz, -0,50 dBm
• Set up R&S SMIQ to transmit a standard GSM GMSK waveform, nominal 200 kHz bandwidth:
- Note that this transmission used 100 % duty cycle and a relatively low power level due to limitations of
the test equipment. In practice a single mobile device would typically transmit at 1/8 duty cycle (in
speech) or less during signalling, but in many locations can be expected to use significantly higher power
(up to 2W for typical mobile devices)
- 0 dBi antenna at 1,5 m above ground level
• GSM 914,8 MHz 14,33 dBm
• GSM 914,8 MHz -0,41 dBm
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14 ETSI TR 103 151 V1.1.1 (2013-09)
• Set up R&S SMIQ to transmit a standard WCDMA QPSK waveform, nominal 5 MHz bandwidth:
- Note that this transmission used 100 % duty cycle, representative of a phone with a connected channel.
The relatively low power level was due to limitations of the test equipment. Mobile devices in this band
are understood to be able to transmit at up to +24 dBm, though power control in the system means that
this will usually occur only in the outer parts of a cell
- 0 dBi antenna at 1,5 m above ground level
• WCDMA 912,6 MHz, 13,49 dBm
• WCDMA 912,6 MHz, -0,20 dBm
• Baseline
• Modulated RFID was set up at 916,25 MHz with attenuators
• RFID 916,25 MHz, 1,56 dBm into 7 dBi antenna at 0,8 m above ground level (table mounted)
• RFID 916,25 MHz, -4,33 dBm into 7 dBi antenna at 0,8 m above ground level
• RFID 916,25 MHz, 8,34 dBm into 7 dBi antenna at 0,8 m above ground level
• Baseline
Friday 15 February 2013 - measurements with the radio devices indoors in the conference room on the site:
• Baseline
• Set up ALD1 in the same configuration as before, 0 dBi antenna, 0,8 m above ground level (table mounted)
• ALD1 915,2 MHz, 13,11 dBm
• ALD1 915,2 MHz, -0,59 dBm
• RFID 916,2 MHz nominal +29 dBm into 7 dBi antenna (actual power level was not calibrated)
• Baseline
5.3 Tests with GSM and UMTS
It should be noted that the WPR has a centre frequency of 915 MHz. The manufacturer claims that the transmitter has a
bandwidth of 2,5 MHz. However, from these tests, the receiver appeared to have a bandwidth of greater than 2,5 MHz
in the low mode. The exact bandwidth has not been determined but may be in the order of double that of the transmitter.
This brings the receiver bandwidth into the MFCN band which may at some point be used for LTE.
Annex B shows the masks produced by the signal generator (R&S ZVL).
6 Analysis of Results
During a wash-up session at the end of the tests, both met office personal made it clear that they had as yet been unable
to analyse the data to determine whether harmful inference was present. All of the data would be subject to post-
analysis at Exeter, including retrieval of data archive files.
The results of the tests for RFID at the perimeter of the site for transmit levels of 10 dBm and above showed that
interference was detectable when the WPR was operating in its low mode. RFID operation produced effects at 10 m and
85 m from the WPR, as well as indoors at approximately 25 m (see figure 5). However there was no immediately
obvious interference present even at transmit levels of 36 dBm when the WPR was operating in the high mode, though
subsequent analysis did indicate changes to the signal-to-noise ratios. A possible explanation for this difference in
behaviour was that the bandwidth of the filters used by the receiver of the WPR were wider in the low mode.
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15 ETSI TR 103 151 V1.1.1 (2013-09)
In many applications an RFID interrogator will transmit for up to 2 s while it reads a collection of tags. Subsequently
interrogations will be repeated at intervals of about 10 s, depending on the nature of the application. The experts at
Exeter confirmed that even intermittent transmission can have a harmful effect on the data. Additional information on
the typical levels of transmissions from RFID systems from common applications is given in annex C.
Assessment of the tests with the ALD emulator, by contrast, showed a range of results with a level of disruption to the
WPR, but without the distinction between low and high modes in this instance.
Although the power from the emulated G3 and UMTS transmissions was restricted to just 10 mW, they still caused
significant levels of interference to the WPR when operated in both its high and low modes. This indicated that the
WPR would be vulnerable to interference from mobile phones, which are likely to be in general use around Camborne
or at the adjacent school.
The likelihood of interference is largely dependent on the proximity of RFID or ALD operating above 915 MHz or from
the primary UMTS operating below 915 MHz. RFID are typically operated within buildings, with their greatest density
of use in commercial distribution facilities. ALD are used typically indoors at educational and public facilities such as
museums and airports. The likelihood of a facility operating either RFID or ALD in close proximity to the WPR site
would need to be considered before setting appropriate parameters for the authorization of RFID or ALD.
6.1 Met Office Test Result and Interference Level Criteria
Full results for all devices tested is provided in annex D. This includes results of testing focussed on interference to
radial (average) velocity measurements. Below is the Met Office's criteria for interference to the WPR system.
Table 1: Criteria for interference to WPR system
Interference Level
Criterion Severe Moderate Slight
Visually Effects Plots Obvious Noticeable Detectable
False Velocity Data Points Consistently Mostly Some
Increased Noise Level ≥ 5 dB ≥ 2 dB ≥ 1 dB
Necessary Conditions 1 out of 3 1 out of 3 1 out of 3

An annotated dwell display example of observed radial velocity interference to the WPR from RFID is given below.
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16 ETSI TR 103 151 V1.1.1 (2013-09)
Case 1a - Windprofiler Low Height Mode – RFID Outdoors at 85 metres
Noise
Level
plot
SNR
plot
Genuine
Targets
Baseline Data with RFID TX OFF
Noise
level
greatly
increase
Genuine
target
SNR
Height greatly
correlated
worsened
Velocity data
‘noise’ present,
‘Genuine’
targets buried
by ‘noise’.
Data with RFID TX ON
RFID Test Conditions Location: Outdoors ~85 metres from Wind Profiler Radar
Frequency: 916.25 MHz Power Level: 8.34 dBm into 7 dBi antenna
Modulation: ON Antenna: 0.8m above ground level
Impact - Severe
Radial Velocity: Height correlated Velocity data ‘noise’ present, ‘Genuine’ targets buried by ‘noise’.
SNR (blue): Genuine target SNR greatly worsened. Noise (red): Noise level greatly increase.

Figure 6: Display of WPR for RFID at 85 m with power set to 36 dBm
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17 ETSI TR 103 151 V1.1.1 (2013-09)
The RFID interference indicated in figure 6 was also reflected in the broader WPR spectral plots for the same time.

NOTE: See note for explanation of ringed identified interference.

Figure 7: Annotated WPR spectral plots for 14/2/2013
See annex D for further annotated dwell display interference plots and a full directory of results for all devices tested.
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6.2 Possible Mitigation for the WPR
In common with many other radar systems the original design did not envisage transmissions within its receiver
bandwidth and therefore the receiver skirts are quite wide. Unfortunately the use of MFCN has introduced a potential
major interference issue for WPR centred at 915 MHz from both base station and mobile equipment. The following
mitigation techniques are valid for this situation and SRD use:
• Consider if the skirts of the filters in the receiver circuit of the WPR could be tightened.
• Consider a band pass or band stop filter.
• Consider how the immunity of the antenna system/enclosure could be improved, possible ways forward are:
reflective/absorbent paint could be applied to the fibreglass container or a wiremesh fence around the
container.
• Consider how an exclusion zone for SRD use may be applied around the WPR - sufficient distances would
need to be calculated based on appropriate additional testing at varying distances.
7 Conclusions
Following the analysis of the results of the tests, the following conclusions may be drawn:
The tests showed that RFID systems operated (in free space pointing at the WPR) at the perimeter of the site at
Camborne may generate interference to the WPR. However taking into account the analysis in annex C, the level of
interference will be similar to that produced by an SRD operating at 20 dBm e.r.p. inside a building that will further
absorb signals
The tests showed that ALD systems also operating in free space, operated at the perimeter of the site at Camborne may
generate interference to the WPR, but to a lesser extent than for 4W ERP RFID devices.
Noise into the WPR receiver bandwidth is additive. Therefore any interference received from RFID or ALD operating
above 915 MHz will add to any signal received from the primary service of UMTS operating below 915 MHz. The
impact of this additional noise needs to be considered against the noise generated by any local UMTS transmissions.
The Interference Level Criteria in clause 6.1 of > 1 - 2 dB suggest that any noise floor increase however generated (a GSM
phone used adjacent to the perimeter fence or even sun spot activity increasing propagation) may have influenced the
output of the WPR in the past and will do so in the future. This is coupled with a lack of pre processing clarity of
interference on the local screen.
Any future roll-out of 4G (LTE modulation) in the band below 915 MHz may change the risk of interference from this
primary service.
In practice, given the location of the sites, the probability of interference from RFID and ALDs into WPR will be
extremely low.
ALD
ALD equipment is designed to assist the hearing of persons primarily inside buildings and any interference, if noted,
would be significantly reduced by the absorption from the building and the additional distance. The closest use would
be at the adjacent school which at least doubles the test distance and the school could use spectrum above the WPR
frequency.
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Annex A:
Details of Wind Profiler Radar
A.1 Operational description
Used to continually assess wind conditions at a site from some 120 m to 8 km above ground level, the system has four
steerable aerials operating in a set sequence. The acquired data is fed back to the Met Office HQ in Exeter and is used
for a variety of purposes including ingestion into Numerical Weather Prediction (NWP) models on a 15 minute cycle. A
local screen shot below provides information on a "good" i.e. non interfered with plot.

Figure A.1: Example of a non-interfered plot
Atmospheric parameters derived by wind profiler (based on moments profiles and profiles of full spectra) include:
th
• Reflectivity - the 0 moments profile is indicative for the gradients in atmospheric temperature and humidity.
Applying a forward operator on profiles of these atmospheric parameters from forecast model outputs allows
verification of the model output and assimilate data for improving the forecast accuracy. In extreme cases,
early warning for quickly developing severe weather can be significantly improved.
st
• Average Velocity - the 1 moment profile is utilized in deriving the wind profiles (wind speed and direction).
In addition it can be used for deriving profiles of the vertical wind velocity, e.g. for assessing severe
convection. It also can be indicative for the presence of precipitation.
nd
• Spectral width - the 2 moment profile enables assessment of atmospheric turbulence. It also can be indicative
for the presence of precipitation.
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• Profiles of full spectra enable assessment of many atmospheric information, e.g.:
- Drop size distribution, allowing to derive Rain Rate and Precipitation Liquid Water content.
- Precipitation type.
- Freezing / melting level height.
- Discrimination between clear air contribution and contribution from hydrometeors to the spectrum,
allowing to better interpret the moments profiles.
A.2 Specifications for Wind Profiler Radar LAP-3000
Operating frequency Typically 915 or 1 290 MHz
Minimum height 1 120 m
Maximum height 2 up to 3 km
Range resolution (typical) 60, 100, 200, 400 m
Factory configurable 45 - 500 m
Wind speed accuracy 3 < 1 m/s
Wind direction accuracy < 10°
Wind averaging time 33 - 60 minutes
RF power output ≥ 600 W peak
0,1 - 100 W average
Occupied bandwidth @1 290 MHz Less than 12,5 MHz @ 400 ns pulse (99 % ITU)
Antenna
Type Electrically steerable micropatch
Phased-array panels
Gain ~26 dBi
~29 dBi with the extended antenna aperture
RF beam width ~9°
~6° with the extended antenna aperture
2 2
Aperture 2,7 m @ 1 290 MHz, 3,0 m @ 915 MHz
6,0 m2 @ 1 290 MHz, 6,2 m2 @ 915 MHz
(extended antenna aperture)
Power requirements 115 VAC/60 Hz; 15 A
230 VAC/50 Hz; 10 A
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Figure A.2a
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Figure A.2b: Plot of WPR waveform
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Annex B:
Spectrum masks
B.1 ALDs
Spectrum plots were taken with an R&S FSV spectrum analyser once equipment was returned to the lab, using the same
settings that were used at Camborne.

Figure B.1: Spectrum of ALD1 at 915,2 MHz, +10 dBm nominal peak output power,
50 % duty cycle; 3 MHz span
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Figure B.2: Spectrum of ALD2 at 915,6 MHz, +10 dBm nominal peak output power,
100 % duty cycle, 1 MHz span
Figure B.3: Spectrum of ALD2 at 915,6 MHz, +10 dBm nominal peak output power,
100 % duty cycle, 10 MHz span
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B.2 RFID
Figure B.4: Spectrum plot of RFID and WPR in high mode
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Figure B.5: Spectrum plot of RFID and WPR in low mode
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B.3 GSM and UMTS
Figure B.6: GSM GMSK 914,8 MHz, +14 dBm nominal peak output power,
100 % duty cycle 1 MHz span
Figure B.7: GSM GMSK 914,8 MHz, +14 dBm nominal peak output power,
100 % duty cycle, 3 MHz span
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Figure B.8: 3G WCDMA QPSK 912,6 MHz, +14 dBm nominal peak output power,
100 % duty cycle: 10 MHz span
Figure B.9: 3G WCDMA QPSK 912,6 MHz, +14 dBm nominal peak output power,
100 % duty cycle, 20 MHz span
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Annex C:
Typical emissions from RFID systems
This annex provides information on the typical field leve
...