RCG-46

Reference: 8B/551 and 8B/TEMP/206

**World Meteorological Organization (WMO)**

**Input Document to Working Party 8B Radar Correspondence Group (RCG)
Meeting**

**Mainz, Germany -- November 16-17, 2007**

**Proposed Response to Liaison Statement from Working Party 8F (8B/551),
Passed to the**

**RCG by the September 2006 Meeting of Working Party 8B**

[Introduction]{.underline}.

The World Meteorological Organization (WMO) proposes the following text
be used to respond to the Liaison Statement contained in document
8B/551. This proposed text addresses the technical characteristics and
issues associated with wind profiler radars operated in the range
440-450 MHz and 470-480 MHz.

**Liaison Statement to Working Party 8F**

**Frequency-related matters for IMT-2000 and IMT-Advanced**

**Related to WRC-07 Agenda Item 1.4 - Consideration of the Band 450-470
MHz**

Working Party 8B received the Liaison Statement 8B/551 (8F/TEMP/435R1)
but was unable to adequately respond to the Working Party 8F requests
due to lack of information within Working Party 8B at its September 2006
meeting. Working Party 8B passed the responsibility for generating a
response to the Working Party 8B Radar Correspondence Group (RCG). The
Radar Correspondence Group held an extraordinary meeting to address the
issues and provided the Chairman of Working Party 8B this response.

Document 8B/551 requests additional information on technical and
operational characteristics on radars operating in and adjacent to the
450-470 MHz band. Wind profiler radars are operated in 440-450 MHz and
470-494 MHz various parts of the world. Work is ongoing within Working
Party 8B to update existing recommendations on wind profiler radars. In
the mean-time, this document attempts to provide the information needed
and provides comments on the potential problems with the study currently
underway.

[WPR Protection Criteria]{.underline}: An established protection
criteria level for wind profiler radars has never been developed within
Working Party 8B. As with other radars, the protection criteria should
be established as an interference level relative to the radar noise
floor, known as an interference-to-noise ratio (I/N). Review of
available literature on WPR spectrum issues indicates a report developed
by the National Telecommunications and Information Administration (NTIA)
and National Oceanic and Atmospheric Administration (NOAA) contains
tentative information on WPR protection criteria[^1]. The report
indicates an I/N level of -6 dB will cause an approximate 0.5 to 1 km
reduction in radar's measurement height. The report continues by stating
that a 0.5 to 1 km detection range reduction may not be acceptable to
WPR operators and data users. The relationship between I/N level and
detection range reduction is based on operational data indicating that
an ***X*** dB increase in system noise results in a ***X***/2 to ***X***
km reduction in measurement height. An I/N of -6 dB results in a 1 dB
increase in the receiver noise floor relative to no interference
present.

Since the publication of NOAA/NTIA report in 1993, when wind profiler
radars were in their infancy, operations and the use of the resulting
data are now much better understood. For a wind profiler radar operating
in the 400 MHz range, a 0.5 to 1 km reduction in height is equivalent to
a performance reduction of approximately 6 %. Since wind profilers are
operated at frequencies in the 400 MHz range to obtain data at high
altitudes, a detection height reduction of no more than 0.5 km is
acceptable. A maximum range reduction of 0.5 km requires the radar
receiver noise floor be raised by no more than 0.5 dB due to the
presence of interference. A 0.5 dB increase in the noise floor leads to
an I/N protection criterion of -10 dB. It is worth noting that this
level is also consistent with other work performed in Working Party 8B
on Doppler weather radars.

[Antenna Pattern]{.underline}: Wind profiler radar antenna main beams
are directed in the vertical or near vertical direction so that the
atmospheric winds can be measured. A minimum of three beams are formed
with the antenna, where the antenna electronically steps through each
beam orientation. As many as five beams may be used for some radars. The
angle between the vertical beam and the oblique beams is typically on
the order of 15 degrees. Refer to the figure below taken from the
NTIA/NOAA report.

![](media/image1.png){width="2.7319444444444443in"
height="4.3180555555555555in"}

Artist Conception of Wind Profiler Antenna Beams

Since the intention is to radiate energy in the vertical and
near-vertical direction and receive reflected returns from the
atmosphere directly overhead, every reasonable effort is made to reduce
the side lobe levels of the wind profiler radar antenna, in particular
in the horizontal direction. The NTIA/DOC report indicates that wind
profiler radars operating in the frequency range of interest have side
lobe levels on the order of -40 dB relative to main beam gain for the
range of 0 to 5 degrees above the horizon. For greater than 5 degrees
but less than 45 degrees above the horizon the side lobe levels drop to
approximately -25 dB below the main beam gain. The main beam gain is on
the order of 32 dBi. Though these characteristics are for a particular
wind profiler radar design, they can be assumed to be generally
applicable to all wind profiler radars operating in the frequency range
of interest.

[Detailed Review of Attachment to Document 8B/551]{.underline}.

Document 8B/551 contains an attachment which contains an initial study
addressing adjacent band interactions between wind profiler radars and
IMT-2000. Review by wind profiler radar experts raises the following
concerns, comments and suggestions:

Section 3.1- Working Party 8F should recognize Resolution 217 and the
WRC-97 decision on wind profiler bands in this document.

Section 3.2.5- The term should be wind profile[r]{.underline} radar
rather than wind profile radar. In addition, Working Party 8B is
developing a new recommendation which consolidates all the information
on wind profiler radars that is currently contained in various ITU-R
Recommendations. The TEMP document is attached. While this document
contains little more information at this time than the existing
recommendations, Working Party 8F may wish to follow the development of
this new recommendation.

Table 3.2.5-1- The table shows the protection criteria to be 10 dB. This
is an incorrect value. Furthermore, it is unclear whether the 10 dB is
referenced to the radar noise power or some other parameter. The
protection criteria for wind profiler radars should be an interference
level specified relative to the radar receiver noise floor. The
reference point for the interference level is at the input to the
receiver. As discussed above, an I/N = -10 is applicable to wind
profiler radars in this band.

Section 3.6.1- The Working Party 8F assumption that the center frequency
of the highest radar signal will fall on 450 MHz is most likely not a
reasonable assumption. In the case of wind profiler radars, a safe
assumption is that the highest center frequency will be 449MHz. In the
band 470-494 MHz, it is likely that wind profiler radar center
frequencies will also be no closer than 1 MHz from the band edge.

The United States National Telecommunications and Information
Administration (NTIA) developed a generally acceptable emission mask
(Radar Spectrum Engineering Criteria - Criteria E, or RSEC-E) for wind
profiler radars, and has been previously used in ITU-R documentation.
This mask should be used to determine the level of wind profiler
emissions falling above 450 MHz, or below 470 MHz, whichever is
applicable. The details of RSEC-E can be found at:
http://www.ntia.doc.gov/osmhome/redbook/5.pdf. Likewise, the IF filter
performance of the wind profiler radar receiver should not be expected
to be significantly different than the emission mask.

It is not clear how interaction between IMT and wind profilers operating
adjacent to each other in separate bands is calculated. It is necessary
to determine the power from the adjacent system falling within the
victim receiver passband. In other studies sent to Working Party 8B from
Working Party 8F, adjacent channel leakage ratio (ACLR) was suggested,
though it is unclear whether use of ACLR was proposed in this case. It
is our understanding that ACLR is for adjacent channel interactions
between systems operating within a single radio service, with similar
channel bandwidth and emission characteristics. This is not the case for
interactions between wind profiler radars and IMT-2000/IMT Advanced. The
basic frequency dependent rejection (FDR) formulas should be used for
calculating adjacent system power falling within the passband of a
victim receiver. Recommendation ITU-R SM.337 contains details of FDR
calculations.

Section 3.6.2- Arbitrary application of filters to radars, wind profiler
radar or otherwise, is not an acceptable approach to prove
compatibility. Many radars operating at this time are planned for
continued use for many more years (15 to 30 years into the future).
Retrofitting a radar with stringent filters that were not planned or
anticipated in the original RF and processor design just is not
achievable. When considering application of stringent requirements on
new radar systems, one must recognize the relationship between pulse
characteristics and the resulting emission spectra. This relationship is
defined by laws of physics and arbitrary filter roll-off levels cannot
be assumed. Furthermore, the pulse characteristics are a critical part
of radar design in order to achieve the required range, data resolution
and accuracy, and target detection performance. Arbitrary application of
filtering can modify the transmit and/or receive pulse characteristics
rendering a costly and complex radar useless.

Section 3.6.3- This conclusion comes back to application filters on
radars. Refer to the previous comment. Working Party 8F may choose to
apply mitigation techniques to the systems for which it is responsible.
However, Working Party 8F should not be attempting to place limitations
on another radio service, in particular when those limitations can
render systems useless.

Section 3.7.1- See the comment on radar center frequency under section
3.6.1.

Sections 3.7.2 and 3.7.3- The previous comments on application of
filtering to the radars apply here as well.

Section 3.8.1- RSEC-E should be used, not the data contained in NTIA
Report 93-301, NOAA Special Report, "Measurement of Wind Profiler EMC
Characteristics". The requirements of RSEC are more representative of
wind profiler radars in general. The requirements of RSEC-E have been
reflected in previous ITU-R documentation.

Section 3.8.2- Use of filtering for the spurious region is more
realistic than filtering near the fundamental emission. However
retrofitting existing radars with filters is problematic, as previously
discussed. Many radars may be in operation for an additional 15 to 30
years. Working Party 8F should concentrate on feasible mitigation
techniques to be applied to IMT-2000.

Section 3.8.3- It is unclear what is meant by "sharing" in this section
and throughout the document. This document appears to address IMT-2000
and IMT-Advanced operating above 450 MHz, and radars operating in the
band below 450 MHz. This is not typically viewed as sharing. The goal
should be to determine the frequency/distance separation that IMT must
stay from the 450 MHz band edge in order to avoid impact. The
determination on the feasibility of use of 450-470 MHz by IMT is whether
IMT operators can accept the distance/frequency separation requirements.

Section 3.9.1- It is not within the purview of Working Party 8F to
dictate to radar operators that they need to implement mitigation
techniques. Working Party 8F may ask Working party 8B to provide
information on feasible mitigation techniques that may be applied to the
radars. However, at this point in time, no techniques are known that
will not degrade radar performance to unacceptable levels due the impact
on the transmitted and received pulse characteristics.

Section 3.9.2- The previous comments on application of filtering apply
to this section as well.

In general, including example calculations of how the separation
distances and frequency separations were obtained would be very helpful
in evaluating the accuracy of the results. It is somewhat difficult to
follow the steps taken to arrive at the numbers presented in the tables.

Finally, the WMO would like to point out the importance of wind profiler
radars. While it is true that some wind profiler radars are used for
atmospheric research, many are used for applications on which the safety
of the public is dependent. One excellent example is the growing
deployment of wind profiler radars around airports to detect wind shear
conditions. Wind shear can have catastrophic effects on aircraft during
take-off or during final approach during landing. Wind profiler radars
have been instrumental in improving air travel safety. May other
applications exist that benefit the public worldwide.

ATTACHMENT 1-

Working Party 8B TEMP/204

Source: Document
8B/478![](media/image2.wmf){width="0.9166666666666666in"
height="0.9993055555555556in"}

Working Party 8B

Working Document Towards a Preliminary Draft New Recommendation (PDNR)
-- Technical and Operational Characteristics of Wind Profiler Radars
Operated in Bands in the Vicinity of 50 MHz, 400 MHz,\
1 000 MHz and 1 300 MHz

Introduction

This document updates the information on wind profiler radars contained
in Recommendations ITU-R M.1085, ITU-R M.1226, ITU-R M.1227, and ITU-R
M.1463 and merges the information into a single Recommendation on wind
profiler radars. Much of the information in the four[^2] existing
Recommendations is redundant, and maintaining four Recommendations on a
single technology is problematic. Merging the wind profiler radar
information contained in the recommendations into a single new
Recommendation will eliminate redundant text, simplify Recommendation
maintenance, and reduce the potential for conflicting text in different
Recommendations. Recommendations ITU-R M.1085, ITU-R M.226 and ITU-R
M.1227 will be recommended for suppression once work on this new
Recommendation is complete. Recommendation ITU-R M.1463 will be revised
to remove the wind profiler radar section. In addition to merging the
information contained in the four Recommendations, new information has
been added.

RECOMMENDATION ITU-R M.\[WPR\]

Technical and operational characteristics of wind profiler radars for
bands\
in the vicinity of 50 MHz, 400 MHz, 1 000 MHz and 1 300 MHz[^3]

\[(2007)\]

Rec. ITU-R M.1085-1

Summary

This Recommendation provides technical and operational characteristics
of operational wind profiler radars in the bands near 50 MHz, 400 MHz, 1
000 MHz and 1 300 MHz. The Recommendation includes representative power
to the antenna line, necessary bandwidth, occupied bandwidth,
representative antenna sidelobe suppression and guidance for wind
profiler radar sharing considerations.

The ITU Radiocommunication Assembly,

considering

a\) Recommendation No. 621 of the World Administrative
Radiocommunication Conference for dealing with Frequency Allocations in
Certain Parts of the Spectrum (Malaga-Torremolinos, 1992);

b\) that wind profiler radars (WPRs) are important meteorological
systems used to measure wind direction and speed as a function of
altitude;

c\) that many administrations have deployed or plan to deploy WPR
operational networks in order to improve meteorological predictions and
warnings, and support studies of the climate and increase the safety of
navigation;

d\) the need for frequency bands in the vicinity of 50, 400, and 1 000
MHz to permit the full performance capability of WPR operations, as
requested by the World Meteorological Organization (WMO);

e\) that WPRs may have to share spectrum with other systems both current
and future;

f\) that it would be desirable to have a limited number of frequency
ranges authorized worldwide in order to minimize research and
development investment in the design of components;

g\) that technical standards would enhance compatibility with other
systems within the same band by minimizing the adverse impact of
spurious and out-of-band emissions;

h\) that the effect of antenna side lobes may be further reduced by the
selection of wind profiler locations to take advantage of terrain and
other siting factors and additional enhancements (e.g. fences, berms)
and antenna orientation may improve compatibility,

recommends

**1** that the minimum performance standards in Annex 1 be adopted by
administrations desiring to construct or operate wind profiler radars;

**2** that the transmitter power should be limited to that necessary to
obtain data at the maximum altitude for which the profiler was designed;

**3** that the occupied bandwidth (see Note 1) should be as close to the
necessary bandwidth (see Note 2) as is technically and economically
feasible to provide the required range resolution, noting that reduced
values of resolution are generally acceptable at higher altitudes.
(values are given in Annex 1);

NOTE 1 -- Occupied bandwidth: the width of a frequency band such that,
below the lower and above the upper frequency limits, the mean powers
emitted are each equal to 0.5% of the total mean power of the given
emission.

NOTE 2 -- Necessary bandwidth: for a given class of emission, the width
of the frequency band which is just sufficient to ensure the
transmission of information at the rate and with the quality required
under specific conditions.

**4** that the unwanted emissions from wind profiler radars should be
reduced as much as technically and economically feasible. (values are
given in Annex 1);

**5** that the antenna radiation pattern should minimize the levels of
the side lobes, especially those at or near the horizon (side lobe gain
values as well as field strength values are given in Annex 1);

**6** that the selection of WPR locations should take advantage of
terrain and siting configuration to minimize the possibility of
interaction with other systems; additional enhancements (e.g. fences,
berms) and antenna orientation may improve compatibility;

**7** that time-sharing should not be considered as a technically
adequate means of protecting sensitive safety-of-life systems such as
the COSPAS-SARSAT;

**8** that frequency bands in the ranges provided in Annex 1 should be
chosen, where compatibility is possible, taking into account the
necessary protection.

Annex 1\
\
Representative values and minimum requirements on system performance\
for wind profiler radars operating

# 1 Introduction

The wind profiler radar is a vertically oriented, ground-based, pulsed
Doppler radar that utilizes scattering from irregularities in the radio
refractive index or precipitation to measure horizontal and vertical
components of wind velocity. Clear-air turbulence causes the fluctuation
of the refractive index in which the scale is half the radar wavelength
(Bragg scattering). The antenna main beam from a linearly polarized,
phased-array is sequentially steered in three or more directions,
through electronic means. Wind profiler radar systems provide hourly (or
more frequent) wind speed and direction values as a function of
altitude. The primary role for wind profilers is in weather observation
and forecasting; however, other applications have been identified,
including severe wind condition warnings, flight planning, space launch
support, and pollution studies. Atmospheric propagation characteristics
require that wind profiler systems operate in the 50 to 1 300 MHz range.

# 2 Frequency considerations

A single solution for a wind profiler frequency band is not possible due
to varying performance requirements, and the performance advantages
various frequency bands offer. Lower frequencies offer the advantage of
lower propagation loss allowing the radar to collect data to a higher
altitude. However the lower frequencies do not provide the resolution at
lower altitudes that some operators require. The higher frequencies
offer high resolution measurements in the lower atmosphere, but the
maximum measurement height is lower. For these reasons frequency
selection is based largely on required performance. To complicate
matters, the frequency ranges identified for wind profiler radar
operation are not consistent worldwide, and sharing with existing
services must be considered. Local spectrum regulatory limitations also
affect frequency band selection.

In a response to a request from the meteorological and scientific
community, WRC-97 identified frequency bands considered suitable for
wind profiler radar operations. The details of the Conference decision
are provided in Resolution 217 (WRC-97). In summary the following
frequency bands are identified:

-- 46-68 MHz (in accordance with No. **5.162A)**

-- 440-450 MHz

-- 470-494 MHz (in accordance with No. **5.291A)**

-- 904-928 MHz (in Region 2 only)

-- 1 270-1 295 MHz.

# 3 Representative characteristics for operational wind profiler radars

This section provides characteristics of wind profiler radars operated
in the various frequency bands identified by WRC-97.

## 3.1 Systems operated in the band 46-68 MHz 

TABLE 1

Systems operated in 46-68 MHz

+---------------------------------+------------------------------------+
| System parameter                | Range of representative values(1)  |
+---------------------------------+------------------------------------+
| Pulse peak power (kW)           | 5-60                               |
+---------------------------------+------------------------------------+
| Average transmitted power (kW)  | 0.5-5                              |
+---------------------------------+------------------------------------+
| Main beam antenna gain (dBi)    | 30-34                              |
+---------------------------------+------------------------------------+
| Beamwidth (degrees)             | 4-6                                |
+---------------------------------+------------------------------------+
| Tilt angle (degrees)            | 11-16                              |
+---------------------------------+------------------------------------+
| Antenna size (m^2^)             | 2 500-10 000                       |
+---------------------------------+------------------------------------+
| Height range(2) (km)            | 1-24                               |
+---------------------------------+------------------------------------+
| Height resolution (m)           | 150-1 500                          |
+---------------------------------+------------------------------------+
| Pulse width (μs)                | 1-10                               |
+---------------------------------+------------------------------------+
| \(1\) Users of this table       |                                    |
| should exercise caution in      |                                    |
| using combinations of these     |                                    |
| values to represent a "typical" |                                    |
| or "worst case" profiler. For   |                                    |
| example, a profiler operating   |                                    |
| with an average power of 5 kW   |                                    |
| while using pulses to yield a   |                                    |
| height resolution of 150 m      |                                    |
| would be an unusual system.     |                                    |
|                                 |                                    |
| \(2\) The maximum operating     |                                    |
| height depends upon the         |                                    |
| product: (average               |                                    |
| power) × (antenna effective     |                                    |
| area).                          |                                    |
+---------------------------------+------------------------------------+

## 3.2 Systems operated in the band 440-450 MHz and 470-494 MHz

TABLE 2

Systems operate din 440-450 MHz and 470-490 MHz

+----------------------------+-----------------------------------------+
| System parameter           | Range of representative values(1)       |
+----------------------------+-----------------------------------------+
| Pulse peak power (kW)      | 5-50                                    |
+----------------------------+-----------------------------------------+
| Average transmitted power  | 0.2-2.0                                 |
| (kW)                       |                                         |
+----------------------------+-----------------------------------------+
| Main beam antenna gain     | 26-34                                   |
| (dBi)                      |                                         |
+----------------------------+-----------------------------------------+
| Beamwidth (degrees)        | 3-8                                     |
+----------------------------+-----------------------------------------+
| Tilt angle (degrees)       | 12-18                                   |
+----------------------------+-----------------------------------------+
| Antenna size (m2)          | 30-150                                  |
+----------------------------+-----------------------------------------+
| Height range(2) (km)       | 0.5-16                                  |
+----------------------------+-----------------------------------------+
| Height resolution (m)      | 150-1 200                               |
+----------------------------+-----------------------------------------+
| Pulse width (μs)           | 1-8                                     |
+----------------------------+-----------------------------------------+
| \(1\) Users of this table  |                                         |
| should exercise caution in |                                         |
| using combinations of      |                                         |
| these values to represent  |                                         |
| a "typical" or "worst      |                                         |
| case" profiler. For        |                                         |
| example, a profiler        |                                         |
| operating with a peak      |                                         |
| power of 50 kW while using |                                         |
| pulses to yield a height   |                                         |
| resolution of 150 m would  |                                         |
| be an unusual system.      |                                         |
|                            |                                         |
| \(2\) The maximum          |                                         |
| operating height depends   |                                         |
| upon the product: (average |                                         |
| power) × (antenna          |                                         |
| effective area).           |                                         |
+----------------------------+-----------------------------------------+

##  3.3 Systems operated in the band 902-928 MHz

TABLE 3

Systems operated in 902-928 MHz

+-----------------------------------+----------------------------------+
| System parameter                  | Range of representative          |
|                                   | values^(1)^                      |
+-----------------------------------+----------------------------------+
| Pulse peak power (kW)             | 0.5-5                            |
+-----------------------------------+----------------------------------+
| Maximum transmitter average power | 50-500                           |
| (W)                               |                                  |
+-----------------------------------+----------------------------------+
| Duty cycle (%)                    | 0.5-10                           |
+-----------------------------------+----------------------------------+
| Pulse repetition frequency (kHz)  | 1-50                             |
+-----------------------------------+----------------------------------+
| Main beam antenna gain (dBi)      | 25-32                            |
+-----------------------------------+----------------------------------+
| Beamwidth (degrees)               | 4-12                             |
+-----------------------------------+----------------------------------+
| Tilt angle (degrees)              | 12-25                            |
+-----------------------------------+----------------------------------+
| Antenna size (m2)                 | 3-15                             |
+-----------------------------------+----------------------------------+
| Height range(2) (km)              | 0.05-3                           |
+-----------------------------------+----------------------------------+
| Height resolution (m)             | 50-500                           |
+-----------------------------------+----------------------------------+
| Pulse width (μs)                  | 0.3-3                            |
+-----------------------------------+----------------------------------+
| \(1\) Users of this table should  |                                  |
| exercise caution in using         |                                  |
| combinations of these values to   |                                  |
| represent a "typical" or "worst"  |                                  |
| case profiler. For example, a     |                                  |
| profiler operating with an        |                                  |
| average power of 500 W while      |                                  |
| using short pulses to yield a     |                                  |
| height resolution of 50 m would   |                                  |
| be an unusual system.             |                                  |
|                                   |                                  |
| \(2\) The maximum operating       |                                  |
| height for a given range          |                                  |
| resolution depends upon the       |                                  |
| product: (mean power) × (antenna  |                                  |
| gain).                            |                                  |
+-----------------------------------+----------------------------------+

## 3.4 Systems operated in the band 1 270-1 295 MHz

TABLE 4

Systems operated in 1 300-1 375 MHz

# 4 Transmitters

## 4.1 Transmitter output power

The peak effective isotropically radiated power (e.i.r.p.) should be
limited to levels necessary for meeting operational requirements. For
systems operating in 440-450 MHz and 470-494 MHz the peak transmitter
e.i.r.p. should not exceed 80 dBW.

## 4.2 Typical emission bandwidth

TABLE 5

+-----------------------+-----------------------+-----------------------+
| Pulse width\          | Necessary bandwidth\  | Occupied/necessary    |
| (μs)                  | (MHz)                 | bandwidth ratio       |
+-----------------------+-----------------------+-----------------------+
| 1-10                  | 2.2-0.2               | \< 2.5^(1)^           |
+-----------------------+-----------------------+-----------------------+
| 1-8                   | 2.2-0.3               | ≤ 2.5^(2)^            |
+-----------------------+-----------------------+-----------------------+
| 0.3-3                 | 0.7-7.3               | \> 2.5^(3)^           |
+-----------------------+-----------------------+-----------------------+
| ^(1)^ Values down to  |                       |                       |
| 1.5 MHz can be        |                       |                       |
| obtained at the       |                       |                       |
| expense of higher     |                       |                       |
| cost and somewhat     |                       |                       |
| inferior performance  |                       |                       |
| resulting from pulse  |                       |                       |
| shaping. The limit    |                       |                       |
| applies to the power  |                       |                       |
| and pulse width       |                       |                       |
| combination producing |                       |                       |
| the highest power     |                       |                       |
| density in the signal |                       |                       |
| sidebands.            |                       |                       |
|                       |                       |                       |
| ^(2)^ Values down to  |                       |                       |
| 1.2 can be obtained   |                       |                       |
| at the expense of     |                       |                       |
| higher cost and       |                       |                       |
| somewhat inferior     |                       |                       |
| performance resulting |                       |                       |
| from pulse shaping.   |                       |                       |
| The limit applies to  |                       |                       |
| the power and pulse   |                       |                       |
| width combination     |                       |                       |
| producing the highest |                       |                       |
| power density in the  |                       |                       |
| signal sidebands.     |                       |                       |
|                       |                       |                       |
| ^(3)^ Values down to  |                       |                       |
| 1.5 can be obtained   |                       |                       |
| at the expense of     |                       |                       |
| higher cost and       |                       |                       |
| somewhat inferior     |                       |                       |
| performance resulting |                       |                       |
| from pulse shaping.   |                       |                       |
| The limit applies to  |                       |                       |
| the power and pulse   |                       |                       |
| width combination     |                       |                       |
| producing the highest |                       |                       |
| power density in the  |                       |                       |
| signal sidebands.     |                       |                       |
+-----------------------+-----------------------+-----------------------+

## 4.3 Spurious emission levels

Spurious emission levels should be measured at the antenna input using
the bandwidth values given below:

IF bandwidth: = 1/*T* for fixed-frequency, non-phase-coded pulsed
radars, where *T *≡ pulse length. (E.g. if radar pulse length is 1 μs,
then the measurement IF bandwidth should be = 1/1 μs = 1 MHz)

= 1/*t* for fixed-frequency, phase-coded pulsed radars, where
*t* ≡ (phase-chip length). (E.g. if radar transmits 26 μs pulses,
each pulse consisting of 13 phase coded chips that are 2 μs in length,
then the measurement IF bandwidth should be  = 1/2 μs = 500 kHz)

Video bandwidth: ≥ Measurement system IF bandwidth

Suppression of spurious emissions: ≥ 60 dB.

## 4.4 Transmitter frequency tolerance

The transmitters in WPRs should maintain a frequency tolerance of ten
parts per million (ppm) or better. The frequency of WPR to be operated
in TV bands should either be synchronized with the nearest TV
transmitter in the same channel, or the frequency stability should be
0.1 × 10--6 or better.

# 5 Antenna characteristics

Wind profiler radar antennas are typically phased arrays mounted
horizontally above the ground. For the low frequency bands the antenna
footprint can be tens of meters in width and length. Since wind profiler
radars use a minimum of three antenna beams for operation, the
electrical phasing of the antenna elements is switch able to produce
different antenna main lobe positions.

## 5.1 Antenna side-lobe suppression

Table 6 provides the sidelobe levels for typical wind profiler radars.
Wind profiler radar manufacturers and operators should strive to
minimize sidelobe in order to promote compatibility with other radio
services.

TABLE 6

Antenna side-lobe suppression for specified angles above the horizon

  ----------------------- ------------------------- ----------------------
  Angle above the         Antenna side-lobe         
  horizon\                suppression\              
  (degrees)               (dB)                      

                          **Median**                **Minimum**

  0-5                     40                        33

  5-45                    25                        23

  \> 45                   20                        13
  ----------------------- ------------------------- ----------------------

## 5.2 Antenna beam swinging

The centre of the antenna main beam generated at any time should be
limited within a vertical cone of 40° included angle, i. e. of
half-angles that are 20° from the zenith.

# 6 Receiver characteristics

The --3 dB receiver bandwidth should be commensurate with the authorized
emission bandwidth plus twice the frequency tolerance of the transmitter
as specified in § 3.4. The --60 dB receiver bandwidth should be
commensurate with the \_60 dB emission bandwidth. Receivers should be
capable of switching bandwidth limits to appropriate values whenever the
transmitter bandwidth is switched (pulse shape changed). Receiver IF
image frequency rejection, when applicable, should be at least 50 dB.
Rejection of other spurious responses should be at least 60 dB. The
receivers of a wind profiler radar should not exhibit any local
oscillator radiation greater than --70 dBW at the antenna input
terminals. Frequency stability of receivers should be commensurate with,
or better than that of the associated transmitters.

NOTE 1 -- In general, the term "commensurate" is approximately
equivalent to the term "equal" and it is used several times in this
section. Furthermore, in the sentence "the --60 dB receiver bandwidth
shall be commensurate with the \_60 dB emission bandwidth", it is
intended for the receiver to be sufficiently broadband to pass all of
the desired signal, but not so wide as to render the receiver vulnerable
to adjacent channel interference.

# 7 Radio frequency compatibility considerations

## 7.1 Interference rejection and protection criteria

Wind profiler radars should have the capacity to tolerate incoherent
pulsed interference of duty cycle less than 1.5% such that peak
interfering signal levels 30 dB greater than the WPR receiver noise
level at the IF output will not degrade WPR performance.

\[further work is needed to define the protection criteria for wind
profiler radars\]

## 7.2 Sharing with other services

In preparation for WRC-97 and in planning wind profiler radar
deployments tests have been conducted and operational experience gained
that provides valuable information on sharing between wind profiler
radars and other radio services.

### 7.2.1 Field strength measurements around an operational WPR at 482 MHz

Tests were conducted in Europe prior to the selection of designated
frequency bands at WRC-97. These tests were intended to provide
information on sharing between wind profiler radars and the broadcast
service (television). The data provides useful information on sharing
between wind profilers and other terrestrial radio services.

Tables 7 and 8 provide the characteristics of the transmitting wind
profiler radar and the measurement system, respectively.

TABLE 7

System parameters of the WPR

Table 8

Measurement parameters

Figure 3 gives 50% location, 50% time values of field strength for six
different antenna directions (dB(μV/m)) measured in the horizontal plane
as a function of distance. Twelve median field-strength values
(indicated as 12 dashed lines in a vertical order at the test points MP
1 to MP 7) were calculated on the basis of the recorded measurement
data.

The trend of the decrease in the field strength was calculated on the
basis of the results obtained for the seven test points and is
illustrated in the figure as a continuous line. This curve shows
a measured decrease in the field strength of 42 dB per decade of
distance. The diagram therefore shows that this measured decrease in
field strength of 42 dB per decade corresponds to the decrease in field
strength of 40 dB per decade calculated in the case of the mobile
service using the Hata propagation model.

Figure 3 can be used in order to assess the radio compatibility between
a wind profiler assigned to the radiolocation service and a TV
broadcasting reception area by reading off the distance at which the
permissible WPR interfering field strength is adhered to.

#### 7.2.1.1 Example of TV service interfered by WPR

-- minimum TV field strength: 52 dB(μV/m) Report ITU-R BT.409
(Düsseldorf, 1990)

-- protection ratio (half-line offset): 39 dB

-- maximum wind profiler field strength at receiving point: 52 -- 39 =
13 dB(μV/m)

-- minimum distance to wind profiler radar (Fig. 3): 70 km

NOTE 1 -- This example deals only with the case of protection of TV for
50% of the time.![](media/image3.wmf){width="6.573611111111111in"
height="8.496527777777779in"}

FIGURE 3/M.1085-1\...\[D1085-03\] = 22 CM

### 7.2.2 Operational experience on sharing with spaceborne systems

\[TBD\]

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

[^1]: *Measurements of Wind profiler EMC Characteristics*, NTIA Report
    93-301, National Oceanic and Atmospheric Administration and National
    telecommunications and Information Administration. Available at:
    http://www.its.bldrdoc.gov/pub/pubs.php

[^2]: Recommendation ITU-R M.1463 contains information on other radar
    systems.

[^3]: ^\*^ This Recommendation should be brought to the attention of the
    World Meteorological Organization.