Transcript WMO Radio Spectrum WorkshopMeteorological Radar Spectrum Issues Presented By: David Franc Office of Radio Frequency Management March 2006

WMO Radio Spectrum WorkshopMeteorological Radar Spectrum
Issues
Presented By:
David Franc
Office of Radio Frequency Management
March 2006
Purpose

Provide background information
on, and current status of radio
frequency issues that may impact
global meteorological radar
operations, and identify items for
consideration by Members
 This section of the workshop
covers radars used for monitoring
the atmosphere with the exception
of Wind Profiler Radars
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Outline
Meteorological radar bands
 ITU-R Recommendations
 Spectrum issues

– WRC-2007 Agenda Item 1.3
– WRC-2007 Agenda Item 1.4
– JRG-1A/1C/8B
– Work of Working Party 8B (WP 8B)

Important points
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Meteorological Radar Bands
Meteorological Radar Bands

Three allocations exist in the Radio
Regulations specifically identified for
meteorological radars
– 2700-2900 MHz- ground based radars
– 5600-5650 MHz- ground based radars
– 9300-9500 MHz- ground based and airborne
radars

Depending on type of use, radionavigation
and radiolocation bands can also be used
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Need for 3 Frequency Bands?

System cost, complexity and operating range
are all limitations that can be addressed
through additional engineering and funding
 Severe weather performance is a physical
limitation that can not be addressed through
additional engineering or funding
 Severe weather performance is dependent
upon frequency of operation
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Severe Weather Performance
Limitation

The ability of a meteorological radar to measure high
wind speeds at its outer operational range is limited
by the frequency of operation
Maximum range
Maximum velocity
Frequency
v * r  1/f
Therefore, as frequency increases, the maximum
range or maximum observable velocity, or both
must decrease
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Performance Comparison of Bands
System Cost:
System Complexity:
Operating Range:
Severe Weather
Performance:
Highest- 2700-2900 MHz
Lowest- 9300-9500 MHz
Highest- 2700-2900 MHz
Lowest- 9300-9500 MHz
~450 km- 2700-2900 MHz
~200 km- 5600-5650 MHz
<75 km- 9300-9500 MHz
Highest- 2700-2900 MHz
Lowest- 9300-9500 MHz
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ITU-R Meteorological Radar
Recommendations
Technical and Operational
Characteristics

The following Recommendations provide
technical and operational characteristics of
meteorological radars
–
–
–
–

ITU-R M.1464: 2700-2900 MHz
ITU-R M.1460: 2900-3100 MHz
ITU-R M.1638: 5250-5850 MHz
ITU-R M.[8B.8-10GHZ]: 8-10 GHz*
Use: Information for conducting sharing
studies
*- Still under development within WP 8B
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ITU-R M.1461
Content: General procedures for
conducting sharing studies with radars
 Use: Guidance to conduct sharing
studies
 M.1461 is very generic and does not
address the specific needs of
meteorological radars

– Companion recommendation on meteorological
radars under development within WP 8B
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Wind Profiler Technical and
Operational Characteristics

The following provide technical and
operational characteristics of Wind Profiler
Radars
– ITU-R M.1226: Around 50 MHz
– ITU-R M.1085: Around 400 MHz
– ITU-R M.1227: Around 1000 MHz

Use: Information for conducting sharing
studies
 In need of review and update
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Current Spectrum Issues
Current Spectrum Issues
WRC Agenda Item 1.3
 WRC Agenda Item 1.4
 JRG-1A/1C/8B: Radar emission masks
 Working Party 8B

– Compatibility analysis procedures
– Protection criteria
– Statistics-based compatibility analysis
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WRC-Agenda Item 1.3

Objective:
– Upgrade radiolocation service (radars) to primary
status in 9300- 9500 MHz
– Earth exploration satellite service (EESS)
allocation extension into 9300-9500 MHz

Impact:
– Radiolocation upgrade raises the status of
meteorological radars to primary status
– Extension of EESS in 9300-9500 MHz could
impact meteorological radars
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Agenda Item 1.3 (continued)

Status:
– Studies underway to evaluate impact of EESS to
meteorological radars in 9300-9500 MHz
– EESS extension could be placed in 9800-10000
MHz- not preferred approach

Advantages:
– EESS could have meteorological applications
– Radiolocation upgrade important for
meteorological radar operations
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Agenda Item 1.4

Objective:
– Consider frequency related issues associated with
IMT-2000 and IMT Advanced
• IMT-2000: Third generation (3G) mobile
telecommunications
• IMT Advanced: Fourth generation mobile
telecommunications

Impact:
– 2700-2900 MHz has been identified as a
candidate band for Agenda Item 1.4
– Use of band for IMT-2000 or IMT Advanced will
cause loss of spectrum for meteorological
operations
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Agenda Item 1.4 (continued)

Status:
– WRC-2000: studies on impact to existing users
(radars) were incomplete- created preliminary
WRC-2007 Agenda Item
– WRC-2003: studies showed IMT-2000 and
existing systems were incompatible - Agenda Item
deleted from WRC-2007 agenda
– Studies now being updated for re-submission to
ITU-R

Advantages:
– None to meteorological operations
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JRG-1A/1C/8B

Objective:
– Develop ITU-R Recommendation(s) on radar
emission masks
– Emission masks define the required roll-off from
the fundamental frequency

Impact:
– Could place design limitations on radar technology

Advantages:
– Limit adjacent channel and adjacent band
interference
– Increased spectrum efficiency
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JRG-1A/1C/8B
Emission Mask Example #1
Source: JRG-1A/1C/8B Doc. 52
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JRG-1A/1C/8B
Emission Mask Example #2
Source: JRG-1A/1C/8B Doc. 52
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JRG-1A/1C/8B
Work Plan

Define necessary 20 dB and 40 dB bandwidth
for various radar technologies
 Define roll-off beyond 40 dB bandwidth- 20
dB or 40 dB per decade
 Need emission data and characteristics for
example radars
– Ensure realistic limits are established
– Identify technology that needs different limits
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Work of Working Party 8B (WP 8B)
 Compatibility
analysis procedures
 Statistics-based compatibility
analysis
 Protection criteria
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Compatibility Analysis Procedures
Methods used for evaluating impact of
sharing spectrum between radars and
other services
 Meteorological radars are different than
other radars
 WP 8B developing a document specific
to Meteorological Radars

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Statistics-Based Compatibility
Analysis

WP 8B is studying ways to use statistical
analysis to improve the accuracy of sharing
studies
 May allow for use of more accurate
propagation models
 Could require radar operators to accept
interference for short periods of time
– Exceedance value greater than 0% associated with
Protection Criteria
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Radar Protection Criteria

Protection Criteria- the maximum interference
level threshold for protection of radar
 Protection criteria for meteorological radars
dependent on
– Base product accuracy
– Minimum usable signal-to-noise ratio
– Radar receiver noise level

Current meteorological radar protection
criteria not clearly defined in the ITU
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Important Points
Important Points

WRC-2007 Agenda Item 1.3
– Radiolocation upgrade benefits
meteorological radar operations
– EESS extension into 9300 - 9500 MHz
• May impact meteorological radars
• may also benefit meteorological operations

WRC-2007 Agenda Item 1.4
– The band 2700-2900 MHz inappropriate for
use by IMT-2000 and IMT Advanced
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Important Points (continued)

JRG-1A/1C/8B
– Should be followed to ensure emission
masks do not overly restrict radar design

Other Work of WP 8B
– Follow discussions on compatibility
analysis procedures, including use of
statistics to ensure meteorological radars
will be protected
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Important Points (continued)

Work with your National Spectrum
Regulators
– Raise their awareness of spectrum needs for
meteorological radar operations


Participate in the meetings of the ITU if
resources allow
Ensure your radar system characteristics
and requirements are documented in
ITU-R recommendations
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