deployment considerations and hardware technologies for ... · deployment considerations and...
TRANSCRIPT
Robert Palumbo , Eric Knapp, Ken Wood, David McLaughlin
Deployment Considerations and Hardware Technologies for Realizing
X-Band Radar Networks
28 June 2012
Acknowledge
P. Keith Kelly
First RF Corporation, Boulder, CO, USA
Chris McCarroll
Raytheon Company, Andover, MA, USA
Apoorva Bajaj
UMass, Amherst, USA
NSF Engineering Research Centers Program
Outline
� CASA Overview– Why radar networks?
� Network Performance Considerations� Why Phased Arrays?� Latest Hardware Technology Development:
– CASA Phase-Tilt Weather Radar System
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Weather
hazards
gap
Collaborative Adaptive Sensing of the Atmosphere (C ASA)Engineering Research Center
DataNumerous
inexpensive,
closely-spaced
radarsMultipleend users
Tasking
Solution
Observe, understand, predict and respond to hazardo us weather events
Some theoretical numbers Assumes regular grid 230km (S), 150km (C), 30 km (X )
“Blanket Coverage” 15% Coverage*
Large Radar (S/C-
Bands)
Small Radar
(X-Band)
Small Radar
(X-Band)
4
*Critical infrastructure, population centers, borders, etc…
USA / CONUS 145 8,511 1,277
Europe / OPERA 217 5,416 812
France 28 712 107
UK 11 270 41
Belgium 2 42 6
Large numbers of small radars –must be inexpensive, easy to deploy
X-Band Weather Radar TechnologiesDeployed Over Past Decade
Performance
(Resolution, Doppler,
Dual-pol, Sensitivity,
Clutter rejection)
5
Clutter rejection)
Size, Weight, Cost, Complexity
Fan beam/ Magnetron
Pencil beam/Magnetron
Coherent, dual-pol pencil beam on 2 axis pedestal
Radar nodes must be a balance between Size/Weight/Cost and Performance
Performance Considerations for X-Band Radar Networks
� Need to establish a performance baseline for X-Band radar systems to be realized in a network:– These numbers are derived from the validated performance of the CASA IP1
radar network
AttributeTop-Level System
RequirementDerived Requirement
Low Profile 1m2 X-Band (9.3 – 9.5 GHz); < 200lb
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Low Profile 1m X-Band (9.3 – 9.5 GHz); < 200lb
Scan Volume100m to 10’s of km
altitude
Azimuth: 360°
Elevation: ~0° to 60°
Range ~ 30km
Radar Sensitivity < 10dBZ at 30km 100W (w/ Pulse Compression)
Spatial Resolution
< 1.3km at 30km 2° x 2° antenna beamwidths
Dual Polarization Bias in Zdr < 0.2dBAlternate T/R (ATAR): ICPR > 20dB
Simultaneous T/R (STSR): ICPR > 40dB
Phased Array Radars have the capability to meet these performance baselines
Why Dense Networks of Phased Arrays
1. Capability of Low Level Situational Awareness– “Mind the Gap”
2. Ease of Installation– Easily installed on the sides of buildings, existing infrastructure– Low weight / low power, no large pedestals requiring dedicated land
3. Low maintenance cost– No moving parts– No moving parts
4. Enhanced reliability– Solid state, active arrays over magnetron/klystron systems
5. Multi-Mode Operation– Can support multiple missions simultaneously
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Phased Array Radars as the Next Generation Technology
� CASA has successfully demonstrated the feasibility of a phase-tilt antenna as a low-cost technology for future weather radars– University of Massachusetts’ research prototype shown
below, parts cost ~$50K (US) per antenna– Demonstrated better than 20dB cross-pol over +/- 45°
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Phase-Tilt Weather Radar� CASA Phase-tilt antenna concept
developed as a commercialized product by First RF Corp., Colorado, USA
� Radar backend (software and transceiver) developed at UMass Amherst
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Performance SpecificationsParameter
Units
PTWR
Frequency Range GHz 9.3 – 9.5
Transmit Power (Peak) W 70
Pulse Length µS .6 - 60
Pulse Compression Gain dB Up to 20
Duty Cycle (max) 30%
Unambiguous range @ max PRF km 31Unambiguous Velocity @ single
Table 1: Phase-Tilt Weather Radar system parameters.
30
35
40Phase-Tilt Weather Radar - Integrated Cross Pol. Ratio
HV
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Unambiguous Velocity @ single PRF
m/s up to 38
Unambiguous Velocity @ Dual PRF
m/s 57 @ (2:3)
Sensitivity @ 30km (@Boresight) dBZ 16
Elevation Beamwidth deg 2.8
Azimuth Beamwidth deg 1.8 -2.4
Polarization Mode Alternating
Integrated Cross Pol Ratio (max) dB -20
Power Consumption600W (average)
-40 -30 -20 -10 0 10 20 30 4015
20
25
30
Azimuth (deg, rel. to boresight)IC
PR
(d
B)
Goal: ICPR > 20dB (Met)
Phase-Tilt Weather Radar meets key performance needs
Effect of Scan Loss on Radar Sensitivity� Scan loss in a phased array degrades radar sensitivity off boresight:
– At Boresight: 16dBZ at 30km– At +/- 45°: 19.5dBZ at 30km
� Sensitivity is enhanced through X-Band network sign al processing
19.5
20Phase-Tilt Weather Radar Minimum Detectable Signal vs. Scan Angle
15
20
X: 30.06
Phase-Tilt Weather Radar Minimum Detectable Reflectivity (@Boresight)
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-45 -35 -25 -15 -5 5 15 25 35 4515.5
16
16.5
17
17.5
18
18.5
19
19.5
Azimuth Pointing Angle (deg, rel. to boresight)
Ze,
min
(dB
Z)
0 5 10 15 20 25 30 35-20
-15
-10
-5
0
5
10
15X: 30.06Y: 15.85
Range (km)
Ze,
min
(dB
Z)
X: 15.61Y: 10.16
*Assuming 40usec, 3MHz LFM Chirp
Performance ComparisonEvent on May 30, 2012 – Amherst, MA
PTWR
23:26:23
23:26:16
UMass “MA1”
23:26:16
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23:26:23
23:22:47
NEXRAD
23:26:16*No attenuation correction
Performance Comparison (movie)Event on May 30, 2012 – Amherst, MA
1/16/2013 13No moving parts were used in the making of this video!
Conclusion
� X-Band Radar networks fulfill a critical need in many government and municipality weather applications– However, development of these networks will only happen if the initial and
recurring costs of the technology is low– Phase-Tilt technology represents a key step towards driving down the
recurring cost of such networks without sacrificing performance
� Have successfully demonstrated the realization of a commercial-grade phase-tilt radar system– Continuing to collect data and study effects of phased array technology on
weather products
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Questions?
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Backup
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Performance Specifications
ParameterUnit
sPTWR
Frequency Range GHz 9.3 – 9.5
Transmit Power (Peak) W 70
Pulse Length µS .6 - 60
Pulse Compression Gain dB Up to 20
Duty Cycle (max) 30%
Unambiguous range @ max PRF km 31
Low transmit power supports the feasibility of
switches capable of supporting Integrated Cross
Pol Ratio requirements
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Unambiguous Velocity @ single PRF
m/s up to 38
Unambiguous Velocity @ Dual PRF
m/s 57 @ (2:3)
Sensitivity @ 30km dBZ 16
Elevation Beamwidth deg 2.8
Azimuth Beamwidth deg 1.8 -2.4
Polarization Mode Alternating
Integrated Cross Pol Ratio (max) dB -20
Power Consumption600W (average)
Pol Ratio requirements