CSU-CHILL Update
S/X band development and recent operations
Solid State transmitter project
CSU-CHILL Radar Architecture
Antenna
Radome
Dual
Receivers
Antenna
Servos
Signal
Processor
Waveform
Generator
Sync
Dual
Transmitters
Radar Trailer
Storage
Processor
Network
Local
Display,
Control
Digitizer,
Filtering
Remote
Display,
Control
GUI with
S-polKa
Gateway
Angle
System
Control
March 4, 2013
Mass
Storage
CSU-CHILL visit for ATS741
Internet
VCHILL
CSU-CHILL Antenna
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•
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•
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Dual-offset Gregorian antenna
Choice of three symmetric OMT feed
horns
– S-band only
– X-band only
– Dual wavelength, S/X
S-band beamwidth 1 degree
X-band beamwidth 0.3 degree
Two way sidelobe levels better than 50 dB
at S-band; 70 dB at X-band
Single-wavelength feeds achieve
exceptional cross-polar isolation better
than 50 dB
– Median LDR in light rain of -38 dB
March 4, 2013
CSU-CHILL visit for ATS741
Main reflector
Subreflector
Feed horn
3
Dual frequency (S and X-Band) horn installed on 8.5m diameter dual-offset antenna
X-Band 3 dB beam width ~0.3 deg; beam axis coincident with S-band
Development of X-band
radar addition to CSU-CHILL
X-Band hardware adopted from
UPRM MRI radar (CSU ECE
collaboration effort)
S/X-Band PPI data: Convergence patterns along eastern edge of convective echoes
X-band delivers nearly same range sensitivity as S-band despite significantly lower power.
Antenna gain is 54 db! Gain ~ Area/λ2
S-band
X-band
Higher resolution at X-band is readily evident
X-band data not corrected for attenuation
Better differential propagation phase sensitivity at X-Band vs. S-Band
Significant advantage for cold season precipitation and microphysics
fdp µ1/ l
“Negative” phidp more evident at X-band,
indicating vertically aligned ice crystals oriented
by an electric field
FROST 2013
• carried out by CSU (Rutledge, Kennedy) and NCAR/RAL
(Kumjian, Rasmussen, Metro State students); 20 hour project
• CHILL X-band; NCAR X-band plus assortment of surface
measurements at NCAR Marshall Field site
• soundings
• documented many winter storms, many overnight
(autonomous) operations conducted
• CHILL X-band polarimetric observations at high resolution
HEAVY AGGREGATE SNOWFALL CAUSED
MAJOR TRAFFIC ACCIDENT ON I-25
15 April 2013
1709 UTC
145 degree RHI
Impressive convective scale
generating cells
Fallstreak
Aggregates
Pristine crystals
Wednesday
11:52 MDT
Z
More examples
• f
rhohv
Zdr
Solid-state S-band Transmitter
upgrade for CSU-CHILL
ASR-11 solid state transmitter
donated to CSU by Raytheon
High level goals
• At the NSF radar workshop, strategic benefits of solid-state class radar
transmitters were discussed and emphasized for modern weather radars,
both from advanced measurement perspective as well as long term
measurements, and robust remote operations for climate observations.
• CSU-CHILL is a very advanced weather radar ,with aligned dual-frequency
dual-polarization antenna, and state of the art signal processor. The
transmitter is the only component that is “classic”, and was the limiting
factor in advancement.
• Air surveillance radars (ASR) operate in the lower S-band, same as
weather radar and they have access to solid state transmitters.
• Demonstrate that the ASR class transmitter can be used effectively for
dual-polarization implementation for weather radars.
• This upgrade will keep CSU-CHILL radar at the forefront of research
weather radars
• This is being developed as a common platform that can be deployed with
other S-band radars such as N-Pol and S-polKa
Solid-state transmitter plan
S-polKa
Solid-state
Transmitter
Common Signal
Processor
Waveguide
Switch
Klystron
Transmitter
Radar Users
Advantages of Solid-state transmitter
• From a facility perspective, the first and foremost is the ability to
have state of the art, robust transmitter for weather radar, with
enhanced, fully remote operation for field deployments
• Range-Velocity Ambiguity Mitigation, through the use of frequency
diversity and coding diversity offer improved performance over
current techniques
• Data Quality Improvement, specifically, reduced variance in
estimated parameters, due to range-averaging of the additional
independent samples introduced by both Frequency Diversity and
Pulse Compression.
• Faster Scanning of a volume, without sacrificing data quality, due to
range-averaging of the additional independent samples introduced
by both Frequency Diversity as well as Pulse Compression
Timeline of major events
Container acquisition,
Oct 2012
Transmitter arrival
Nov 2012
Container HVAC,
electrical: February 2013
Design Review:
March 2013
Microwave chain: Apr
2013
Waveguide hardware:
May 2013
ASR-11 transmitter
DXR development: Jun
2013
Preliminary Testing: Fall
2013
• Major events
and milestones
on the
development
timeline are
shown
– Each
subsystem is
considered
complete after
it has been
bench-tested
CSU-CHILL projects
• Major support for DC3 in summer 2012; NSF REU
2012
• Winter 2013, FROST (20 hour in collaboration with
NCAR
• Three spring 2013 VCHILL remote tours/instruction;
SUNY Oswego, North Carolina State and Iowa State
• Summer 2013 projects include NSF REU and
Unmanned Aircraft System Sensor Calibration (U. of
Nebraska), several 20 hour projects
• Summer 2014, FRONT-PORCH (proposed)
AMS Short Course on Weather Radar Calibration
Laboratory:
14 Sept 2013, CSU-CHILL Site , CO
•
The goal of the course is to provide not just the theory, but practical
demonstrations calibration methods, so that the practitioners understand the
intricacies of good calibration. The course is aimed at students and scientists who
desire to know the details of radar calibration from a practitioner’s view point.
•
The course will be divided into two parts. The first will describe briefly the
fundamental physical principles of calibrating radar and the special aspects of
calibrating weather radar. This segment will also introduce the recent advances
such as calibration of dual-polarization radar. The second part will demonstrate
the practical procedures, and with emphasis on laboratory style work.
•
The organizer and chief instructor of this course is Prof V. Chandrasekar, Colorado
State University. He will be joined by leading experts in the field, namely, Prof Paul
Smith (Professor Emeritus SDSM&T), Dr Nitin Bharadwaj ( PNNL ) and Dr Luca
Baldini ( ISAC).