1. CSU-CHILL Update S/X band development and recent operations Solid State transmitter project

2. CSU-CHILL Radar Architecture
Antenna
Radome
Radar Trailer
Signal
Processor
Dual
Transmitters
Waveform Generator
Storage
Processor
Mass
Storage
Sync
Network
Local
Display,
Control
Remote
Display,
Control
GUI with S-polKa
Dual
Receivers
Digitizer,
Filtering
Antenna
Servos
Gateway
Angle
System
Control
Internet
March 4, 2013
CSU-CHILL visit for ATS741

3. CSU-CHILL visit for ATS741
CSU-CHILL Antenna
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
Main reflector
Subreflector
Feed horn
March 4, 2013
CSU-CHILL visit for ATS741

4. X-Band 3 dB beam width ~0.3 deg; beam axis coincident with S-band
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

5. Development of X-band
radar addition to CSU-CHILL
X-Band hardware adopted from UPRM MRI radar (CSU ECE collaboration effort)

6. 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

7. Better differential propagation phase sensitivity at X-Band vs. S-Band
Significant advantage for cold season precipitation and microphysics
“Negative” phidp more evident at X-band,
indicating vertically aligned ice crystals oriented
by an electric field

8. Attenuation
correction

9. 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

11. HEAVY AGGREGATE SNOWFALL CAUSED
MAJOR TRAFFIC ACCIDENT ON I-25

13. 15 April 2013
1709 UTC
145 degree RHI
Impressive convective scale
generating cells

15. Aggregates
Fallstreak
Pristine crystals

16. Wednesday 11:52 MDT Z
Zdr
More examples f
rhohv

17. Solid-state S-band Transmitter upgrade for CSU-CHILL
ASR-11 solid state transmitter donated to CSU by Raytheon

18. 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

19. Solid-state transmitter plan
S-polKa
Waveguide
Switch
Klystron
Transmitter
Solid-state Transmitter
Common Signal Processor
Radar Users

20. 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

21. Timeline of major events
Container acquisition, Oct 2012
Transmitter arrival
Nov 2012
Container HVAC, electrical: February 2013
March 2013
Design Review:
Microwave chain: Apr 2013
Waveguide hardware: May 2013
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
ASR-11 transmitter

22. 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)

23. 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).