CSU-CHILL Update

S/X band development and recent operations

Solid State transmitter project

CSU-CHILL visit for ATS741

CSU-CHILL Radar Architecture

Antenna Radome Radar TrailerSignal

Processor

AntennaServos

DualTransmitters

DualReceivers

Waveform Generator

Digitizer,Filtering

Network

SystemControl

StorageProcessor

MassStorage

LocalDisplay,Control

Gateway

Sync

Angle

Internet

RemoteDisplay,Control

GUI with S-polKa

March 4, 2013 VCHILL

CSU-CHILL visit for ATS741 3

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

Feed horn

March 4, 2013

Subreflector

Dual frequency (S and X-Band) horn installed on 8.5m diameter dual-offset antennaX-Band 3 dB beam width ~0.3 deg; beam axis coincident with S-band

X-Band hardware adopted from UPRM MRI radar (CSU ECE

collaboration effort)

Development of X-band radar addition to CSU-CHILL

S/X-Band PPI data: Convergence patterns along eastern edge of convective echoes

Higher resolution at X-band is readily evident

X-band data not corrected for attenuation

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

Better differential propagation phase sensitivity at X-Band vs. S-BandSignificant advantage for cold season precipitation and microphysics

“Negative” phidp more evident at X-band,indicating vertically aligned ice crystals orientedby 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 scalegenerating cells

AggregatesPristine crystals

Fallstreak

More examples

• f

Z Zdr

rhohv

Wednesday 11:52 MDT

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

WaveguideSwitch

KlystronTransmitter

Solid-state Transmitter

Common Signal Processor

Radar Users

S-polKa

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 eventsContainer acquisition,

Oct 2012

Transmitter arrival Nov 2012

Container HVAC, electrical: February

2013

Design Review: March 2013

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

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).