December 3-4, 2003 Green BankGBT PTCS In Progress Review

Future Development Program

Kim Constantikes, Richard Prestage

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PTCS / High Frequency Environmental Envelope

s s

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Goals for October 2004/Early 2005

• Production Q-band (50GHz) operation (pointing/focus, surface efficiency/beamshape) under “benign” conditions.

• Extend Q-band capabilities to “normal” conditions.

• Prototype W-band (92GHz) performance under “benign” conditions for engineering commissioning of Penn Array Receiver.

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Approach

• Incremental approach using combination of traditional techniques and innovative use of simple technology (temperature sensors, inclinometers, holography).

• Laser rangefinders in specific roles if needed.• Concrete intermediate deliverables.

• Attempting to correct for effects on timescales of ~1min or longer. No need to address >1Hz effects at this time.

=> No need for new control architecture yet.

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Approach

Pointing/Focus

Efficiency/Beamshape

Instrumentation

Algorithms

Astronomical Measurements

Astronomical Measurements

Algorithms

Instrumentation

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Instrumentation and AlgorithmsNew Instrumentation Existing Instrumentation/Techniques

Instrument/

Technique

Inclinometers Star Tracker Penn Array Receiver

Temperature Sensors

(struct. / air)

Quadrant Detector

Holography

(trad. / oof)

Laser Rangefinders

Algorithms/

Development

• Track irregularities• Wind lift/drag• Vibration

• Test 1” differential capability• Substructure rotations, e.g., primary

• Rapid beam maps•Surface improvements

• Quadrant Detector path• LRF GRI• Thermal imaging• Add sensors

• Residuals, stability • Wind• Vibration

• Extend over grav, temp, wind• Improve FEM• Surface Peak-up

• Beam expand• Pointing• Diode replacement• Surface / collimation improvements

Enable W-Band Performance Under Benign Conditionsand Q-Band Performance Under Normal Conditions

Prototyping, Commissioning Experiments and Transition to Production Capabilities

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Phased Approach: Surface Improvements I

• Benign conditions only:– Static improvements at “geostationary satellite” (~rigging

angle) elevation: Holography.– Extend over elevation: Holography, FEM improvements.– Refined active surface control/data processing: Better

“knobs”

• Short campaign December?

• Extensive campaign February.

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Phased Approach: Surface Improvements II

• Extended thermal environments:– Simple thermal corrections (more BUS sensors, thermal

imaging, models)– Astronomical “peak-ups”

• Prototype/Prepare during Summer 2004

• Highest priority for October 2004.

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Phased Approach: Pointing

• Effects:– Az track irregularities– ~10s of seconds to minute timescale wind.

• Instruments:– Inclinometer– Star Tracker

• Complete/install instrumentation Spring 2004

• Prototype/Commission Summer 2004 (astronomical experiments at optical, C and X-band)

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Other Items I

• Completion of current work:– Production version of dynamic temp corrections– Production version of thermal stability monitor– Prototype installation of inclinometers

• Active Surface Control System Upgrade:– Need to refactor Active Surface manager for flexible,

convenient control (e.g. Zernike polynomials, SOAP)

• Antenna Manager Improvements:– Completion of pointing/focus model work– Trajectory calculation improvements– May need dynamic corrections to subreflector (0.1 Hz)

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Other Items II

• Need to be able to characterize conditions for high-frequency observing:– Site Interferometer– Radiometer– Climate

• Cannot address these with resources currently available to PTCS group

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Summary

• Address performance improvements incrementally.– Productionize thermal improvements– Development priorities: Wind, az track, surface phase I

• We have the real antenna available to us – use it!

• Many original concerns have turned out to be less important than expected.

• Only need to address << 1Hz effects in coming year.

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Schedule

Q4 2003

Production versionsDynamic pointing/focus

Static Surface Accuracy improvements

Pointing Instrumentation/Techniques

Q-band under normal conditions

W-band under benign conditions

Pointing CommissioningExperiments/

production useSurface Improvements II

Production Q-band, Engineering W-band for winter 2004

Q1 2004 Q2 2004 Q3 2004