1. December 3-4, 2003 Green Bank GBT PTCS In Progress Review Future Development Program Kim Constantikes, Richard Prestage

2. 2 PTCS / High Frequency Environmental Envelope ss

3. 3 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.

4. 4 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.

5. 5 Approach Pointing/Focus Efficiency/Beamshape Instrumentation Algorithms Astronomical Measurements Algorithms Instrumentation

6. 6 Instrumentation and Algorithms New InstrumentationExisting Instrumentation/Techniques Instrument/ Technique InclinometersStar TrackerPenn 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 Conditions and Q-Band Performance Under Normal Conditions Prototyping, Commissioning Experiments and Transition to Production Capabilities

7. 7 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.

8. 8 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.

9. 9 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)

10. 10 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)

11. 11 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

12. 12 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.

13. 13 Schedule Q4 2003 Production versions Dynamic pointing/focus Static Surface Accuracy improvements Pointing Instrumentation/ Techniques Q-band under normal conditions W-band under benign conditions Pointing Commissioning Experiments/ production use Surface Improvements II Production Q-band, Engineering W-band for winter 2004 Q1 2004Q2 2004Q3 2004