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PTCS Project Planning Page

This page is intended to be the top-level page providing an overview, and links to work related to continued PTCS improvements in the areas of servo performance, pointing accuracy, collimation and small-scale surface errors.

Proposed Accelerated PTCS plan

Link to: PTCS annual group planning meeting -- 06 March 2007

Table of Contents:

• Work packages
• Long Term Goals
• Near-term Goals
• 2008 Task List
• 2007 Task List
• Overview of work planned during Spring/Summer 2007
• Status of Task List from 2006
• Other Notes

Work packages

• Pointing model and azimuth track analysis (Todd)
• Antenna characterization and commissioning (Frank)
  • pointing runs
  • gain curves
  • tracking effects / improvements
• Servo Improvements (John)
• Holography projects (Todd)
  • OOF holography improvements
  • Traditional holography system and strategy
• Laser Range Finder (LRF) system (instrument development and system architecture) (Steve)
  • instrument development
  • surface measurement system
  • pointing (elevation axle pose) system
• PTCS instrumentation (John)
  • Tipper
  • Phase Interferometer
  • Pyrgeometer
  • Optical pointing camera

Long Term Goals

• See Refined Scientific Requirements for the PTCS by Jim Condon, and especially table 1.
  • Ultimate goal (Winter 2010/11) is to provide acceptable performance at 115 GHz.
  • Intermediate goal (Winter 2008/09) is to provide usable performance at 86 GHz for the Penn Array (the fully-sampled array receiver has less stringent pointing/tracking requirements than a single-pixel heterodyne receiver) - see MustangEngSpecs
  • Near-term goal (Winter 2007/08) is to provide good performance at Q-band (52GHz), and explicitly to widen as much as possible the environmental envelope within which this performance can be delivered.
• Entry in NRAO Five-Year plan:
  • The detailed plans for FY2008 are described in the Program Plan. The long range goals for FY2009-2012 are to deliver the critical improvements to the telescope that are required to enable efficient 3 millimeter operation, and to provide the ancillary instrumentation needed to make optimal use of the available 3 mm weather conditions in the context of dynamic scheduling. Specifically, these goals include:
    1. the reduction of the small-scale surface error of the primary reflector,
    2. improvements to the servo control systems for the primary, secondary and active surface system,
    3. fielding additional instrumentation to more accurately track the performance of the telescope and its environmental conditions
  • Having recommissioned the traditional holography receiver in FY2008, we plan to use it in FY2009 to obtain detailed maps of the surface which should allow us to derive more accurate zero point positions for the 2209 surface actuators. During FY2009-2010, we also plan to continue to develop and implement new digital servo control systems for the primary, secondary and active surface that will replace the aging and limited analog systems delivered by the contractor. These systems are now needed in order to improve the pointing and tracking performance of the telescope in non-benign conditions by enabling the use of modern, advanced servo algorithms.
  • Some of our plans for 2010-2012 are naturally contingent on the success of our efforts in preceding years. Depending on the results traditional holography, we may need to make engineering refinements to the holography system, or we may attempt further improvements to the surface via the laser range finder system that remains under development. Once the servo improvements are complete, we will focus on providing ancillary instrumentation to better track the real-time observing conditions. A multi-color tipping radiometer and a cloud monitor are two devices that would provide valuable input into the dynamic scheduling pipeline.

Near-term Goals

• Improve pointing and collimation
  • Windy conditions
  • Thermally unstable conditions
  • Benign conditions
• Improve servo performance
• Measure and improve small-scale deformations
• Make incremental improvements to PTCS instrumentation

2008 Task List

• Antenna characterization and commissioning (Frank)
  • Coordinate and perform commissioning and characterization observations
• Servo Improvements (John)
  • Improve the performance of the GBT's servos, including short- and long-term improvements
• Interlock upgrade (John)
  • This task is to replace the interlock system on the GBT with a PLC-based system for better maintainability. It is now under the Servo Improvements project.
• Quadrant detector (Todd/Paul)
  • Investigate the existing QD data and determine its utility for estimating pointing error
• Traditional holography project (Todd)
  • Rebuild interface to the existing backend to support higher data rate transfers
  • Perform lab tests on the holo receiver and redeploy it.
  • Perform simulations and re-examine old data.
• OOF holography project (Todd)
  • Coordinate efforts to promote rapid, user-friendly OOF measurements on the GBT
• LRF system (instrument development and system architecture) (John)
  • Coordinate the Laser Rangefinder System developments
• Ancillary PTCS instrumentation (John)
  • Coordinate development of other miscellaneous PTCS instruments such as tippers, interferometers, etc.

2007 Task List

• New Pointing Analysis Package (Todd)
  • Complete the design and implementation of a new analysis package for a new pointing model.

Overview of work planned during Spring/Summer 2007

We have several projects in the works.

• Improved pointing models incorporating explicit track measurements via inclinometers.
• Servo improvements
• Servo interlock system (not strictly PTCS, but the same group of people are working on it)
• LRF Version 2 work
• Data processing supporting new pointing models.
• Complete campaign of antenna characterization commissioning exercises
• Characterize surface error length scales via moon or bright calibrator scans.
• Develop and deploy traditional holography system
• LRF Investigations:
  • Steve to find "knee in the curve" of current rangefinger performance (early spring)
  • Brainstorm potential surface measurement configurations
  • have Fred Schwab convert these to specific performance requirements

Status of Task List from 2006

• Maintain PTCS Instrumentation in state of readiness: active surface, temperature sensors (structural and air), weather stations.
  • Accomplished.
• Resurrect quadrant detector and integrate into M&C for logging data in standard format
  • Accomplished
• Begin design and development work on Elevation Axle Pose measurement system
  • Work on LRF originally slated to be used here is ongoing
• Servo investigations and improvements
  • Trajectory generation
    • It seems that the trajectory generation is not the problem. Rather, the response of the servo to the trajectory is poor.
  • Tracking at low azimuth rates
    • Friction Compensation seems to drastically improve this. We are continuing to test this.
• Bring someone up to speed on generating pointing models, incorporate new techniques (e.g. inclinometer measurements of track) - see PointingFocusDevelopmentFall2006
  • Underway
• Bring someone up to speed on OOF models; start incorporating new techniques including JWST Wavefront Sensing and Controls Group collaboration - see OOFDevelopmentFall2006
  • Underway
• Investigate measurements and adjustments for small-scale surface errors.
  • Underway
• Begin working on planning for work for track shutdown period (servo/controls upgrade)
  • Underway
• Investigate instrumentation for wind measurements.
  • Not yet started

Other Notes

• See attached proposed OUT OF DATE draft project schedule
• PTCSRiskManagementPlan
• PTCSCommunicationsPlan

• main.mpp: Project Schedule for PTCS development

Attachment:	Action:	Size:	Date:	Who:	Comment:
main.mpp	action	278528	12 Jul 2006 - 18:08	JohnFord	Project Schedule for PTCS development