Minutes from the October 27, 2004 GBIPG Meeting




1.  Spectrum summaries
2.  PMRF Spin DF / WJ VHF DF System
3.  IPG position paper
4.  DirecWay coordination on Allegheny Mountain
5.  Powerkut ballasts for the GB Public Library
6.  NSC Filtering
7.  Anechoic Chamber EEseal filters
8.  Propagation model verification
9.  RFI surveys
10. Jansky Lab shielded rooms
11. Josler Video Cameras
12. RFI call outs
13. Navy equipment and calibration
14. OASIS II software demo
15. Cognitive radio seminar


Attendees:  J. Acree (via phone), R. Fisher, J. Ford, F. Ghigo, W. Sizemore, D. Wirt



The purpose of this meeting was to document the status of various projects and determine completion requirements with input from Jeff, who recently returned to work for the Navy.

  1. Spectrum Summaries – Positive feedback has been received from observers using the spectrum summaries that have been developed.  The PF1-450 summary seems to be the preferred format.  Jeff recommended we continue to develop summaries.
  2. PMRF Spin DF / WJ VHF DF System – The IPG received a Watkins-Johnson VHF DF system in “trade” for our labor investment of refurbishing PMFR Spin DF system.  Wes will request assistance from Bud Berryman of NSGA, Sugar Grove, to refurbish the antenna array and check the system out.  Manuals should arrive soon (this week?). 
  3. IPG position paper – Awaiting approval from Phil Jewell, Director, NRAO-GB. 
  4. DirecWay coordination on Allegheny Mountain – Richard Laska (customer) has received the second required cable from us, but has not yet installed it.  Upon installation, Laska is to contact Wesley who will install the cable ends.  At that point, the DirecWay installer can be scheduled.  An additional coordination is underway for Charlie Myers so he can have broadband access and the ability to work from home.  It is hoped that the antenna pattern, once received from Hughes, will be sufficient to verify the installation will meet the ERPd limit.
  5. Powerkut ballasts for GB Library – Ballasts have been received.  Works area (Rusty) will install these as their schedule permits.  Mike Holstine approved the Works area performing work at the GB Library. 
  6. NSC Filtering – The compact fluorescent fixtures are the worst offenders.  Carla has designed a shielded enclosure for the ballasts of the C3 fixtures and filters are on order.  The Works area will systematically remove the fixtures and take to the shop for retrofit.  Then, Wes or Chuck can install the filters and return to the Works area to reinstall.  Wes will take the Carla’s drawings to John.  A similar effort will follow for the other style compact fluorescent fixture.  HVAC filter replacement is another outstanding item in the NSC.  Bad filters have been removed and are “bypassed”.  Jeff has identified (and purchased?) a more robust filter that is not as susceptible to installation damage by over tightening.  Some filtering effectiveness may be sacrificed, though.  Reduced NSC winter hours may provide a convenient time for this work
  7. Anechoic Chamber EEseal filters – Filters have been ordered; these will allow use of the indoor antenna test range without having to disconnect all the cables.  Gary Anderson can perform the installation. 
  8. Propagation model verification – Gary Brown, Virginia Tech, has sent an introductory email to Tom Gergely, NSF regarding this hopeful effort.  Tom will consider our suggested proposal and provide direction to Gary as to the best approach for funding.  Jeff suggested that an initial measurements survey could be carried out jointly between DoD and NRAO-GB, regardless of any NSF or Virginia Tech involvement. 
  9. RFI surveys - Jeff mentioned that someone will need to pick up the responsibility of working closely with astronomers in support of RFI surveys.
  10. Jansky Lab shielded rooms – It needs to be determined whether or not the Flectron installation is necessary around the shielded windows.  Wes and John will investigate whether the copper tape is curling which might require installing the Flectron to finish off the window.
  11. Josler Video Cameras – Cameras are located in the Janky Lab, NSC and dormitory(?).  Jeff and Rick Reefer of Josler have developed an RFI mitigation solution of using a fine mesh placed over the domes and filtering the dc leads before exit.  The camera will need to be disassembled and taken to the shop for bead blasting and chromating the inside.  The next step is to install the mesh, bolt in place and seal around filters and barrel connector with copper wool.  Jeff believes this fix is good for the Jansky Lab distances and beyond, but not any closer to the GBT.  Jeff also suggested purchasing RF gasket material to replace the braided shield being used in the assembly.
  12. RFI call outs – The new contact person is Wesley Sizemore (ext. 2144 or 456-3123).
  13. Navy equipment and calibration – Jeff will try to assist us in the future with equipment calibration and equipment for propagation model validation.
  14. OASIS II software demo - Wesley and Denise viewed a very impressive demo of the OASIS II spectrum monitoring software, which is a computer interface that drives up to four instruments including receivers and spectrum analyzers.  The FCC monitoring station recently purchased this software and it looks very promising to enhance our monitoring station capabilities.  Wesley will arrange another demo.
  15. Cognitive radio seminar – Jeff attended a seminar in D.C. on cognitive radio.  Any persons interested in hearing more about it may contact Jeff directly.