NATIONAL RADIO ASTRONOMY OBSERVATORY Green Bank, WV MEMORANDUM Aug. 12, 1998 TO: R. Fisher, R. Lacasse, R. Norrod, M. McKinnon, C. Niday, T. Weadon FROM: R. Lacasse SUBJ.: Minutes of Interference Protection Group 8/11/98 Meeting In attendance: Fisher, Ford, Lacasse, McKinnon, Niday, Weadon Minutes Approved. Budget The following funds have been allocated to the IPG for 1998: from M&S, 15K, and from RE 10K. This compares with 35K last year. This should be sufficient to get parts (detectors, filters) to complete the continuum detection system, and to get a good start on the monitoring station. ****Action item (Lacasse and Fisher): Discuss requirements for detectors and filters in continuum detection system. Call Outs McKinnon received a call from Don Nelson at the 140' complaining of broadband pulsed interference at 575 MHZ. Sizemore confirmed the characteristics, and postulated that it may have been ignition noise. The source also may have been welding on the GBT. The source was not located. GBT Receiver Room Shielding Effectiveness Test The turret gasket has been ordered and received. Bob Simon will install it in the near future. ****Action Item (McKinnon): Discuss, with Bob Hall, the list of things ComSat must complete so that NRAO can perform shielding effectiveness tests. ****Action Item (Lacasse and Weadon): Check to see if the cables in the feed arm servo cabinet are properly terminated. PC based Continuum Detector Both the hardware and software are ready to be used in the test chamber. The system includes "Exceed" software which will allow the control of the Spectral Processor from the PC. ****Action item (Weadon): Put together a 1 page "cheat sheet" on the operation of the system. NRQZ Review Committee A draft report of the committee was received by McKinnon on Aug 10. He will review it and most probably distribute it in the near future. Mckinnon's general impression of the meeting was that the committee was favorably impressed by our approach and focus. Much of the discussion had to do with the regulatory aspects of the quiet zone, rather than interference measurement and suppression. Niday commented that the public education aspect of the NRQZ administration could be improved. In particular, public safety organizations, who have a lot of interest in the use of radios for communications, are largely unaware of the details of the quiet zone operation, and could benefit from such knowledge. McKinnon noted that Lockman and Sizemore had a meeting with the Randolph County Emergency Services. The purpose of the meeting was to discuss an upgrade to their communications system. As a result of the meeting a system that was not only cheaper than what was originally proposed, but also caused much less harmful interference to Green Bank, was settled upon. One recommendation of the committee will probably be that we should be able to test to FCC Class B requirements. The specifications for this are not readily available. ****Action item (Fisher and Niday): To locate FCC Class B requirements and test procedures. ****Action item (Niday and McKinnon): To discuss quiet zone education initiatives. IPG Measurements of Devices Emissions There was a general discussion of whether to disseminate device emission information measured by the IPG group (mostly Niday). Information on commercially available devices may be of interest to other radio observatories. On the other hand, given all the NRQZ litigation, these measurements may be used against NRAO in court. Most of the group members were of the opinion that, as long as NRAO was taking positive action in response to the measurements, the measurements would be viewed as favorable to NRAO. A decision on this item was postponed to future meeting. Site Radios Crystals for the demonstration system have been ordered. The demonstration radio is being modified and repaired. If this radio does not work, then a few radios from NRAO vehicles can be used to put together a test system. Interference Reporting System McMullen and Balser still need to incorporate comments from the IPG before training of operators can begin. Miscellaneous No progress on the PC enclosure. New Gateway PC's with clock speeds of 400 MHz were received on Aug. 10. It would be interesting to test one of these. Next Meeting Aug 25, 1998, at 0800