MEMORANDUM

In attendance: Fisher, Ghigo, Lacasse, Niday, Weadon

Minutes of Previous Meeting

Approved.

 None.  Ghigo plans to use the spectrum analyzer at the 140 ft. to monitor signals at the 20-meter telescope.  He reports that occasionally the correlator staff reports unusual fringes which may be caused by interference.

The OVLBI group has requested that an automatic paging system be used to contact personnel in their group when errors occur in their system.  The paging system would use the site 43-MHz, 60-W transmitter.  It would be capable of penetrating buildings.  In contrast, the new system under development is much lower power (0.2 W) and does not have the capability to penetrate all parts of all buildings on site.  Members of the IPG group voiced opposition to this proposal for several reasons: since it is automatic, it is more difficult to disable the system when it would interfere; it only provides coverage when people are on site, or very close by; an automatic transmission for a nuisance problem could conceivably mask an emergency transmission.  The IPG concluded that coverage for the OVLBI telescope was an Operations problem.  Fisher will talk with Bignell about this and invite him to a meeting if it seems worthwhile.

Egan has located a unused turntable near the water tower.  It is fairly massive, but might be suitable for use in the chamber if it were modified.  Niday will inspect it and report back.

Approximately 1K remains in the IPG coffers for 1999.  After some discussion, it was decided to allocate $300 for shielding and filtering the amplifiers and associated supplies in anechoic chamber.  The balance of the funds were allocated to the monitoring station.

The possibility of using the 140-ft. telescope as a ground station for the SOHO mission was brought up recently at a scientific staff meeting.  This would require that the 140-ft. have a transmitter which would make it noncompliant with the Quiet Zone requirements.  The transmit power would be somewhere between 20 and a few hundred watts.  Calculations by Fisher and subsequent discussions between Fisher and Norrod recently led to the conclusion that the radiated power would cause receivers on the GBT, 560 meters away, to operate near saturation.  It was noted that it is possible but expensive to put filters in the receivers.  It raises the moral dilemma of NRAO requiring certain radiation limits from outside groups while it violates those limits by large amounts internally.  The motivation for this use of the 140-ft. is to bring in some dollars to supplement the existing tight site budget.  The IPG concluded that it should go on record as opposing this transmitter on the 140-ft.  It was pointed out that a transmit antenna could be located at some distance from Green Bank, and that the 140-ft. could be used as a receive-only station.  This option is more palatable to members of the group.  Fisher will communicate this to Jewell.

The rate of progress on this and other IPG projects has been frustratingly slow.  Engineering and technician time for IPG projects comes from "what's left over" after other projects are serviced.  With the GBT nearing completion, the time available for IPG projects has dwindled remarkably.  Possibly more time will be available when the GBT is complete, but, by then, some interference problems which should have been designed out will be designed in, and be difficult to retrofit.  If a conscious decision is made by management to allocate some time for the IPG then progress should be more noticeable.  Fisher will discuss this with Ford.

Temporary FCC authorization has been received for the transmitter.  Niday hopes to begin installation on the water tower in the next few weeks.  Work on a permanent license is in progress.  

No report.

Requests for bids are due in September 25 for exhibits for the tour center.  (Initially, these will be housed in the existing tour center.)  The bidders have been given no formal direction with regards to RFI emitted from their proposed exhibits.  After some discussion, the IPG concluded that with such short notice, the only reasonable thing to do was to send the bidders a letter stating that their exhibits must comply with FCC Part 15, class B.  This is a fairly common requirement met by most home appliances, including computers.  Niday revisit data on FCC Part 15 Class B compliant equipment that has been measured by the IPG and report to Fisher.

 It was pointed out that the Continuum Detector System should have been used for the recent of  RFI from rectifiers and contactors.  Lacasse and Weadon will try this in the near future.

Next Meeting: October 12, 0800.