NATIONAL RADIO ASTRONOMY OBSERVATORY
                     Green Bank, WV


MEMORANDUM                               March 10, 1998

TO:            R. Fisher, R. Lacasse, R. Norrod, M. McKinnon, C. Niday,
T.
Weadon
FROM:     R. Lacasse
SUBJ.:    Minutes of Interference Protection Group 3/10/98 Meeting

     In attendance: Fisher, Lacasse, McKinnon, Niday, Weadon, and
Balser for part of the meeting.

Interference Reporting System

     Balser reported on progress towards an interference database system
for the 140'.  Key design requirements are that it be platform
independent and user friendly.  A web-based approach seems to meet
these requirements.  This approach has been used very successfully for
the VLA calibrator list.  The list is stored in an AIPS++ binary
table.  Programmers at the VLA have recommended that a JAVA interface
be developed to interact with the table.  McMullen and Cornwell will
formulate the binary table for the interference database.  Balser and
McMullen will program the JAVA script.  Reeves will test the system.
The interference report should include the equipment used for the
observation.

     The first iteration of this system will probably not include any
graphics.  However a long term goal would be to incorporate that ability
to easily store or reference plots in an interference report, and to
pull these plots back up at will.  A second long term goal would be to
incorporate other databases into the system.

Approval of Minutes

     Minutes were approved.

Iridium Tests

     McKinnon reported on recent observations of some Iridium
satellites.  Details of the measurements are presently proprietary, and
will be made public at a later date.

Interference Source at 1612 MHz

     The IPG minutes for the Jan 13, 1998 meeting included a memo by
Lockman reporting on interference he observed at 1612 MHZ.  Fisher
reported on recent follow-up observations he performed in this band.
Plots showing interference from the Glonass constellation near 1607
and 1615 MHZ were distributed. 

However, RFI from these satellites does not account for the feature seen
by Lockman and again by Fisher at 1612.17 MHZ.  The next step in
identifying this feature is to determine its direction.  This can be
done once the monitoring station is operational.  During his
observations, Fisher reported being wiped out by strong Glonass
signals about 2% of the time.

RFI Testing Summary

     Niday reported on his efforts to tabulate the results of tests on
various pieces of equipment.  He has produced a table in html format and
passed around paper copies for comments.  Fisher remarked that
detection limits ought to be supplied for equipment from which no
interference was detected.  Otherwise, the table format met with the
approval of all present and will be posted on the web.

Next Meeting

     March 24, at 0800.