RF CURRENT



Welcome to RF Current, a weekly electronic newsletter focusing on Broadcast technical and F.C.C. related issues. This newsletter is part of The RF Page @ www.transmitter.com, a web site devoted to TV Broadcast RF engineering. For more information see the What is... guide to the R.F. Page site.

Issues are dated each Monday, although recently I've needed an extra day or two to complete each issue. Articles may be posted earlier if time permits or if there is a major, breaking story.

<<< Back to November 8 - Issue 190

NOTE: RF Current will not be published November 29 due to the U.S. Thanksgiving holiday. The next issue will include stories released through November 24. Any items released on November 25-29 will be included in the December 6 issue.

November 15, 1999 - Issue 191 Final Edition

SPACE - NASA Helps Satellite Operators Watch Ups and Downs of Leonids Meteor Shower (Nov. 12)
Bill Cooke, an engineer for CSC Corp, working in the Space Environments Team at NASA's Marshall Space Flight Center, wasn't concerned about meteors crashing to earch during the upcoming Leonids meteor shower. He said "Leonids never make it to the ground. They vaporize at heights of 100 to 160 km." Earth orbiting satellites, of course, are above this height and are vulnerable. The danger isn't damage from the collision itself as much as it is the potential for electrical short circuits caused by the plasma cloud formed when a dust grain hits a part of the satellite.

NASA has set up a special Leonids Environment Operations Center at NASA/Marshall to operate for 90 hours centered on the expected peak influx of Leonid meteors. The Center will provide "situational awareness" to satellite operators. Cooke estimated the chances of any one satellite getting hit range from 1 in 1 million to 1 in 10,000. While this is a minimal threat, there is a chancls cde a satellite could be damaged. In August 1993, in the Perseids shower, an Olympus communications satellite was lost when a meteor hit formed a plasma cloud that caused electrical discharges that zapped its attitude control system.

Satellite operators can turn off all but the most crucial electronics and point sensitive optics and solar arrays aways from the Leonids to reduce the chances a damage from this years meteor shower, which will peak from November 17 to 18. No damage was reported from the Leonids shower last year. Over the next few years, Earth will pass through higher than normal particle densities from the remants of comet Temple-Tuttle. Last year, the comet reached its closet point to the sun in its 33.25 year orbit.

More information on the Leonids is available from NASA news release Heads up! NASA to help satellite operators watch ups and downs of Leonids. GE Americom also has a Leonid Meteor Shower 1999 web page, which includes a conversation with Nick Chilelli, Principal Spacecraft Engineer, GE Americom.

FCC Grants GE Americom Request to Locate C/Ku band hybrid GE-4 at 101 degrees West (Nov. 12)
In an Order and Authorization (DA 99-2519) the FCC granted an request by GE American Communications, Inc. to reassign GE-4 from the position it was assigned in October 1998 at 72 degrees West Longitude to 101 degrees West Longitude. GE Americom. The FCC also allowed GE to move its SN-4 satellite from 101 degrees WL to 72 degrees WL. GE also requested authorization to use the 13.75-14.0 GHz "extended" Ku-band from GE-4. The FCC decided any GE-4 operation in this band had to be consistent with U.S. and international regulations. GE Americom requested use of the 11.45-11.7 GHz band for domesitc and international service from GE-4. The FCC did not grant GE Americom permission to use these frequencies for domestic operations, but said, "we believe that GE Americom can use the 11.45-11.7 GHz band for international service, subject to international and domestic coordination requirements."

GE Americom was also granted permission to use 72 degrees WL for testing GE-4, on the condition the spacecraft "not conflicting with the operation of authorized users of the spectrum and/or not causing harmful interference to any authorized user, particularly those operating in adjacent orbit locations." Refer to the Order and Authorization (DA 99-2519) for a discussion on the FCC action and more details on the authorizations.

SATELLITE - Loral Skynet and Loral Orion Rename Satellites Under Telstar Name (Nov. 11)
Loral Skynet and Loral Orion satellites will lose their old names and known under the Telstar name. The changes include:
Orion 1 becomes Telstar 11
Orion 2 becomes Telstar 12
Apstar IIR becomes Apstar IIR/Telstar 10

More information is available in the Loral Space and Communications Press Release.

OTHER Items of Interest

>>>>Next November 24 - Issue 192


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Last modified November 23, 1999 by Doug Lung dlung@transmitter.com
Copyright 1999 H. Douglas Lung