Goddard Space Flight Center, Greenbelt, Maryland 20771 

ENGINEERING COLLOQUIUM 

Monday, December 7, 1998 / 3:30 PM, Building 3 Auditorium 

John V. Evans

ABSTRACT -- Commercial communication satellite systems were originally developed to provide long-distance communications (e.g., between countries) and later for broadcasting television to domestic cable head ends.  Recently, new systems have been proposed and/or are being constructed to provide services to individual customers.  These systems fall into two classes: a) systems to provide voice (and FAX or low-rate data) communications to mobile users via small handsets and b) systems to provide multimedia (i.e., high-rate data such as Internet services) via small fixed terminals.  The former systems all operate at L- or S-band, while the latter are planned for Ku- or Ka-band (though some have been proposed for Q/V-band.  Described in this talk will be the systems now being developed and the new satellite technology that is required for them to be successful.  The propagation difficulties that must be overcome in the various systems designs will also be reviewed -- for the handheld phone systems, these are primarily the obstructions caused by buildings or trees, while the multimedia systems must contend with rain outages.  A few observations concerning the likely commercial success of these systems will be offered.  

SPEAKER: Dr. John V. Evans is Vice President and Chief Technical Officer of COMSAT Corporation, a position he assumed in September 1996.  He joined COMSAT in April 1983 as Vice President for Research at COMSAT Laboratories.  He became Director of the Laboratories later that year and was named President of COMSAT Laboratories in September 1991.  During his tenure as Laboratory Director, he was responsible for overseeing a transformation of the Laboratory from a largely corporate-supported entity concerned chiefly with spacecraft design and construction to one only partially supported by the Corporation and involved primarily with development of new satellite services, including commercial products to permit these services.  Prior to COMSAT, Dr. Evans worked at MIT Lincoln Laboratory, which he joined in 1960.  While there he was involved in high-power radar studies of the upper atmosphere and ionosphere, on which programs he published over 100 scientific papers.  A member and fellow of many national organizations, he served on the U.S. National Committee of the International Union of Radio Science and as its Chairman in 1975-1978.