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MARISAT nostalgia

MARISAT nostalgia

Hello all from the past,

It was interesting and nostalgic to read the current COMSAT Retirees news, especially Ed Martin's article "INMARSAT Ends Service After 32 years." That article picks up the MARISAT story with the statement, " Following initial design studies…" without including anything about that earlier work.. So here's some additional history.

In the Spring of 1972, when it was recognized that a marine satellite communications system might be built, Ed Martin organized a research project intended to answer the question: what should such a system look like from RF and environmental viewpoints. Two COMSAT General engineers, E. J. (Ernie) Wilkin son , RF, and R.J. (Bob) Matthews , ME, were then selected to conduct a design study. Several fundamental questions needed addressing. Given that the system would operate at L- band , what types and sizes of antennas might be used? What were the implications on pointing , tracking and system capacity by selecting a large, high gain stabilized antenna versus using a low gain antenna?

Similar questions arose regarding environmental requirements. Should the antenna be enclosed in a radome for weather protection? If so, what survival conditions should be met? Precedents available from U.S. Navy were not particularly useful because of the large cost differences between MIL-spec and commercial equipment.

All of these considerations were examined, analyzed and reported in "Technical Memorandum, L-Band Ship Terminal Design Study" number ESID-1 dated 16 March 1973. Many of the recommendations in the report prepared by Mr. Wilkinson and myself were incorporated as requirements in the initial MARASAT ship terminal specifications, and later in the INMARSAT-Standard A requirements. From hindsight it is now easy to feel that a shipboard satellite communication system should of course include a parabolic-type antenna, housed in a radome, and typically mounted on a stabilized pedestal rugged enough to withstand severe ship motion combined with vibration. Back then that set of characteristics for marine satcom systems was not at all obvious.

The writer is grateful for having participated in development of requirements for and deployment of the original MARISAT ship earth stations, Scientific-Atlanta's, Model 3055 system.

I am particularly glad to have had the opportunity to create a company, Sea Tel, which has thrived on business evolving from the MARISAT program.


Ed Martin - 12/11/2007 That's great. Bob was a key player in the decision to use a mechanically steered antenna rather than a phased array.
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