Tuesday, July 6, 2010

MDS and Satellites

Situated between the amateur 23 cm and 13 cm bands are two particularly interesting commercial services. The weather satellite band used for studying cloud formations from approximately 20,000 miles above earth employs 1691 MHz while the public carrier service of MDS (acronym for Multipoint Distribution System) employs the range of 2100 to 2150 MHz.

Although reception of weather satellites has previously appealed primarily to commercial services, numerous amateurs are realizing the advantages of this capability,and are constructing their own receiving systems. Several inexpensive receiving kits have been recently introduced for satellite reception.

The MDS band may best be recognized by its recently dubbed nickname of "microwave TV braodcasting." Carrying restricted- type viewing similar to cable-TV programming, microwave-TV systems operating in the 2.1 GHz range are springing up across the nation. Reception of these pay-TV signals may be accomplished through the use of relatively inexpensive 2.1 GHz downconverters.

Additional information concerning this commercial activity is presented later in this book. The United States space shuttles also use the 2.2-to 2.4-GHzrange during flights. Numerous educationaltelevision services also frequent this spectrum for point-to-point relays .