By: Michael Fitzsimmons

Since the mid 20^th century, satellite communication has played a vital role assisting forecasters with early detection of winter storms, severe weather and hurricanes. As a result of the major impact of satellites on the forecasting of these events, loss of life and property has greatly diminished. Satellite communication is not just used in forecasting the weather. There are roughly 20 satellites and other spacecraft in non-geostationary orbit that offer many different communication opportunities to the radio amateur hobbyist.

Radio satellite communication has opened a whole spectrum of opportunity for HF DXing (long-distance communication).  However, as the amateur quickly finds, this mode of communication does not come without plenty of decision-making, commitment of time, effort, and financial resources. If you are able to overcome these obstacles, then another unlimited resource of worldwide communication is at your disposal. What is even nicer is that whatever level amateur radio ticket you hold; Technician, General, or Extra, you can access any form of communication from the spacecraft.

Satellite operations provide a number of communication modes to the amateur. Satellites carry transponders, (devices that allow transmission on one band and retransmission on another such as 2 Meters and 10 Meters), and will support analog types of communication like Morse code (CW) or Single Side Band (SSB). The digital modes of communication use the transponder downlink to share time between telemetry and communications. The downside to this communication mode is the lack of live two-

must make depend on exactly what you want to accomplish. Knowing the mode of operation, either analog or digital, the frequencies you want to transmit and receive on, and the satellite(s) orbit you choose will help you achieve your goal in satellite communications.

Currently a number of satellites are in orbit which include OSCAR, AMSAT, RS-10/11, RS-15, and others. Additional information

on these satellites can be found at the American Radio Relay League (ARRL) website and through numerous radio satellite publications. In addition, several tracking software packages are available from the ARRL. For more information on radio satellite  communications, contact Michael Fitzsimmons KB1ELT or your nearest amateur radio club.

way QSOs between amateurs.

Linear transponders will repeat everything they hear without missing a beat. What's actually being broadcast by way of CW will then be transmitted as CW. The same will hold true for SSB. On the other hand, FM voice has a disadvantage through satellite communications in that it requires a huge amount of space on the passband and eventually strains the transponder's resources. So,  having a basic knowledge of satellite communications will help you decide how to construct and operate your base station.  Satellite communication frequencies can cover a wide spectrum but generally are found from 21 Mhz on the HF band to 24 Ghz on the microwave band.

There are a number of similarities that exist between direct or repeater communications and satellite communications. Both forms of communication require you having a transmitter and transmitting antenna along with a receiver and receiving antenna. For digital communications, assorted modems, TNCs and a computer would be required also. The decisions you

Michael Fitzsimmons, KB1ELT at (207) 496-0136, or email at:

michael.fitzsimmons@noaa.gov