Ham Radio Allows Digital Communication

An amateur ham radio allows digital communication across the world.

| November/December 1983

The author of this column is the inventor of slow-scan television . . . a method of amateur radio transmission that allows ham operators to both hear and see each other during short wave broadcasts.

In what may be the finest example yet of high-tech volunteerism, two grass-roots organizations are cooperating to design, produce, and launch a packet radio satellite by mid-1985: AMSAT (Amateur Satellite Corporation) is the group through which a host of radio amateurs and volunteer space technologists have worked to produce the OSCAR series of ham radio communication satellites. And VITA (Volunteers in Technical Assistance) is an association of 4,000 unpaid workers who offer their specialized skills to facilitate projects in developing countries. The two forces are now focusing jointly on the establishment of PACSAT, a low-altitude satellite that will bring worldwide digital communication within the financial reach of individual Western hams, as well as those in impoverished Third World countries.

VITA is known throughout the developing world for its emphasis on village technology . . . the sort of practical engineering that E.F. Schumacher advocated in his book Small Is Beautiful. VITA workers have helped people all over the globe to find simple, low-cost ways to provide such basics as food, water, and shelter. Why, then, is VITA involved in a high-tech project encompassing satellites, microelectronics, and digital communication?

Well, that interest actually has several roots. One is VITA's own communication problem, which is caused by the fact that, although most VITA volunteers live in North America, the vast majority of the organization's projects are in other parts of the world. At present, almost all of its dealings between technicians and their contacts in developing countries are by slow (and often unreliable) international mail. So a two-way system that could deliver messages in just hours, rather than weeks or months, would greatly enhance the group's effectiveness.

Also, many people in the Third World are calling for leading-edge technology - wherever its use seems appropriate - but the cost is often prohibitive for them. To help sort out its own role in this area, VITA recently held two workshops on the subject of microelectronics and development, and among the many possibilities that emerged from these gatherings was the idea of a satellite that could act as a "flying mailbox" . . . picking up messages as it passed over one part of the world, and delivering them as it passed over others. Discussions about a joint VITA/AMSAT project followed shortly thereafter.

The new satellite, in fact, is a natural next step for AMSAT. Although each OSCAR satellite launched to date has been more technically sophisticated than the one before, all have been basically direct repeaters, receiving a signal on one frequency and simultaneously retransmitting it on another. A major disadvantage of this setup is that the satellite must be within line-of-sight radio range of both the sending and receiving stations during the entire transmission period. Thus, the maximum range of the system is limited to just a few thousand miles, making it impossible to communicate with a station on the other side of the world.

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