

HAMSATS or AMSATS as they are officially called are AMateur SATellites
put in orbit to provide two-way radio communications for licensed radio
amateurs (popularily called Hams).

All AMSATS have the name of "OSCAR" (Orbiting Satellite Carrying Amateur
Radio). Oscar1 was launched as early as Dec. 12, 1961. We are now up to
OSCAR 13 and the degree of sophistication and cost has grown enourmously.
OSCAR 1 was built with donated parts whereas todays OSCARs are funded by
various Amateur Radio organizations and cost hundreds of thousands of
dollars.The Russians and the French also have launched Satellites for
amateur radio use.

The advantage of using satellites for amateur radio communications is the
vast distance that can be covered with relatively little power and simple
equipment. It's not uncommon to hear 2 hams carrying on a clear conversa-
tion over thousands of miles with only 10 watts of power. Of course, this
can sometimes be done wihout the use of satellites at lower frequencies,
however it's not reliable and subject to atmospheric conditions.

All AMSATS operate at VHF frequencies which for the most part are regarded
as line-of-sight communications. One ground station aims a transmitting
antenna at the satellite and any other ground station within line-of-sight
can receive the downlink which is always at a different frequency from the
uplink. Depending on the height of the satellite (this can vary since
HAMSATS have eliptcal orbits) the line-of-sight communications can reach
thousands of miles. Don't ever expect to actually see the satellite; its
small size and great distance makes that impossible.

AMSATS can operate in several modes and the details on their operation can
fill a book, however if you're interested in hearing the AMSATS (you don't
have to be a licensed ham to receive communications, only to transmit) try
tuning around 29.3 - 29.5 MHz, 145.8 - 146.0 MHz and 435.0 - 438.0.
These are the downlink frequencies. You won't need any special equipment
to receive as the satellite passes overhead, however if you want to maintain
communications over several minutes you'll require tracking the satellite
with a beam antenna.

The Moon, of course, is also a satellite and it's interesting to note
that the first two-way communications by bouncing signals off the moon was
accomplished by Hams a couple decades ago. Though common today, it still
requires the maximum legal transmitting power of 1 KW and the most
sophisticated receiving equipment to establish two-way communications.

For more information on AMSATS you should contact the Amateur Radio Relay
Leaque at 225 Main St., Newington, CT 06111
Courtesy Vanguard Electronic Labs 718-468-2720