AMSAT is a name for amateur radio satellite organizations worldwide, but in particular the Radio Amateur Satellite Corporation (AMSAT-NA) with headquarters at Silver Spring, Maryland, near Washington DC. AMSAT organizations design, build, arrange launches for, and then operate (command) satellites carrying amateur radio payloads, including the OSCAR series of satellites. Other informally affiliated national organizations exist, such as AMSAT Germany (AMSAT-DL) and AMSAT Japan (JAMSAT).
AMSAT-NA was founded in 1969 in Washington DC to continue the efforts begun by Project OSCAR. Its first project was to coordinate the launch of OSCAR 5, constructed by students at the University of Melbourne. Some design modifications were needed and were made by AMSAT members, and the satellite was successfully launched on January 30, 1970 on a NASA Thor Delta launch vehicle.
AMSAT's next launch was AMSAT-OSCAR 6 (AO-6) on October 15, 1972. AO-6 was AMSAT's first long-life satellite, and was built with participants from Australia and West Germany. Command stations in Australia, Canada, Great Britain, Hungary, Morocco, New Zealand, the United States and West Germany controlled the satellite, contributing greatly to its 4½ years of service. Further launches continued to emphasize international cooperation, with AMSAT-OSCAR 7 (AO-7) launching with a new transponder developed and built by Karl Meinzer and AMSAT Germany (AMSAT-DL). AMSAT Japan (JAMSAT) contributed a transponder to AMSAT-OSCAR 8 (AO-8).
In order to launch its satellites, AMSAT has worked with space agencies and commercial launch contractors to develop new ways to take advantage of unused areas of launch vehicles. In return, AMSAT sometimes can negotiate a reduction or waiver of launch costs. One of the most significant is the Ariane Structure for Auxiliary Payloads (ASAP), developed and manufactured in partnership with the European Space Agency in 1990 for use on its Ariane IV launch vehicle. AMSAT was again able to take advantage of unused space with the launch of AMSAT-OSCAR 40 (AO-40), occupying unused space on an Ariane V.
The IPS (Interpreter for Process Structures) programming language was specifically written for the RCA 1802 AMSAT Phase III satellite.
AMSAT satellites operating frequencies: http://www.amsat.org/amsat-new/satellites/frequencies.php
p/s: For your info, Malaysian Class B Amateur Radio (9W2, 9W6 or 9W8) operator can transmit to amateur satellites