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AMSAT Phase 3E, abbreviated P3E, will become the new satellite to enable stable communications from
continent to continent for radio amateurs. The satellite, which is already under construction, should
be ready for launch in mid-2007. With its transponders for 145, 435, 1268 and 2400 MHz, it continues
the successes of its predecessors AO-10, AO-13 and AO-40. Radio amateurs, who were already active via
those satellites, can be active over P3E immediately. Newcomers often already have at hand the most
important elements for making radio contacts over the satellite.
The 150 KG satellite will have its own thruster to bring it up to its final orbit. At a maximum
orbital altitude of at least 35,000 KM, it will enable radio contacts for many hours over distances
of nearly 18,000 KM on Earth. Thus it will be clearly an improvement over satellites in near-Earth
orbits. Thanks to its slower motion across the sky, communications are possible without the need to
re-aim the antenna constantly.
As a communications satellite, P3E will carry several transponders useful to radio amateurs and having
bandwidths between 50 and 200 KHz. The emphasis will lie on the lower VHF/UHF frequencies between 145
and 2400 MHz. That simplifies the free world-wide radio operation independent of the propagation
variability of short-wave and away from the anonymity of Internet chats. Due to the efficient
HELAPS transmitter technology and a newly developed, software-defined transponder (SDX/STELLA),
radio operation will also be possible for small and portable stations. The software technology will
also enable flexible digital transmission methods. For microwave experiments, P3E includes additional
beacons and transponders.
Downlink bands: 145 MHz, 2400 MHz, 10.45 GHz, 24 GHz, 47 GHz.
Uplink bands: 435 MHz, 1268 MHz, 2450 MHz, 5.67 GHz.
P3E is currently being built under the direction of AMSAT-DL by an international team, including
groups from Finland, Belgium, Netherlands, Czech Republic, Hungary, AMSAT-NA (USA/Canada) and
AMSAT-UK (Great Britain). The mechanical satellite structure is nearly finished and is being
prepared for integration of electronic modules. An extensive test phase is planned to start in the
spring of 2007.
In addition to its assignment as communications satellite, P3E will also carry preparatory experiments
for a future AMSAT Mars mission. These include a new onboard computer and an ultra-stable reference
oscillator, which can be used to improve communications also. The pictures from two new navigational
cameras will enable new, live views from space.
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