Poster URSI GA 2005

1
www.amsat.it
Abstract
Radio-amateurs have always been involved and are
willing to pursue research on ionospheric
propagation. AMSAT-Italia since the end of the
year 2000 initiated a space-based radio-amateur
programme aiming to contribute to the
international research effort on Space Weather
and ionosphere. The full programme is divided
into coherent sub-projects SkyWave is the
Space Segment of the mission, based on a small
satellite that will carry one scientific
instrument specific to the ionosphere as well as
radio-amateur communications payloads Ionosfera
is the Ground Segment of the mission. It is
basically a web site that will inform the
international community on the state of the
mission and will allow users to obtain
information on propagation and Space
Weather. Ionosfera has been selected by the
European Space Agency (ESA) to be a part of its
programme on Space Weather (The website is
http//esa-spaceweather.net/sda/ionosfera/
. RATS (Radio Amateur TopSide Sounder) it is
the scientific payload proposed to be embarked on
SkyWave and also planned to be developed within
the radio-amateur community. The whole paper is
meant as an invitation to discuss and/or to
collaborate on our programme
2
Skywave
SKYWAVE satellite project was started within
Amsat-Italia in the year 2000 to provide another
instrument to contribute to the amateurs and
hopefully to the scientific community to better
understand radio propagation through ionosphere.
Amateurs have built and orbited many satellites,
most were and are of microsat class which will be
also the class of SKYWAVE.
MICROSAT This class of satellite is well known
among amateurs.
ORBIT The selected orbit is circular, polar
this to obtain a global coverage of Earth and, at
the same time, to allow amateurs to communicate.
Height will be 1000 km which is a good compromise
for amateur activities and sounding activities.
3
Ionosfera
The best tool for informing and reaching a
community of users spread all over the world is
internet. That is the reason why we decided to
propose and create a website through which any
interested user, scientist or amateur or just a
curious person could use to be informed on the
current state of space weather, skywave mission
and related stuff. Moreover, on the website, are
available a set of tools that could help in radio
propagation forecasting. The collection and/or
retrieval of the data needed to perform
prediction or other actions are organized as
follows
4
Ionosfera
Ionosfera is essentially a website that will
provide two kinds of (free-of-charge) services
The provision of operational data on
radio-amateur communications and on Space Weather
RF effects. A radio-communication prediction
service based on several tools allowing to
predict/understand long-range radio-communication
links. Ionosfera will obviously be focussed on
Radio-amateurs needs and expectations but will
also attempt to create an European (hopefully
Worldwide) network of motivated persons
participating to and taking benefit from the
Project.
5
R.A.T.S.
RATS stands for Radio Amateur Topside Sounder, it
is the main scientific payload which will be
onboard of the Skywave satellite. It is a
completely dedicated topside sounder.
Starting from the block diagram above, which is
the result of what we plan to realize, we started
our effort on design and development of RATS
basic functions on the master RF signal
generator. We choose a new approach, using Direct
Digital Synthesis (DDS) techniques to generate,
control and command the carrier frequency
necessary for sounding. With this approach, we
intend to make a reliable and very precise and
stable signals for transmit and receive block of
RATS.
6
R.A.T.S.
For test we have designed and built a single,
simple board, in order to check and validate our
ideas a single DDS chip from Analog Devices was
used to generate a carrier from 0.1 and 20 MHz.
This board was controlled externally by PC and
was capable to generate a good spectral signal
around entire range of interest. On another
board, we used a small microcontroller (from
Atmel) for frequency settings of DDS.
In the figures above and below first testings
results on some parts of our sounder.
7
www.amsat.it
Contacts
Amsat-Italia c/o Ing. Fabio Azzarello Via S.
Caterina, 14 89121 Reggio Calabria Italy Email
iw8qku_at_amsat.org fabio.azzarello_at_gmail.com