OSIS owns and operates the only privately owned
satellite
reception ground station in South Africa (The only other one is run by
the
parastatal, CSIR). Due to the initial high start up costs of this
equipment
the first system was purchased in partnership with Climate Systems
Analysis
Group (CSAG) a
department
of the University of Cape Town in 1999 over a 3 year agreement after
which
the equipment reverted to OSIS. Since then the formal agreement has run
out
but the agreement has continued on bi-annual terms due to the initial
successful
implementation.
The demand for the derived products from the systems
have
been so great that we have purchased and commissioned a second entire
system
to ensure total redundancy and 100% reliable data feed for our clients.
In
the picture below the 2 sets of control units can be seen alongside
each
other on the shelf.
The reception equipment has been supplied by an
English
company, who have proven to be very reliable and provide excellent
quality
equipment (over 3 years operation on the one unit before the only
failure
on the unit) and consists of several modules. One section controls the
tracking
of the dish and consists of a 2 dimensional tracking parabolic dish
with
an azimuth and elevation rotators that allows the dish to track the
satellite
as it passes across the sky. The rotators are controlled via and
auto-tracking
unit and control box that is in turn controlled by a computer running
the
tracking software (the units can be seen on the photo below, the 2
silver
units and the 2 top grey units). The other section receives the data
transmitted
by the satellite and this consists of the helical antenna and very high
gain
pre-amplifier attached directly to the antenna which is positioned at
the
focus point of the parabolic dish. The amplified signal then enters the
receiver
module (grey module with one gauge in photo) that receives the signal
at
the correct frequency and passes it on the decoder (bottom right
modules)
which process the signal to a computer readable format which in turn is
passed
on to the computer for further processing.
The entire data reception, assimilation and
satellite
tracking is controlled by the software provided with the equipment,
unfortunately
the software runs on MS Windows, which has proven to be the only point
of
weakness of the system, due to regular system crashes (These two
machines
are the only Microsoft OS systems at OSIS). The software is
otherwise
reliable and easy to use and provides a good user interface for the
system.
(A screen shot of the main tracking and reception window is provided
below)
The raw data is continually streamed to the Linux
computers
where the data is processed into a industry standard format using
custom
software that converts the data to a format that is read by image
processing
software.
OSIS uses custom non interactive software to process the images
into
the published product allowing for no necessary user intervention in
the
entire process of reception to publication allowing more time for
personnel
to interpret the final product.
Initial product generation and data investigation is
done
using high end remote sensing software that is highly flexible allowing
for
data algorithms and manipulation techniques to be developed and tested.
As
this software can process nearly every type of satellite data
available,
we are able to process Ikonos, Quickbird, Landsat, Radar, EOS/Modis,
Spot, Seawifs imagery as well others for special applications on
request.
Affiliated to the Noaa Satellite Imagery that is
received
is the 10 channel data from the Chinese Feng Yun 1d satellite , the
sensor
is similar to the Noaa polar orbiters however it has 4 channels
in
the visible spectrum, thus the data can provide true colour image as
well
as provide information on biological activity in the ocean.