Dr Sandile Malinga, CEO of the South African Space Agency
unveils South Africa’s first CubeSat – Image credit CPUT
The amateur radio CubeSat designed and built by students at the Cape Peninsular University of Technology in Bellville is expected to launch in the 4th quarter of 2013.
Dr Sandile Malinga, CEO of the South African Space Agency
unveils South Africa’s CubeSat Program – Image credit CPUT
Since the defenceWeb article was written it is believed ZACUBE-1 and ZACUBE-2 have changed designation and the references to the 3U Cubesat ZACUBE-1 should instead read ZACUBE-2.
Students at the Cape Peninsula University of Technology (CPUT) have been building an amateur radio 3U CubeSat ZACUBE-1 that will carry out propagation research using a beacon on 14.099 MHz.
The objectives of the mission are:
1) Training of post-graduate students in Satellite Systems Engineering.
2) Earth observation using a visible band matrix imager payload and an S-Band payload data transmitter (2.4 to 2.45 GHz).
3) UHF Store & Forward system (70 cm amateur band).
4) Experimental 115200 bps L-Band to S-band data transponder.
5) HF beacon payload for characterization of Hermanus Magnetic Observatory’s Dual Auroral Radar Network antenna at SANAE base in Antarctica (14 MHz).
ZACUBE-1 will conform to the 3U CubeSat standard with a maximum separated mass of 4 kg. The spacecraft will be 3-axis stabilized using a novel Attitude Determination and Control System (ADCS) developed by the University of Stellenbosch. The spacecraft’s Telemetry, Tracking, and Command (TT&C) system will operate in the 70 cm band and will be commanded from the amateur ground station at CPUT.
The website defenceWeb quotes a launch date of 2013.
The IARU Satellite Frequency Coordination Panel have agreed these frequencies:
Uplinks on 437.525 MHz and 1260.25 MHz and downlinks on 437.345 MHz and 2405.00 MHz.
Renier Siebrits ZS1MIR gave this presentation about the project on August 7, 2011.
Watch ZACUBE-1
CPUT students are currently involved in the development of a second amateur radio CubeSat, ZACUBE-2, which will be 10x10x10 cm with a mass of one kilogram.
CPUT unveils South Africa’s first CubeSat http://www.cput.ac.za/files/images_folder/news/newsletters/mojo/Moja%20Newsletter%20October%202011.pdf
CPUT CubeSat Projects http://active.cput.ac.za/fsati/public/index.asp?pageid=956
defenceWeb: South Africa’s CubeSats promoting space ambitions http://www.defenceweb.co.za/index.php?option=com_content&view=article&id=23165:south-africas-cubesats-promoting-space-ambitions&catid=90:science-a-technology&Itemid=204
Southern African Amateur Radio Satellite Association (SA AMSAT) http://www.amsatsa.org.za/
United Nations General Assembly Committee on the Peaceful Uses of Outer Space – Implementing small satellite programmes: technical, managerial, regulatory and legal issues November 28, 2011 http://www.oosa.unvienna.org/pdf/reports/ac105/AC105_1005E.pdf
In this monthly feature, Hans van de Groenendaal ZS6AKV, executive chairman of the South African Amateur Radio Development Trust (SAARDT), looks at various technologies and activities that drive amateur radio. SAARDT is dedicated to the development of amateur radio in South Africa with a special interest in the youth. The organisation is funded by donations and supports the South African Radio League and SA AMSAT.
While the single CubeSat will be dedicated to the Hermanus Magnetic Observatory science payload supporting the HMO operations in Antarctica, it will provide interesting antenna characterisation opportunities for radio amateurs.
The beacon operating on 14 099 kHz will be used for optimising the SuperDarn HF radar system operated by the National Space Agency Space Science (previously the Hermanus Magnetic observatory).
The electrically conductive upper layer of the Earth’s atmosphere (known as the ionosphere) sometimes connect directly to the solar wind. If there is a strong coupling then there is an increased chance that the space environment immediately surrounding our planet will be disrupted – the fast-moving solar wind blowing past the Earth can drag the polar ionosphere with it. Scientists use the SuperDARN radar system to measure how the ionosphere is moving above the polar cap by detecting echoes reflected by patches of electrically charged particles.
In our increasingly high-tech society, space research is becoming an important research area because some modern technologies, both in space and on the ground, are vulnerable to rapid changes in the space environment known as “space weather”.
Why satellite signals?
As with all radio systems phase characteristics change with time. The phase path through the system needs to be calibrated on a regular basis and this can be achieved by introducing another signal into the system and then measure the phase coming out.
As the CubeSat passes over the Antarctic it will be in full view of the radar antennas. Scientists will then measure the signal and determine what the phase difference is.
Ean Retief ZS1PR, a Cape Town radio amateur with a special interest in radio propagation, suggested that the signal be used for determining the coverage (beam) pattern of 20 m antennas. Currently obtaining a reasonable coverage pattern for an antenna takes a long time as testing with other radio amateurs introduces a number of variables such as variation in ionospheric propagation conditions (day to day, seasonal, time of the day and the stage of the sunspot cycle), different power levels of the distant stations and different antennas being used by the distant stations.
The CubeSat HF beacon will be a known unchanging (same output and same antenna) source and with a known flight path the angle and range of the cube-sat will be known for the entire traverse. Therefore the observer simply needs to note time and received signal strength every few moments.
A “lobe pattern” can be drawn for the particular path followed by the CubeSat during a pass. With three to six passes available daily a rough estimate of the antenna pattern can be estimated after only one day of monitoring.
After a week of observation it should be possible to draw quite a good “in situ” coverage pattern, as not only will the lobes of the antenna be recorded but also any local screening effects of mountains, hills and nearby buildings.
If the antenna is then modified in any way, the effects of such modifications will be easily detectable after observing a few passes.
Propagation research
The beacon signal can also be used for the study of various modes of propagation. Questions such as “how does an HF signal above the ionosphere behave during various times of the day and sunspot cycle” can be answered. Will it penetrate through the ionosphere as the layers change or will it travel along the upper layer before penetrating?
As monitoring of the CubeSat signal will only require a receiver with a “S” meter and an accurate clock, the possibility also exists for constructing simple antenna configurations at youth camps or schools. By re-orienting the antenna in direction or configuration (i.e. “straight” dipole versus “inverted-V”) the effect should be noticeable during the next pass of the CubeSat and will give quick “hands on” learning. Varying the height above ground will also show the change in pattern.
The beacon signal can also be used to demonstrate the different effects of different antennas. For instance it will show the difference in signal strength during different parts of a satellite pass between different antennas (i.e. dipole giving better results at higher elevation while vertical gives better result at lower elevation). Coupled with modern antenna modelling software it will give participants the “proof of the pudding” of what they saw on a computer screen.
A simple satellite beacon can be used for so many interesting experiments and activities and add new interest to amateur radio.
AMSAT-UK 
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