The University Wuerzburg Experimental Satellite 4 (UWE-4) successfully used its propulsion system in order to conduct orbit control. The 1U CubeSat, developed and built at the Chair for Robotics and Telematics, is equipped with the electric propulsion system NanoFEEP which has been developed by TU Dresden. Several manoeuvres have been performed within 11 days between June 23rd – July 3rd 2020 such that the altitude of the CubeSat was reduced by more than 100 m, compared to an average of 21 m with natural decay. This marks the first time in CubeSat history that a 1U CubeSat changed its orbit using an on-board propulsion system. As chance would have it, the team of UWE-4 received a conjunction data message (CDM) in the morning of July 2nd 2020 from the United Air Force’s 18th Space Control Squadron. A conjunction of UWE-4 with a non-operational Iridium satellite (ID: 34147) in the morning of July 5th 2020 with a minimum range of about 800 m was a threat to the safety of UWE-4. An analysis has shown that the altitude of UWE-4 would already be below the Iridium satellite at the time of conjunction. Thus the on-going altitude lowering manoeuvre could only improve the situation and can be considered as a collision avoidance manoeuvre. No further CDMs have been issued regarding this possible conjunction. An analysis of the orbit of the two spacecraft after July 5th 2020 results in a closest approach of more than 6000 m.
The Figure shows the altitude of UWE-4 since launch on December 27th 2018 based on Two-Line Elements published online by the North American Aerospace Defence Command (NORAD).
Lowering the altitude of a spacecraft in low earth orbit (LEO) is equivalent to a reduction of its lifetime, since satellites in LEO usually burn up during re-entry due to the friction with the Earth’s atmosphere. Thus, this experiment is a concept demonstration of a de-orbiting manoeuvre shown at the smallest class of spacecraft in LEO. Today, there is no commitment to carry a propulsion system for spacecraft. However, due to the vastly increasing number of satellites in mega constellations such obligations are being discussed in the space agencies of several space faring countries. The experiment of UWE-4 presents a de-orbiting solution for the fraction of space debris of operational but unused satellites of today and for the mega constellations of tomorrow. Stay tuned for more updates on UWE-4 and the upcoming launch of NetSat – a formation flying nano-satellite mission from our partner institute Center for Telematics which is expected to be launched September 2020!
UWE-3 News: Today UWE-3 is celebrating his 6th birthday
On a drizzly day in November 2013 for the first time UWE-3 saw the lights of the stars. Since this 21st of November in 2013 six years passed by in which UWE-3 and the team had a lot of work and fun together.
Day by day many radio amateurs from around the world send us UWE-3 beacons to supply us with the health state of UWE-3, which is still excellent. For example the batteries are still in a good shape:
Since the very first day we received great support from the radio amateur community. Our database counts already 291.104 external beacons sent to us from you.
Hopefully, UWE-3 will keep its good shape and the great support from you!
gr-satellites: a collection of decoders for Amateur satellites by Daniel Estévez
It is an OOT module encompassing a collection of telemetry decoders that supports nearly 40 different Amateur satellites. This open-source project started in 2015 with the goal of providing telemetry decoders for all the satellites that transmit on the Amateur radio bands. It supports most popular protocols, such as AX.25, the GOMspace NanoCom U482C and AX100 modems, an important part of the CCSDS stack, the AO-40 protocol used in the FUNcube satellites, and several ad-hoc protocols used in other satellites.
This OOT module can be very useful as a supply of building blocks for people interested in developing their own communications systems for satellites and other applications, as a material for the study of how different satellite modems are implemented, or as a readily available ground-station solution for many existing satellites.
This was something I was looking for, for a long time. The plugin makes it possible to stream the demodulated SDR# audio via UDP to another program that is listening on that specific TCP/IP address and UDP port. The same function was already available within GQRX. This for example makes it possible to receive and demodulate satellite telemetry and send it to GNURadio where the final telemetry decoding will be done.
The plugin consists of two files and the magic line for the SDR# plugin.xml file.
Also for HAM Radio enthusiasts SigintOS can be a way to get acquainted with the Linux operating systems and SDR radios.
SigintOS; as the name suggests, SIGINT is an improved Linux distribution for Signal Intelligence. This distribution is based on Ubuntu Linux. It has its own software called SigintOS. With this software, many SIGINT operations can be performed via a single graphical interface.
Hardware and software installation problems faced by many people interested in signal processing are completely eliminated with SigintOS. HackRF, BladeRF, USRP, RTL-SDR are already installed, and the most used Gnuradio, Gsm and Gps applications are also included in the distribution.
SigintOS works live from a DVD or USB memory stick. Users can also perform the installation process on the hard disk. For installation, simply download sigintos.iso from this download link and write it to a USB flash drive or DVD. It can also run smoothly on virtualization applications such as VMware or VirtualBox.