DTU Space has developed a system for ground-to-ground communication via balloons, which is to be tested over a distance of 1,000 km in collaboration with the technical university EPFL in Switzerland.
Since last autumn, the communication system—known as Strato-link—has been tested successfully over short distances. In the autumn, signals were sent over 190 km via a single balloon, and, more recently, two balloons were used over a short distance. The new system will now be tested with two balloons over a distance of approximately 1,000 km in cooperation with the Swiss technical university EFPL in Lausanne, Switzerland.
The purpose of the test is to establish how well the system functions over distances corresponding to approximately the same range as satellites in low orbit around the Earth. If the test is successful, the technology may perhaps be used for testing in the stratosphere 10-50 km above the Earth, which today requires assistance from ESA or NASA.
“Weather permitting, the plan is that in May we will launch a balloon here from DTU in Lyngby and a corresponding balloon from EPFL in Switzerland. It is a distance of approximately 1,000 kilometres, and the balloons reach a height of 25-30 kilometres. And we then hope to be able to send signals and chat back and forth,” says René Fléron, MSc in Engineering and project manager at DTU Space.
Collaboration between students from DTU and EPFL
René Fléron has developed the technology together with student Andreas Rosenberg. They have combined commercially available technology with satellite communications technology developed at DTU. The new test involves both experts and students from the two universities in the first direct collaboration between the universities on the development of new, innovative technology.
Strato-link is a sender/receiver unit that makes it possible to communicate directly over large distances without using mobile phones or the Internet. The system can be used for ground-to-ground communication via balloons at a height of up to 30 km above the Earth.
The aim is to develop a long-range communications system which can be used for tests performed high above the Earth.
When the system was tested last year, this was done using a single balloon. Via the balloon and Strato-link system, it was possible to chat over 190 km between DTU in Lyngby and a car in Central Jutland, Denmark. And communication was recently established over a short distance using a tandem system consisting of two balloons launched at the same time with a total of three sender/receiver units and two cars, as well as an earth station at DTU, which each had one sender/receiver unit.
“The most recent test showed that we can handle several balloons and sender/receiver systems concurrently. This bodes well for our Danish-Swiss test next month,” says René Fléron.
Laboratories in the stratosphere in the future
These tests are a step towards the establishment of laboratories borne by helium-filled balloons for use in the stratosphere. The idea is that the Strato-link system can be used to communicate with instruments in balloons that collect data in connection with studies or tests in the stratosphere.
In the previous tests, it has been possible to simulate distances of up to 1,900 km using so-called attenuators. But the equipment must now show whether it can actually handle such communication. Two teams on the ground in Denmark and Switzerland will attempt to send data to each other from earth stations via the two balloons.
In addition to this communication, the students from EPFL will attempt to retrieve data continuously from an experiment conducted on board the balloon in Switzerland. The Swiss balloon is therefore equipped with two sender/receiver units.
“The new test is to show partly that we can communicate over ‘satellite-range’ distances and partly that we can handle several sender/receiver units concurrently. It will be super exciting,” says René Fléron.