FUNcube at Lauriston
This is an account of one school’s experience with the FUNcube satellite since its launch on November 21st, 2013. We captured frames of data from the satellite and uploaded them to the data warehouse on launch day (UTC). Since then, we have experimented with a number of approaches to using this educational satellite.
Lauriston Girls’ School is an independent school in Armadale, a suburb of Melbourne, Australia. About 800 girls attend the school at primary and secondary level. The school prepares students for both the local Victorian Certificate of Education and the International Baccalaureate and has an active approach to STEM (Science, Technology, Engineering and Mathematics) at all levels.
I teach Physics, Science and Mathematics and contribute to STEM activities at Lauriston. I have been active in amateur radio and satellites for over 30 years and developed a satellite programme at Mentone Girls’ Grammar School in the 80s, particularly focussing on the UoSat satellites. The technology has changed since then but the underlying principles are the same – get students involved with the equipment, capture and analyse data, explore the physics and have fun.
The first step this time around with chasing satellites was to acquire a FUNcube dongle. The school placed an order online and our dongle arrived a few days later – thank you to the efficient suppliers. Software-defined radio was a new area for me, so I took some time to look at software options. The FUNcube Dashboard had not yet been released, so I looked at SDR#, HDSDR and SDRConsole. I mainly use SDR# now, which supports FCDPro+ and is easy to use. I spent some time getting used to the idea of having a wide view of a band available and have found this immensely valuable for shortwave and amateur radio monitoring.
The FUNcube Dashboard
The release of the FUNcube Dashboard allowed us to see before launch how the satellite would appear once available, using files recorded from the engineering model satellite. The pre-recorded files also allowed an insight into how SDR# and the Dashboard can work together to provide a clear view of the base signal, the data spikes and frequency changes due to the Doppler shift. This is invaluable in a school setting. The FUNcube dongle integrates seamlessly with the Dashboard and supports automatic data capture and upload, perfect for schools learning about satellites without an ‘expert’ on hand.
I have a roof-mounted 2m/70cm vertical available so I could practise using the dongle by listening to local air band and amateur transmissions. I also have a hand-steered 2m/70cm Yagi pair, so the 70cm half was removed and the 2m half was mounted on a camera tripod. This gives lockable azimuth and elevation movement as well as a 90 degree swivel to change polarisation as required. This arrangement proved ideal for student use. The beacon is at full power during the day, when schools are most likely to be operating. The 2m/70cm transponder is on at night with the beacon on reduced power.
There are plenty of options available nowadays for orbit predictions, real-time tracking and Doppler correction. The easiest approach is to use Heavens Above ( www.heavens-above.com ) for orbit predictions. I am familiar with Orbitron, which is free and shows the access circle of the satellite on a world map, as well as continuously updated azimuth, elevation and Doppler shift.
Most recently, I downloaded Satellite Tracker, an iPad/iPhone app developed locally in Melbourne by Susan VK3ANZ. This is ideal for school use, as it offers a graphic display showing the next pass. This has a spirit-level type ‘bubble’ – if this is kept over the satellite symbol during a pass by pointing in the right direction and tilting to the appropriate angle, it is very clear where to point the antenna.
I also use the Star Walk app, which shows a real-time view of the sky. The satellite is selected from the list and its location in the sky can be clearly seen using the augmented reality feature. The iPad camera shows the view in front and the satellite icon is clearly visible as it travels from horizon to horizon. This makes the shape of the satellite pass very clear to students and it helps with pointing the antenna in the right direction.
FUNcube in practice
We operate in two modes, automatic and hands-on. The automatic mode works well to introduce students to the basics of satellite operation, while the second can involve all students in a group, each with their own job to do before, during and after a pass.
In the automatic mode, a fixed antenna is used so tracking is not required. The roof-mounted vertical antenna works well for all but the highest passes. The FUNcube dongle and Dashboard software combination works extremely efficiently (well done, developers!). The auto-lock manages the Doppler shift, so frames are captured and sent off to the data warehouse without user input.
For schools, the hands-on team approach presents more opportunities for learning. For Lauriston, this takes place outside on the school’s playing field, so all electronic equipment is battery-powered. Two students use a laptop to keep an eye on Orbitron, one calling out azimuth and elevation to the student steering the antenna as the satellite travels across the sky. The other passes Doppler-shifted frequency information to a radio operator using a handheld receiver connected to an amplified speaker running on rechargeable batteries.
The antenna steering is further supported by students with iPads using the Satellite Tracker and Star Walk apps. Another student looks after a laptop running the FUNcube dongle and Dashboard. The school’s wi-fi network extends far enough outside for the data to be sent via the Internet to the data warehouse in real time, so the count is called out of frames captured and successfully forwarded. Other students monitor the data warehouse web site and call out (quite excitedly!) whenever Lauriston appears as a data provider.
Orbit details can be presented at a level suitable for primary students, whose first question is always “How fast is it going?”
The radius of the earth is 6400 km and the satellite is 600 km up, so the radius of the satellite’s orbit is 7000 km. The circumference of the orbit is 2πr, so approximately 6 x 7000 or 42,000 km. FUNcube takes about 90 minutes to complete an orbit, so it is travelling at 42,000 / 1.5 or about 28,000 km per hour – impressive! Dividing by 3600 gives us a value of 7.8 km every second, which is about the distance I travel to work, so this gives students a very clear idea of the high speed involved.
Summer holidays have now started for Lauriston students, so activities for next year are being planned. These include a study of the physics of satellite motion and an analysis of whole-orbit data, now available as a daily download. Both areas will be included in the senior physics course, both IB and VCE. I will post an update on the FUNcube forum soon.