Case Study published in the printed edition of “Pure Live 2017”
Wireless technology with relais airplane and GPS antenna tracker for World Run in Olten, Switzerland
“Wings for Life World Run“ is a charity run, which takes place annually in 33 countries worldwide and is broadcast live. This year, it took place for the fourth time in a row since 2014. The running courses are designed with very long distances, which is the result of this sport event’s special regulations: on the course, runners are followed by a so-called “catcher car”, which starts to pursue runners 30 minutes after they have started and gradually gets faster. The car catches the runners one by one. The runners’ athletic effort is ended, once they are caught by the car. The majority of runners successfully complete between 10 and 23 kilometres; the world’s fastest have nearly made 90 kilometres. In terms of time, the run takes several hours until the catcher car takes the last runner of each respective run out of the game. In Switzerland, the run took again place in the canton of Solothurn, in and around Olten. The winner of this race succeeded in achieving a distance of 68.11 kilometres. The live broadcast of such a sport event of this size poses a special task at any location. The leading runners are broadcast live by cameramen on motorcycles with wireless camera systems. This called for a wireless and interruption-free transmission over very large distances. The company HDwireless from Mechernich near Cologne, Germany, was responsible for the run’ transmission on May 7th, 2017, in Olten. Thus, the Managing Director Patrick Nußbaum’s HDwireless team was also on site for the their fourth Wings for Life World Run.
“Here, we’re the complete service provider for video, audio and communication.”
HDwireless is often responsible for the broadcast in large areas or for complex video transmission applications and has long-lasting experience when it comes to a secure transmission at major events – from Formula 1 to the SemperOpernball in Dresden, Germany; from cable way broadcasts to large-scale city networks with broadcasts from city centres. The requirements for the Wings for Life World Run in Olten included the recording with multiple cameras and the broadcast of image and sound in broadcast quality using directional transmission. Further tasks included director’s and communication radio for all relevant locations: from the course, the broadcast positions, the production vehicles including OB trucks. The six-hour live broadcast was to be transmitted without disruption across the complete course and time. The so-called “Wireless Video Village”, the site of receiving antenna, production vehicles and OB trucks, was to transmit the decoded video signal to the broadcaster.
“The optimum selection of HF broadcast technology and transmission coordination are decisive in the planning phase”
The size of the area covered, the canton Solothurn’s topography and the timeframe of around six hours of live broadcast immediately suggested the use of a relais airplane instead of a download link via helicopter. The advantages were numerous. Helicopters have a high flying price per minute and cannot stay in the air for the whole duration of the event. They need to refuel. In order to do so, they either need to head for either a regular airfield or a temporary landing location, which has been approved and constructed solely for this occasion, where a fuel truck can refuel the helicopter. Both lead to an inevitable and undesired interruption of the transmission. Additionally, helicopters fly considerably lower than airplanes. This has disadvantages for the directional radio in the area to be covered and causes a grave dependency on the weather during the event. During bad weather or even a thunderstorm, the helicopter has to terminate the broadcasting operation and land. The relais airplane on the other hand circles at the optimum altitude above the broadcast region, its interruption free and thus considerably more cost-effective. For this project HD wireless selected a German flying partner that could lift off in Germany and circle above Solothurn for the duration of the broadcast. Additionally, the airplane’s equipment including prepared wireless technology in the flight racks was easier to handle from Germany with no inconvenient customs proceedings. After the approved and completed deployment, the airplane simply returned to its German airfield. The relais airplane’s task was to receive the HF data signals from the motorcycles’ wireless camera systems via antenna and to transmit these to a receiver in the Wireless Video Village. For the transmission of the video data from the motorcycles, the latter were accordingly prepared and equipped. For this, HDwireless cooperated with TVtek, which offeres customised motorcycles on which the cameraman sits on the back and can film with a hand camera. The wireless camera systems installed on the motorcycles are based on Sony PDW 700 cameras with a 1080/50i image format. The motorcycles were equipped with broadcasting technology in the RF frequency range between 2 and 3 GHz for the live broadcast and additionally with a frequency range of 450 to 470 MHz for communication with the director. For this purpose, HDwireless planned an in-house developed data network for use on site. GPS position information are very important for projects with moving camera transmitters, flying relais stations and also special receiver devices. GPS information not only serves as position control but also to operate – manually for the pilot’s flight course or even automatically for the RF antenna. This way, the GPS positions could be played into Google Earth for a clear visualisation and then for example made available to the director. For the optimisation of the receiver quality, the pilot could adjust the relais airplane’s route using the GPS position data. An automatic processing of the GPD data for the antenna systems’ receiver optimisation can now also take place using HDwireless’s in-house “GPS antenna tracker”.
“With our new GPS antenna tracker we are able to significantly improve the directional audio quality of moving HF senders”
For moving senders, a rigidly aimed antenna inevitably receives signals fluctuating in strength, depending on the respective sending position. Sport events such as marathons or cycle races naturally stretch over large areas. Cameras, senders and relais stations are thus always moving – as was also the case for Wings for Life with its particularly long course. The transmitter range had an especially large influence on the radio link’s transmission reliability. And this could be considerably increased using the new HDwireless technology – by not rigidly aiming the antenna but rather flexibly adjusting according to the mobile sender. The system was developed, constructed and built as a prototype for the first tests by HDwireless at the beginning of the year. The in-house software constantly aligns the GPS tracker’s alignment with the mobile sender’s GPS data. In doing so, the optimum setting for the radio transmission is calculated using the position data and the attached antenna are set freely rotated and swivelled. The system operated in a very variable way and can follow senders on vehicles or be used for download links from helicopters and airplanes. This way, broadcasting chains from cars can be created in a urban environment, where the GPS tracker with its antenna is mostly positioned on a high building to allow a disturbance-free transmission in an urban setting. In contrast, the maximum radio distances in the “line-of-sight” between a flying sender and the GPS tracker on a high mast can be achieved in a direct transmission path without structural or geographic obstacles. Meanwhile, the system is available as HDwireless GPS antenna tracker and enables an even more extensive broadcast of widespread events with simultaneous transmission stability and cost effectiveness. At the World Run in Olten, the antenna alignment took place according to the relay airplane at 10,000 feet altitude; its GPS position data served to fully automatically align the GPS antenna tracker.
“In the end only the uninterrupted, smooth operation counts”
The signals from all time synchronous runs worldwide were gathered in the broadcast headquarters in Salzburg, Austria. The different sources for the World Run’s live broadcast were created and the live programme for RedBull-TV and the Internet stream were produced. The broadcaster supplied the live signal via satellite from Olten from the OB truck in the Wireless Video Village. Here, HDwireless operated its RF receiver and signal conversion stations. For this purpose, the GPS antenna tracker with its antennas was located on a 40 metre high riser in order to receive the RF signal directly from the relais airplane. The signal reached the RF control station, which was located in HDwireless’s RF1 production vehicle, via HDwireless RFiber technology. Here, the signals were converted and decoded for the transmission as a video signal to the OB truck. Additionally, the RF1 served as headquarters with its own communication network and transmitting stations for the team and director’s radio. At the same time, the GPS data from the data network was read out here and used to operate the GPS antenna tracker on the 40-metre riser. Extensive planning and radio communication along with a customised technical set-up needed to be implemented for a reliable transmission of video signals in a 1080/50i format – to thus provide vivid live images of the runners. The major event Wings for Live with its complex requirements regarding RF radio transmission is an excellent case study for a large-scale video and director radio solution. The application and the coordination of all components including customised solutions such as the GPS antenna tracker enabled a reliable and also cost-effective realisation.