Time transmissions, Jizerska 50



  • RipEX 400 MHz
  • Split time transmissions
  • Online TV broadcasting
  • Three locations, Multiple hops
  • Flexible protocol
  • Highest possible reliability
  • 25 kHz, 4CPFSK

Nowadays it is almost impossible to organize and run certain sporting event without split times on TV displays in the centre of the event and in TV broadcasts. Spectators seldom realise the challenges involved in transferring split time data from the course to the event centre, especially for sports that take place over a large area like orienteering, mass runs, cycling, cross-country skiing, triathlon etc.

When cables cannot be used, wireless technology must be utilized; Radio modems or Cellular routers from RACOM then become an obvious solution.

In reality, 3G or 4G networks are not the best choice. The cellular network covering the area is not ready to cater for the demands of the large numbers of spectators that are coming just for the event; It is overloaded and becomes unreliable. Sometimes cellular network coverage is also missing in more remote parts of the course. In such a case, the best solution for split time transfer is using a private radio network with RipEX radio modems temporarily installed just for the event.

On Line System is a recognised supplier of accurate timing at sports events including Jizerská 50, one of eleven races of Visma Ski Classic long distance cross country ski championships. This race in Czech Republic attracts around 5000 competitors every year. On Line System started experiencing increased issues with 3G/4G networks over a number of years. In 2018 they decided to make the change and use RipEX radio modems in order to provide higher levels of reliability and the levels of service they are renowned for.

Each year, split times are recorded at the same three points around the course, so there was no possibility to change the locations. Because of that, one set of split times had to be transmitted over a distance of 15km using three radio hops to provide the levels of reliability required.

In order to further guarantee reliability, radios were set up to operate on a 25 kHz channel using ‘only’ 4CPFSK modulation in Flexible protocol. The Application uses TCP/IP transmitting 70B packets per split time. New packets are queued for transmission awaiting TCP acknowledgement from the centre for each previous packet, ensuring the radio network is not unnecessarily overloaded.

As a further test of the robustness of the RipEX solution, split times were being transmitted from three independent locations on the course that could not hear each other. The efficiency of the RipEX radio protocol is such that it was able to comfortably manage all collisions created by simultaneous transmissions from these three locations and two repeaters.

Petr Blazej, owner of On Line System said, “We are delighted with the performance levels achieved by RipEX throughout the event. Knowing that the data was being transmitted over a secure and robust link made the whole event a more relaxing experience for us and we are looking forward to using RipEX in a similar capacity in future events”.

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