Radio Orienteering Additional Information

Last edited: 11th Jul 2013


The sport is not a recognised IOF discipline because Radio-O events are held under the auspices of the International Amateur Radio Union (IARU). This is partly for historic reasons, as amateur radio direction finding (ARDF) originated in the early 20th century and also because the radio transmitters placed at controls need to be operated by someone holding an amateur radio licence. However, Radio Orienteering has much more in common with Foot-orienteering than any of the other forms of orienteering recognised by the IOF. Good radio orienteers need good orienteering skills to interpret the map, select routes and to relocate. In addition they need to be able to use the radio equipment effectively to determine the location of the controls and this creates an additional mental challenge.

The sport now has a worldwide following but is particularly strong in the former Eastern Bloc countries and China. Russia and Ukraine do particularly well in international competitions. Following the collapse of the Soviet Union the sport has spread westwards and the strongest countries in Western Europe are the Czech Republic and Germany.

For a comprehensive written description of most aspects of the sport see Wikipedia. or Google “ARDF Wiki”.

To see competitors in action you may wish to look at some of the video links below. These all have a Czech commentary but you should still be able to get a good idea of what is involved and how much people enjoy it.

Video of Czech Junior competition (5 min)
Shows that juniors can find the sport exciting and competitive. An example of the audio broadcast by Transmitter 2 (da-da, da-da-da, di-dit) can be heard at 2min 21secs.

Czech TV video (first 8 mins)

Czech TV video of 16th World Championships held in Kopaonik, Serbia 2012 (25 min)
A long video covering the various types of competition held at a World Championships. 550 competitors from 33 countries took part.

Official website for the 16th World Championships 2012 held in Kopaonik, Serbia
Andy Soltysik G4KWQ, a member of the British team who came 8th in M40, features in one of the scrolling photos at the top of the page. Has links to results and shows the countries that participated.


In the UK the governing body is the Radio Society of Great Britain (RSGB).
A small band of enthusiasts organises about 12 events each year and details of these and past results can be found here:

A World Championship is held every 2 years. In 2012 the British team had 10 members and Bob Titterington (LEI) became our first World Champion (in the M70 class). The M40 team came 5th, only 3 secs behind the strong Czech team and 4 minutes behind the Ukrainian team in 3rd place. Regional Championships are held in the intervening years in each of the three IARU regions. (See Wikipedia link for details). The next IARU Region 1 (essentially European) Championships will be held in Poland in September.

Britain is a fairly compact country with a relatively large number of active orienteers. This combination is rare in other countries and it appears to be conducive to increasing the number of Radio-O events and participants. It is anticipated that some orienteers might relish the different mental challenges of the occasional Radio-O event while continuing to participate in foot-O. It seems reasonable to suppose that Britain could achieve very much more in international Radio-O competitions with some modest increase in participation. Would you like to be a World or European Champion?


The radio receiver (Rx) used by competitors is lightweight and can be carried easily in one hand. The audio picked up by the radio is fed to an earpiece or headphones. The IARU rules specify two frequency bands and different receivers are used for each band. The 80m band (3.5MHz) is being used at Culbin and this uses compact receivers. Some of the videos show the larger 2m receivers in use. The receivers are just turn on and go and no special radio skills are required.

The Chinese made PJ-80 receivers that are being used at Culbin have a directional horizontal ferrite rod aerial. This means that the signal strength varies when they are rotated, just like a transistor radio. As the end of the rod is rotated towards the transmitter (Tx) the signal will weaken noticeably over quite a small angle and then it will then rise again. The signal is weakest when one end of the rod aerial is pointing directly at the Tx. The signal is at its maximum when the rod is at right angles to the Tx but the change in signal is much less pronounced than at the minimum, so the minimum gives a more accurate direction. A slight problem is that there are two ends to the rod, so how do you know which end points to the Tx? A button on the side of the receiver gives it an asymmetrical reception pattern. If the receiver is turned so that the rod aerial is at right angles to the Tx (and therefore the audio is at its maximum) then by holding in the button and turning the receiver through 180deg (and back again - several times if necessary), one direction will sound louder than the other and this resolves the problem. This is probably the hardest bit to learn but a little bit of practice should make this much clearer.


Normal orienteering controls and kites will be used and they should be visible from a distance of at least 20m. Unlike normal foot-O, the control does not have to be located on a mapped feature. The transmitter will be located close to each control but you are unlikely to notice it.

The Culbin event is based on the most common form of Radio-O and this uses 5 Txs which come on in turn for one minute over a five minute period before the cycle repeats. There are only five controls on the course. Results are determined based firstly on the number of controls visited and then on fastest time. There will also be an option to choose a shorter course where you only have to search for a specified 3 of the 5 controls.

Each Tx transmits a slow, but distinctive, repeated sequence of dots (dits) and dashes (dahs) using a slow Morse code. This can be heard in one of the video links. Tx1 transmits the letter M (dah dah) followed by the letter O (dah dah dah). It ends with the letter E which is just dit (1 dot). It is the single dit at the end that shows it is Tx1. Tx2 has two dots at the end so it transmits MOI: MO followed by the letter I, which has 2 dots (di dit). Tx3 has 3 dots at the end so it transmits MOS; MO followed by S which has 3 dots (di di dit). MOH (4 dots at the end) and MO5 (5 dots) complete the sequence. The MO part is just a lead in; it is the number of dots at the end that uniquely identifies each transmitter. The transmitter cycle should be synchronised with normal clock time so that Tx1 should start transmitting on the hour and then again at five past and ten past. Tx2 should transmit for one minute starting at one minute past the hour and then again at six and eleven minutes past the hour.

For the Culbin event there will be short practice course where all 5 Txs will be located within two blocks of forest which are marked on the map, and within 500m of the start / finish. The main course will use 5 transmitters on a different frequency and these will lie outside those two blocks and will be more than 500m from the start / finish. The practice course is to help you learn some of the techniques before embarking on the longer course which has an optimum route of about 4km. If demand is high you may only be given time to try to locate two or three practice controls so that the receivers can be recycled more quickly. Once the receiver is tuned to the correct frequency for the course it should not be necessary to adjust it again unless the tuning knob has been disturbed. All transmitters should be audible over the entire mapped area.

The map will show only the start and finish. You have to use the radio transmissions to try to find the controls in the time allotted. After the first, or possibly second, five minute cycle you should know the direction of each Tx and ideally know which ones sound louder or softer than the others. You can then try to work out which one to visit first and a route to it. Culbin is very runnable, so in most cases you could go in a straight line, but it is not always that simple. As you get close to a Tx the signal strength will increase noticeably. You may also find that the direction of the transmitter is changing rapidly: in that case you are very close to it. If the Tx comes to the end of its transmission before you find the control you have to decide whether you are close enough to start searching or whether to keep running; but try to avoid overshooting. As you travel round the area the directions to the Txs will change and you should be able to improve your ideas about where the Txs are. You may wish to change your plan!

There is a strict one hour time limit for the long course. Please do not exceed this as the radio receivers will need to be recycled. Competitors taking longer than 1 hour will be placed below those who return to the finish in the time limit.

The Start and Finish are located near to each other, so make sure you go to the Finish control at the end. It is assumed that orienteers should have no difficulty returning to the finish using normal orienteering techniques. If lost head south towards the edge of the forest, then east towards the access road to the car park, then north back to the Radio O registration.


Please do not stray into the Out of Bounds area marked on the map as you could interfere with the Trail-O course and competitors. The Out of Bounds area is there to provide a buffer between the two competitions and is at least 500m wide.

Categorized under: Competition Rest day

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