What is ARDF?

Amateur Radio Direction Finding (ARDF) is an amateur racing sport that combines skills for radio direction finding of radio transmitters through the use of equipment (radio receiver) with map and compass skills of orienteering. A competitor’s good physical condition (ensuring quick movement between the individual transmitters) is of huge importance for the final standings. This is a time-oriented competition in which participants compete against each other, and the one who chooses the shortest route to find (“collect”) all transmitters (also called “foxes”, from which comes the other name of the sport “Fox Hunting”) wins. The sport is most popular in Europe, China, Kazakhstan, and Japan, where in many countries it is part of the physical education curriculum.

History

ARDF originated in Eastern European countries in the late 1950s. The sport’s popularity grew rapidly, and by 1970 several European Championships had already been held. In 1980, the first World Championship took place in Poland, with competitors from across Europe and Asia. In 1990, the USA joined the ARDF family, and in 2000 the first World Championship outside Europe was held in China. Every year the number of participants in major events grows – at the 2004 World Championship in the Czech Republic, 400 competitors from 29 countries took part, while at the 2006 World Championship in Bulgaria more than 500 competitors from 32 countries on four continents participated.

Variations

For many years there were only two classic disciplines (in their current definition) – 144 MHz and 3.5 MHz. Currently, ARDF features four disciplines:

• Classic 3.5 MHz
• Classic 144 MHz
• Sprint
• Foxoring

Rules

The rules of the sport are the same in all countries and regions, with small differences in some of them. The main rules are approved by the IARU-R1 working group. ARDF competitions are held both in rough terrain and in city parks, including in populated areas (mainly for the purpose of promoting the sport). Each competitor receives a detailed topographic map of the competition area, showing only the Start (marked on the map with a triangle) and Finish (marked on the map with two concentric circles).

Classic disciplines 3.5 MHz and 144 MHz

The location of the transmitters (“foxes”) for the classic disciplines is not marked on the map and is unknown to the competitors. Each transmitter emits a Morse code signal, with each having a different signal, so competitors can distinguish them. There are 5 transmitters in total (plus 1 finish transmitter located at the start of the finish corridor). They operate in a “cycle” – each transmitter transmits for 1 minute, rests for 4 minutes, and then transmits again, making a 5-minute cycle in which each transmitter is heard once. Depending on the age category, the competitor must find 2, 3, 4, or all 5 transmitters and then reach the finish line by the shortest possible route. The competition is held on two different bands on separate days – “two meters” (144 MHz) and “eighty meters” (3.5 MHz), using different receivers for each band.

Sprint

The Sprint is held on 3.5 MHz. It has 10 transmitters divided into two groups of 5, operating on different frequencies and speeds with a 12-second cycle (within one minute all 5 transmit once). The two groups are called SLOW (lower frequency, 30–50 characters per minute on 3510 kHz) and FAST (70 characters per minute on 3550 kHz). Between them, the intermediate finish continuously transmits the letter S (on 3530 kHz). Competitors must pass it after finding the slow transmitters before starting to search for the fast ones. The final continuously transmits on the highest frequency – usually 3600 kHz. Depending on the category, a competitor must find between two and five transmitters from each group, in the sequence most convenient for them. They must start with the slow group, then pass the intermediate finish, then the fast group, and finally the finish. The distance between transmitters is small – 200–500 meters – with winning times expected to be 13–20 minutes. The competition map shows START, INTERMEDIATE FINISH, and FINISH.

Foxoring

Foxoring is the discipline most similar to classic orienteering. It is also held on 3.5 MHz. At the start, each competitor receives a map with START, FINISH, and up to 10 low-power transmitters (beacons) that transmit continuously. Each beacon can be heard from the center of the circle drawn on the map, though it may not be exactly within the circle. No beacon can be heard from more than 250 m away. The sequence in which beacons are visited is the competitor’s choice, and the number depends on the category. For continuous receiver operation, beacons transmit on three different frequencies, with both slow and fast speeds. The finish transmits continuously at high power on a separate frequency.

Entry Categories

The following age categories are officially recognized in international competitions:

1. Youth Championships:

• M14 – Boys up to 14 years
• M16 – Boys up to 16 years
• W14 – Girls up to 14 years
• W16 – Girls up to 16 years

2. European and World Championships:

• M19 – Boys up to 19 years
• M21 – Men (no age limit)
• M40 – Men aged 40 and above
• M50 – Men aged 50 and above
• M60 – Men aged 60 and above
• M70 – Men aged 70 and above
• W19 – Girls up to 19 years
• W21 – Women (no age limit)
• W35 – Women aged 35 and above
• W50 – Women aged 50 and above
• W60 – Women aged 60 and above