Amateur Radio Direction Finding
Backwoods Orienteering Klub.
Radio-O, or Amateur Radio Direction Finding (ARDF) is a sport where with an orienteering map, compass, and a Direction Finding Radio Receiver you locate transmitters out in the forest.
Transmitters are placed out in the woods, but they aren’t marked on the map. You have an orienteering map of the area, a compass, and a radio receiver with a directional antenna so that by pointing the antenna and listening to the signal you can see from which direction the signal is coming and how strong the signal is. Using this information you navigate to the transmitter and like orienteering you “punch in” using your “finger stick” to record the time you arrived at the transmitter. The start and finish are marked on the map and there is a radio beacon at the finish to help guide you back. To qualify as finishing you must find at least one transmitter on your course and reach the finish within the time limit.
The basic equipment that you need is a compass, finger stick, and directional receiver. BOK will loan you the compass and receiver at no charge, and a finger stick for $5. We will have instruction to get you on your way. The fees are the same as regular orienteering events at BOK.
Types of ARDF events:
We have 3 levels of Radio Orienteering that introduce the skills necessary for the Expert Classic level.
- Radio White 2-3 k – There are 5 numbered controls with transmitters that stay on all the time. Each transmitter broadcasts on a different frequency. You find the transmitters in the assigned order by tuning in the correct frequency and using the directional radio receiver to locate the controls.
- Radio Yellow 2-3 k – The transmitter setup is similar to White, but you can take them in any order so in the beginning you can listen to all the signals to make a good decision.
- Radio Orange 3-6 k – Again there are 5 transmitters coded 1-5 all on the same frequency. Each one stays on for a minute broadcasting its code and then shuts off so the next one can start. After they all take a turn it starts over. You take an assigned subset of the transmitters in the assigned order.
- Radio Expert (Classic ARDF) 4-8 k – Similar to Orange except you have to determine the order to visit the transmitters.
Besides Classic there are two other styles of Radio Orienteering
- Radio Sprint 2 k – One or two loops of 5 transmitters per loop. All the transmitters on a loop are on the same frequency. Each transmitter stays on for only 12 seconds before handing off to the next transmitter, so the whole cycle of 5 transmitters takes one minute. Each loop is on a different frequency.
- FoxOring 3-8 k – FoxOring has a stronger orienteering component because the approximate locations of the transmitters are marked on the map. The transmitter and control may be as far as 100m from the location marked on the map. As you approach the marked location you will be able to tune in the very low power transmitter to locate the control. Like the others, you may not be assigned all the transmitters and your place is determined first by how many transmitters you found and then by your time.
Other Links for ARDF in the USA
This site has information lots of basic information from a more technical point of view.
Joe Moell, ham radio callsign KØOV (That’s K-zero-O-V) maintains this site.
Thirteenth USA and Seventh IARU Region II ARDF Championships
Hosted by the Backwoods Orienteering Klub
In the Uwharrie National Forest Birkhead Wilderness October 8-13, 2013