Discussion: 2010 US Amateur Radio Direction Finding (ARDF) Champs Resullts

The 2010 US Amateur Radio Direction Finding (ARDF, aka radio orienteering) Championships resullts, were held last weekend in Oxford, OH.

Ian Smith and Lori Huberman, both of CSU, are US Champions on the M21 and D21 (F21) categories, respectively, in both 2 meter and 80 meter (wavebands) competitions.

Full results (and splits) are posted here.

Now a bit of explanation...

Unlike standard point-to-point foot orienteering, controls are not on the competitors' maps -- only the start, GO control and finish. Competitors use receivers with directional antennae to find controls/transmitters -- of which, there are only five (not including the GO control). Each band -- 2 meter and 80 meter -- is contested on separate days -- Saturday and Sunday, respectively.

Similar to a score-O, the controls can be punched in any order, and there is a time limit -- 3-hours. However, the penalty for exceeding the time limit is disqualification. The distinction between classes is which controls do not count, and thus can be skipped. For example, M21 and D21 competitors are expected to find all five, while M60 and D60 only need to find three, the controls to be skipped being specified. Punching at fewer than the specified number of controls does not disqualify the competitor; it just ranks him/her below those who punched more controls.

This event had a few anomolies, which are reflected in the results: There was no GO control on the 2 meter competition; and the number of controls to be skipped was one fewer for many categories on the 80 meter competition.

Just a bit of explanation for those that have had a look at the results.

On the 2m competition I am listed as coming in before Ian Smith, but I was an overseas visitor so I am scored separately. (Actually I was supposed to be in the M40 category, but I purposely run down a grade for more of a challenge. Ian certainly provided that!) On the 2m competition it is easy to make mistakes as the bearings often lie.

If you have a look at the 80m results though its a different story. Ian well and truly trounced me on this event both in running speed and navigation ability. Bearings on the 80m event are a lot more accurate and aren't affected by "reflections" as they are on 2m. Good orienteers excel on this band .... and I'm not a very good orienteer!

Route Gadget is here. Not many people have entered their routes yet.

There are some problems with the routegadget, esp the 80m course. Because of the holiday weekend, it might take a while to fix.

There were competitors from around the world, as far away as Australia, including Germany, Sweden, and Canada.

In September, the US team will travel to Croatia to compete at the World Championships which is held every other year. Team selection will be complete soon based on this year's and last year's US Championship competitions. Three competitors can compete in each class. The US will field a good team including many primarily foot-O orienteers who have learned direction finding from the hams. The team roster will be posted soon.

Congratulations to Lori and Ian for their fine showing...Champions!

This is fascinating. I used to occasionally do "transmitter hunts" as we called them then, years ago with my dad and brother, with the local ham radio club. Long before we discovered orienteering. As practiced then, it probably bore more resemblance to modern-day geocaching than orienteering. (No competition map, just an indication of what direction to travel in, and well, a vague idea of how close you were getting.)

Combining this with orienteering as described here gets me trying to visualize the process and wondering how the strategy might work. With several controls to visit, and with them only transmitting for a minute at a time in sequence, I imagine you not only want to take down some bearings on your map to try to triangulate the locations, but don't you also need to plan your time in order to visit each one while it's transmitting? In other words can you get enough from sketched bearings to find a control while it's silent? Or are they hidden well enough that you need them to be on while you're on the final approach?

I'm imagining the game starts by taking an initial bearing on each control, and then, as you move around the map, take one or two more to roughly pin down the location of each, perhaps giving you something roughly analogous to an orienteering control circle in which to search. Then you plan your time and your route to try to get to and attack each one while it's live. That seems like a lot of variables to juggle, in addition to all the equipment... Let's see: map, compass, pencil, straight-edge?, SI stick, receiver, antenna, switched attenuators (or is this built into the receiver these days?), what am I leaving out?

How do the organizers prevent competitors from taking an initial bearing on each control in the start area while awaiting their start time? Or is that just allowed because it's too hard to prevent?

Maybe when my kids get a few years older we'll have to whip up some gear and give this a try!

A lot if what said is the case. At the start, you get the map 10 minutes ahead so that you can put it on a board or do whatever it is you want to do. Your receiver is impounded until just before the start and you can not turn it on until the go. All transmitters are on the same frequency, or close to it. You do need to figure out which direction each is in and about how close. I'm not good with the triangulation part yet. I just go to where the signal is taking me once I've decided which control to go to. None are within the first 750 meters of the start and none are closer than 400 meters from each other.
You actually can find the controls off-cycle if you are close and know which direction you are going in. Just keep going straight. It's nicer too because then it's not blaring at you as you approach it. I'd say I've found at least half that way. Controls are also not necessarily on features, they can be anywhere but tend to be fairly easy once you see where they are. At least that's what I've seen so far. The receiver is attached to the antenna and the frequency is set before the competition. I don't think anyone uses a straight edge. The Germans put their map on a board and use push pins to show where they think the control is and then one to mark it once they've gotten there. Others use wax pencils to draw lines in the direction of the control from where they are.
The transmitters are also called foxes and regular fox hunting is done by driving around in a car getting close to a semi permanent transmitter, from what I understand and then walking to the transmitter. I've never done that.
Usually people have equipment to lend especially on 2 meters.

Thanks for the questions, fossil.

How do the organizers prevent competitors from taking an initial bearing on each control in the start area while awaiting their start time?
Before the start of each race, all our receivers are impounded - given to the organizers and stored near the start. We are only allowed to turn them on when we start.

No control can be within 750 meters of the start or 400 meters of the finish. Controls cannot be closer to each other than 400 meters; these are called "exclusion zones." These constraints coupled with park geometry allows ARDFers to infer some information about likely control locations knowing only the start and finish locations.

Juggling variables is a good way to describe ARDF; it's a classic incomplete information problem. The strategy I have adopted and that my coach (Vadim Afonkin) has trained me for is to start in the likely direction of the first control based on geometric considerations. Because of the 750 meter start exclusion zone, it's highly unlikely you will be in a position to attack a control within the first five minutes. During that time, you must run hard while tracking bearings and estimating distance based on signal strength. From that first five-minute survey, you must get a sense of what the correct order is to take the controls. Much like a score-O, if you choose the wrong order, you will lose time (in ARDF: in five-minute increments). To be competitive, you have to collect accurate bearing information while executing a plan and running at full speed.

It is difficult, though not impossible, to find a control off-cycle. You typically only find controls off cycle when you were within 100-200 meters as the cycle ends. You can continue down the last known bearing and look for it, but it is difficult. When you are close to a control as it comes on cycle, you maximize your success by running as hard as possible in the direction of the control; your information will improve as you get closer, and you will cover much more distance.

Triangulation is very important (especially for later controls), but in general, approaching and overshooting the control between cycles is a fast strategy. Suppose you hear a control on cycle; instead of moving in another direction to triangulate, run as far as you can toward the control in the four minute interval between cycles. Ideally, when it next comes on cycle, you will have passed it and so zero in more precisely on the location.

This image from the ARDF wikipedia article depicts the equipment well. The runner has an 80m receiver, headphones, SI stick, compass, and map board with grease pencils. The receiver, antenna, and attenuators are all integrated into the unit. I personally don't use a map board or pencils - I remember the bearings and run with my map O-style.

Controls are also not necessarily on features, they can be anywhere but tend to be fairly easy once you see where they are.

A pet peeve of mine regarding ARDF -- and one which, IMO, must change in order for ARDF to enjoy wider appeal among orienteers.

I disagree - it is important that the only information that can lead you to the radio transmitters is the signal (and the exclusion zones). If the radio signals indicated a region with few point features, it would be simple to check that region.

Wow. Thanks, Ruth and Ian, for the crash course. I wonder when and where the next one of these will be.

Ruth, the fox-hunting by car is what we used to do in the 70's with the ham club. Back then it was 2m FM, with a live person running the hidden transmitter. The playing field was restricted to "anywhere in the county". It started out just in cars. And then one time somebody got the bright idea to hide in a place you couldn't drive all the way to. We managed to win that one, largely because the setup I'd lashed together was the easiest to grab out of the car and take off on foot with. While everyone else was scratching their heads over what to do next when they ran out of road, we were off on foot first and got the advantage.

The rule back then was whoever won was the one to hide next time. So my dad decided we should hide in a 5-foot diameter concrete drainage pipe that crosses underneath the Erie Canal. This gave peope a lot of trouble, as it took them a surprisingly long time to find us. My brother was wandering around with a camera topside snapping photos of wandering competitors and even managed to get a few of one guy walking down the towpath bending over peering into the water!

So antenna, receiver, and attenuators all integrated! My how times have changed. I built a box of attenuators out of resistors and micro-switches, which then had to be plugged inline between the receiver and antenna. Later I found a commercial version at a flea market and ended up putting both of them in series to increase my total available attenuation. It was a lot to lug around, but I ended up winning a foot-only competition that was held on the grounds of a large hamfest. Haven't done any of this since graduating high school.

Ian, you mentioned estimating distance based on signal strength. I'm struggling to envision that, but I only have experience with 1970's technology to ponder it. Are you saying you can make a reasonable estimate of distance based solely on signal strength? Or is this more of a solution-space fitting exercise, where after you've looked at the geometry of the map and estimated roughly where the controls have to be based on the exclusion zones, you then assign an ordering of distance based on the relative signal strengths of the controls. Or in other words, control S is the loudest, so it must be the closest, and 5 is the weakest, so it must be the farthest, etc.

It sounds like an awful lot of thought has gone into the strategy of this. Far more than I had at first imagined. Keeping track of all this info without using a pencil strikes me as very difficult. I know just for example when I'm doing a regular O sprint course, the farther I run at full speed, the easier it becomes for me to make seemingly simple errors. And that's with the course drawn out for me on the map. Juggling all this in memory while looking at a mostly blank map.... My hat is off to you guys! Are you able to do some sort of regular training exercises to prepare for the US and World chanps? Does anyone hold ARDF meets in this country other than the US champs?

it is important that the only information that can lead you to the radio transmitters is the signal (and the exclusion zones). If the radio signals indicated a region with few point features, it would be simple to check that region.

Point features are not the only kind that can be used. In the 80m comp, #2 could have been placed in one of the small reentrants rather than the middle of the flat area between them all.

I just believe that being able to read the map should provide more benefit than just being able to move between the general control locations -- and get to the finish -- more efficiently. Trying to run the course using only the receiver should place one at a distinct disadvantage,

I initially thought that conrols should be restricted to features and control descriptions provided, but then realized that would give too much advantage to orienteers.

Guy,

The problem with using reentrants is that is where you will have reflections so you may not go in the right direction even when you are close. Generally, you hope that 2M controls are placed high but I've been told that this is not always the case.

I was also initially frustrated with placement not being on features, but it became irrelevant since I am going to the transmitter and as you get close the volume increases rather quickly.

Fossil,

There are some local training events and possibly competitions in a few places. Southern California seems to be pretty active and the Boston area practices a lot. We can in North Carolina since someone has transmitters and receivers, but haven't been. Many people don't get to practice at all which is very unfortunate.

Here's a link to a very informative site. http://www.homingin.com/index.html#toc

Re: GuyO - The map is already important because of the geometric considerations from the exclusion zones and the general shape of the park. I appreciate your sentiments, but ARDF already requires mastery of a wide range of skills. Given that it is radio direction finding, I do not see a compelling reason to offer any of informational compromise and incorporate more orienteering components.

A sport with some compromise that would be more attractive to orienteers is the confusingly named Fox Oring. Equipment is probably the biggest barrier to entry into ARDF.

I can't see any reason why the controls would need to be on features. In orienteering, the reason why features are used is so that the competitor knows what object in the circle he's looking for, and to ensure that course-setters place controls in specific locations. In ARDF, the map does not provide any information about the location, it's just there for planning your motion, e.g. heading straight toward the transmitter is not a good plan if there's an uncrossable swamp between you and it, or maybe you can cover a bunch of distance by diverting to one side and taking a trail.

Forgive laziness on my part but what are the approximate radio equipment costs, both for the organisers putting on and individual competitors participating in an ARDF event? I'm wondering how high the barrier to entry for ARDF is, assuming you've got someone licensed to operate the transmitting equipment.

If anybody is looking for an old steel measuring tape, I've got one that I'll distribute for free.

Jtorranc: I haven't purchased any equipment since Vadim Afonkin has sets that we use for training and competition. Ruth was looking into purchasing a 2m receiver from tigger; I believe typical units cost $200. Also note that you need a different receiver for 80m and for 2m. That includes everything except headphones (I use standard, cheap earbuds).

Most groups putting on ARDF meets will probably have at least some equipment to loan out. Certainly if US ARDF is to grow, it will be necessary for organizing clubs to own equipment, because a $200 barrier to an unfamiliar sport is hard to overcome.

A brand new 2m handheld radio (like a Yaesu FT-250R) goes for about $120. (Assuming that's a suitable thing to use.)

A normal handheld really isn't the best thing to use, although it is possible to use a handheld along with a directional antenna and an offset attenuator, both of which can be built fairly easily.

It's much better to buy equipment made for ARDF, but unfortunately, that kind of equipment is hard-to-find. Most of the Eastern European stuff you buy as an assembled product. There are a variety of kits, but they assume some level of technical skill to build.

I recommend to most people that they first try to identify some local interest. Here in Cincinnati, we have 4 people who are serious. If you can share the course-setting responsibility and the gear buys and builds, it is a lot easier. The minimum interest level is 2 people to have meaningful courses, but more is much better.

While it is possible to buy "club gear"---stuff like transmitters and antennas---commercially, it is very expensive. We first assembled pieces---batteries, transmitters, controllers (a little circuit that sends the morse code at the right time), and antennas---to make our "fox boxes". They were big and heavy and a nuisance. We're on our 2nd attempt at 2m transmitters, and it's now possible to carry all five transmitters in a larger daypack. There are some fairly new products that are low-powered, so they're not usable for a full-size course, but that are reasonably priced---Somewhere between $100 and $200 for a set of five.

Real ARDFers make their own receivers. Ian is fast approaching this rite of passage, so he should soon be able to instruct aspiring ARDF knights in the inexpensive construction of their own equipment.

I understand that cost of equipment is very much an issue. As a producer of receivers that are used particularly for ARDF I know this all too well. There is a heck of a lot more to it all than just the cost of the parts!

Amateur transmitter hunting is a relatively small subset and it may surprise some to learn that the MK4 receiver that a lot of people use would not be viable if it wasn't for its use in commercial purposes. However even these have gone a little quiet in the last 12 months which is making viability difficult.

I have had a project in the background for some time that is suitable for entry level with a target cost of less than $100. The biggest problem I had faced until recently was how to produce it. As a full kit it is too complex for a typical home constructor, loading the boards in house by hand was too much work and getting an external SMT loader to do the job in such a small quantity was just way too expensive.

I learned from the last 80m project that even producing a relatively simple full kit takes a hell of a lot of time to support. I have come to the conclusion that it had to at least be a built and tested board level product. But even then the last time I did this about half of the boards ended up on people shelves and never got used. Most sport and non technical people want an "out of the box" solution. But I'm hoping the board level product may be useful for club or even scout projects or those on a shoestring budget.

I now have my own automated SMT facilities. Though procured mainly for doing commercial projects I plan to use it to revisit the board level 2m project as well as an out of the box 80m receiver in the 2nd half of this year. I would welcome any comment or suggestions particularly for the latter. As its only use would be for ARDF, (which currently represents only a few % of the total users of the MK4) coming up with a viable product could be tricky!

Might also add that several clubs here own their own equipment for loan. 2m fox-oring events are very popular here with both orienteering and scouts, much more so than ARDF which has a very steep learning curve. Though this band choice is mainly because of availability of receivers on 2m. In most other countries fox-or is done on 80m.

bshields: Real ARDFers make their own receivers. Ian is fast approaching this rite of passage, so he should soon be able to instruct aspiring ARDF knights in the inexpensive construction of their own equipment.

tigger: I now have my own automated SMT facilities. Though procured mainly for doing commercial projects I plan to use it to revisit the board level 2m project as well as an out of the box 80m receiver in the 2nd half of this year. I would welcome any comment or suggestions particularly for the latter. As its only use would be for ARDF, (which currently represents only a few % of the total users of the MK4) coming up with a viable product could be tricky!

So, combining these two thoughts gives me a vision. If you can design an ARDF receiver/antenna that looks like a light saber, and modify the audio to make the authentic light saber sound as you twist it around searching for a null, I can just see hundreds of 8-12 (or more) year-olds running through the forest waving them around!

I would like to see FX Lightsabers added to the list of mandatory ARDF equipment. Alternatively, they could be prizes.

I think ARDF will become deeply interesting to orienteers in the United States when orienteering course designers here take an interest in placement of beacons for ARDF events. To me, the available course analyses suggest that the default tactic of running on a direct bearing often works well. Imagine orienteering with a GPS, the GPS showing an arrow direct to the control.

I am glad to see ARDF using orienteering control flags and not hiding the beacon. I like orienteering for the navigation, and I don't want to invest time in relatively mindless searching.

I'd like to read more reflections on course design from both ARDF competitors and course designers.