Open ARDF – Page 2 – A place to find and share open designs for radio orienteering equipment

Ranking Part 2: Adjusting for Difficulty

ARDF is conducted in nature. So, like golf, mountain bike racing, or skiing, the venue influences the game’s difficulty level. Navigating in a sparse forest is easier than in jungle-like undergrowth. Running on flat smooth terrain doesn’t require as much effort as climbing steep rocky hills. Some ARDF courses are going to be more difficult than others, and that will always be the case.

So when a competitor scores highly on a difficult course it says more about his/her fitness and skills than acing an easier course. And because an ARDF score is derived from one’s finish time relative to other competitors on the course, prevailing against stiff competition is also a better indicator of an athlete’s skills and fitness level.

Venues across the USA have diverse terrains, and course difficulty can vary widely. So if we are going to compare scores achieved in competitions held at different venues those scores need to be adjusted accordingly. Ideally, the scoring system would be designed to handle adjustments automatically. In orienteering this is accomplished by calculating scores relative to the average times of the top finishers. Because orienteering competitions consistently have a sufficient number of highly-skilled entrants, the top performances establish a good baseline by which to compare the subordinate finishers.

But many ARDF categories at USA events lack highly-competitive entrants and sometimes contain only a single competitor. So the question arises: how to adjust ARDF scores to make them comparable from one event to the next?

Ideal Time

One proposal is to utilize the concept of ideal time ( $T_{i}$ ). Ideal time is the expected finish time for an elite ARDF athlete traversing a course with the following results:

Finds each assigned transmitter in optimum order following the shortest practical route based on the competition map;
Unaffected by chance. E.g., doesn’t find any flags off-cycle, makes no wrong turns, etc.;
Runs at a speed that is realistic for his/her age and gender category taking into account the running conditions present along the route followed.

Note that ideal time is not YOUR ideal time, nor is it the ideal time of any of the competitors in the competition. Ideal time represents what a healthy elite athlete should be able to accomplish without anything unpredictable happening.

There isn’t currently a software program capable of calculating ideal time, so it is a manual process. Although it is a manual process, it is not very difficult, and the process can be documented in detail in order to allow almost anyone to perform the calculation. Calculating ideal time involves spending some time analyzing the competition map, plotting the shortest practical route from start to finish along the optimum order of transmitters, and estimating a realistic speed of movement along that route. A unique ideal time is assigned for each course for each competition held during an ARDF event.

Once calculated, the ideal times represent the results that an elite athlete in each age/gender category could have achieved. Ideal time can be applied to the scoring approach presented in Part 1. By doing so, the scores of all competitors who found all the assigned transmitters will be adjusted, making them more reflective of what they would have scored had an elite athlete actually participated.

Adjusting for Competition

Calculating ideal time and inserting it into the race results has the effect of adjusting all competitors’ scores to reflect what they would have been had an elite competitor actually participated. This will be the case even for categories in which only a single competitor participated. Utilizing ideal time in this manner doesn’t require any special formulas, and the adjusted scores still reflect the correct finish order.

Examples

Consider the M40 results from a Classic 80m competition in which the ideal time was calculated to be 60 minutes (3600 seconds)and there were five transmitters for the M40 competitors to find.

(Example 1) M40 competitor “A” found all five transmitters and finished with a time of 75 minutes (4500 seconds). He had the best overall time (i.e., $T_{1} = T_{A}$ ) amongst all M40 competitors who found all five transmitters. Without putting ideal time into the results, competitor “A” would have a score of:

$S_{A} = (5 + T_{1}/T_{1})\cdot 16.7 = 6 \cdot 16.\overline6 = 100.0$ points

Including ideal time ( $T_{i}$ ) in the results adjusts the score of competitor “A” as follows:

$S_{A}^i = (5 + T_{i}/T_{A})\cdot 16.7 = 5.8 \cdot 16.\overline6 = 96.\overline6$ points

(Example 2) M40 competitor “B” who found only four of the five assigned transmitters. No adjustment for ideal time would be calculated for this competitor. Ideal time is only calculated for a course that includes all the assigned transmitters. Those who find fewer transmitters will not receive adjusted scores.

(Example 3) Let’s look at a very slow M40 competitor “C” who found all five transmitters but required the full time limit of 3 hours (10800 seconds). His unadjusted score would be:

$S_{C} = (5 + T_{1}/T_{C})\cdot 16.7 = 5.41\overline6 \cdot 16.\overline6 = 90.2\overbar7$ points

Adjusting for ideal time gives:

$S_{C}^i = (5 + T_{i}/T_{C})\cdot 16.7 = 5.\overline3 \cdot 16.\overline6 = 88.\overline8$ points

Adjusting for Course Difficulty

The value calculated for ideal time will be greater for difficult courses and lesser for easier courses. Therefore, by comparing the ideal time calculated for an actual course with the ideal time calculated for a standard reference course, a unitless ratio can be derived. That ratio can be used to adjust competitor scores to account for the course’s difficulty.

So long as the standard reference is consistent the adjustment will be fair, since it will affect all competitors’ scores identically. So, for both consistency and simplicity, a reference of one hour is suggested for Classic and Foxoring courses, and fifteen minutes for Sprint, since those are the generally-used length targets used by most course designers. This reference can be named the ideal reference time $(T_{i}^R)$ and uses the same time units (seconds) as ideal time.

The unitless ratio to be used for adjusting for course difficulty is calculated as follows:

(1) $\begin{equation*}\gamma = T_{i} / T_{i}^R\end{equation*}$

Where:
$\gamma$ is the unitless course difficulty factor,
$T_{i}^R$ is the ideal reference time, and
$T_{i}$ is the ideal time.

The more difficult a course is the greater its ideal time. If the course designer made a course so that elite competitors complete it in the targeted amount of time (1 hour Classic/Foxoring or 15 minutes Sprint) then $T_{i}^R \approx T_{i}$ so that $\gamma \approx 1$ . And as a course is made more difficult the value of $\gamma$ increases above $1$ , and less difficult courses will have $\gamma$ values less than $1$ .

$\gamma$ only applies to those factors affecting a competitor’s overall time. Therefore, only the time component of a competitor’s score should be multiplied by $\gamma$ . $\gamma$ should not be applied to the component of a score derived from the number of transmitters found.

When $\gamma$ is multiplied by the time component of a competitor’s course score adjusted for the ideal time, the result is the adjusted score ( $S_{c}^{adj}$ ) that can be compared apples-to-apples to any other adjusted score for the same type of competition and age/gender category. Since transmitter count is not involved in the computation of the adjusted score, it is fine to rescale the score without regard to the number of transmitters. So the formula for adjusted score is simply:

(2) $\begin{equation*}S_{c}^{adj} = 100 \cdot \gamma \cdot T_{i} / T_{c}\end{equation*}$

Where:
$S_{c}^{adj}$ is the adjusted score for competitor $c$ ,
$\gamma$ is the course difficulty factor,
$T_{i}$ is the ideal time for the course, and
$T_{c}$ is the finish time for competitor $c$ .

Inserting the right side of Equation 1 for $\gamma$ into Equation 2 gives the following equation for $S_{c}^{adj}$ that allows us to skip the calculation of $\gamma$ :

(3) $\begin{equation*}S_{c}^{adj} = 100 \cdot T_{i}^2 / (T_{i}^R \cdot T_{c})\end{equation*}$

Where:
$S_{c}^{adj}$ is the adjusted score for competitor $c$ ,
$T_{i}$ is the ideal time for the course,
$T_{i}^R$ is the ideal reference time,
$T_{c}$ is the finish time for competitor $c$ .

Example

(Example 4) Consider the M40 results from a Classic 80m competition in which the ideal time ( $T_{i}$ ) was calculated to be 60 minutes (3600 seconds).

With the information above, calculate the adjusted score ( $S_{c}^{adj}$ ) for Example 1. First, select the appropriate ideal reference time:

$T_{i}^R = 3600$ seconds (For a Classic competition.)

Use $T_{i}^R$ , $T_{i}$ , and $T_{c}$ to calculate the adjusted score for competitor “A” from Example 1. Using Equation 3:

$S_{A}^{adj} = 100 \cdot T_{i}^2/(T_{i}^R \cdot T_{A})$

$= 100 \cdot (3600)^2 / (3600 \cdot 4500) =$ 80.0 points

Other Comments

Because ideal time assumes no chance events, it is possible that some elite competitors will achieve finish times shorter than ideal time. When that happens in the scoring system described in Part 1, those athletes will receive scores greater than 100.0 after the ideal time is applied to the overall results. Such outcomes are acceptable and should be interpreted as indicating that some transmitters were probably found off-cycle.

The scoring methodology described in these posts does not attempt to adjust for differences between the various competition formats, competitor age, or gender. Therefore, adjusted scores must only be compared or combined with other adjusted scores for the same competition format and age/gender category.

There have been some questions regarding Equation 3 and its use of the square of ideal time ( $T_{i}^2$ ). The ideal time is squared in the calculation of adjusted score ( $S_{A}^{adj}$ ) because it is being used to compensate for two separate and independent factors: the strength of the competition, and course difficulty. So it is necessary for it to be applied twice.

Note that the adjusted score contains only a time component and therefore isn’t affected by transmitter count. The effects of transmitter count were accounted for in the calculation of ideal time and adjusted score. So it is reasonable to combine (e.g., average) and compare adjusted scores within the same age/gender category from competitions of the same format having differing numbers of transmitters.

Experimentation with the formulae above is encouraged. Their use over time will no doubt reveal improvements to this scoring approach.

Summary

Because ideal time assumes the technical skills and fitness level of an elite athlete, it can be used to adjust for the absence of strong competition at a particular event. Because ideal time takes into account the actual course lengths and terrain, it can be used to adjust for the effects of the venue on competitor scores. Because the process of calculating ideal time can be documented and repeated by trained individuals, it can be applied objectively and precisely.

But, ideal time is not an ideal solution. It would be better to have a sufficient number of elite competitors at each ARDF competition to utilize orienteering’s scoring approach. But until the day of highly-competitive USA ARDF contests arrives, the use of ideal time as presented above is a reasonable approach allowing results to be compared between events having different levels of difficulty, even when few (or no) elite competitors were in attendance.

The approach described in this writing will not impact the order of finish for any event, but it achieves two important goals:

It allows competitors to see how they would have scored relative to elite competitors like those they might find at a World Championships.
It provides a way to fairly compare scores from events held at different venues and presenting different levels of difficulty.

Number 2 above will be examined more closely in Part 3.

Ranking Part 1: Scores for ARDF

Among other duties, the ARRL ARDF Committee is tasked with establishing a fair and equitable ranking system for use in team selection. It has been rightly pointed out that there are many considerations when selecting a team. Some considerations deal with subjective factors that have little or nothing to do with how well a candidate performed historically at ARDF events.

But competitive performance is one useful and objective factor that can be readily quantified and analyzed. And so competitive performance at ARRL-sanctioned ARDF events should be calculated and utilized as one component of a fair team selection process. It will also be helpful to competitors wanting to track their performance relative to their competition.

ARDF rules stipulate that the place (1st, 2nd, 3rd, etc.) of an individual competitor depends firstly on the number of transmitters found, and secondly on his or her running time. The rules provide no numerical formulae for deriving a single number to represent a competitor’s performance. But such a number would be helpful for facilitating a mathematically-rigorous ranking system, and would be the first of three steps to establishing such a system:

Establish a scoring system for ARDF competitions.
Define an approach for adjusting competition scores to make them comparable between courses with different difficulty levels.
Create a formula for combining adjusted scores to obtain a competitor’s rank relative to other competitors in his or her age/gender category.

The subject at hand is the first bullet above: how to represent a competitor’s ARDF performance at a single competition as a single numerical score. The other two bullets will be addressed in later postings.

Scores for ARDF

ARDF rules require that both the number of transmitters found, and the amount of time a competitor takes to reach the finish line, be used to determine a competitor’s place. And since a competitor’s score should accurately reflect their placement relative to other competitors, the score calculation must also utilize both the number of transmitters found, and a competitor’s total time, to derive their score.

Since the rules require the total transmitters found to be decisive in a competitor’s placement, time must never contribute more to a competitor’s score than does a single transmitter. In other words, no matter how fast a competitor runs a course, his/her score for that race must be less than the score of any competitor who found more transmitters. The rules demand it.

Most other properties of a score may be chosen arbitrarily. For instance, whether a score is proportional or inversely proportional to a competitor’s placement is totally a matter of convention. So, to keep things simple, the following scoring conventions will be used here:

A higher score reflects a higher (better) placement with a score of 100.0 being awarded to the first-place finisher(s) of an age/gender category.
All transmitters count the same amount toward the calculation of a competitor’s score.
Competitors’ times are scored relative to the fastest time of any competitor who found the same number of transmitters.

Item 3 is worthy of additional discussion. Note that all competitors within an age/gender category are always assigned the exact same course to run, and therefore the same number of transmitters to find. But the rules allow any competitor to choose, at their own discretion, to find only a subset of the assigned transmitters. A competitor might elect to find fewer transmitters if, for instance, finding more transmitters seems likely to result in their being classified Overtime (OVT). By choosing to find fewer than the assigned number of transmitters a competitor can avoid being classified OVT. But by choosing to find fewer transmitters a competitor accepts a placement below all the competitors who find more of the assigned transmitters than they. So, in effect, by choosing to find fewer transmitters they place themselves in a separate category of finisher. Since the rules effectively segregate finishers’ placements by the number of transmitters found, it is appropriate then that their times be likewise segregated and compared only to the times of others in their category who elected to find the same number of transmitters.

Score Calculations

Since all transmitters count the same toward a competitor’s score, and a competitor’s speed performance (time) must count no more than a single transmitter, each transmitter and the time component of the score is assigned a maximum score value of:

(1) $\begin{equation*}s_{N} = 100 / (N + 1)\end{equation*}$

Where
$s_{N}$ is the point value of each transmitter found (and maximum points awarded based on finish time),
$N$ is the total number of transmitters assigned to a competitor.

So, for example, if an M40 competitor is assigned five transmitters to locate, then each of the transmitters will have a score value of $100 / (5 + 1)$ or $16.\overline6$ points. The maximum number of points the M40 competitor can gain by having the fastest overall time among all M40 competitors on that course is also $16.\overline6$ points. So the total score for competitor “c” is given by:

(2) $\begin{equation*}S_{c} = (n_{c} + T_{1}/T_{c})\cdot s_{N}\end{equation*}$

Where
$S_{c}$ is the score for competitor $c$ ,
$n_{c}$ is the total number of transmitters found by competitor $c$ ,
$T_{1}$ is the overall time in seconds of the fastest of the competitors who found $n$ transmitters,
$T_{c}$ is the competitor’s overall time in seconds, and
$s_{N}$ is the value derived in equation (1)

Examples:

(Example 1) M40 competitor “A” is assigned to locate five transmitters and finds all five, and also has the best overall time (i.e., $T_{1} = T_{A}$ ) amongst all M40 competitors who found all five transmitters. He would have a score of:

$S_{A} = (5 + T_{1}/T_{1})\cdot 16.7 = 6 \cdot 16.\overline6 = 100.0$ points

(Example 2) M40 competitor “B” who found only four transmitters, and who had the best overall time amongst all M40 competitors who found four of the transmitters would have a score of:

$S_{B} = (4 + T_{1}/T_{1})\cdot 16.7 = 5 \cdot 16.\overline6 = 83.\bar3$ points

(Example 3) Let’s look at a very slow M40 competitor “C” who found all five transmitters but required 10 times as long to reach the finish line as did the competitor in Example 1:

$S_{C} = (5 + T_{1}/(10 \cdot T_{1}))\cdot 16.7 = 5.1 \cdot 16.\overline6 = 85$ points

Note in Example 3 that the slow finisher finding all five transmitters still received a score substantially higher than the best competitor who found only four transmitters in Example 2.

Other Observations

Note that equation (1) implies that the more transmitters assigned to competitors the smaller the effect of each individual transmitter and of time on the competitors’ scores. Consider: if there were only one transmitter to find, equation (1) says that finding the single transmitter would account for 50 points, and one’s finish time could account for up to an additional 50 points. But if we increase the number of transmitters to nine, then finding a single transmitter adds just 10 points to one’s score and time accounts for just 10 points as well. This can be difficult to reconcile when combining scores (e.g., for averaging, etc.) from competitions in which different numbers of transmitters were assigned.

To avoid the pitfalls of mixing or comparing scores derived from differing time and transmitter component values, the following approach is suggested:

Only scores for the same competition format will be combined or compared.
Only scores for competitors finding the same number of transmitters on the same course in the same age/gender category will be combined or compared.

Limitations of Scoring

The above approach for deriving a single score for competitors’ ARDF race results can be helpful for comparing performance among those competing within the same age/gender category and on the same course. But it would fall short if it were used to compare performances on courses of significantly different levels of difficulty. That subject will be addressed in Part 2.

GPS White Paper

Several years ago the IARU Region 1 ARDF Working Group added a rule (T4.2) that permits the use of GPS devices lacking map displays. Some have assumed that there is no navigation assistance possible without a digital map. Those folks assumed that T4.2 effectively banned all GPS navigation assistance during a competition. Those persons were mistaken. There is considerable navigation support that GPS can provide to ARDFers even if no map is presented. Some have begun utilizing those GPS navigational aids in international competition.

Having been an EE who worked with GPS as part of my job and hobbies, and having created several GPS-related App Store apps for smartphones, I believe that I can speak with some authority on the capabilities of GPS and the assistance it can provide. To encourage informed discussion on the subject I have written a white paper. It is available at no cost and may be shared freely by all. The pdf can be downloaded here.

No national ARDF team wants to put itself at a disadvantage. Since GPS assistance is currently allowed under the rules applied to most ARDF World Championships (WC) there is strong pressure for the same assistance to be permitted at competitions used to determine national teams. Not doing so could prevent a team from being adequately equipped to compete against other teams that are fully utilizing GPS capabilities. Because of the gravitational tug to conform to WC rules, all national teams are affected by the decisions made by the dominant regional organizations. Therefore, all national organizations should represent their points of view on the subject to IARU regional ARDF rules makers.

This thread is not for debating GPS issues. The facts are laid out in the white paper. Those who disagree with the facts or recommendations in the attached document should write their own white paper, or contact me directly with their concerns.

73,
Charles E. Scharlau – NZ0I
nz0i@openardf.org

Location, location, location

It’s important in real estate, and also in navigation sports such as orienteering and ARDF. Fundamentally, all location information is the same. Whether it is derived using map and compass or received as a latitude and longitude from a GPS instrument: a location is simply a position on Earth.

If you are only carrying a map and compass then a lat/lon position will not be of much use to you. You need a position that is referenced to your map. With a map-referenced location, you can point to where you are on the map, and identify feature locations relative to where you are standing. You can derive optimal routes to where you need to go. You’ve got all you need.

If, in addition to a map and compass, you are carrying a handheld computer, then a lat/lon position becomes much more useful to you. Although a lat/lon position is not referenced to your map, it is referenced to the Earth’s surface. So with a single known position on your map (such as a waypoint set at the Start) lat/lon data can be referenced to your map, allowing you to view your distance and magnetic compass direction relative to the Start. That information can be provided in text format in meters and bearing angle in degrees magnetic so that a glance will give you immediate confirmation of your approximate location on the map.

But a lat/lon position can be much more useful than that, especially if you have lots and lots of lat/lon positions and a computer capable of calculating great-circle trigonometry equations. Just about all modern micro-controllers can do that. Here is a sampling of some of the cool features that can be readily implemented using GPS location and compass direction information:

o A display of your complete track since leaving the Start along the path to your current location.
o Any waypoints you set along the way, such as fox locations.
o The exclusion zones around the Start and any found foxes, and your position relative to those exclusion zones.
o Bearings you have taken and the precise locations at which they were taken.
o Intersections of the bearings you have taken and an estimated location of the fox based on those intersections.
o Distance and compass direction to the estimated fox locations – even an arrow (or audio indication) pointing the way.
o Straight-path navigation guidance with cross-track error in any direction you choose.
o Distance traveled along your route or any segment of your route.
o More. How much more depends on one’s imagination, know-how, and processing power.

Although a graphical display (no map needed) would be ideal for presenting the above information, audio tones and synthesized voice played in one’s headphones can be even more effective at allowing one’s eyes to remain on the paper map and trail ahead.

There seems to be general agreement that showing a competitor their map location would provide an unfair advantage. But is it a greater advantage than all the navigation assistance that lat/lon location data can provide? We shouldn’t be surprised that GPS simplifies a navigation sport. Map position and latitude/longitude are exactly the same things: positions on Earth’s surface.

Some will argue that their GPS equipment doesn’t work all that well, and isn’t much of an advantage. That might be true right now. But that will change. ARDF receiver builders don’t have the skills and knowledge of smartphone or GPS device manufacturers. But take a look at some of the GPS-based apps available for Android and iOS, or features of handheld GPS devices. They use GPS data, standard position filtering algorithms, and widely-available trigonometric equations. The apps and devices aren’t optimized for ARDF, but they provide many of the features listed above. And they do them very well indeed. That is the future.

There is an unwritten rule that most competitors recognize upon seeing it, even if they had never contemplated it before: ARDF competitors should not receive navigation assistance from man-made signals coming from outside the competition boundary. It would not be fair play for observers to radio their bearing measurements to their friends competing on the course. How, then, is it right for competitors to carry receivers that let them receive navigation assistance from Earth-orbiting satellites? ARDF is about using the fox signals for navigation – that is what defines ARDF.

GPS, GLONASS, and similar technologies are not comparable to having a receiver that displays a fox’s signal strength. They aren’t even comparable to having a processor convert the signal strength to an estimate of meters to the fox. Navigation systems providing lat/lon position data work unlike any other type of instrument and support features that no other technology can. They hand you location. Your precise location. No thinking required.

I like GPS very much. I have worked with it professionally and as a hobby. It can do tremendous things. It might be used to help simplify navigation sports to avoid discouraging beginners. It definitely simplifies course design and supports accurate course setting. As much as I like GPS technology, I would never want to compete against it.

A Sensitive Issue

ARDF rules can have a large impact on the cost of equipment. There are many examples of this that can be cited. But there is one notable example where current rules are unnecessarily increasing the cost-of-entry to the sport. And this issue can be readily addressed with a simple clarification of the rules.

High-end ARDF receivers costing US$250 or more, typically provide excellent performance specifications: selectivity, stability, weight, ergonomics, and sensitivity. Inexpensive alternatives generally underperform the expensive units in all respects. But the most significant parameter that prevents under-$50 units from being usable is sensitivity. If you can’t hear a signal, you can’t hunt it. Period.

Not to get too geeky, but sensitivity on the 3.5 MHz band is noise limited. That means that the background noise level is well above the sensitivity threshold of most receivers. The receiver might be plenty sensitive to receive a weak signal, but the received noise is louder than the signal, making it unreadable.

Noise performance is improved by increasing selectivity (narrowing the receive bandwidth) to allow less noise through while still allowing the desired signal to pass through. But high selectivity requires high stability, otherwise a receiver would drift outside the narrow passband and lose the desired signal. So high-sensitivity 80m receivers must also have high selectivity, and high stability. That means that the requirement for high sensitivity affects many aspects of the receiver design. The bottom line is that greater receiver sensitivity means greater overall receiver complexity and cost.

The bottom line is that greater receiver sensitivity is achieved by increasing the complexity and cost of the receiver.

A question we have to ask ourselves: is high receiver sensitivity an essential part of ARDF? Is it really necessary to promote the use of high-sensitivity, and therefore high-cost, receiver designs in all ARDF events?

Is it really necessary to promote the use of high-sensitivity, and therefore high-cost, receiver designs?

I submit that it is fitting and proper that some ARDF events be conducted in a manner that allows low-cost receiver designs to be used. I believe that competitors can still exhibit their quick feet, quicker thinking, and signal interpretation abilities even if the signals they are hunting are relatively strong. Furthermore, we need to have events that accommodate inexpensive receivers in order to lower the cost-of-entry to the sport. And this could be done simply by requiring sufficiently-high radiated power levels from the fox transmitters and beacons.

We need to have events that accommodate receivers that pose a lower cost-of-entry to the sport.

The obvious candidate for a low-cost-of-entry event is sprint. The small field of play means that quite low radiated power levels from the foxes could be used while still allowing receivers with poor sensitivity to detect them all from every location on the competition map.

In fact, the Region 1 rules appear to require sufficient radiated power levels already. See Region 1 ARDF Rules Part B paragraph S6.1. The minimum sprint transmitter power is 300 mW. So why can’t a low-cost R3500D receiver hear all the sprint transmitters on a regulation course?

So why can’t a low-cost R3500D receiver hear all the sprint transmitters on a regulation course?

The answer: the rules do not specify the foxes’ radiated transmit power. The rules specify only the transmitter output power. The rules say nothing about the antenna match, or the antenna’s efficiency. And according to my observations, little of the minimum 300 mW of output power is actually being radiated by sprint fox antennas. At least, not on the sprint courses I have experienced in the USA.

The rules say nothing about the antenna match, or the antenna’s overall efficiency. So little of the minimum 300 mW of output power is actually being radiated by sprint fox antennas.

One solution to the apparent rules deficiency would be to specify a specific antenna design and placement. Another solution: have the rules specify the actual amount of power radiated from the sprint fox antennas. But those rules could prove difficult for organizers to implement or measure. Instead, I would suggest that the rules simply describe a reference transmitter output power and matched-feedpoint antenna system to be used for comparison.

With a standard output power and antenna design, organizers would only need to compare their fox transmitters’ signal strength to that of the reference. If the fox signals were as strong, or stronger, than the reference then all is good. If not, then the fox transmitter’s output power might be increased, or some modification to the foxes’ antennas or the antenna matching system could be made. In most cases, the comparison exercise would only need to be performed once for a given fox (transmitter plus antenna) system design.

With a standard output power and antenna design, organizers would only need to compare their fox transmitters’ signal strength to that of the reference.

Such a radiated-power reference system could be specified for each of the four event types used in ARDF. This would eliminate the need for the vague and non-existent “receiver of average sensitivity” called for in current Region 1 rules (see Part B, paragraph 27.3).

The reference-based approach could allow low-cost receivers to work just fine for sprint, and perhaps some other events as well. Allowing newcomers to fully participate in at least one ARDF event format for an initial investment under US$50 could prove to be a big deal.

What is a USA ARDF Championship?

It is that time of year again. The 2019 USA and IARU Region 2 ARDF Championships are in the rear-view mirror. Now we see in the dim glow of the headlights the 2020 USA ARDF Championships up ahead.

Before asking any group to take on the task of hosting the 2020 USA ARDF games, it is only right to inform them of what is involved in that undertaking. To do that, we need to take a careful look at what constitutes a USA ARDF Championship.

What We’re Talking About

The USA Championships is not the World Championships nor even an IARU Regional Championships. It is the ARRL-sanctioned ARDF games customarily held on even-numbered years. The results of which are used to help determine who is extended an invitation to participate on Team USA at the next World Championships and, potentially, at other international or inter-regional ARDF competitions.

Below, components of a USA Championships are divided into three groupings: Essential, Important, and Nice-to-Haves. The names are pretty self-explanatory. It ain’t a USA Championships unless all the essential items are provided. The Championships are improved by adding more of the important elements. The nice-to-haves are just icing on the cake.

For brevity, not every component of a USA Championships is listed: just those that require a significant investment of planning, time, effort, or funds. Justification for each item’s categorization is not provided below. Healthy debate over differences of opinion is encouraged. But remember when debating: those who choose to host a USA Championships have a much louder voice in deciding how things are done for the games they organize!

For those considering hosting the USA Championships, please keep in mind that you don’t have to do or provide everything yourself. Equipment and volunteers can be provided by other groups within and outside your area. The ARDF Committee can help locate what you need.

The Essentials

Competition formats, courses, terrain, maps, transmitters, antennas, and time-recording equipment that conform reasonably closely to Region 1 rules.
Custom-designed courses for each of the age/gender categories that will be in attendance (adult and youth).
First-aid, safety and communications provisions appropriate for the venues and activities being held.
Official sanction of the competition by the ARRL ARDF Committee.

Important

High-quality orienteering maps for all courses.
A sufficient number of workers to have Start, Finish and Download areas constantly supervised while they are active.
Trained workers to set courses and pick up afterward.
Awards for the top three finishers in all age/gender categories.
Practice sessions for each competition format.
Effective advertising and communications with competitors before, during and after the championships (e.g., web site, email list, Facebook group, etc.)
A date for the competition that falls no later than June.

Nice-to-Have

Banquet.
Award ceremony.
Recently-updated maps.
Trophies or medals as awards.
Local transportation provided for competitors.
Training sessions before the practices or championships begin.
Observers stationed at foxes and keep-out areas.
Snacks and water at the finish or download area.
Special provisions for large groups of foreign visitors.
Close proximity to major airline hub.

Bottom Line

A USA ARDF Championships that provides all of the Essentials, and a majority of the Important items, could be a very successful competition even if none of the Nice-to-Haves were provided. This is particularly true if the venue were especially nice or the costs were low.

Want to jumpstart ARDF activity in your area? Perhaps hosting the USA Championships can be just the spark needed to get local hams, orienteers, Scouts, and friends involved and active in ARDF.

Questions, comments, or want to float a proposal for 2020? Leave a comment or contact the ARDF Committee at ardf@arrl.org.

USA ARDF Championships 2019

USA and IARU Region 2 ARDF Championships

Registration is open for the USA and IARU Region 2 ARDF Championships, July 28 – August 4 in Raleigh, NC.

Visitors and first-timers are always welcome at the championships events. You may attend to observe at no charge. You may register to participate in one or more of the events even if you’ve never attempted ARDF before. There will be practices and demonstrations. There are no age limits or license requirements for participants. Please contact the organizers for details.

The bulletin and link to registration are at http://ardf.us
More information at http://www.arrl.org/news/registration-opens-for-usa-ardf-championships

Rules Impact on Organizers

It seems that the precise birthdate for ARDF was never recorded. But it seems reasonable to assume that sometime in the late 1940s, as surplus World War II equipment made backpack-portable radios a possibility, some outdoor-minded hams (likely in Scandinavia) took up maps and compasses and headed into the woods to settle a bet on who had the better radio direction-finding skills. When the loser couldn’t cite a violation to disqualify the winner, the need for formal ARDF rules documents was realized.

Whatever those first ARDF rules looked like, one thing is certain: equipment availability played a major role in determining the details. Super-regenerative receivers used by the competitors likely made it necessary to maintain large distances between competitors in order to prevent receiver-to-receiver interference. High power requirements of both receivers and transmitters would have limited the time duration of competitions. The bulk of the equipment likely placed restrictions on the course length. Lack of equipment probably restricted the number of foxes that could be fielded.

The same is true today: the equipment influences the rules. Smaller, lighter, and less power-hungry equipment has allowed the rules to define events with more fox transmitters, longer overtime periods, and more closely-packed competitors. Because competitors generally outnumber the foxes, and out of the desire to keep the sport affordable for all, rules generally favor placing any added cost and complexity into the transmitters and not the receivers. But recently a problem has arisen.

Four major events are defined in recent rules documents and are featured at most championship ARDF competitions: Classic 80m, Classic 2m, Sprint 80m, and Fox-O 80m. Because the radio band, power level, and timing requirements are so different among those events, different transmitters are generally required for each event. Classic 80m requires five foxes and one homing beacon, Classic 2m requires a like number for that band, Sprint requires at least eleven transmitters, and Fox-O at least twelve. That adds up to 35 separate transmitters plus spares. Add in the same number of antennas, and organizers have a sea of equipment to construct or purchase and maintain.

A high transmitter count poses a significant burden on the competition organizers and increases the chances of hardware failure. At some point, the burden of holding an event becomes unaffordable to too many organizers. Has the point of “organizer overload” been reached already?

Flexible transmitter designs can support operation across multiple bands, power levels, timing configurations, and identification patterns. But pushing the complexity into the transmit hardware increases the cost of each transmitter, so it doesn’t solve the problem. To keep costs down, the rules need to take into account the organizer burden. The two steps below, if done together, could help prevent organizer overload.

Define events that use transmitters with identical, or nearly identical, characteristics: band, power level, timing, identification, etc.
Allow championships to include a subset of all event types, so that organizers can choose what they can best support with their hardware.

The way the Region 1 ARDF rules documents are now organized, certain event characteristics are described in the body of ARDF Rules Part B, and some are described in the appendices. For instance, Part B, Section 27 describes transmitter requirements. But not all the events described in Part B appendices adhere to the transmitter requirements in Section 27. It would make more sense to move all event descriptions (Classic, Sprint, and Fox-O) each to its own appendix, and remove all event-specific rules from the body of Part B. This would simplify rules organization, and make it easier to find and identify all the rules specific to each event. With that done, event-specific rules could be analyzed and modified more readily and with less confusion.

With each type of event described independently in its own appendix, the event descriptions could be tweaked to bring transmitter requirements of different events closer together. New events could be added to allow organizers more options. Events with similar characteristics could be grouped into event types or “families”. Organizers then might be allowed to choose from the list of approved events, selecting the ones that can most readily be supported by available equipment, provided that they select one event from each family.

Thought should be given to devising fun and challenging events that emphasize a variety of skills and abilities yet utilize existing equipment capabilities. Examples:

A relay event could test overall team strength and might include both men and women competitors on different relay legs.
A mass-start event, perhaps modeled on the popular “Goat” orienteering events, could provide a fun and entertaining race.
Group events, involving 2-or-more team members working together, could test competitors’ cooperation and strategic thinking.

The possibilities for expanding the event list, without expanding needed transmitter capabilities, are endless.

ARDF has evolved over the past 70 years. The changes suggested above should be considered as part of ARDF’s evolutionary process. Let’s innovate with the equipment, and the rules, taking care that the rules don’t impose too great a burden on either the competitors or the organizers.

Outsmarting Smart Devices

In an earlier post I argued that the Region 1 rules, as currently written, are not restrictive enough on the use of satellite navigation systems in ARDF. In a subsequent post I maintained that satellite navigation systems, particularly those contained in personal electronic devices, should be used much more in ARDF, and that it can be done is such a way that prevents the misuse of those devices. In this post, I will explore how smart devices can be brought into ARDF without changing the nature of the sport, and without putting additional burden on event organizers.

In 2017 we are marking the end of the first decade of the iPhone, which ushered in official manufacturer support for independently-developed smartphone applications: apps distributed through online stores run by the device manufacturers. But the use of these capable devices, and the apps that run on them, has made little headway in ARDF over the past decade; due in large part to how capable those devices are! The unchecked use of GPS, mapping, and communications capabilities of modern cell phones could totally transform the sport of ARDF from an individual test of navigation and radio skills, into a mass collaborative-geocaching event.

But banning all use of smart communications devices is unnecessary. Device capabilities can be restricted, and those restrictions enforced, by the same application software that makes them so useful. Rules should be put in place encouraging the legitimate use of smartphones and tablets, while putting the onus of proving rules adherence squarely on those who choose to utilize those devices during competition. Likewise, the burden of developing, testing, certifying, and distributing ARDF-approved applications should also rest on the app developers, while the event organizers monitor rules adherence, and enjoy the benefits of improved safety and efficiency afforded by the new technology.

Below is a description of how a very secure system might work. The full system needn’t be implemented if an Organizing Society considers it unnecessary. But verifiable adherence to the rules is possible, and could be used for World Championships, and similar “high stakes” competitions.

The components and participants include:

ARDF-Approved Apps: These are the only applications allowed to run on electronic devices carried by competitors. And an approved app must be running in the foreground at all times while a competitor is competing.

Rules: There must be rules in place governing what ARDF-Approved Apps must, and must not, do; As well as how they are published, stored, distributed, and utilized.

Device-Carrying Competitors – those who choose to carry a personal electronic device (smartphone, tablet, etc) during a competition are subject to certain rules that do not apply to other competitors, and must accept certain risks in order to take their devices with them on the course.

App Developers – those who write ARDF-approved applications will need to adhere to the rules regarding the apps, and apply to organizers for app approval well in advance of a competition.

Organizers – event organizers will need to take certain measures to ensure adherence to the rules by all participants. They will need to designate an Independent Authority responsible for building and submitting apps for distribution, and other technical details. Most of the adherence assurance tasks can be automated.

Independent Authority (IA) – this is an individual or a small group designated by the event organizers. The IA must have sufficient technical knowledge and resources to build and submit apps to the app stores for distribution. Those involved in IA responsibilities should be independent in the sense that they have no personal interest in the outcome of the event, or as a group they are able to oversee one another to ensure .

ARDF-approved applications must have the following characteristics:

Open Source – so that anyone can examine the source code and verify its capabilities and restrictions, and even compile and run it to test its operation.
Distributed Publicly, Worldwide, Free of Charge – on official device-manufacturer app distribution sites. This will help provide a level of control over the source of apps, making it possible to require participants to download an app under supervision, for instance.
Built and Released by an Independent Authority – an appointed individual or team will build and submit the openly-available software to the official device-manufacturer app store(s) for distribution.
Licenses applied to any software must allow others to freely copy, modify, and use the code for any purpose: truly Open Source.

Rules governing the operation of ARDF-approved applications must include at least the following restrictions:

Apps must not provide any features or functionality expressly prohibited by the rules. This would include being able to communicate with others, display digital maps, etc.
Apps must record a continuous log file in a specified format along with the competitor’s name, bib number, and any security “key” data. Logging must begin automatically at app start-up, and end when the app is closed or terminated, logging at least the following information at 10-second (or shorter) intervals: Lat/Lon position, UTC time, device’s battery level. It must also specifically log the position and time of certain device events: shutting down the app, placing the app in the background or accessing any other app, placing or receiving a phone call or digital message.
Apps must provide a verification mechanism (specified by the rules), allowing a key or code to be entered to verify two things: that the app is genuine, and that any log it generates can be traced to that installation of the app.

Competitors choosing to carry a smartphone would accept the following responsibilities:

To run a single approved app at all times while on the course, never shutting the app down, placing it in the background, running another app, or using the device for communication (except in emergencies).
Submit the full log file recorded during the event directly from the device to the organizers, within 5 minutes of reaching the finish. This could be done automatically by email after reaching the finish.
Accept the consequences of a system crash, loss of the phone, or any other event that could affect the recorded log file: resulting in the disqualification of the competitor.

ARDF-approved-app developers would accept the following responsibilities:

Release and publicly post all source code to a version-controlled open-source distribution site (e.g., GitHub) before the published deadline: this could be six months or more prior to the date of a championships, to allow time for the Independent Authority to build and submit the apps to the app stores, and for the apps to be approved and released on the stores.
Defray any cost incurred by the Independent Authority in order to submit the app to the app store(s). A nominal fee could be charged to the developers in order to cover any costs incurred by the IA.

Organizing Society Responsibilities

The society responsible for organizing a competition will have the following responsibilities:

Validate personal electronic devices to be used by competitors to ensure compliance. Entering a short unique “secret key” into each competitor’s ARDF-approved app should be all that is needed to accomplish this task.
Collect all log files submitted by competitors, and confirm that the logs are genuine (inspect recorded key), and contain no entries indicating rules violations. This process could be totally automated. A sophisticated analysis tool could even identify exclusion zone violations, or following.
Investigate any detected or reported rules violations.
Organizers must have the authority to revoke the approval of any app at any time, even the day of the competition, if it is demonstrated to violate any rules. Developers of apps shown to be in violation can be banned from future participation

Since the applications are open source, freely available, and run on standard commercially-available hardware, everyone can inspect them for violations. It is in the competitors’ interest to find and report app violations, since others who use them could gain an unfair advantage. Reports of violations should be investigated by an Organizing Society, or by the ARDF Working Group, and dealt with appropriately.

Apps for Radio Athletes: Sign the Petition

We, the Signatories to this petition, recognizing that:

o Amateur Radio Direction Finding (ARDF) has been practiced in IARU Region 2 for the past 20 years.

o The IARU Region 2 ARDF Working Group has members with decades of experience in administering the sport, who are well qualified to create and establish permanent rules for Region 2.

o IARU Region 2 can better promote the growth of ARDF if the Region’s rules are tailored to best serve its participants.

o There is precedent for permitting personal electronic satellite positioning system receivers (GPS) in ARDF World Championship competitions, codified in current IARU Region 1 ARDF rules.

o The properly-administered use of smart personal electronic devices (smartphones) running specialized apps poses no greater risk of misuse than do GPS devices.

o ARDF in Region 2 can benefit from the use of smartphones, in terms of safety, and broader appeal of the sport among the Region’s populace.

o The lack of permanent rules specifically allowing the use of smartphones, provides no assurance that their use will be permitted on an ongoing basis, and therefore is a disincentive for experimenters and innovators to develop useful apps for the sport.

o The IARU Region 1 ARDF rules documents constitute a proven template for the establishment of permanent rules for Region 2, shortening the process for creating a preliminary rules document.

Therefore, we call upon the IARU Region 2 ARDF Working Group to act swiftly to:

Establish permanent ARDF rules for Region 2 no later than January 1, 2018.
Include provisions in those rules for the use of smartphones running suitable apps.
Establish that Region 2 championship competitions be conducted under Region 2 rules from January 1, 2018 onward.
Work with IARU Region 1 ARDF Working Group members to reconcile any rule differences between the Regions as appropriate, while retaining any Region 2 rules differences that specifically benefit that Region.