GeoFox Engineering: Tweaking Course and Event Factors for Success

As my good friend Bob KØNR likes to say, “The universal purpose of amateur radio is to have fun messing around with radios.” And the key word here is fun. But why limit fun to only messing around with radios? Why not have fun with radios and other gadgets together? That’s exactly what GeoFox is all about!


GeoFox is the clever blending of the popular geocache sport with radio transmitter hunting, orfoxhunting. Hence the name, GeoFox. With some careful consideration and planning, these two technologically based amusements reinforce one another and multiply the fun had messing around with radios and other gadgets in the outdoors. GeoFox is a terrific way to introduce newbies to amateur radio or to really challenge those grey beard foxhunters. In this article we’ll consider many of the factors crucial to establishing a successful GeoFox event tuned to the experience level of the intended participants and the event goals. But first, let’s briefly review the fundamentals of the two activities that are artfully mixed in GeoFox.

gf_gps_deviceGeocaching: Geocache enthusiasts use handheld GPS receivers to track down hidden caches that have been concealed by other geocachers. A cache may consist of a sizable water tight container of exchangeable trinkets, notes, and almost always a visitor’s log. Alternatively, micro-caches may be simply a small visitor’s log and pencil tucked into a tiny container and cunningly hidden to increase the challenge of the find. Internet web sites are commonly used to register and advertise the latitude-longitude coordinates of caches, whether in metropolitan areas, in the middle of a public park, or high on a forested mountaintop. Geocache hunters download the coordinates along with any hints provided by the cache owner, and they take off in search of the prize. It makes for an interesting way to explore new areas, to take a great hike or car trip, or to discover interesting new things about a location.

Foxhunting: Foxhunters use radio direction finding equipment to track down a hidden transmitter. The transmitter is usually cleverly camouflaged or hidden, and sometimes positioned to create some frustrating and misguiding RF reflections. Usually the transmitter will transmit for brief periods of a few seconds in regularly timed intervals. Various types of equipment and augmentations to receivers can be used to improve hidden transmitter hunting performance. For instance, a common tool used by foxhunters is attenuator circuits that allow a receiver to be variably adjusted in sensitivity. This way, when the foxhunter gets close to the transmitter the received signals can be attenuated to maintain good directional signal strength variability. If your received signal strength indicator shows maximum signal strength in every direction, it is rather difficult to locate the fox! Yagi or directional loop receiving antennas are often coupled with attenuators, HT radios, various tracking and receiving techniques, and other receiving equipment to track down the transmitter as efficiently as possible. [Direction Finding, ARRL].In GeoFox, a hidden transmitter find reveals the latitude-longitude coordinates for a GPS-led cache hunt. Find the geocache and you find the frequency to tune for another hidden transmitter. In each type of find additional clues may be provided to assist the GeoFoxers, or possibly as accumulating keys to a grand puzzle to solve. The goal may be to find all of the caches and foxes in a strictly prescribed sequence and perhaps in a timed competition with others. Alternatively, the goal may be to find the most caches and transmitters in a random sequence determined by the participants, usually in a strictly limited event time.Many creative variations on GeoFox are possible with the selection and design of course characteristics. By tweaking several factors an event’s character and a course’s difficulty level may be adjusted. Let’s begin our examination of these design factors with an example GeoFox event as an introductory reference point. My GeoFox experience has been in creating Boy Scout events with my central Colorado-based troop.


GeoFox teams each used Yaesu FT-60R HT radios and home-brewed tapemeasure Yagi directional antennas.

Colorado Troop 6 GeoFox: The troop’s first GeoFox event was featured in QST Magazine in August 2011, and also in Boys Life Magazine in October 2011, and a second similar event was held the following year. The purpose of these events was to exercise land navigation skills, to improve radio operational skills, and to introduce new scouts to amateur radio fun. Each of the scouting GeoFox events was a team competition format, with teams balanced in experience, membership, and equipment. The equipment allowed to each team was very basic, as it was not feasible to equip all teams with attenuators or more advanced receiving equipment. Each event was held in a remote forested mountain area with multiple 2-meter band hidden transmitters and multiple hidden geocaches, all to be located in a strictly prescribed sequence within a few hours’ time.

Teams, Equipment, and Oversight: The scout teams were inexperienced foxhunters, but moderately experienced geocachers, and with various levels of land navigation experience through scouting. Each team was comprised of 3 or 4 members ages 10 to 15 years, with near equivalent average age per team. Six to eight total teams were deployed in each event, with total time to complete the course as the competitive figure of merit.


Scouts made their foxhunting tape-measure Yagi antennas in a workshop prior to the GeoFox event.

Each team included one or two recently licensed Technician Class ham operators with dual-band 2-meter/70-centimeter (440 MHz) HT radios. The most popular radio owned by the participants was the Yaesu FT-60R, and this rig has an S-meter with excellent sensitivity for use as a directional signal strength meter. These operators also had one home-brewed 2m tapemeasure Yagi that had been fabricated in a preceding radio workshop with adult operator assistance. The Yagi and HT, combined with simple direction finding techniques, provided basic foxhunting capability. Radio operators received training and practice in foxhunting prior to the GeoFox event.

Each team had one or two GPS receivers with which team members had familiarity. Teams also carried a magnetic compass and a terrain map of the course area with a latitude-longitude grid overlay. The teams could readily steer to geocache coordinates, take fixes with the GPS receiver, plot positions on the terrain map and make informed decisions about the best path to take for terrain. GPS operator knowledge and competence with the device was verified in advance of the GeoFox event.

Teams were required to regularly radio to the event headquarters to report their position to the adult leadership for centralized tracking, and assistance could be requested if needed. Adult marshals equipped with HT radios, GPS receivers, extra water and snacks, and first aid kits were distributed about the course area and perimeter to ensure safety.


A GeoFox course sequence on a terrain map depicting each find point and other course features. Latitude-longitude overlay grid aids participant positional awareness using GPS. Participants were provided this map without the red find point and path positional indications.

A GeoFox course sequence on a terrain map depicting each find point and other course features. Latitude-longitude overlay grid aids participant positional awareness using GPS. Participants were provided this map without the red find point and path positional indications.

The Course: Each of the troop’s GeoFox courses was a prescribed sequence among the geocache and transmitter find points through a forested, mountainous area of approximately two square miles. Two or three 2-meter transmitters were hidden along with three or four geocaches to produce a land navigation circuit of 3.5 to 4.5 miles total. Teams were stagger-started on the course sequence at 20-minute intervals to help avoid overrunning of one team upon another or the bunching up of teams along the course. Each team’s start time and completion time was recorded for the timed competition. Teams required 2.5 to 4.0 hours to complete the courses.

The fox transmitters and geocaches were alternated, although in some instances two geocaches were arranged back-to-back in the sequence for convenience of course route manipulation. Each find point, whether geocache or transmitter, provided clear and simple printed instructions to the teams. The instructions identified the type of find point to be sought next, along with coordinates for geocaches or a frequency for a transmitter. The course was arranged to begin and to end at the headquarters location.


At some of the find points teams were tasked with additional activity challenges! In one GeoFox event the headquarters staff used radio to issue a trivia question about scouting knowledge at each find point. An incorrect answer resulted in a time penalty added to the team’s total time score, or a requirement to seek an extra geocache find point along the course – teams answering correctly were awarded a shortcut that avoided the extra cache requirement. In another instance the hidden fox included Morse Code characters in its transmission, and the code characters had to be properly decoded to fill-in the last three digits of the subsequent geocache latitude-longitude coordinates. In another instance teams were allowed to evaluate an optional bonus geocache position and decide whether or not to go after it to earn a time cut. The optional cache coordinates and time bonus information were provided, but teams had to evaluate the mapped terrain, estimate travel time to the bonus cache, and decide whether or not it was worthwhile. In one event each find point provided a secret word to record, and the set of words collected had to be reassembled into a coherent phrase or statement and correctly reported at the course end point as the team’s clock-stopping action. There are many ways to add fun and competitive excitement to a GeoFox course, and these examples each worked very well.With the Troop 6 GeoFox event example in mind, let’s take a step back and consider several variables that may be manipulated to shape the characteristics and difficulty level of a GeoFox course and event.

Your GeoFox Event and Course Control Variables: GeoFox events can be a lot of fun and generate a lot of excitement when the event and course are well tuned to the capabilities of the participants. The converse is also true, of course. A too-simple course will not enthrall highly experienced foxhunters and geocachers, and a too-difficult course can quash the enthusiasm of the novice or young GeoFoxer. A rewarding participant experience requires a bit of careful control over the course variables during the design phase. Here we’ll consider seven control variables of course design that you can use to tweak the course difficulty to suit your event purposes and participant capabilities.

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      Individual, Team, or Combination Participants: Depending on your event purpose, a GeoFox event may have individual participants or team participants, or a combination of both. You may wish to create competition categories for team or individual, and possibly run these as two separate events altogether. If you have many novice foxhunters and geocachers, a team format is practically demanded, perhaps with an experienced GeoFoxer planted on each team as a guide and instructor. With young participants it may be prudent to place an adult guide on each team. As with the example scouting GeoFox events, teams may be balanced in age and experience to improve competitiveness and to ensure equitable distribution of equipment and skills. In other purposed scenarios teams may be self-formed or randomly formed. Determine your participant format and formation based upon your event participants’ backgrounds, the event purpose, and the course design.
    2. Prescription or Random Sequence: Two basic event formats may be used: 1) Prescribed Sequence, or 2) Random Sequence. The prescribed sequence was illustrated with the description of the Troop 6 scouting events. Participant teams are required to find caches and transmitters in a strict sequence. Generally, each find point provides information to only the next find point in the designed sequence. The goal is to find all transmitters and caches in the least amount of time. This event format is easier to control, more readily allows for “engineered difficulty levels,” and it promotes easier tracking of participants over a large area. However, the time required to complete an event of this format is not as easily controlled as in the random sequence GeoFox format. Let’s take a closer look at the random sequence format, as it requires some unique considerations.

      In a typical random sequence course format the participants are provided information about multiple find points and allowed to determine their own search sequence with that information, usually with limited options each step of the way. There are several ways to accomplish this, but one method is a shotgun start in which each team or participant is initially assigned a single unique find point. Discovery of the initially assigned find point provides information about two or more other find points – frequencies of hidden transmitters and/or geocache coordinates from which to select for the next goal. Depending on numbers of participants and numbers of find points, more than one wave of shotgun start may be necessary, separated in time. A random sequence GeoFox event is less controlled, but a finite time limit may be imposed since there is no requirement to find every transmitter and cache, and there is no strict course path or sequence. Competitive measures may be the number of points found in the time allotted, possibly combined with other measures such as total time out on the course or return time sequence. Additionally, a balance should be struck between the number of competitors and the total number of find points. If the ratio of participants to find points is great, participants will likely bunch up at the find points and give away the location to other approaching competitors. This diminishes the challenge and fun of discovery, but it also injects another competitive factor into the game equation – get away from the find point quickly to avoid giving your competitor the advantage of your own effort!Other considerations unique to your course will also apply to the random sequence event. See a summary list of basic considerations at the end of this article that should get you well on your way to a good course design. The random sequence format offers the course designer greater design flexibility but requires greater care and analysis than the design effort for the prescribed sequence format.

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      Terrain selection has a big impact on the character of the GeoFox course. Hilly terrain impacts radio transmitter performance and increases the physical challenge!

      Terrain selection has a big impact on the character of the GeoFox course. Hilly terrain impacts radio transmitter performance and increases the physical challenge!

      Terrain Selection: Although you may be limited in the available areas and associated terrain in which to engineer your course, terrain is obviously a factor impacting the difficulty of the course. Terrain selection implies the general nature of the course terrain as well as the specific terrain features that may be encountered along the paths between find points. Terrain is particularly significant if your course is entirely a foot course, or hiking course, involving no automobile travel. Keep in mind the following:

      1. Rolling or hilly terrain will be more physically challenging than flat terrain, and will increase travel time through the course.
      2. Rolling or hilly terrain may impose radio transmitter drop-outs in low-lying areas that can confuse novices.
      3. Dense or forested terrain reduces visibility between competing participants, masking the ability to follow along another’s lead. But the visibility of marked find points is also reduced and foliage tends to degrade positional awareness, thereby increasing difficulty.
      4. Rivers or streams, ravines, steep climbs or descents, fence lines, dense foliage, and other factors that can impose safety or physical concerns should be carefully evaluated, and usually avoided.

      In our scout GeoFox events we purposefully selected rough and rolling forested terrain to impose a challenge. Each scout had at least basic land navigation proficiency and experience, every team had one or more very experienced scout, and part of the event purpose was to improve land navigation proficiency through peer interaction. However, these young men were novice foxhunters, and even with training and practice the frequent attenuation and rocky reflections of radio signals imposed by the terrain caused problems for some teams.

    4. Find Point Visibility: One of the easiest factors to adjust, and one that offers great latitude in affecting the ease or difficulty of a GeoFox course, is the visibility of the geocache or fox transmitter position. Given experienced and capable participants with advanced foxhunting gear, you may wish to conceal the find points with camouflage or other methods, keeping the visibility near zero.


      Our young scouts were novice foxhunters using only very basic foxhunting gear with almost no close-in direction finding capability, so we made the transmitter positions highly visible among the forest foliage by planting blaze orange survey flags in the vicinity. This way, if they got within the engineered radius of visibility of the flags, they were sure to have a successful find. However, the geocache locations were made to be less visible since the GPS receiver precisely guided the hunters to the find location.By adjusting the radius of visibility almost any level of find point difficulty can be achieved – from hidden and camouflaged caches and transmitters to brightly colored, exposed, elevated, and even leading markers in the environment around the find location, or nearly anything in between.

    5. Course Area and Distances: Another rather obvious factor that is relatively easy to manipulate is the size of the course. Whether your event is strictly a foot traffic event or combines some automobile or bicycle travel, a larger area in which to search and greater distances to cover will usually extend the time required and increase the difficulty of the course. However, course area and distances interact with the terrain characteristics, conveyance, and with fox transmitter strength. A large, spread out course in difficult foot terrain can mean a long day, and it may mean that you need to use stronger transmitters within that larger area. With strong transmitters close-in foxhunting becomes more challenging and requires more sophisticated equipment, such as receiver variable attenuators. A smaller course with shorter distances usually allows lower power transmitters to be used that are easier to find with basic direction finding gear. Of course, a tiny course risks participants converging with one another frequently. Find a good balance to these interacting factors. As noted in the Troop 6 scout GeoFox event, our forested course of about 2 square miles worked well for a hiking-only course.


  • Number of Caches and Foxes: It’s no surprise that the sheer number of things to find has an impact on difficulty and time. But keep in mind the following less obvious points and recommendations:


    1. Generally, hidden transmitters require more time and effort to find than geocaches.
    2. The number of find points must be balanced with course area to avoid excessive competitor convergence or “spying,” or simple accidental viewing of another competitor’s track.
    3. As compared to inserting or shifting positions of transmitters, it is easier to insert, shift, or delete geocaches in a prescribed sequenced course to manipulate travel paths and times required. Consider the desired positions and performance of transmitters first, and then insert geocaches to finish out the course design.
    4. As previously noted, with the random sequence course format the number of find points should increase with the number of participants to reduce traffic convergences at find points and to offer greater variety of potential course paths and sequences.
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    After locating a transmitter (lower right), these GeoFoxers had to contact HQ to answer trivia questions about scouting knowledge to determine their next prescribed course goal.

    Find Point Activities: The challenge of finding transmitters and geocaches in unfamiliar terrain while racing the clock may be enough for many folks. However, there are additional ways to spice up your GeoFox event! Particularly with the prescribed sequence course format, required activities may be injected at some or all of the find points. In the random sequence format, activities will likely work best in a limited manner, perhaps at only one or two find points. This is because activities usually add to time at a find point, and delay at the find point increases the opportunity for undesirable uncontrolled participant convergences. Several different activities were described with the Troop 6 example GeoFox event earlier in this article, and they included:

    1. Trivia questions issued over radio at find points, with rewards and punishments for correct or incorrect answers.
    2. Prescribed Course Options, such as an extra find point for bonus scoring, but requiring more time.
    3. Decoding Morse Code on hidden transmitters to get complete information about another find point.
    4. Grand puzzle piece collection at find points for assembly or deciphering as a course completion time terminator.
    5. Other puzzles to solve at the find point, necessary to reveal another find point’s frequency or coordinates.

Use your imagination and come up with additional or customized activities for your event and participants, and fit the activities to your overall purpose and goals. They can be used to increase overall difficulty, to increase the potential scoring spread among competitors, to present challenges to highly performing teams or individuals, to diversify the skills and knowledge required for team success in the event, and to enhance fun and competition.

Activities can really make… or break… a GeoFox event, so plan carefully, keep it simple, and don’t overdo it with too many or too complicated activities for your participants!

Practical Advice on Course Establishment: Here are a few practical recommendations for engineering your GeoFox course.

  1. Survey prospective course areas in person to evaluate terrain first-hand.
  2. Use web-based terrain mapping and satellite imagery tools to map a tentative course, identifying potential find points and evaluating intervening terrain. Determine fox transmitter positions first, and then determine geocache locations.
  3. Develop clear and unambiguous find point instructions to participants, and have others review the instructions to ensure clarity. This is particularly important if you are implementing find point activities or course options that may be more complex than simply identifying the next cache coordinates or transmitter frequency.
  4. Find point visibility is one of the easiest control variables to adjust across a broad range of possibilities. With consideration for the desired level of difficulty, you may wish to use brightly colored markers or flags, even “leading in” young or inexperienced participants if necessary with visual markers. For highly experienced participants you may wish to conceal or camouflage the find point, making for a really challenging hunt!
  5. Geocaches are easy to position and require little testing beyond validation of the cache coordinates with a GPS receiver. However, be sure that all participants know and understand the particular coordinate format that is being used on the course. “Degrees and Decimal Minutes” format is one of the most common in use in the United States, but“Decimal Degrees” and “Degrees, Minutes, Seconds” formats are also popular.
  6. Fox transmitters can be much more challenging to position and to adjust well for a desired participant experience, equipment, and skills.
  1. Particularly in small course areas and when receiver attenuators are not readily available to participants, transmitters may require attenuation to very low power output (100 mW or less) to avoid receiver S-meter saturation far from the fox find point. This must be balanced with an ability to receive the transmitter signal from a preceding find point or while traveling along a path prescribed by a preceding find point.
  2. Metal objects in or near the course area can produce misleading reflections and steer inexperienced participants astray from the course. Try to avoid the creation of severe reflections when novice foxhunting participants are involved.
  3. In mountainous, hilly, or rolling terrain, signals may be masked or highly inconsistent when transmitters are placed in a low-lying area. Consider the experience level of your participants along with terrain when positioning fox transmitters. A high position will usually provide a more easily discovered fox.
  • Test, test, test! Run the course yourself before the event using equipment just like that available to the participants. Check for unexpected conditions such as un-receivable transmitters, overpowering transmitters, un-purposeful misguiding reflections, dangerous terrain or obstacles, or unexpectedly long completion time. If possible, have individuals unfamiliar with the course make trial runs of it as well, timing them and even observing them along the way.
  • After you have tested your course, make adjustments to the control variables to tweak it to the difficulty level, completion time, and overall experience that you seek to provide the participants. If you make significant tweaks, test again all affected course segments.
  • Provide training and practice when possible for inexperienced participants. Use course guides or marshals in the field to ensure the safety of young participants and to provide assistance if needed.
  • On event day, staff a headquarters location with strong radio coverage across the course. With novice participants it is prudent to centrally track their progress through the course by radio position reporting. The HQ staff should also maintain radio contact with course marshals or guides, providing instructions when necessary to provide aid on the course. Use a large map of the course with erasable markers or magnetic markers, or an electronic utility, to maintain a centralized status of participants, updating the map with each radio report from participants and marshals. Have more manpower at HQ than you think you’ll need, with multiple radio operators, mapping trackers, time/finds recorders, and utility players. In a busy event it is very easy to become overwhelmed!
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    Geofox events can be a blast when well designed. Courses can be established to suit brand new radio operators and unlicensed team participants, or wise, experienced foxhunters and geocachers looking for a new and different kind of challenge. By forming teams of experienced and new hunters, GeoFox offers a terrific forum in which to introduce folks to the fun to be had with amateur radio.

    I hope you’ll consider trying a GeoFox event with your group. Plan carefully, consider the recommendations and factors defined in this article, and have a lot of fun messing around with radios, GPS receivers, and other gadgets! Good luck, and 73!


    Summary Table of GeoFox Event Considerations and Impacts:

    Event Considerations Primary Course Factors Impacted
    Purpose of Event Team/individual/combo
    Prescribed or random sequence format
    Find point visibility
    Terrain selection
    Course area/distances
    Activities / Type of activities
    Terrain selection
    Participant Experience Level Find point visibility & difficulty
    Number of find points
    Activities / Type of activities
    Terrain selection
    Sophistication of Participant Gear Find point visibility & difficulty
    Course area/distances
    Time Available for Event Prescribed or random sequence format
    Find point visibility & difficulty
    Number of find points
    Course area/distances
    Activities / Type of activities

    Summary of Basic Considerations for Random Sequence Course Design:

    1. A greater number of find points will usually be necessary than for the prescribed sequence format to avoid too much coincidental converging traffic at find points.
    2. The competitive figure of merit can be the number of finds, or a scoring system in which transmitters and caches are valued differently or in which more difficult find points are valued more highly.
    3. Each find point may provide clues to multiple other find points, either transmitter frequencies or geocache coordinates, allowing participants to strategize and to choose their next goal. This can help promote triangulation for transmitter locating if participants are provided a transmitter frequency to track while hunting other caches or foxes. However, careful analysis of potential find point sequences should be undertaken to ensure feasible path sequence combinations result from the design and that closed loops or dead-end sequences are avoided.
    4. The follow-on find point information provided with a cache or fox discovery can be manipulated to extend or shorten the course. The follow-on information may provide only distant find points, or only nearby find points, or a random combination of point distances. Keep in mind the geocache coordinates will reveal the distance of the next point to find, while a transmitter frequency will not.
    5. Rules may be established regarding the requirement to locate specific numbers of each type of find point. For instance, “At least one transmitter and at least two geocaches must be found to qualify for a prize or placement.” Rules may also be imposed to steer participants within the course area, such as, “At least one geocache must be located north of 37° 06.333.”
    6. A rule should normally require that all participants return to the starting point or another designated location at or before the termination of event time. As noted, the sequence of returns (representing total time on the course) may figure into scoring schemes. Such a provision also injects another factor of strategy into the game – can you find that last GeoCache and get back to the starting line before the clock expires?

    Photos courtesy of Beth Wald Photography