KQ6XA Bonnie Crystal
Radio-Orienteering in a Compact Area
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The New "Walking Foxhunt"
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What is ROCA?
ROCA is currently an experimental event under development by ROG. It is intended to be fun and skillful for all ages and physical conditions of the participants, with emphasis on Radio Direction Finding.  It is a modified ARDF Radio-Orienteering competition with a much smaller course and more transmitters. ROCA was originally patterned after the "Technical Class ARDF" rules which have been proposed by the China group as a separate class of International ARDF competion. ROCA is now developing into an event which can be held in a variety of locations such as small parks, urban or suburban environments, school campuses,and  hamfests, at night or in the daytime.

Skilled Direction Finding, Not Running
The smaller size of the course increases the skill needed to differentiate between the transmitters, and eliminates any advantage of running in the course. Thus, it is a competition for the best radio direction finding skills, but with some need to walk around to zero-in on the exact locations of the camouflaged transmitter beacons.

Many Beacon Transmitters, No Morse Code.
All of the 6 to 24 camouflaged low power transmitters are on the same frequency, transmitting for about 10 seconds out of every minute. The transmitters identify over the air with audio using voice chips, thus they can be readily differentiated from each other without the need to know Morse Code. The finish line has a transmitter operating continuously on another frequency with announcements about the event.

The participant copies a number from a numbered index card which is placed near each real transmitter. However, dummy cards with dummy numbers are also placed randomly thoughout the course! The participant with the most valid numbers (minus the dummy numbers) at the end of 2 hours wins. In case of a tie, the participant with the best time wins.

ROCA at Hamfests or Flea Markets
ROCA can be played at a Hamfest or other event where many beacon transmitters are placed on people who move about the event. Standard name cards can be used as control marks.

Typical ROCA Event

Objective and Course
The objective in ROCA is for Participants to find as many of the hidden transmitters as possible and report to the Finish Line before the time limit expires. The time limit is usually about 2 hours, depending upon the number of transmitters and difficulty of the course. The ROCA event takes place in a suitable area such as a small park, campus, or hamfest. The walking distance is about half a mile (or less than one kilometer). Participants may start all at the same time, or at staggered intervals if there are many participants.

Map of the Event - Start and Finish Lines
Each Participant is given an Official Event Map with the boundaries of the event marked. A Start Point and Finish Line are also marked on this map. The finish line has a continuous homing beacon on a different frequency from the other transmitters. The Finish Transmitter also carries announcements about the event. At the Finish Line, all scores and times are posted on a scoreboard for everyone to see. Winners are announced at the end.

Identifying Hidden Transmitters
Between 6 and 24 concealed transmitters are hidden within the boundaries of the event. These are called Control Transmitters. Each of the Control Transmitters sends a beacon with a unique voice identification for about 10 seconds out of each minute, sharing the same frequency at random or synchronized timing. They are camouflaged or completely hidden from view, and use low power (about 10 to 200mW).  Each transmitter is assigned a letter of the alphabet. Typical audio transmissions would be repeated single words by voice such as "Alpha... Alpha... Alpha."  or "Delta... Delta... Delta." or phrases such as "Anyone out there? Can you find me?".  Another possible audio transmission might be a distinctive sound such as "glass breaking", "random tones", or "train whistle".

Control Marks

Radio Orienteering Group Patch (ROG)
Official Control Mark
(actual size)
Each Control Transmitter has a postcard-size numbered sign (such as the one above) mounted near it called a Valid Control Mark. "Dummy Control Marks" looking exactly like Valid Control Marks are randomly placed throughout the course but not at transmitters. It is up to the skill of the Participant to determine Valid marks from Dummy marks.

Score Cards and Markings
Participants keep a score card (called a Control Log) of the marks they find, and give their score card to the judge when they reach the finish line. Each Valid Control Mark counts one point, but a Dummy Mark counts one negative point!

ROCA Control Log 
(Participant's Score Card)
Participant Name Participant Callsign (optional) Participant Team (optional) Participant Category Participant Signature and Date
25 - 35
Ronnie Radeow 
17 April 1999
ROCA EVENT: Bay Area National Foxhunting Weekend 
DATE: 17 April 1999 
ORGANIZER: Radio Orienteering Group
Control Transmitter
Control Transmitter Identification Audio Signal
Control Mark Number
Valid Control Mark
judges use only
+ 1 Point
Dummy Control Mark Score
judges use only
- 1 Point
"Alpha. Alpha. Alpha."
"Bravo. Bravo. Bravo."
"Excuse me, let me out of here!" (toy voice).
"Warning, Warning! Danger, Will Robinson. That does not compute." 
(robot voice)
"Echo. Echo. Echo."
"Foxtrot. Foxtrot. Foxtrot."
sound of glass breaking
"Here, lizard, lizard, lizard!"
sound of star trek phaser
sound of random tones
Start Time 
judge use only
 10:43 Control Score 
judge use only
 + 8
 - 1
Finish Time 
judge use only
 12:14 Total Score 
judge use only
Judge Initials 


Total Time 
judge use only
 1:31 RANK 
judge use only
 2nd Place
Final Judge Inititials 


 Radio-Orienteering in a Compact Area (ROCA)
Table of Terms, Rules, and Procedures for Organizers and Participants
Draft ROG981127E  by Bonnie KQ6XA 
Participant The Participant is the individual person who takes part in the event for score.
Age or Gender Categories If Categories of Participants are designated, the Category definitions should be clearly announced by the Event Organizer in the pre-event publicity prior to the event. It is suggested that no more than 3 separate categories be used to differentiate between age of participants. It is suggested that no categories be based upon gender.
Score Score is the number of Valid Control Marks listed minus the number of Dummy Control Marks listed by the Participant on the Participant's Control Log. The maximum possible Score is equal to the number of Control Transmitters. In the event of a tie, the best time wins.
Control Transmitter A Control Transmitter is a unique radio beacon transmitter used as a locating and/or scoring point for radio direction finding in a Radio-Orienteering event.
Number of Control Transmitters The number of Control Transmitters used in the event is not less than 6 or more than 24. The Finish Control Transmitter is not counted.
Transmitter Power Level The output power of each Control Transmitter is not less than 10mW and not more than 100mW.
Control Transmitter Distance The distance between Control Transmitters is no less than 5 meters. The distance between any Control Transmitter and the Finish Control Transmitter is no less than 25 meters. The distance between any Control Transmitter and the Start Point is no less than 25 meters.
Transmitter Frequency All Control Transmitters transmit on the same frequency. Suggested frequencies are: 146.565 (coordinated T-Hunt frequency) or 147.450MHz (standard microprocessor crystal). Any clear frequency within the 2 Meter Amateur Band may be used.
Transmission Audio Mode Control Transmitters use FM modulation with standard 5 kHz Deviation. 
Transmitter Antenna Any antenna with a single feedpoint may be used for each Control Transmitter. Minimum physical size of antenna radiating element is 40cm. Maximum antenna size is 1.5meters in any dimension. Ground plane is not included in antenna measurement. A full size dipole or quarter wave whip antenna is suggested. 
Transmitter Antenna Polarization Any polarization of Control Transmitter Antenna may be used. 
Transmission ON Time Control Transmitters should transmit 5 to 15 seconds per transmission. 
Transmission OFF Time ControlTransmitters should remain off the air for 45 to 60 seconds between each transmission. 
Transmission Synchronization  Synchronization of Control Transmitter transmissions is not required. If synchronization is used, no more than 21% of transmitters should be synchronized to transmit simultaneously, and these intentionally simultaneous transmitters should be located at a distance of no less than 75meters apart. 
Control Transmitter Location  For purposes of the event scoring, a  Control Transmitter Location is considered to be the feedpoint of the antenna or main radiation center of the antenna. All Control Transmitter Locations are within 1.5meters of  free publically accessable areas within the boundaries of the event as indicated on the Event Map. Control Tranmitter locations are not marked on the map, and should be kept secret from all persons except the Event Organizer, Referees, and Judges.
Control Transmitter Visibility  It is suggested that a Control Transmitter may be hidden and/or camouflaged from direct view. Tampering with visibility or camouflage of the transmitter by the Participant is not allowed. Event may be held during hours of darkness to facilitate invisibility of Control Transmitters.
Control Mark A Control Mark is designated as a unique number between 001 and 999 which is printed or written in black on a white, yellow, or orange background upon a suitable object such as paper, wood, plastic, cloth, or metal. The print size is to be 36 point or larger. The minimum white, yellow, or orange background size is to be no smaller than 12cm by 7cm (3inches by 5inches). Another background color may be used to conform to local environmental aesthetics. A verification mark or logo may be printed in addition to the number, to aid in authentication of the Control Mark.. 
Valid Control Mark A Control Mark which is placed within 1.5meters of a Control Transmitter Location is designated as a Valid Control Mark. Only one Valid Control Mark is used for each Control Transmitter Location. All Valid Control Marks are listed in the Official Event Control Log. 
Dummy Control Mark A Control Mark which is further than 1.6meters away from any Control Transmitter Location is designated as a Dummy Control Mark. The number of Dummy Control Marks is to be at least 2 to 5 times the number of Valid Control Marks. 
Control Identification Each Control Transmitter is assigned a Control ID which is a single letter of the alphabet. The Control ID is transmitted by recorded voice using ICAO phonetics and repeated at least 3 times during each transmission. No knowledge of Morse Code should be needed to differentiate between Control IDs. A list of Control IDs is to be given to each Participant prior to the start of the event. 
Alternate Control ID A common or easily recognizable word, word group, or unique sound corresponding to the Control ID may be transmitted as the Alternate Control ID instead of a phonetic letter. A list of all Alternate Control IDs must be given to every Participant prior to the start of the event.The unique sound used as the Alternate Control ID must be significantly different from other Control IDs. 
Control Log Each Participant is given a card or sheet of paper upon which each and every Control Identification is listed, along with any Alternate Control ID. A space is provided next to each Control ID to write corresponding Control Mark numbers. Control Logs are returned to the Finish Line Referee immediately upon crossing the Finish Line. The Participant is to mark their own name and team name on the Control Log prior to starting the event. The Participant is to sign the Control Log at the Finish Line at the time it is delivered to the Finish Line Referee. 
Transmitter Identification Each transmitter should transmit the call sign of the amateur station in Morse Code or voice not using phonetics. 
Starting Point The physical point at which all Participants begin the event. The Starting Point is marked on the Event Map. 
Finish Control The physical point at which all Participants end the event and return their Control Logs. The Finish Control and Finish Line is marked on the Event Map.  
Finish Control Transmitter The Finish Control Transmitter is a beacon transmitter on a different frequency than the other Control Transmitters that transmits continuously and identifies with a unique identifier which has been listed for all Participants on their Control Log and Map. The Finish Control Transmitter is located at the Finish Line and transmits with a power of 100mW to 300mW with a full size vertical dipole or ground plane antenna elevated to a height of 3 meters. It is suggested that announcements about the event be transmitted on the Finish Control Transmitter. 
Referee The referee is a person designated by the Event Organizer to be a non-participating observer and to report to the judges on any activity which may be considered an infringement of the rules. 
Finish Line Referee The Finish Line Referee is the referee which collects the Control Logs from the Participants and determines and records the final time of the Participant. The Finish Line Referee informs the Participant of the time score for that Participant. 
Start Point Referee The Start Point Referee is the referee which monitors the Start Point and verifies that all Participants start at the same time. If staggered starts are used, the Start Point Referee records the start time for each Participant in the Event Log. 
Judges The Judges determine the winners of the event and adjudicate any protests or rule judgements. Judges are designated by the organizers and are not Participants in the event. 
Team A Team is 3 to 8 individual Participants who aggregate their top 3 individual scores. An individual may designate as a member of only 1 team, prior to the start of the event. Team members must participate in the event on an idividual basis, without help of any kind from their team mates or any other person. (Exception is Extenders for differently- abled persons---see "Extender") 
Extender and Differently -Abled Participant An Extender is a person that assists a  Participant who is differently-abled. A Differently-Abled Paritcipant is entitled to have up to 2 Extenders, and is classified as a single Participant for all purposes. Only 1 Extender may operate Direction Finding equipment, and that Extender does so at the sole direction of the Participant. If radio is used for the Differently-Abled Participant to communicate with the Extender(s), that communication should occur on another frequency band than the one used by the event for Control Transmitters, and the power should be limited to less than 1W.
Time Limit A suitable Time Limit is to be determined by the organizer. All contestants must return to the finish line before the Time Limit has expired, or be disqualified. Recommended time limit is 2 hours. 
Course Distance The recommended Course Distance is about 1km to 3km. This is considered to be the distance of travel from the Start Point to the Finish Line, by the most direct route via all Control Transmitter Locations. 
Start Point The Start Point is to be designated on the Event Map. All Participants start at the same Start Point. The distance from the Start Point to the Finish Line is not less than 75meters. There are to be no Control Transmitters within 25meters of the Start Point. 
Finish Line The Finish Line is to be designated on the Event Map. All Participants finish at the Finish Line and deliver their Control Log to the Finish Line Referee. There are to be no Control Transmitters within 25meters of the Finish Line. 
Event Map The Event Map is a map of suitable scale to show the boundaries of the event on a standard letter size A4 or 8.5 by 11 inch sheet of paper. The Finish Line and Start Point are to be marked on the map. Any out-of-bounds or hazardous areas are to be suitably marked on the Event Map. A north arrow is clearly marked with the direction of true north. It is suggested that other features such as paths, roads, and topographic information using standard orienteering notation be included as well. 
Official Event Record The Official Event Record is a bound book in which the following information is officially recorded by the organizer:  
1. The Event Name  
2. The date and time of the event.  
3. The frequencies and Control  
     Identifications used for each 
4. Participants names and team 
5. Start and finish times for each 
6. Number of Valid Control Marks 
     listed by each Participant.  
7. Number of Dummy Control Marks 
    listed by each Participant. 
8. Signature of Participant. 
9. Score and ranking of each 
10. Location of the event. 
11. Official Event Contol Log and Map. 

It is suggested that photographs of the winners also be placed in the Official Event Record.

Official Event  
Control Log  
Official Event  
Control Map
The Official Event Control Log and Map of each Control Transmitter with corresponding Valid Control Mark, power level, antenna, and Control Tranmitter Location are used as the reference to judge validity of Participants scores and to aid in adjudication of other issues. Only the Event Organizer should have access to these until the Time Limit has expired for all Participants. 
Local Rules The Organizer of the event may apply additional rules to limit or enhance the event, and to facilitate the coodination of the event with the locality in which it takes place. All local rules should be clearly marked upon the event instructions and informed to all Participants in the pre-event publicity and prior to the start of the event.
Tampering With the Course Any Participant who tampers with the visibility, operation, or location of a Control Transmitter, Control Mark, or other feature of the course may be disqualified. Tampering is defined as touching, moving, disabling, or changing a feature in any way.
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Page Updated and Counter Set 07DEC1998 by Bonnie KQ6XA