Homing In

The Art and Science of Radio Direction Finding (RDF)

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Provided by Joe Moell, ham radio callsign KØOV. (That's K-zero-O-V)

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Latest RDF News Headlines

Radio-OTHRDFS cover Results and photos of the on-foot transmitter hunting session at Schabarum Regional Park on Saturday, April 19, 2014 will be in this site soon.  The next session will be Saturday, May 17 at Tri-City Park in Placentia.  There will be some practice transmitters to find plus a five-fox ARDF course that's suitable for beginning radio-orienteers.  Experts will be on hand to get you started with your own equipment or with loaner gear.  (Click for directions and times).  For earliest notification of future sessions, join the southern California ARDF mailing list.  If you live elsewhere, click to get contacts for other North America ARDF sessions. 

Boston ARDFUSA's fourteenth annual championships of on-foot direction-finding will take place near Boston, Massachusetts on the first weekend of June, 2014.  There will be formal competitions on two meters and 80 meters on Saturday and Sunday, June 7-8, plus optional sprint and foxoring events on the two prior days.  USA ARDF Championships are open to all.  Visiting competitors from outside USA are welcome.  USA's medal winners may be invited to compete on Team USA at the ARDF World Championships in Kazakhstan this September.  Registration is now open.  Latest information is in this Homing In site.

KazakhstanKazakhstan Federation of Radiosport and Radioamateur (KFRR) will host the Seventeenth ARDF World Championships, September 6 through 13, 2014. The site will be Burabay in Kazakhstan.  At least 30 countries are expected to participate, including USA.  There will be formal competitions on two meters and 80 meters, plus sprints and foxoring.  Each country may have up to three persons per age/gender category on its team.  Team USA positions will be filled based on performance in recent ARDF events, but there will be room for inexperienced foxhunters in some categories.  If you want to be on Team USA to travel to these Championships, please declare your interest.  Get the details here.

BOKCQ-VHFThe Thirteenth USA and Seventh IARU Region 2 ARDF Championships were in the beautiful Uwharrie National Forest near Asheboro, North Carolina.  The training camp, sprints and foxoring were October 9 - 11, 2013, followed by full-course 2m and 80m competitions on the weekend of October 12 - 13.  Sponsoring organization was the Backwoods Orienteering Klub.  The events were open to anyone at any skill level, with or without a ham radio license.  USA's medal winners may be selected for positions on our team to the 2014 World Championships in Kazakhstan.  There were visiting competitors from Canada China, Germany, Russia, Sweden, United Kingdom and Ukraine.  Read more about these championships and view over 90 photos in this site.

CQ-VHFThe Fall 2013 issue of CQ VHF Magazine was the last issue of that publication.  That issue is available only in digital form to current CQ-VHF digital subscribers.  In it, my Homing In column tells the stories of two unusual interference sources and how they were tracked down.  Included are construction plans for a six-meter shrunken quad that is ideal for mobile RDF.  Current CQ-VHF subscribers click here for information about how the remainder of your subscription will be fulfilled.  Your local ham store may still have the print version of the Summer 2013 issue of CQ-VHF, in which my Homing In column has the story of a new radiolocation system that may impact Amateur Radio activities on the 902-928 MHz band.  CQ Publications is now combining the content of CQ-VHF Magazine, Popular Communications and Worldradio into a new publication called CQ Plus, available as a supplement to the digital edition of CQ Magazine.  It can be viewed on PC, Mac, iPad, iPhone and Android.  My Homing In column is scheduled to appear four times a year in CQ Plus, starting with the May 2014 issue.  I welcome your input for future articles, so please continue to send me your news of mobile and on-foot transmitter hunt activities.

Foxoring mapFor three decades, international-rules radio-orienteering competitions have had two major competition days.  Each participant must compete on the two-meter band and the 80-meter band.  The 2012 USA and World ARDF Championships included competitions in two new events:  sprints and foxoring.  The sprint is a shortened form of the five-fox 80-meter ARDF run that's intended to be a demonstration for the public.  Foxoring is a combination of classic orienteering and direction-finding on 80 meters.  More information about these new events can be found here.

AppWant to see what you've been missing by not reading Homing In in CQ-VHF Magazine? Read this article from a recent issue, titled "Innovators in RDF: An Inventor, a Code Writer, and a Fox Meister." It tells about a pioneer in electronics and radio who may have patented the first switched-antenna RDF system, a new app for iPhone that triangulates RDF bearings, and the hams of Nashville who have fun with transmitter hunting and also have used it to help their community.

Quick Links to Information for Beginners
What Do You Want to Do?

CQ Mag April 2009 Learn about international-rules on-foot hunting (ARDF, radio-orienteering)

Obtain RDF equipment for two-meter hunting on foot

Attend a southern California on-foot transmitter hunt

Participate in national and world championship hunts

Learn about mobile transmitter hunting (T-Hunting) and the equipment that hunters use

Attend a southern California two-meter mobile T-hunt

Buy or build a two-meter "fox" transmitter

Learn about 80-meter transmitter hunting

Top-Hit Transmitter Hunting Topics

USA ARDFMore and more hams and orienteers are discovering the fun of tracking down hidden transmitters out in the woods. It's a worldwide sport with opportunities for friendly competition at home and abroad. A ham radio license isn't a requirement, but it makes it lots more fun. Learn the basics and get the international hunt rules at the "International Style Transmitter Hunting Comes to the Americas" page of this site.

GeohuntThe Southern California T-Hunts for Beginners page has two monthly mobile hidden transmitter hunts in the Los Angeles and Orange County area where first-timers are especially welcomed and encouraged. There is also information about the always-on GeoHunt, a two-meter transmitter that you can hunt on your own at any hour of the day or night. Mount some RDF gear on your vehicle and come on out!

T-hunting vehicleMobile hidden transmitter hunters have regularly prowled the streets in search of the elusive sources of unusual signals for more than four decades. Equipment has evolved, but the adventure and intrigue remain the same. Read "T-Hunting Then and Now -- From Gooney Birds to GPS" in this site for stories of classic mobile T-hunts in the Los Angeles area. Some of them, but not all, could be done again today. Then to find out what it's like nowadays, and to help get your club started in this activity, read "Transmitter Hunting, Southern California Style."

Ammo-can foxWhen it's your turn to hide the transmitter, what will you use? It depends on the range and duration of the hunt, as well as whether or not the transmitter must be unattended and automatic. It's important to match your foxbox and its location to the level of proficiency of the hunters. There are many options, and you can read about them in the Foxboxes for Mobile and On-foot Transmitter Hunts page in this site.

1998 World ChampionshipsUSA first attended the ARDF World Championships in 1998. The people we met and the lessons we learned helped set the foundation for our current success. Here is my classic article from CQ-VHF magazine about the first Team USA trip to Hungary. Learn how a Hungarian ham was instrumental in getting ARDF started in the Western Hemisphere. This ham became a world medal winner again in 2008.

Dual-polarization QuadFor over ten years, I have used a special cubical quad for mobile transmitter hunting on two meters. From inside the vehicle, I can select the signal polarization. Find out why this is important, why I like this antenna and how to make one for yourself in a classic Homing In column titled "Build a Multiple-Polarization Quad."

DFjrThe Agrelo DFjr Doppler RDF set has been out of production for over ten years, but there is still a great deal of interest in it. DFjr was the first inexpensive plug-and-play Doppler set designed for interface to computer mapping systems and APRS. For those who own one or are considering buying a used one, the DFjr page on this site has a downloadable manual, my 73 Magazine review, antenna system improvements, and frequently asked questions about this product.

There are over 100 additional fact-filled pages in this site, including techniques, product information and build-it-yourself projects for radio direction finding. For the complete Table of Contents and site search, click or scroll down.

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What's "Homing In?"

Homing In refers to the process of tracking down the source of a radio or other electromagnetic signal using radio direction finding (RDF) equipment.

Homing In is also the title of my regular column on RDF that ran for 15 years in 73 Amateur Radio Today magazine and is now in CQ VHF magazine. At this Homing In site, you will find more about these columns, plus RDF articles that I have written for other publications, including Monitoring Times, CQ VHF and QST magazines. There is also information about my comprehensive book on the subject.

Start of a mobile T-huntRadio direction finding is used to find sources of interference to any form of wireless electronic communications, including broadcast and two-way radio, television, and telephones. It is also used to track missing or stolen cars and other property. Search and rescue workers use it to find persons in distress. Emergency Locator Transmitters in downed aircraft are tracked with RDF techniques.

Most of the information at this site pertains to RDF equipment and techniques for Amateur Radio (ham) operators. Hams use RDF to track jamming stations and stolen equipment, but more often, they use it just for fun. Hidden transmitter hunting has been done by hams for about fifty years and it is a growing activity. T-hunting refers specifically to hunts involving hams driving in RDF-equipped vehicles. A mobile T-hunt is best described as hide-and-seek for all ages with radio gear. When you set out on a T-hunt, you never know where you'll end up, and you have no idea what you're going to find. No form of ham radio contesting is more fun! Mobile T-hunting is done in cities and towns all over the USA, and elsewhere in the world. Depending on the frequency band and the nature of the hunt, the hunters use loop, yagi, quad, doppler and time-difference-of-arrival RDF antenna systems mounted on their vehicles. Click here for for general information about mobile T-hunting or click here for beginner-level T-hunts in southern California.

Start of an on-foot hamfest huntMobile T-hunting is called foxhunting in some parts of the USA, but everywhere else in the world, the terms "foxhunting" and ARDF refer to another kind of RDF contest, done completely on foot in large woods and parks. It's a map-and-compass sport similar to orienteering, with about a half-dozen "fox" transmitters to find in a period of two hours or so. Someday this sport, which is also called foxtailing, fox-teering and radio-orienteering, may become an Olympic event. Meanwhile, it's a fun-filled activity for your hamfests and Scout Jamborees. Try it, and you may find yourself at the next annual national USA ARDF Championships. You might even become a member of ARDF Team USA, which has competed in five foxhunting World Championships. Click here for for general information about radio-orienteering or click here for beginner-level ARDF events in southern California.

Keep reading---you will find lots more about foxhunting, T-hunting, and other uses of RDF at this site.

What's at the Homing In Site?

Find your topic of interest below in the complete Table of Contents (or as some call it, the Site Map). Or you can Click here for the Site Search page.

Getting Started -- The basics

RDF Topics in Print -- Read all about it

Home-built RDF Projects -- Inexpensive and educational

Commercial RDF Equipment -- Getting the most from it

Follow-up and Support -- for readers of THRDFS and Homing In

Championship Radiosports -- Taking on the world

Results, stories and photos of ARDF sessions, large and small

Volunteer Opportunities -- Use your RDF skills to help researchers and protect wildlife

Other resources

Spending a few minutes at this Homing In site will give you a jump-start into the world of transmitter hunting. After that, you can find out how to get involved in mobile T-hunts in your area by visiting local T-hunt/foxhunt web sites and contacting nearby Homing In Correspondents listed on the links page. You'll find manufacturers and suppliers of RDF gear there, too.

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Joe MoellWho is KØOV? A registered professional electronic engineer and an active Amateur Radio enthusiast since age 11, Joe Moell KØOV has over 40 years of experience designing radio-frequency circuits and systems for broadcast, communications, and radar, ranging from near-DC through microwave frequencies. He has designed new devices for radio direction finding and has written about RDF and other topics for almost every ham radio publication in the USA. In February 1998, he was appointed by the American Radio Relay League (ARRL) as the USA's first ARDF Coordinator, to promote international-style foxhunting and to organize Team USA for international ARDF competitions. He also conducts the annual CQ Worldwide Foxhunting Weekend.

Joe collaborated with Tom Curlee WB6UZZ to write TRANSMITTER HUNTING---Radio Direction Finding Simplified, a comprehensive text on RDF, and has written over 230 published articles on the subject, including his monthly Homing In columns that ran for 15 years in 73 Magazine and now appear in the quarterly CQ VHF Magazine. As a Technical Advisor to ARRL Headquarters, he authored a new chapter on RDF for The ARRL Handbook and has made more than 100 presentations on transmitter hunting to clubs, conventions, classes and seminars. As time permits, he is available for private engineering consulting.

Joe and April (WA6OPS) Moell are graduates of the University of Nebraska. They have served as Course Marshals and Jurors at international foxhunting championships. When not participating in transmitter hunts or writing about it, they teach ham radio licensing courses and help support the emergency communications needs of the hospitals in their county.

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G-RatedHaving problems browsing here? No pages are "under construction," but linking errors and server glitches can occur. If you get an error message when attempting to link to a page at this site, please send e-mail to me, stating which page you could not access. Also please report any stale links you encounter or any problems in displaying these pages. They are designed to look good and load rapidly on any browser version and at any screen resolution. They're printer-friendly, too. No annoying frames, fancy backgrounds, pop-up windows, animations, Google ads, background music, tickers, sponsored links, cookies, third-party banners or LIKE buttons here --- just an abundance of original and useful information, suitable for all ages. My privacy policy is very simple: I don't collect any identifiable information about you when you surf here. If you send me an e-mail inquiry or buy a book, I won't give your e-mail address or other information to anyone else without your permission.

Although not about RDF, another great ham place to browse is the Hospital Disaster Support Communications System (HDSCS) site. There you will learn how volunteer Amateur Radio operators can be an important backup communications resource for hospitals, if the hams are well organized and trained. The eighty members of the HDSCS in Orange County, California have served over 35 hospitals in over 115 communications emergencies during the past 30 years. We have rapidly responded following earthquakes, wildfires, floods, power outages and internal switchboard failures. If you think that your local ARES® or RACES group is presently serving all of the disaster communications needs of your community, you may consider taking on a new mission after seeing this site.

Surfing suggestion: For a quick start into the world of RDF and mobile hidden transmitter hunting, jump to Let's Go T-Hunting.

 

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Please note that this Web site is built and maintained independently by Joe Moell. It is not sponsored by or affiliated with CQ Publications, 73 Amateur Radio Today, Wayne Green Enterprises, TAB/McGraw-Hill, ARRL, or any other commercial or non-commercial entity. All content is protected by applicable intellectual property laws.

Entire site Copyright © 1996-2014 Joseph D. Moell. Text, photos and original graphics may not be served or reproduced elsewhere without permission.

StudySphere Award Contact info:
Joe Moell
PO Box 2508
Fullerton, CA 92837
k0ov@homingin.com

This page updated 19 April 2014

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Mobile T-Hunting | ARDF/Radio-O | CQWWFW | Local Events | Wildlife Tracking | Projects
Site Map | About | News | Results | Foxboxes | FAQs | Book | Articles | Mail Lists | Links | Search | Contact