This site provides information on ARDF and projects to help the DF
enthusiasts equip themselves for a 2m or 80m ARDF competition or even
host an event.|
On-foot ARDF, also known as Radio-'O', has been popular in a
countries for many years, particularly in Central and Eastern Europe.
The more formal competitions, at both national and international level,
conform to rules set by the International
Amateur Radio Union (IARU).
It is a combination of Radio
direction finding and orienteering.
Five beacons are located in a
wooded site and transmit for one minute, in sequence,
on the same frequency. A unique call sign identifies each transmitter.
The objective is to work out their locations from radio bearings,
devise a route plan and then visit them,
on foot, as quickly as possible.
Each competitor has a receiver
and a compass and is given an individual start time.
At, or near, the time of the
departure, the organizer will issue a map (1/10000 or 1/15000) showing
only the course start and finish.
A control card is also issued, and must be marked with a pin ( or
at each transmitter location as proof of discovery.
Each transmitter will be
co-located with an orange coloured orienteering flag.
The competitor, using his/her
receiver, will try to identify
the location the various beacons, by taking bearings and optionally
plotting them on a map.
Your radio bearings may
initially be ambiguous and you will need to refine your route plan as
you progressively uncover the location of the controls.
Some will follow bearing
directly, others prefer to circumvent
obstacles by map reading, and then use well marked paths... it is all
is matter of strategy.
A popular 'handy cap' format in
the UK is to specify a different number of transmitters to find, (from
3 up to 5), for various age group but with a single results list.
The winner will be the one who finds their quota of foxes in the
In larger international ARDF events these age categories will be kept
On average, the event is
limited to 120 minutes. Penalties for going over the limit are very
severe. If you do over-time you will be ranked by time alone,
regardless of the number of transmitters found !
International events usually
take place over two days.
One day using 2 meters (144MHz), the other day using the 80 meters band
At first sight you may think ARDF is more like tracking animal radio
tags or using a metal detector, but remember, the beacons only transmit
for a maximum of 1 minute in 5.
You try to estimate your control locations when the beacon is active
and then map navigate to, and between them, exactly as you would in
Orienteering. Following a straight line route, as in foot-O,
will rarely be the productive option.
The biggest problem for established orienteers is - it will take 3
or 4 events to master the radio techniques . Unfortunately in this
learning period the radio aspect is likely to completely dominate.
If you can persevere, you will be rewarded for your efforts because
thereon, Orienteering skills and fitness will be the key to becoming
2m Events in Region 1 continue to use AM for the MCW Morse code
signature, in contrast to 'new world' regions, where FM has been
adopted, due to the popular of the FM-handy.
stick with AM? It's primarily a
legacy from the long establishment of ARDF in Region-1, but staying
with AM has advantages.
Simple manually controlled AM
receivers, without AGC, make very good DF receivers. i.e. the volume of
the received signal is relative to the signal strength.
The availability of simple
cheap receivers which are intuitive helps to keep the 'sport' open for
beginners, youth and non-amateurs.
The logistics of organizing an ARDF event are much more demanding than
a club 2m foxhunt. You will almost certainly need help to assemble all
the equipment and need participants from outside your club to make it
Planning an ARDF event shares a
lot in common with traditional orienteering.
Establishing contact with your local Orienteering Club, is very highly
recommended. Orienteering Clubs will have maps and knowledge of
suitable venues. In addition orienteers with a passing interest in
technology or Amateur Radio are often keen to try ARDF.
Most Orienteering events are
open to all, with 'colour coded' courses for a wide range of ages and
abilities. Just going an event and seeing the organization, will prove
to be a valuable experience. If you feel a little more adventurous,
take a compass with you and try a beginners 'Orange' course for a
British Orienteering Federation
web site for more information.
Please let the existing UK ARDF
community know of your ARDF activities so, they can coordinate a
national events calendar.
See the RSGB
Amateur Radio Direction Finding Committee Site
for more information.
Only simple receivers and QRP
transmitters are required for ARDF, so home brewing equipment is
economic, rewarding and productive.
All the designs and commercial
products on this web site have been extensively field or event tested and more probably
Please contact for further details on the availability
and pricing of the advertised items. This web site is non-commercial, therefore supplies may be erratic!
2m ARDF Projects
|WB2HOL 3 element yagi
|ROX-2T 2m integrated AM
receiver using the TA7613AP (TDA1083)
|2m ARDF Transmitter
- Construction details
- Double sides,
through-plated PCB - £6.00
- PCB with a ICS525R
driver chip and Xtal fitted and tested.
|| £20.00 (1st) £15.00 (repeats)
G3ZOI. (only supplied in small
quantites to ARDF enthusiasts)
configurable clock multiplier.
Up to 50mW output at 145Mhz using a standard xtal.
|These are now available ex-stock from www.digikey.com
|TA7613AP (TDA1083) 1
chip AM/FM radio
|TOKEN 10.7mHz filters
||20kHz, 110kHz or 150kHz-£1.00 each