1. Mobile Fox Hunting in Northern Germany by Peter, DK5BD
Using advanced motor driven direction finder and sophisticated software.
Just for information, not intended to scare hams as simple homebrew equipment can do the job as well

2. Mobile Fox Hunting Basically quite simple equipment is needed
Directional Antenna with acceptable back to front ratio (we use 4 to 7 element yagis)
Mast (pipe etc.) with some sort of bracket
360° scale with pointer fitted to the mast
A topographical map of the area
A compass or/and a small transmitter (mW) for finding „North“
145 MHz Receiver with analog S-Meter

3. Mobile Fox Hunting Procedure/Rules (just an example)
A: Taking Bearings
5 foxes (VHF 10 to 20W, horizontal halo antennas) are hidden within an area of 6 x 10 Miles
They transmit a carrier for 2 Min one after the other on the same frequency.
A second round transmission will follow for 1 Min each totalling 15 Min transmission time
A 45 to 60 Min time will be given to the hunters to search for a second position
Again the foxes will transmit as mentioned under 2. and 3.
The bearings should now cross within the area. The positions of the foxes will be marked on a 1:50,000 topographical map

4. Mobile Fox Hunting Procedure/Rules (just an example) B: Visiting Foxes
After the maps have been marked with the position of the 5 foxes, the maps have to be delivered to a check point
Three of the foxes will now start continuous transmission on the same freqency.
The hunters have now to visit all three foxes

5. Mobile Fox Hunting Evaluation
If the foxes are marked in their exact position, the hunter will get 50 points for each fox. In this case 250 points are the maximum.
As the above normally cannot happen, the hunter will get minus points for each mm offset. (1/16“?)
For foxes being visited, the hunter will get additional points: 50 for the first, 30 for the second, and 20 for the third fox.
A maximum of 350 points are theoretically possible

6. Mobile Fox Hunting Potential
We do fox hunting in northern German for more than 40 years
We continuously tried to improve the equipment in order to achieve
Higher precision
Easier assembly /disassambly of antennas
Motor driven antennas
Computer control
Also the rules have been adjusted in order to avoid racing and accidents
Allow sufficient time
Give beginners a chance

7. Mobile Fox Hunting Sophisticated Radio Direction Finder
Roof rack mounted motor unit with
Car wiper motor including contol electronics
Angle sensor either by potentiometer or industrial angle sensor
Processor controlling RS232 and combining S-Meter reading and angle
Software running under Microsoft Windows
Controlling antenna turning
Listing bearings including statistics
Showing antenna patterns
Controlling digital topographical map
Drawing bearings and positions on map
Showing position from GPS mouse

8. Mobile Fox Hunting Configuration yagi USB Data Motor commands
Angle & S-Meter as
digital text string
Motor unit
Arduino control
Receiver
Notebook Computer
145
S-Meter (analog)

9. Hunter Software Position 1
Mobile Fox Hunting
Hunter
Software
Position 1

10. Hunter Software Position 2
Mobile Fox Hunting
Hunter
Software
Position 2

11. Hunter Software, Hunt-Window for visiting foxes incl. map
Mobile Fox Hunting
Hunter Software, Hunt-Window for visiting foxes incl. map

12. Hunter Software Manual Control Needed for service
Mobile Fox Hunting
Hunter
Software
Manual
Control
Needed for
service

13. Hunter Software Configu- ration of COM Ports and algurithm
Mobile Fox Hunting
Hunter
Software
Configu-
ration of
COM Ports
and
algurithm

14. Hunter Software Information Initialisation & Evalution
Mobile Fox Hunting
Hunter
Software
Information
Initialisation
&
Evalution

15. DK5BD at Position 1 ready for taking bearings
Mobile Fox Hunting
DK5BD at
Position 1
ready for
taking
bearings

16. Mobile Fox Hunting
Fox Hunting is great fun and also a social event involving quite a number of hams either as hunters or as foxes.
The mechanical motor unit including 2 microprograms have been
developped by Horst, DJ4TA. The first control software has been programmed in VB also by him. (
The new control software „Hunter“ based on Horst‘s VB software has been programmed by Jan, the son of DK5BD in C#. Jan studies IT at Bremen Universty in Northern Germany.
There are comprehensive details about our Mobile Fox Hunting competitions here: (unfortunately in German)