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 well1

Basically quite simple equipment is needed

1.Directional Antenna with acceptable back to front ratio (we use 4 to 7 element yagis)2.Mast (pipe etc.) with some sort of bracket3.360° scale with pointer fitted to the mast4.A topographical map of the area5.A compass or/and a small transmitter (mW) for finding „North“6.145 MHz Receiver with analog S-Meter

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Procedure/Rules (just an example)A: Taking Bearings

1.5 foxes (VHF 10 to 20W, horizontal halo antennas) are hidden within an area of 6 x 10 Miles2.They transmit a carrier for 2 Min one after the other on the same frequency. 3.A second round transmission will follow for 1 Min each totalling 15 Min transmission time4.A 45 to 60 Min time will be given to the hunters to search for a second position5.Again the foxes will transmit as mentioned under 2. and 3.6.The bearings should now cross within the area. The positions of the foxes will be marked on a 1:50,000 topographical map

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Procedure/Rules (just an example)B: Visiting Foxes

1.After the maps have been marked with the position of the 5 foxes, the maps have to be delivered to a check point2.Three of the foxes will now start continuous transmission on the same freqency.3.The hunters have now to visit all three foxes

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Evaluation

1.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.2.As the above normally cannot happen, the hunter will get minus points for each mm offset. (1/16“?)3.For foxes being visited, the hunter will get additional points: 50 for the first, 30 for the second, and 20 for the third fox.4.A maximum of 350 points are theoretically possible

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Potential

1.We do fox hunting in northern German for more than 40 years2.We continuously tried to improve the equipment in order to achieve

o Higher precisiono Easier assembly /disassambly of antennaso Motor driven antennaso Computer control

3.Also the rules have been adjusted in order to avoid racing and exidents

o Allow sufficient timeo Give beginners a chance

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Sophisticated Radio Direction Finder

1.Roof rack mounted motor unit witho Car wiper motor including contol electronicso Angle sensor either by potentiometer or industrial angle

sensoro Processor controlling RS232 and combining S-Meter

reading and angle

2.Software running under Microsoft Windowso Controlling antenna turningo Listing bearings including statisticso Showing antenna patterns o Controlling digital topographical map o Drawing bearings and positions on mapo Showing position from GPS mouse

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Configuration

RS232 Data1.Motor commands2.Angle & S-Meter as

digital text string

Receiver

145145

S-Meter (analog)Notebook Computer

yagi

Motor unit

8

HunterSoftware

Position 1

9

HunterSoftware

Position 2

10

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

HunterSoftware

ManualControl

Needed forservice

12

HunterSoftware

Configu-rationofCOM Portsandalgurithm

13

HunterSoftware

Information

Initialisation&Evalution

14

DK5BDatPosition 1

ready fortakingbearings

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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. (www.dj4ta.de)

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: www.mobilfuchsjagd.de (unfortunately in German) 16