|Exact name||Foxhunting / Fuchsjagd|
|Generated Design (experiment here)|
|Description||Find hidden radio transmitters|
|Persons working on||RealD
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|Tags||Foxhunting, Game, foxhunting, fox hunting, foxoring, Fuchsjagd, Amateurfunk, find, hidden, radio, beacons, transmitter, 2m, 144Mhz, ARDF, Amateur Radio Direction Finding, Amateurfunkpeilen, hamradio, ham radio, Geofoxing, geocaching, SDR, software defined radio, RTLSDR, rad1o|
|Located at village||Village:TMS|
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MCH2022 Foxhunting is over! Winner is Oh8etb who found all 5 foxes in under 1 hour. See you all at next camp!
Map as pdf: https://tildepipe.de/mch2022/Printkarte0.1.pdf
- Go to the marked search points and start your receiver.
- Find transmitter signal between 144.000 and 144.005 Mhz.
- Go to place with strongest signal and find tag (Example tag here) with station code.
- Log fox online. (URL on Tag)
- Repeat until you have found all foxes.
- The nearest transmitter may not be the strongest. Remember the place if you listen to several transmitters at once. This might be a good place to go back if you have found the stronger one.
- Pay attention to the different beep patterns. From which direction is which signal coming?
- Foxes beep (in different patterns). If you receive a constant signal this is not from a fox.
- It is not necessary to cross heavy vegetation. Stay on the paths as long as possible!
- Be careful! Don´t hurt yourself or somebody else!
- Do NOT open a transmitter! Please. They are old and fragile.
- If something is not working please report to User:RealD .
- Have fun!
- Please tell your friends about this.
One out of:
- RTL-SDR/Hackrf/Rad1o with OTG capable Android phone with RTL-SDR driver and demodulator app (RF Analyzer with SDR driver seem to work). Bring a powerbank to recharge you phone during run. RTL Sticks consume surprisingly much power.
- RTL-SDR/Hackrf/Rad1o with PC and installation of gqrx (Linux, Mac)/SDR# (Windows) or similar. Second person might be helpful to carry all the stuff. :-)
- RTL-SDR/Hackrf/Rad1o with PC and installation of gnuradio if you want to create a receiver by yourself.
- Any receiver for 144Mhz region with SSB (or CW) demodulation mode.
Directional Antenna recommended. For some antenna building ideas see the #FAQ: below.
Settings to start with:
- Frequency range is 144.000000 - 144.005000 Mhz
- Set demodulation mode to SSB (USB or LSB). Tune slightly next to the signal to hear a tone. Of course you can use CW mode but then the frequency has to fit exactly.
- Set RF gain to manual mode. Start with a medium or smaller value.
- Disable automatic gain control if possible.
- It might be helpful to zoom into this small frequncy range
- The spectrum should look like: File:Spectrum_Example.png
- What is a fox?
- A radio transmitter transmitting different beep codes. Here they will have a very small range (50-150m).
- I see a strong continous signal. Is this a fox?
- Probably not. Might be a harmonic of the local oscillator of your RTL stick. Disconnect your antenna; if the signal is still there it can´t be a fox.
- I want to build my own transmitters. Where can I find instructions?
- Maybe here: http://www.df1fo.de/index.html#2mTX . Please be aware that you normally need an amateur radio license in your country.
- I want to build my own directional antenna. Where can I find instructions?
- Yagis here: https://www.qsl.net/dk7zb/PVC-Yagis/3-Ele-2m.htm
- Tape Measure antenna: https://www.instructables.com/The-Tape-Measure-Antenna/
- Can I borrow a directional antenna for 1 or 2 hours at this event?
- Yes. I can offer one with SMA and MCX connectors and one RTL-SDR dongle. Please contact User:RealD.