Session:2m Foxoring

Description Find small hidden radio transmitters
Type Hands-On
Kids session No
Keyword(s) game, outside
Tags Foxoring, ARDF, Hamradio, ham radio, Amateur Radio Direction Finding, Amateurfunkpeilen, Geofoxing, geocaching, SDR, software defined radio, RTLSDR, RTL-SDR, Fuchsjagd, Amateurfunk
Person organizing User:RealD
Language de - German, en - English
de - German, en - English
Related to Projects:2m Foxoring
Other sessions... ... further results

Starts at 2019/08/20 18:00
Ends at 2019/08/25 18:00
Duration 7200 minutes

Subtitle 2m Foxoring - Day 1
Starts at 2019/08/21 00:00
Ends at 2019/08/22 00:00
Duration 1440 minutes

Subtitle 2m Foxoring - Day 2
Starts at 2019/08/22 00:00
Ends at 2019/08/23 00:00
Duration 1440 minutes

Subtitle 2m Foxoring - Day 3
Starts at 2019/08/23 00:00
Ends at 2019/08/24 00:00
Duration 1440 minutes

Subtitle 2m Foxoring - Day 4
Starts at 2019/08/24 00:00
Ends at 2019/08/25 00:00
Duration 1440 minutes

Subtitle 2m Foxoring - Day 5
Starts at 2019/08/25 00:00
Ends at 2019/08/25 18:00
Duration 1080 minutes

Find small hidden radio transceivers! They are hidden around the campsite. Play and learn about radio signal propagation, antennas and demodulation. See the area around the camp site. Have a nice walk. And of course, it´s fun, too. :-)

So bring your 2m radio receivers or SDRs. Directional antennas are helpful, too.


  1. Find red circle on map (File:2m Foxoring Printkarte v1.pdf). Go there and start your receiver.
  2. Find transmitter signal between 144.000 and 144.004 Mhz.
  3. Go to place with strongest signal and find tag (Example Tag) with station code.
  4. Log fox online.
  5. Repeat until you have found all foxes.
Foxoring Map

Version 1. Map data: © OpenStreetMap contributors. DEM data produced using Copernicus data and information funded by the European Union - EU-DEM layers.


  • 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 tba .
  • Have fun!
  • Please tell your friends about this.

Needed Hardware/Software:

  • RTL-SDR/Hackrf/Rad1o with OTG capable Android phone with RTL-SDR driver and demodulator app (RF Analyzer seems to work). Directional Antenna recommended. 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. Directional Antenna recommended, second person might be helpful.
  • Any receiver for 144Mhz region with SSB (or CW) demodulation mode.

Settings to start with:

  • Frequency range is 144.000000 - 144.004000 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

Transmitter Status:

Fox Transmitter Status
1 offline
2 offline
3 offline
4 offline
5 offline
6 offline
7 offline


No. Number of Foxes Nick/Call
1 7 DM5AHA
2 7 dl2wag
3 7 kai
4 7 Snoil
5 7 Caddy
6 5 abrain
7 5 PSJ
8 2 jof DO6BGP
9 1 antrares&eri!
10 1 DO7NX
11 1 N1QGQ


  • 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 no. 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?
  • Can I borrow a directional antenna for this event?
    • Yes. I can offer one with SMA and MCX connectors and one RTL-SDR dongle. Please contact tba.