Using an Airspy HF+ Discovery to Hunt for HF Beacons

Over on YouTube Tech Minds has posted a video of him using an Airspy HF+ Discovery to hunt for signals like non-direction beacons (NDB's) and other morse code CW beacons. The Airspy HF+ Discovery is a new software defined radio that builds upon the already excellent original Airspy HF+.

One key improvement that many people have been experimenting with is it's improved VLF and LF capabilities, which is where most beacons are. It is capable of tuning down to 0.5 kHz (500 Hz). Over on Twitter, @prog (creator of these Airspy products) has been experimenting with simple and small ferrite loop antennas for VLF/LF and finding excellent results due to the low noise figure and good impedance matching of the HF+ Discovery.

Hunting LF/MF/HF Beacons With An Airspy HF+ Discovery


  1. Larry Van Horn

    Just a small tweek. In my interview with Prog this morning he stated you could actually go down to 5 Hz with the Discovery. Quote, “You could plug a microphone into the input.” But the listed spec is 500 Hz. This is a pretty remarkable SDR for the money in my book.

  2. Ken Sejkora

    Martin Francis in Canada provides a very useful database of various beacons in both the LF and MFbeacons.
    Here is a link to his website:
    The database is searchable by frequency, call sign, location, etc.It includes a variety of beacons, including non-directional navigation beacons (NDB), differential GPS (DGPS) beacons, navigation text (NAVTEX) beacons and others.

  3. Timothy M Tapio

    where can I find more information on FSL and air loop antennas? There is some interest in an alerting system just below 200 KHz and I was unsure about antennas. Seeing the new Airspy HF+ has rekindled my interest. I’m wondering about impedance, inductance and physical dimensions. I have several 3′ hula hoops (ain’t no way you’re gonna catch me trying to use one….those days are long past) and I was planning on somehow spacing them and then winding a LONG piece of wire. I have a consumer range VNA so I could fairly easily fine tune this. I have a drive motor with a speed controller…and was going to run that through a vernier or stacked verniers. I could then operate it from far enough away to minimize some body capacitance effects…but I don’t know about coupling to the SDR. Lots of questions….I see Gary DeBock listed (from Puyallup…I’m from western Washington so I know where that is) but I didn’t see a callsign associated and was unable to pull up his name in QRZ. Any help would be greatly appreciated.

    Tim Tapio K4SHF
    [email protected] (hmmm…I used to work with satellite dishes at work…I guess I’m now moving down the spectrum from Ku)

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