Decoding and Plotting VOR Signals with an RTL-SDR: Part 4

Previously we posted about Will’s (aka hpux735) project [1] [2] where he has been using an RTL-SDR dongle to help understand and decode aircraft navigation VOR signals. VOR is an acronym for VHF Omni Directional Radio Range and is an older method of navigation used by aircraft which is used to provide a heading towards a VOR transmitter.

In his latest video, Will has been able to finish his code which allows him to actually plot some VOR data that he obtained from a flight on a map. In the video the VOR data is used to draw a heading line between three recorded VOR transmitters and the aircraft. The video clearly shows the accuracy of the VOR signals (about 1 degree) and shows what happens to the heading accuracy when reception is bad.

VORs and SDRs Part 4: Fusion!

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Michael Winthrop

I cannot find the source code for hpux735 project. I would like to see if it will work with a moving map on a phone from a raspberry pi. Please reply.

Mike Winthrop

I wrote software for a Palm Pilot in “PocketC”. It uses manually input VOR information to plot location, speed, and direction (magnetic/absolute) from pairs of VOR fixes. It also provides DME. Location is lat/lon. I plot location on a simple grid without map data. I have been considering porting the code to a raspberry pi in a more useful language and wanted an SDR to get the VOR data. Current mapping data is much better than when I wrote the code (1998). I considered using the plotted data as a substitute GPS input to one of the pilot programs like iFly. The idea is that GPS sometimes fails but the VORs are still used for IFR. Whie it is true that the FAA is fazing out VORs, I think it will be a long time coming.

Julian Bone

Hi very iteresting.
I do a bit of flying and knowing which VORs are available at any stage of the flight would be very helpful.
Currently you have to tune to a nearby VOR and see what happens.
Your scanner looks ideal.
An RNAV receiver like the KNS 80 could then be quickly tuned to give location (together with it’s DME).
Regards Julian