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60 Minutes Australia's recent video FINDING MH370: New breakthrough could finally solve missing flight mystery describe's research by Richard Godfrey which is said to be able to track the trajectory of MH-370 and pinpoint the location where it went down using WSPR or Weak Signal Propagation Reporter data.

From here one can find a link to download a PDF presentation.

I won't ask about this particular example, but instead I'll just ask about what capabilities have or have not been demonstrated and tested on other flights with known flightpaths.

Question: Can WSPR really track commercial aircraft? Has the veracity of this proposed technique been convincingly demonstrated?

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  • $\begingroup$ this and links therein may be helpful $\endgroup$
    – uhoh
    Feb 21, 2022 at 1:00

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Very little has been proven. The ionosphere is simply too variable, and WSPR data too sparse, for aircraft scatter to stand out against the natural background of doppler and fading with any kind of confidence over long distances.

In his HamSCI poster Dr. Westphal has pointed out some data that could be explained as scatter from flights to and from Antarctica in 2020 and 2021, and some data that could be explained as scatter from MH370 during known parts of its flightpath in 2014, but it's not terribly rigorous, and doesn't make any effort to evaluate the likelihood of those WSPR spots having been made by ordinary ionospheric or tropospheric (i.e. non aircraft scatter) modes.

The poster doesn't really say anything about methodology. It says that certain correlations (or coincidences if you like) exist between WSPR spots and known flights, but I don't see anything that demonstrates an ability to start from a collection of WSPR spots and predict "this set of spots is aircraft scatter, this is the flight path that generated them; these other spots are not aircraft scatter", let alone test the accuracy of those predictions.

To its credit, the poster states "The wreckage of MH370 probably cannot be located using just WSPR data", and rather suggests that, with more analysis, WSPR could be added as just one more element in the pile of available data to compute probable areas.

To the best of my knowledge, no one else has made any claims of being able to track aircraft using WSPR except for Godfrey, and to put it politely, I don't think that Godfrey brings any new science to the table, only new claims.

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    $\begingroup$ Coincidentally I was in the same poster room as Dr. Westphal. $\endgroup$
    – hobbs - KC2G
    Feb 21, 2022 at 1:49
  • $\begingroup$ Thanks for your answer! I've tried to focus away from MH-370 and instead asked about "what capabilities have or have not been demonstrated and tested on other flights with known flightpaths." In that case there will be large bodies of both WSPR and flight data that could be analyzed. $\endgroup$
    – uhoh
    Feb 21, 2022 at 3:15
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    $\begingroup$ @uhoh yeah, I've tried to answer that as well as I can, but it's colored by the fact that, the way I see it, no one has successfully demonstrated anything really worthwhile, and the only people who have claimed to demonstrate anything at all have spoken about it in relation to MH370. $\endgroup$
    – hobbs - KC2G
    Feb 21, 2022 at 3:48
  • $\begingroup$ Okay I see, pretty much "probably not" and "AFAIK no" to the question's title. $\endgroup$
    – uhoh
    Feb 21, 2022 at 6:20
  • $\begingroup$ Suffering from a bit of insomnia (certainly for reasons other than this!) I found myself back here. I went back to the poster again with "fresh eyes" and tried to look for something, anything encouraging. "but I don't see anything that demonstrates an ability to... let alone test the accuracy of those predictions." Yes, to me, the poster has some of the earmarks of crank-ness, i.e. they can see it working in their head, and "oh, if only 'the scientists' (or in this case communications engineers) would look into it they'd find out I'm right." That's just my take, thanks again for your answer! $\endgroup$
    – uhoh
    May 23, 2022 at 18:46
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Aircraft reflect radio signals, this leads to local enhancements, doppler shifts etc.

Here's a picture of mine, analysing the audio signal from a distant beacon, showing two or three close-by aircraft. (50 MHz AM/morse beacon, the regular vertical bars are the morse code of the beacon).
enter image description here

And another, using a different signal source, the carrier of a very distant HF AM radio station. Ideally you select a beacon that illuminates the aircraft but not your station directly. You can see plenty of aircraft here.
enter image description here
You can hear the beating of the doppler-shifted signal with the original by ear when the offset / relative speed is small.

In the posters he shows something similar - that a local aircraft interferes with the strength and shape of the WSPR signals.

Also, Passive Bistatic radar exists and can track aircraft. One system I'm familiar with receives and processes several [fairly broad band] broadcast radio stations. It has three receiving sites located ~50 km around the area of interest.

Finally, HF propagation works well but the signals interact with an enormous volume of the ionosphere, and large patches of ground/water. Aircraft have a large RCS compared to fresh air, insects and birds, but not compared to the ground or the ionosphere in the middle of a decent skip path.

So I think it's a huge jump to go from this to suggesting that the WSPR records of successful decodes might contain information about distant flights.

There's no demonstration that aircraft can be detected by analysis of narrow-band signals, over long distances where ionospheric paths dominate. There's no plausible mechanism for it. And if there were, it would show up in careful analysis of wideband recordings, not the sort of decoded results stored in WSPR[.net?] databases.

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    $\begingroup$ Very interesting! It took me a few seconds to understand the first diagram. The times when there is no broadband signal (the vertical black stripes) are when the beacon is transmitting. The streaks in the black vertical stripes are the beacon signal reflected off the three aircraft, doppler-shifted by the aircraft's relative velocity towards or away from the transmitting antenna. Do I have that right? $\endgroup$
    – rclocher3
    Feb 23, 2022 at 0:53
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    $\begingroup$ Agreed. If you had coherent RF recordings with line-of-sight conditions or at least not a strongly time-variant dispersive channel, you could do passive radar, in principle. But claiming successful decodings of a HF mode even suggest a flight path... that's more than a stretch. At these ranges, clouds have way more radar cross sections and attenuation effects than a single plane. $\endgroup$
    – Marcus Müller
    Feb 26, 2022 at 10:27
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    $\begingroup$ @rclocher3 the beacon is AM morse, for 10 seconds it's unmodulated carrier, then 8 seconds callsign. The graph is only 200 Hz tall so the modulation sidebands aren't shown, but the carrier gets more noisy from key clicks etc. So both clean and noisy parts of the graph are valid. The Doppler shifted streaks are aircraft with large change in path length. This is easy and fun to try at home, listen to a distant HF or VHF beacon with an SSB receiver and a (narrow band) spectrogram app. This method can't see 'stationary' aircraft, for that you need a modulated signal and autocorrelation. $\endgroup$
    – tomnexus
    Feb 26, 2022 at 13:05
  • $\begingroup$ I don't have any first-hand knowledge of this, but the 2nd image with all the aircraft here certainly makes me feel as though if one had plenty of time and ambition (and good FR24-like ADS-B transponder data) one could assign some flights to at least some of those. It reminds me of how a lost Earth satellite was rediscovered e.g. space.stackexchange.com/a/32757/12102 and space.stackexchange.com/a/24677/12102 But "feels possible" falls well short of "veracity convincingly demonstrated" :-) Thanks for your thorough answer and insight! $\endgroup$
    – uhoh
    May 23, 2022 at 18:54

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