Category Archives: Software

“Flugzeug-Scatter und WSPR” in Fachzeitschriften

Endlich eine Basis für fachliche Diskussionen: Veröffentlichung in der Fachzeitschrift “Funkamateur” (5/2022, Hintergrund) und Titelgeschichte der Fachzeitschrift “Funktelegramm”, 06/2022.

Immer noch finden Richard Godfrey & Co. unter der Yellow Press enormen Zuspruch für ihre Schmonzette, nach der sie meinen, die Route von Flugzeugen (speziell Todesflug MH370) durch WSPR-Logdaten über tausende von Kilometern nachweisen zu können.

Allerdings haben sie sich offensichtlich bislang geweigert, ihre Luftschlösser in anerkannten Fachmedien zu veröffentlichen, wo diese von einem Fachpublikum entweder schon im Manuskript (peer review) oder nach Publikation begutachtet, nachvollzogen und diskutiert werden können. Sie hingegen bevorzugen die Laienpresse, deren Journalisten aus Faulheit und/oder Unkenntnis nur zu oft treudoof einseitig das wiedergeben, was Godfrey & Co. so zusammenphantasieren.

Auch wenn etwa der Entwickler von WSPR, Nobelpreisträger Prof. Joe Taylor (K1JT), diese Luftschlösser in das Reich des Unsinns von “Leuten, die nicht wissen, was sie tun verbannte und Prof. Bruce Ward, Mitentwickler des autralischen HF-Radars JORN, das ebenfalls im Reich des blühenden Blödsinns veortete, halten Godfrey & Co. wacker an ihren unwissenschaftlichen Tagträumen fest.

Start einer fachlichen Diskussion

Um eine ernsthaft-fachliche Diskussion außerhalb des oft selbst-referentiellen Internet anzustoßen, habe ich in zwei funktechnischen Fachzeitschriften dieses Thema mit den Augen eines Praktikers betrachtet, ohne dabei jedoch den theoretischen Hintergrund aus den Augen zu verlieren:

  • “Flugzeug-Scatter auf Kurzwelle”, FUNKAMATEUR 5/2022, S. 368-372 (Aufl. 32.600) und
  • “Flugzeugscatter: Was geht? Und was geht nicht?” FUNKTELEGRAMM, 6/22, S.

Das Manuskript des ersten Artikels hatte ich auch der CQ DL des DARC zur Publikation angeboten. Erfolglos, natürlich.

DARC: Wie Diskussionen verhindert werden

Wie man zudem hört, soll der Vorsitzende des DARC, Christian Entsfellner, DL3MBG, bei einem meiner Arbeitgeber gegen die Veröffentlichung im “Funkamateur“ interveniert haben. Auf Anfrage mochten freilich weder er, noch der DARC-Vorstand das kommentieren und schon gar nicht dementieren. Diese einer Nötigung gleichkämenden Intervention reihte sich mühelos in die mal erfolgreichen, mal weniger erfolgreichen Versuche von Vereinsfunkern ein, Funkamateure zu bedrohen, zu nötigen, zu mobben und zu diskriminieren.
[Zuletzt betroffen davon: Arthur Konze, DL2ART, den man bei Behörden denunziert hatte, nachdem er sich in seinem interessanten You-Tube-Kanal “Funkwelle” kompetent mit der Entwicklung der Funkamateure, der Vereinsamateure und den Ursachen für den Verfall vor allem letzterer beschäftigte.]
Dass sich hingegen wiederum der Arbeitgeber von Christian Entsfellner, die renommierte Rosenberger-Gruppe, zumindest innerhalb ihres Unternehmens ausdrücklich gegen Mobbing und Diskriminierung wendet, ist für ihren leitenden Mitarbeiter Entsfellner offenbar kein Grund, seinen DARC auf ebendiesen Sozial- und Ethik-Mindeststandard (SA8000) für den Umgang miteinander zu verpflichten.

Und dass Entsfellner etwa auf eine denunziatorische Mail von Godfrey überhaupt eingeht (schon dies durchaus eine Charakterfrage und eine Frage der Ethik dazu) sowie – wider alle Physik und Vernunft – hurtig dessen Scharlatanerien zum Gespött von Experten mit großer Fanfare weiterverbreitet, ist eine Schande für den Amateurfunk als technisch-wissenschaftliches Hobby.

Repressionen statt Diskussionen!

Ebenso seine diskriminierende Strategie des Mobbings, mit der er Diskussionen verhindert. Was er selbst ganz&gar treuherzig-zynisch bei einem virtuellen Mitgliedertreffen zugegeben hatte: “Wir” seien der “Elefant im Raum”, also ein offensichtliches Problem, das niemand anzusprechen wage. Und warum nicht? Auch das weiß Entsfellner aus augenscheinlich eigenem Tun ganz genau: “Aus persönlicher Angst vor Nachteilen und Repressionen.”
Ob daraus für ihn oder die bei diesen Worten ihres Vorsitzenden ebenso treu wie stumm dabeisitzenden Mitvorständler möglicherweise etwas folgt, eine seit 30 Jahren vielfach angeregte Verhaltensänderung, etwa? Etwa ein beherztes: “Wer im DARC mobbt und diskriminiert, der fliegt!“, gar?

Nee, natürlich nüscht. Soll ja so bleiben.

Der Ast, auf dem der Elefant sitzt …
Bebildert hatte Entsfellner diesen “Elefanten im Raum” und seine umständlich-pomadige Erklärung dieser Metapher aus jedem beliebigen Manager-Bullshit-Bingo übrigens mit einem Cartoon, der die Rückenansicht eines einsam auf einem dünnen Ast sitzenden Elefanten zeigt, der in eine menschenleere Savanne blickt (genau, wie auf dieser Peter Gaymann-Zeichnung der frühen 1980er-Jahre). “Voller Innenraum” in der Metapher = “menschenleere Savanne” im Bild – weißte nun Bescheid, wie der DARC tickt? Immerhin das mit dem dünnen Ast, auf dem der Elefant sitzt, lässt sich noch metaphorisch deuten – wie die menschenleere Savanne, in die er blickt.
Die bei Lumas liegenden Bildrechte zur Verwendung des Cartoons ließ er den Verein augenscheinlich einiges kosten. Wenn.

Durchaus passend zu dieser Haltung mehren sich leider die Hinweise, dass der “Entwurf der Strategie ’75 plus 100′ für DARC e.V.”, den ich noch vor Tagen für eine “brunzdumme Fälschung” hielt, möglicherweise doch echt sei. Inklusive Lob des SA-Mann als Märtyrer und Ansichten über freiheitlich-demokratische Regierungsformen, angesichts derer ich nur schwer zwischen “noch AfD oder doch schon Reichsbürger?” zu entscheiden vermochte. Auch hierzu natürlich nix Offizielles vom DARC. Ich hoffe doch sehr, dieser Sache bei Gelegenheit näher auf den Grund zu gehen.

Aircraft Scatter – Much Power, Little Glory

Figure 1: One of the strongest Doppler received via scatter from a DX station was from LX814 on April 11, 2022. The vertical signal in the middle of the spectrogram is the carrier from Kashi/Xinjiang at a distance of 5’109 km. The strongest Doppler is from LX814 [Airbus A320-214], Zurich-Hanover with touch-down at 07:10:53 UTC.

I was asked to give a short overview of how to calculate the received power, scattered by an aircraft on HF. The answer is easy if we focus on AM DX signals from broadcasting stations, illuminating an aircraft. In this case the spectrogram, Figure 1, shows the carrier as well as the scattered signal – the latter being the Doppler trace. We also can easily measure both signal strength and calculate their difference. This has been done for the maximum values of carrier and Doppler in Figure 2 below:

Figure 2: Level of carrier [-31.11dBm] and peak level of Doppler [-62.98dBm] at -10.2Hz from carrier; resulting in a difference of -31.87dBm. Measured at 07:07 UTC, at the maximum level of the Doppler trace.

Mean value of the carrier in the analyzed 10-minute’s part of the whole observation is -32.7dBm at a standard deviation of 4.98 – see Figure 3 below.

Figure 3: Variation of carrier 07:00 to 07:10UTC

Broadcaster’s Footprint

Backbone of all calculations is the well-established Radar Equation. Let’s think of it as a reliable, but Black Box. Critical points are in this case:

  • illuminating power
  • distance aircraft -> receiver
  • reflectivity of the aircraft at the specific frequency (radar cross section, or RCS)

I took a strong broadcaster, namely Kashi, running 500kW AM (250kW carrier) on 17’650kHz on a curtain array antenna with a gain of ca. 20dB towards Central Europe. Effective Radiated Power (ERP) of the carrier is 104dBm. An approximate calculation (free-space loss, the prevailing attenuating factor with propagation) over this distance of 5’109km and at 17’650kHz via Matlab’s fspl function yields an attenuation of 131.5dB, resulting in a signal of -27.5dBm. As 2-hop ionospheric HF propagation is not exactly free-space propagation,so a VOAAREA HF propagation simulation had been done, giving the transmitter’s footprint in dBW (add 30dB to get dBm):

Figure 4: A simulation of the footprint with VOACAP shows a receiving level at my location of around -35dBm [-65dBW].

Scattering Power

The illuminating power, a proxy for transmitter power within the -65dBW footprint in Figure 4, measures -32dBm. The minimum slant distance between the aircraft and my location measures 1000m. The RCS of this aircraft is given at 10 … 100, let’s generously take 100, because the wingspan of the given aircraft (35m) almost exactly measures 2*wavelength (17m) in this case providing strong forward and backward scatter.

What value can be caclulated from as scattered signal which me measured -63dBm at highest? According to the equation #6 given in OTH-B Radar System: System Summary of the University of Massachusetts Lowell, we land at a level of -62.1dBm, given the mean value of the carrier with -32.7dBm. This almost exactly matches the measured value of -63dBm.

Now some people claim to “see” and even identify aircraft not over a few tens of kilometers, but over many thousands of kilometers. Let’s check this. Figure 5 shows the development of reception levels over distance, sticking to the Kashi example as above. You see the signal peaking to slightly above -20dBm at about 1’800km distance from the transmitter. And you see the separation from one-hop to two-hop propagation at a distance of 3’000km from the transmitter.

Figure 5: How Kashi’s level develops over the distance from transmitter to receiver.

Please keep in mind that this is only a rough calculation, not taking into account several factors, among them:

  • fading of the carrier (see Figure 3)
  • pearlstring effect of the Doppler
  • change of effective RCS due to different horizontal and vertical illuminations angles

That’s a powerhouse – but what about WSPR?

In praxi, I observed Doppler traces only from aircrafts at a distance not more than a very few ten kilometres from my location – given that they are illuminated by a multi-hop DX signal from a strong broadcaster.

In contrast, some people claim to have not only observed, but even identified aircraft

  • over thousands of kilometres,
  • illuminated by a 5W transmitter

Let’s take a look on this, same conditions as with the Kashi case above. First, we do the VOAAREA simulation. I took extraordinary benevolent conditions, taking a 50W transmitter (WSPR mainly runs between 1 and 10W) at an isotrope antenna of 10dBi gain. The system loss mounts to about -50dB over the Kashi case. The VOAAREA simulation (Figure 6 below) largely reflects this situation, delivering a signal of about -115dBW/Hz [WSPR] over -65dBW/Hz [Radio China International].

Figure 6: Compared to Kashi (see Figure 4), the WSPR case lacks about 50dB.

How far will the scattered signals reach?

Now for the crucial question: How far will scattering from both signals (-65dBW from the broadcaster, -115dBW from WSPR) reach? You will find an answer in Figure 7, below:

Figure 7: Scattered Levels vs. Distance, see text.

From Figure 7 we see scatter from the strong broadcaster sinking into the noise from a distance aircraft-receiver of 200km. WSPR from DX is good only for distances up to 10km.

This calculation has been done under unusually generous conditions, among them:

  • RCS has been set to 100, where 10 … 50 would be the regular case, resulting in a much reduced performance
  • forward/backward scatter have been applied to the calculation as well as to the measurements. This seems justified where the aircraft heading was 295° and Kashi->DK8OK was 302°, resulting in backward scatter from the wings and, thus, the strongest signal
  • the wings of this Airbus A320 do perform like a dipole of two wavelengths
  • only the strongest signals have been taken into account
  • neither fading of the illuminating station, nor the pearlstring-effect of the aircraft – due to phase changes under moving – have been taken into account

In praxi, such a strong DX signal never showed Doppler traces at distances of more than, say, 60km. I owe this observation also to the physicist Dr. Victor Iannello, who kindly examined many of my spectrograms with a Python program written specifically for this purpose and determined the distances of even the faintest Doppler traces, as seen at .1Hz bandwidth (+10dB system gain).

Caveat: Please keep in mind that this case is valid only for DX (i.e., multi-hop) signals illuminating the aircraft. If aircraft is illuminated by a transmitter’s backscatter signal (at a distance of ca. 100 – 1’000km from the receiver), other mechanisms take place resulting in Doppler traces from aircraft at an height, which “sees” both transmitter and receiver – see for “radio horizon”. This speical case is not covered here, and plays no role either in the texts of the WSPR/MH370 proponents.

WSPR & MH370: Richard Godfrey lügt wie gedruckt

So lügt Richard Godfrey: Oben verspricht er noch, jeder könne alles in seinem Blog schreiben. Dann löscht er meinen Eintrag, der in diesem Screenshot noch auf Godfreys “Moderation“ wartet, dann aber umgehend gelöscht wird.

Im Blog mit dem großspurigen Untertitel “Serving the MH370 Community” treiben Richard Godfrey et. al. allerlei Unfug. Mit scharlatanesquen “Technical Papers” versuchen sie, Flugzeuge über Tausende von Kilometern anhand von WSPR-Logdaten zu orten. In unverantwortlicher Weise spielen sie mit den Hoffnungen von Hunderten von Angehörigen jener Passagiere, die beim Crash von Flug MH370 ums Leben kamen.

Während bisher keine seriöse technisch-wissenschaftliche Zeitschrift diesen schrägen Thesen Platz eingeräumt zu haben scheint, finden sie vor allem in der Yellow Press und beim Laienpublikum Anklang. Vorschlägen, die “Thesen” einem Peer-Review zu unterziehen, wollten die Autoren natürlich nicht nähertreten: Der mit viel Unwissenheit und beträchtlicher Eitelkeit mühsam aufgeblasene Ballon würde noch vor dem Abheben platzen. “Sie wissen nicht, was sie tun”, urteilte Physik-Nobelpreisträger und WSPR-Entwickler Prof. Joe Taylor, K1JT, über diese “verrückten” Experimente.

Hauptsächlich verbreiten Godfrey et al. ihre verdummenden “Thesen” über Godfreys Website. Ein Publikum, das etwas von Funkausbreitung, WSPR und bistatischem Radar verstehen würde, verwiese diese Thesen in einen Bereich, der nicht mehr in die Zuständigkeit der Physik, sondern in die der Sozialpsychologie fiele.
Die einzige Ausnahme, wenn es denn eine gibt, scheint der DARC, der Deutsche Amateur Radio Club, zu sein. Dessen Vorsitzender, Christian Entsfellner, DL3MBG, und seine Webseite machen kräftig Werbung für diesen unwissenschaftlichen Hokuspokus. Er sollte es besser wissen. Und ich bin mir sicher: Er weiß es besser. Das macht es alles – nur eben nicht besser.

“Radio DARC” – eine der Schleimtrompeten (S. Kracauer) des “Bundesverbandes” – überschlägt sich gar: “Die unglaubliche Geschichte – exklusiv auf Radio DARC! Die unglaubliche Geschichte – exklusiv auf Radio DARC!” [ab 39:35]

Auch der DARC scheint, wie Richard Godfrey selbst, eine ernsthafte technisch-wissenschaftliche Diskussion über dieses Thema mit allen Mitteln verhindern zu wollen. Godfrey behauptet sogar schamlos gegenüber einem Autor: “@Omar Ahmed, jeder kann sich an diesen Diskussionen beteiligen. Alles wird wie gewohnt auf dieser Website veröffentlicht. Es gibt nichts zu verbergen.” (am 22. März 2022 um 21:09 Uhr, siehe Screenshot oben).

Das ist eine Lüge.

Das Gegenteil ist der Fall: Eben nicht jeder kann sich mit Beiträgen an der Diskussion auf seiner Website beteiligen. Und nicht alles wird veröffentlicht. Schon gar nicht, “wie gewohnt – as usual“, und/oder wenn es sich um technisch-wissenschaftlich seriöse Beiträge handelt. Auch das zeigt der obige Screenshot des Blogs, aus dem u.a. folgender Eintrag nur kurz aufschien, um umgehend gelöscht zu werden:

Richard – auch dem neuen Paper entnehme ich keinen Beweis im technisch-wissenschaftlichen Sinne, dass aus den WSPR-Logdaten Aircraft Scatter über Tausende von Kilometern bestimmten Flugzeugen, darunter auch Hubschraubern, zugeordnet werden kann.
Meine Empfehlung: Suchen Sie sich eine technisch-wissenschaftlich orientierte Zeitschrift mit einer technisch kompetenten Redaktion. Veröffentlichen Sie dort Ihre Thesen und Beweise. Die CQ DL des DARC wäre ein Anfang, und man wird Ihnen sicher gerne behilflich sein. Vielleicht kann Ihr Manuskript auch einem Peer-Review unterzogen werden. Am Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik FHR (ex-FGAN) gibt es genügend Experten und sogar Funkamateure, die Ihre Manuskripte bestimmt gerne begutachten.
Übrigens stimmt es nicht, dass auf Ihrer Website jeder einen Kommentar abgeben kann. Ganz im Gegenteil. Ich konnte (kann?) das nicht, und Sie haben mich beim DARC-Vorsitzenden verleumdet, ohne dabei eine einzige Zeile zur Physik zu verlieren. Die Tatsache, dass der DARC-Vorsitzende sofort über dieses Stöckchen gesprungen ist, sollte Ihnen den Schritt in die tatsächliche und wissenschaftlich überprüfende Öffentlichkeit erleichtern.
Ihre Bemühungen und Ihre Begeisterung in Ehren. Aber Sie sind auf dem falschen Dampfer.
73 Nils, DK8OK


Richard Godfreys unverantwortliche Tätigkeit ist eine Schande für alle Fachleute, die sich ernsthaft mit dem Thema “Funktechnik” beschäftigen. Und es ist höchst unethisch, mit den Hoffnungen der Menschen zu spielen. Dass der DARC das nicht nur mit allen Mitteln kräftig unterstützt, sondern sein 1. Vorsitzender, Christian Entsfellner, DL3MBG, sich dem Vernehmen nach sogar bei anderen Medien für eine Unterdrückung technisch-wissenschaftlicher Artikel zu diesem Thema einsetzen soll, ist ein weiterer trauriger Tiefpunkt des Vereinsfunks.

MH370 and WSPR: Richard Godfrey’s outright lie

This is how Richard Godfrey lies: At the top he still promises that anyone can write anything on his blog. Then he deletes my entry, which disappeared rather quickly….

In his blog under the loudmouthed subtitle “Serving the MH370 Community” Richard Godfrey et. al are up to all sorts of shenanigans. With charlatanesque “Technical Papers” they try to locate airplanes over thousands of kilometers based on WSPR log data. Irresponsibly, they are playing with the hopes of hundreds of people who are pinning their hopes on locating the crash site of flight MH370.

While so far no serious technical-scientific journal seems to have given space to these theses, they mainly find appeal in the Yellow Press and among the lay public. Suggestions to submit the “theses” to a peer review, the authors of course did not want to accede to: the balloon, laboriously inflated with a lot of ignorance and considerable vanity, was burst even before take-off. “They didn’t know what they were doing”, judged physics Nobel laureate and WSPR developer Prof. Joe Taylor, K1JT, about these “crazy” experiments.

Mainly Godfrey et al. distribute their stultifying “theses” via Godfrey’s website. An audience that prima vista would understand anything about radio propagation, WSPR and bistatic radar relegates these theses to an area that is no longer the responsibility of physics but of social psychology.
The only exception, if there were one, seems to be the DARC, the German Radio Amateur’s Association. Their chairman, Christian Entsfellner, DL3MBG, and their web page make strong advertisement for this unscientific mumbo-jumbo. He should know better. And I am sure: he knows better. Which makes it all – just not better.

Because he also seems to try, like Richard Godfrey himself, to prevent a serious technical-scientific discussion about this topic by all means. Godfrey even shamelessly claims to an author: “@Omar Ahmed, Everybody can be part of these discussions. Everything will be published on this website as usual. There is nothing to hide.” (on 22 March 2022 at 21:09).

This is an outright lie.

The opposite is true: Not everyone can participate with contributions to the discussion on his website. And not everything will be published. Especially not when it comes to technical-scientific serious contributions.
His irresponsible activity is a disgrace for all experts who seriously deal with the topic “radio technology”. And it is highly unethical to play with people’s hopes.

WSPR and MH370, revisited: Some notes on Fading

It seems to be a never ending story: again Richard Godfrey and Dr. Robert Westphal, DJ4FF, go on a fool’s errand regarding “WSPR and MH370”. Against all physics and reason, they continue to try to prove that it is possible to detect aircraft – and now: missiles – based on the log data of weak WSPR signals documented every 110 seconds. Even WSPR developer and Nobel laureate Joe Taylor, K1JT, has relegated this to the realm of unscientific folly: “Anyone who does this doesn’t know what they’re doing.”

Although in the aviation press and also among HF experts the support of these charlanteries is rapidly dwindling, the duo nevertheless succeeds in promoting them successfully and with great fanfare, especially among radio amateurs and their media – “because they don’t know what they’re doing” (both parties). There a scientific discussion is suppressed so far, on the contrary: One feels reminded of the flickering will-o’-the-wisp in the windows of burning asylums.

The duo’s latest folly is titled “SpaceX Falcon Launch and WSPRnet Detection,” to be precise: not doing that. In this, they stir together ignorance of HF propagation and apparent lack of expertise of what WSPR can and cannot do into an unpalatable mush. Again, it is a matter of inferring aircraft from data in the WSPR log when the signal-to-noise ratio in the logs behaves “unusually”.

With another new approach, I would like to show that what is ordinary about HF propagation is precisely its unusual nature. For this, I studied the carrier of the Riyadh radio station on 15380kHz (two hops) over four consecutive days for two hours each. The transmitter radiates with 500kW transmit power at a HRS4/4/.5 with about 20dB gain towards 310° and is thus able to provide also for some aircraft scatter detectable by Doppler traces.

The first question is: How do the signals develop, day by day? The figure below shows the levels on the four days with a resolution of one second.

Same hours, different days: The received level of Riyadh transmitter.

The second question is: Is there any correlation of the levels? The figure below clearly says: Nope.

Riyadh’s levels: Zero correlation. See correlation coefficients in the top left corner.

But the WSPR log saves only the average SNRs in chunks of 110 seconds each. So, the third question is: How do those chunks develop day by day? The figure below gives an overview:

Here, the levels of the first figure have been averaged over chunks of 110 seconds each to simulate WSPR log data.

This also calls for a correlation matrix:

Correlation matrix of 110 seconds’ chunks. 8 of 12 combinations do show no correlation, whereas with four combinations we see a “weak correlation” – by mere chance.

The fourth question gets us right to the core: Can we see from the SNR data, by their “unusual change” some aircraft scatter?
To scrutinize this question, I calculated the level difference of one chunk to the next. The idea behind it: If aircraft scatter is detected, there will be an “unusual” change of the level, most probably to a higher one. See below for this figure:

Differences from chunk to chunk: What is “usual”, what is “unusual” propagation? A few critical points have been marked in red, see spectrograms below.

Now let’s check the spectrogram of the HF recording to see where there are some real aircraft scatter, and if they correlate with the peaks of above figure. Here, I did this only for the first day because the result is similar on all days:

The spectrogram shows a nice aircraft scatter (LSB) at 06:48UTC, where the chunks show nothing unusual: the averaged level reads about minus .1 dB!

So, “nothing heard”, as they say in DXpeditions … Let’s try it vice versa: we not the biggest peak around 08:28UTC. According to Godfrey and consorts this should be “unusual”, and hint towards an aircraft! But see the spectrum below: Nope!

When we note the biggest peak in the chunks’ levels, no aircraft scatter can be found!

I am convinced that these easy-to-understand, yet scientific accounts of the actual propagation conditions should convince even the simplest mind: The detection of aircraft etc. with WSPR log data is not possible.

Last but not least, the figure below shows how little aircraft scatter affects the carrier signal. Moreover, most of the Doppler signal is outside the 6 Hz bandwidth of a WSPR signal. And for fun, everyone can calculate that the Doppler signal is at least 40 dB below the carrier signal. If the carrier signal is -50 dBm and the Doppler signal -90 dBm, the latter would be raised by 0.0004 dBm. If, yes, if this Doppler trace fell directly on the carrier …

Doppler & carrier: A strong Doppler from a strong broadcaster’s carrier. If you follow the course of the carrier and that of the Doppler, you will see that correlations are purely random.

Surely some proponents of the thesis that nevertheless airplanes are detectable at great distances from WSPR log data (admittedly only on an earth as a disk, which they may believe in …) will not be further disturbed by the physics presented here. What again does not disturb me. As a disgrace for the amateur radio, however, I feel, if these people bring their crazy mumbo-jumbo, as usual, with denunciatory mails to institutions of the amateur radio and these – obviously from low motives – also still give place to it. This makes amateur radio look technically dumber than the majority of radio amateurs actually are.

Therein lies the real scandal.

[Receiver: Winradio Excalibur SIGMA, Antenna: MD-300DX-2x5m, Software: SDRC & Matlab]

P.S.

Since scientific discussion on the website “The Search for MH370” under the half-megalomaniac subtitle “Serving the MH370 Global Community” is suppressed by its operator Richard Godfrey, a pensioner from Hesse, my blog is explicitly offered for corresponding discussions and rebuttals. It may be easier to successfully suppress facts in this matter with denunciatory e-mails to the DARC chairman – to write such mails is as much a question of character as to follow them at all – but nevertheless it can be exciting to learn something more about “alternative physics”.

Here is my comment suppressed on Godfrey’s website:

Hi – the new paper by Westphal et al. attempts to demonstrate a rocket start from WSPR log data. However, it is not clear from the paper in which way this proof should have succeeded. Apparently, “SNR anomalies” of the HF propagation are used for this purpose without distinguishing the term “anomalies” from the “normal case”. It would be interesting if the authors could explain exactly this in a comprehensible way. I am also asked for the long announced paper, in which the authors wanted to dedicate themselves to HF propagation and aircraft scatter and in which hopefully also representations/calculations of the radar cross section find entrance. There is a lot of preliminary work on this that meets scientific standards – and the community is now eagerly awaiting a methodology that will make this surprisingly possible for WSPR log data as well.
How strong the dynamics of the ionosphere are, and that Aircraft Scatter is clearly not detectable in the sum signal, but only by FFT analysis, I have presented in my latest blog entry:
https://dk8ok.org/2022/02/14/wspr-and-mh370-revisited-some-notes-on-fading/
73 Nils, DK8OK

WSPR & MH370: Facts against Fake News

How Aircraft Scatter generally works. This adaption from Gary S. Sales’ paper “OTH-B Radar System” (University of Masschusetts, Lowell/USA, 1992) should add to some other entries on my website. Double-click the picture to enlarge it.

Furthermore, there are people who claim against all facts and reason that they can prove aircraft movements with aircraft scattering of WSPR signals from their log data. Surprisingly or not, they find enthusiastic approval in the popular press, but also in technical-scientific organizations like many ham radio associations, first and foremost the notorious German DARC. Whether one deals with supporters of “conspiracy theories” at all (Nobel laureate Joe Taylor, K1JT, said having too little time for such obvious and non-scienctific nonsense), or whether one meets their convoluted theories with technical-scientific arguments, is quite controversial and a topic more of social psychology than one of physics.

Nevertheless, “Never Give a Sucker an Even Break” as the great comedian and juggler, W.C. Fields stated 1941. And that is why I would like to deal with some “arguments”, which would not be difficult because of the subject matter, but because of how these people “argue”. For the sake of clarity and brevity, let’s do this in the form of a question and answer game.

Do aircraft affect RF signals?
Certainly. HF signals are scattered on the electrically conductive metallic hull of aircraft.

How does Aircraft Scatter work at all?
The drawing at the top explains it: Radio waves from a transmitter reach the receiver directly on the one hand, and via aicraft scatter on the other. On the receiver side, both signals add up. Thanks to the Doppler effect, which the signal part scattered by the aircraft has, both signals can be separated from each other again with a method called FFT; see my website for a couple of examples. However, this is not possible with WSPR log data, here only the total signal is noted.

How big are these influences?
They mainly affect the signal strength and are around 35 to 50dB+ below the original signal. There are exceptions. Downward, there are far more cases than the exceedingly rare constellations where the scattered signal may be larger than the original signal. Above 30 MHz this occurs more often, below 30 MHz I have never observed it as there always was at least some backscatter of the original signal.
Signals or field strength can be measured and calculated. Generally speaking, a suitable form of the “Radar Equation” will do the calculation, see here. They largely match the values being measured by the method “separate original signal and scattered signal”.

Facts, please – how big … ?
Sorry, yes. Say, a booming signal by a broadcaster in the 19 meter band hits your antenna with a level of -40 dBm. Then a Boeing 747, flying over your house to touch down at your airport nearby (“in your backyard”, as they say) at a distance of 500m only, this will peak at -86dBm.
Not bad, and easily visible by FFT analysis.

How much does this scattered signal adds to the original signal?
Good, with this you steer to the central point, because WSPR measures only this total signal. You just have to add -40dBm and -86dBm and with this most favorable constellation you get a total signal of -39.999890911528446dBm.
Believe me: you cannot distinguish it from the level of the original signal, being -40dBm.

Oh, that’s disappointing … but they tell they can identfy aircraft not only 500m, but some/many 1000km away?
First, physiscs may be disappointing. Secondly, I took a most favourable case – booming broadcaster, short distance. The effective power of a stronger WSPR transmitter may reach 40dBm, compared to 100dBm+ of many broadcasters. The difference of 60dBm and more is whopping.

“Whopping” – what do you exactly mean by this?
Take the example of the broadcaster, reading -40dBm on my S-Meter. If the transmitter were an even above-average WSPR transmitter it reading of the S-Meter would be -100dBm. Still readable, and WSPR would give a decode.

So, it works?
Wait a moment, for introducing the scattered signal, also 60dB down. It will peak at -160dBm, and it reliably is eaten by noise which will start between -130 and -140dBm.
By this, the orginal signal of -100dBm will be enhanced and strengthed to -99.999995657057354dBm. Quite an achievement!

I understand, it cannot work. Does a greater distance improve things?!
By no means. A greater distance worsens things even exponentially.

OK, but what the hell are they measuring to come up with such far-reaching results?
They are measuring indeed fluctuations of the signal but without knowing the reason. And there are much more and of stronger influence to the received signal level than aircraft scatter. Prevailing is multi-path leading to near-normally distributed changes of the signal level of around ±8dB from second to second, and often more than 30dB within just a few seconds!

But – they mention “drift” … and “Doppler” means “drift”?!
Yes, but the “moon shapes” of a few signals surely have other reasons, much more obvious – just think of bad power supplies, meteor scatter (stronger and more often seen compared to aircraft scatter) and travelling waves within the ionosphere itself. Have you ever asked yourself, why in the presented cases the whole signal is shifted, instead of seeing a Doppler signal branching out from the original signal? „They don‘t know what they do“, says K1JT into their direction.

How much can I rely on the quality of WSPR signals?
Look yourself at the screenshot below, showing three hours of WSPR signals, showing drift, over-modulation, noisy signals. All fine for decoding WSPR but on only very few you consider those rocks where you want to build your church on (Mathew 16-18). You see instabilities at many scales, and also the duly repeating (!) half-moon footprints which for some ghostseers are the evidence of aircraft.

Drifting away: Three hours of WSPR signals on 20m. Their quality works for decoding WSPR, but it is difficult to use them as reference …

They work with the concept of “tripwire”. Any comment on this?
Well, they seem to consider propagation working by distinctive, laser-like “rays”, not fields of energy. (This is just a guess from this blog entry.) Each object crossing this ray causes a-normal propagation which they fail to precisely specify. This is a fundamental misconcept of how HF propagation works plus an incomprehensable application of PropLab Pro 3.1, the propagation software, which they seem not to understand. Propagation doesn’t produce “tripwires”. And if you need some parallel, you should more think of a booby trap, thanks to which not only signals are pulverized, but with them all the dream fantasies that this or that plane may have caused them to go off.
They must use “Broadcast Coverage Map” with PropLab Pro to get a realistic view of electromagnetic fields and their propagation, see secreenshot below.

No “tripwire”: HF propagation doesn’t work by laser-like rays, but by electromagnetic fields. This PropLab 3.1 Broadcasting Coverage Map screenshot gives a general impression of this – transmitter Tiganesti/Romania, simulated a sector of ±30° of the antenna’s direction. And you can try to get your own impression for free with e.g., VOACAP online.

Can I understand your assertions?
Absolutely! In theory, as well as in practice. You can find many examples on my website. A SDR and software are all you need. Oh, and, last but not least: and unbiased view not on the possibly desirable, but on the physically possible!

But why do they still spread their charlanteries with great success?
Look around you. The world is full of castles in the air. That’s actually not so bad. Here, however, they are built by those who could know better and they are spread with enthusiasm by those who know better. Or at least should know better.
But that is the usual pattern of Fake News. Only that it undermines the technical-scientific competence of the radio amateurs and makes them look ridiculous.

SDRC: New Bitmap Display helps to raise DX!

Bitmap Display showing 24 hours from 0 to 25MHz from a recording of 23NOV2021.

Simon Brown, G4ELI, author of free SDRC software to control (and much more …) most of the SDRs walking on earth, again surprised the community: he added a stunning fast “Bitmap Display” to get a literally overlook onto the content of a recording. The screenshot at the top shows a 25 MHz recording over 24 hours, made with Winradio’s Sigma SDR (16 bit), produced from a near-9TB file within only few seconds. It clearly shows how propagation follows the sun. Medium wave signals thin out after sunrise (06:56UTC here on 23NOV2021) to fade in just before sunset (15:16UTC). You also see the still active broadcasting bands, and, alas, also some interference from PVs at the higher end of the spectrum. You also see the power of s state-of-the-art SDR like this Winradio Sigma, at a professional wide-band active vertical dipole antenne MD-300DX.

See, for comparison, the range of 24MHz/24 hours on a summer day, namely 08JUN2021 (SR 04:00/SS 19:39 UTC), with Elad FDM-S3:

During a short June’s night, the lower frequencies are only sparsely populated And on the higher frequencies you see something of a “summer’s depression”, where in the late autumn’s screenshot they get some boos from the “winter anomaly”, but fading in later and fading out much earlier.

This “Bitmap Display” is called via the tab “Rec/Playback“, then menu “Navigator“. It works on recorded HF files with a fixed width of 4096 data points. So, with a recording of 25MHz width you get a freqeuncy resolution of roughly 6kHz. This makes it ideal for AM broadcast under 30MHz, as well as for all wider modes above 30MHz, let it be the full FM band to identify even short openings, the airbands to check most active channels etc. The time resolution can be set between on second and 60 seconds, see screenshot below.

The time resolution can be set in seven steps.

This “Bitmap Display” adds to the alread known “Grid Display” which still is on board, see the two screenshots below.

Toggle between “Bitmap” and “Grid” display …
“Grid Display”: set ot 06:00 UTC.

Both displays set the recording to the matching time by just a mouseclick. The frequency, however, has to be set separately in the “Receive” Panel. You can switch beween this two windows with a tab at the left bottom, see the following two screenshots.

Toggle between Receive and Playback with Bitmap/Grid.
The reception frequency is shown on the “Bitmap Display” as a white dashed double arrow, pointing to this frequency on the scale at the bottom of the display (here: 9420kHz has been tuned).

The ingenious double function “Click and display time and frequency” is still reserved for the File Analyser module, which is somewhat more complex to operate.

More than just a consolation for this, however, is the loop function: here you set the times for the start and end of the loop by numerical input or simply by mouse click – and off you go! See the both screenshots below:

Start and end of the playback loop can be set either numerically, or …
… by a right mouse click which will duly transfers the time for starting and finishing into the numerical display shown above. This has the advantage to match start/end time visually to the footprint of a signal.

One very fine feature is zooming into the “Bitmap Display”. Even though this software zoom does not change the resolution, this function is an important tool for checking the occupancy of a broadcast band, for example, and for jumping specifically to the start of a broadcast.
Frequency-wise – by position and bandwidth – the slider below the running Spectrogram (“Waterfall”) of the main window is responsible for this. This can be moved as well as changed in its width, so that the corresponding area is displayed. The following two screenshots are more helpful than any quick guide.

The slider has three handles which a mouse click transform into a double arrow to change lower end, upper and end centre. For a better time resolution, this has been changed here from 60 seconds to 1 second per pixel. With the scrollbar on the right you may scroll through the whole “Bitmap Display”.
Here the zoom has been set to the 25 meter broadcast band (slider), and the time resolution set to 1 second/pixel. With the scroll bar, I scrolled the “Bitmap Display” to around 13:00 UTC, and I clicked to 13:26 UTCon 12’040kHz.

It is also possible to tune to a specific frequency when only the “Playback” window is open, and not the “Receive” window. This workaround-like procedure is done by the function/window “Frequency Database” which has to be filled with at least one set of channels. I use the voluminous ILG for this.
With this or another database already loaded, click View -> Frequency Database. Your SDRC window should look like the screenshot below:

How tuning is accomplished by the “Frequency Database”.

Then set all the demodulation controls to match the type of signal you want to recevie, i.e., AM and 5kHz etc. for broadcast. In the next step, simply double-click to the frequency entry in your “Frequency Database”. The “Receive” frequency changes (as you might hear). If your displays had been zoomed and the new frequency is out of focus, a simple trick brings the new channel to full glory: click to “Centre”, see screenshot below.

A click onto the “Centre” icon, and the zoomed “Bitmap Display” window etc. is changed to that channel.

Thanks, Simon, for another great feature of your software!

Q&A:

What are the main differences between the “Bitmap Display” and the “File Analyser”?
* The “Bitmap Display” is by far faster to build up a spectrogram. It also features the whole bandwidth of a recording.
* The “File Analyser” is more flexible in frequency resolution, offers “see, click, tune” when a spectrogram has been built up, and features flexible CSV export of data – up to the whole spectrogram. But it takes much looonger to build up.

Can the “Bitmap Display” also being used to raise short-living utility signals like ALE?
* It depends. Limiting factor is the frequency resolution. With some experience, I can clearly make out ALE signals in an 1MHz wide recording, 1 second time resolution.

Do you have a wishlist? Thanks for asking, but it is an only small one:
* It would be nice if there were several options for (higher) frequency resolution. OK, it will slow down processing, but …
* As I like to process spectrograms, a CSV export would be welcome (as with the File Analyser).
* Undoubtedly, to change not only time, but also frequency would be the ice on the cake.

WSPR & Flight MH370; Richard Godfrey & DARC e.V.: Zwei erledigte Fälle

Seit Wochen führt Richard Godfrey, ein Renter aus dem Hessischen, die Fach- und Publikumspresse mit folgender These an der Nase herum: Mit historischen Logdaten von WSPR, einem Amateurfunk-Mode geringer Leistung, ließe sich der Todesflug MH370 verfolgen.

Ich habe diese These lange ignoriert, weil deren Unwissenschaftlichkeit für mich auf der flachen Hand lag. Als sie allerdings immer mehr Publizität gewann, sah ich das technisch-wissenschaftliche Image des Amateurfunks ins Lächerliche gezogen und schaltete mich mit eigenen Untersuchungen zu diesem Thema ein. In diesem und in diesem Beitrag versuchte ich auf technisch-wissenschaftlicher Basis und mit einer Unmenge von Daten die Scharlatanerien von Godfrey zu widerlegen.

Da war ich nicht der erste und schon gar nicht der einzige. Siehe unter anderem hier.

Zugleich schickte ich dem DARC e.V. eine kurze Information über meine Untersuchungen und deren Ergebnis. Erst 2019 hatte dieser “Bundesverband für den Amateurfunkdienst” Nobelpreisträger (Physik, 1993) Prof. Joe Taylor, K1JT, als Entwickler von WSPR (2008) endlich seinen “Horkheimer-Preis” zuerkannt, wofür ich mich schon Jahre zuvor erfolglos eingesetzt hatte – der Verein hat es offenbar immer noch nicht so mit moderner Technik. Mit meiner Information wollte ich erreichen, dass Godfrey nicht weiter den Amateurfunk und auch die Arbeit eines Nobelpreisträger lächerlich macht:

WSPR und MH370: Eine kritische Würdigung
Immer wieder gibt es in der Fach- und Publikumspresse Nachrichten darüber, dass Logdaten des WSPR-Datennetzes bei der Lokalisierung von Flugzeugen helfen können. Insbesondere geht es darum, den tatsächhlichen Absturzort des Fluges MH370 festzustellen. Diese Bemühungen laufen im Wesentlichen darauf hinaus, in den archivierten WSPR-Logdaten “ungewöhnliche” Pegelsprünge und Frequenzänderungen (“Drift”) festzustellen und diese Reflexionen bestimmter Flugzeuge zuzuschreiben (“Aircraft Scatter”). In einem Blogeintrag unterzieht Nils Schiffhauer, DK8OK, diese Theorie erstmals einer kritischen Würdigung. Diese fußt einerseits auf der jahrelangen Beobachtung von Aircraft Scatter auf Kurzwelle sowie einer Untersuchung von gut 30 Dopplerspuren. Die Ergebnisse dieser aufwendigen Analyse von über 10.000 Daten allein in einem Beispiel lesen sich ernüchternd: Die Auswirkungen von Aircraft Scatter auf das Gesamtsignal bewegen sich fast immer deutlich unter 0,3 dB. Eine Korrelation zwischen Pegelveränderungen des Gesamtsignals und Flugzeug-Scatter nachzuweisen, erscheint anhand des WSPR-Datenmaterials kaum möglich. Die Gründe sind vielfältig, liegen aber vor allem in der Kurzwellenausbreitung, bei der Pegeländerungen von 30 dB innerhalb weniger Sekunden eher die Regel als die Ausnahme darstellen. Da bei den bisherigen Untersuchungen am WSPR-Datenmaterial jedoch der örtliche und zeitliche Zustand der Ionosphäre nicht bekannt ist – er wird in professionellen OTH-Radar-System parallel erfasst und aus dem Empfangssignal herausgerechnet -, lassen sich Pegelsprünge allein aus dem Summensignal kaum eindeutig zuordnen. Dieser Befund wird im Blog durch weitere Argumente gestützt.

Wenngleich ich nichts vom DARC hörte, so landete diese Information jedoch auf mir unbekanntem Wege bei Richard Godfrey. Der reagierte in seinem Blog wie folgt:

Sie sind in diesem Blog nicht willkommen! Sie wurden 1992 aus dem Deutschen Amateur-Radio-Club (DARC) ausgeschlossen. Trotz 3 Einsprüchen auf regionaler und nationaler Ebene sowie vor Gericht sind Sie auch 29 Jahre später noch von der Mitgliedschaft ausgeschlossen. Dafür gibt es sehr gute Gründe. […]
Ich habe mich bei Christian Entsfellner DL3MBG, dem derzeitigen Vorsitzenden des DARC, über Ihre Forderungen beschwert, gegen meine Arbeit und die von Dr. Robert Westphal (DJ4FF) offiziell auf der DARC-Website zu MH370 und WSPRnet zu protestieren.
Ihr Papier ist schlichtweg falsch und Ihre Argumente sind unangebracht.
Ich schlage vor, Sie gehen woanders hin, denn ich bin sicher, dass es andere MH370-Websites gibt, die Leute wie Sie willkommen heißen. Und Tschüss!

Also: keine inhaltliche Diskussion, sondern eine denunziatorische Mail an “Christian Entsfellner, DL3MBG, den derzeitigen Vorsitzenden des DARC”. Da Entsfellner das Produkmanagement eines Unternehmens verantwortet, das mit HF-Technik handelt, dachte ich, er werde beide Ansichten fachlich prüfen und natürlich zur Erkenntnis gelangen, dass Godfreys Thesen technisch-wissenschaftlich nicht überzeugend sind. Ob jemand überhaupt Mails mit denuziatorischem Inhalt ernst nimmt, ist freilich eine Charakterfrage – wie jene, solche Mails zu schreiben.

Allerdings lief alles so, wie Godfrey es sich gedacht haben mag: von Stil und Inhalt her hatte er genau ins Schwarze getroffen! Denn daraufhin veröffentlichte der DARC eine Presseinformation, in der er die Godfrey’schen Schwurbeleien in den Himmel hob. Verantwortlich dafür: das “Presseteam“* des “Bundesverbandes”, dem man dafür den “Aluhut mit Raute” verleihen sollte.

Warum sich die Vereinsfunker nicht kundig machten, wenn sie schon nicht selbst die Sachkenntnis gehabt haben sollten, ist mir ebenso ein Rätsel wie die Frage, warum sie zwar Godfrey in die Sache einbanden, nicht jedoch K1JT, wozu eine E-Mail an den Preisträger ihres Vereins gereicht hätte!

[Das heißt: So groß ist das Rätsel wiederum auch nicht. Und hätte ich eine Versuchsanordnung mit unfehlbar diesem Ausgang designen müssen – exakt diese wär ‘s gewesen!
Du glaubst es nicht? Hier der Beweis: Am 8.12.21 schrieb ich in Godfreys Blog dazu:
“Ganz ohne Zweifel wird Ihr ‘Protest’ (nicht: irgendwelche Argumente) bei DARC-Präsident Christian Entsfellner, DL3MBG, auf fruchtbaren Boden fallen. Er wird sich Ihre Meinung zu eigen machen. Denn, so vermute ich, er wird sich nicht von den technisch-wissenschaftlichen Argumente leiten lassen. Sie scheinen die gleiche Voreingenommenheit zu teilen.”
Und: Horch, Glöckchen! Am 9.12.21 gab der DARCs eine diesbezügliche ‘Presseinformation’ raus.
Siehste, ist doch gar nicht so schwierig, den DARC zu einer Pawlow’schen Reaktion zu bewegen!]

Auch wenn es zwecklos ist, Scharlatanerien mit sachlichen Argumenten zu begegnen, hatte daraufhin der US-amerikanische Physiker Dr. Victor Ianello sich bei K1JT zu dessen Meinung zum Thema “WSPR und MH370” erkundigt. Die Antwort des Nobelpreisträgers fiel zum wiederholten Male eindeutig aus:

“Wie ich bereits mehrfach geschrieben habe, ist es verrückt zu glauben, dass historische WSPR-Daten dazu verwendet werden könnten, den Kurs des verunglückten Fluges MH370 zu verfolgen. Oder, was das betrifft, jeden anderen Flugzeugflug… Ich verschwende meine Zeit nicht damit, mit Pseudowissenschaftlern zu streiten, die nicht verstehen, was sie tun.”

Prof. Joe Taylor, K1JT

Verrückt” und “Pseudowissenschaftler, die nicht verstehen, was sie tun” – das ist deutlich genug. Aber auch die Konsequenz, sich mit solchen Leuten erst gar nicht zu beschäftigen. Sollen sie weiterhin unter ihresgleichen auf Dummenfang gehen.

Der DARC, mit unten zitiertem Anschreiben davon in Kenntnis gesetzt mit der Bitte, diesen dem technisch-wissenschaftlichen Image des Amateurfunks schädlichen Scharlatanerien keinen Raum zu geben, reagierte bislang nicht. Das Anschreiben:

Guten Tag – nachdem ja einiges Wunschdenken zum Thema “WSPR und Flug MH370” die Publikums- wie Fachmedien beherrschte und auch der DARC mit einer Pressemeldung Partei für diese Scharlatanerien ergriff, hat nun Nobelpreisträger Prof. Taylor selbst diesem “verrückten Glauben” eine deutliche Absage erteilt.
Ich meine, dass ein weiteres Festhalten an diesem Wunschdenken das technisch-wissenschaftliche Image des Amateurfunks untergräbt. Irren und erst recht Wunschdenken ist menschlich. Aber man sollte sich, wenn schon nicht durch technisch-wissenschaftliche Argumente, so doch durch das Machtwort eines Horkheimer- und Nobelpreisträgers (was immer davon die härtere Münze im DARC sein mag) überzeugen lassen.
Vielleicht ist ja im nächste Deutschland-Rundspruch Platz für folgende Meldung, deren Inhalt auch gerne für eine erneute Pressemitteilung des DARC zu diesem Thema genutzt werden mag.

Godfrey aber kann sich gratulieren: er wusste genau die richtigen Fäden zu ziehen, um dem DARC-Vorsitzenden, dessen Verein sich trotz vielfacher Aufforderung nicht gegen Denunziation als Mittel der Diskussion im Amateurfunk ausgesprochen hat, seine schrägen Thesen schmackhaft zu machen. Christian Entsfellner wiederum hätte diese technisch und unvoreingenommen überprüfen können und müssen, das “Presseteam“* ebenfalls. Wer es nicht kann, ziehe Experten hinzu.

Dass in der technisch-wissenschaftlichen Community der Amateurfunk immer weiter zur Lachnummer verkommt, ist insofern nicht verwunderlich, sondern mit Fleiß selbstgestrickt.

Zwei nur halbwegs ernstgemeinte Prognosen, nun: zum einen wird Richard Godfrey Ehrenmitglied des DARC e.V. (mit vollem Recht, denn er hat mit den dafür goldrichtigen Methoden dem Ansehen des Amateurfunks einen schweren Schlag versetzt), zum anderen wird man die Black Box von MH370 an der prognostizierten Stelle finden – was dann aber auch ganz & gar nichts mit WSPR zu tun haben wird. Und die “Pseudowissenschaftler” werden jubelnd ihre Aluhüte in die Luft werfen.

* Wenn auch technisch-wissenschaftliche Themen nicht so ganz die Kragenweite des “Presseteams” sein mögen, so leistet es doch geradezu Herausragendes bei der “Anpassung von Vorstandshemden”:
In einem kürzlichen “Mitgliedertreff” äußerte sich ein Vorstandsmitglied des DARC ganz begeistert darüber, wie er “vor Steffi strammstehen durfte” (gemeint ist Dipl.-Soz. Stephanie “Steffi” Heine, DO7PR, stellv. Geschäftsführerin des DARC e.V. und offenbar leitende Presseverantwortliche), um sich ein “Vorstandshemd” anpassen zu lassen. Der DARC-Vorständler war darob ganz hin und weg: “Top und schick … mit Stickereien!” Worauf besagte “Steffi” flötete: “Das machen wir doch gerne!”
Man glaubt es unbesehen. Und dass es dafür dann beim “Bundesverband” mit technisch-wissenschaftlichen Themen gelegentlich ein wenig hakt, wollen wir gerne nachsehen: Das “Vorstandshemd” sitzt halt näher als der Rock.

In solchen Händen sind die technisch-wissenschaftlichen und die ethisch-charakterlichen Grundlagen des Amateurfunks ebenso vorzüglich aufgehoben, wie genau diese Eigenschaften für viel Geld in alle Welt geblasen werden!

Wer das nicht noch weiter mit seinem Geld unterstützen möchte, sondern wer für ein seriöses technisch-wissenschaftliches Hobby eintritt, das vom Ham Spirit getragen wird, sollte, falls er wirklich noch Mitglied im DARC ist, aus diesem austreten. Noch heute.

RTL-SDR Active Patch Antenna

Weather-proof: and this is only one of the benefits of this nice tool.

Since August 2021, the RTL-SDR Active Patch Antenna delights the community worldwide. It is small, yet highly efficient. With RTL-SDR Dongle and some software, it combines to a surprisingly high performance receiving post for INMARSAT, IRIDIUM (which I first used with a mobile phone 20 years ago on a tour through Mongolia and China with stunning quality), and GPS – all for just about 100 US-$.

Plug the USB stick into your PC, connect the patch antenna to the stick’s by a cable and set it on a flexible tripod (all contained in the set!), and the sky becomes open. In the screenshot below, I used the nuandRF to show at least half of the bandwidth of the antenna, because this SDR covers 60 MHz:

The 60MHz wide window of the nuand bladeRF SDR shows half of the bandwidth and sensitivity of the RTL-SDR Patch antenna. Caveat: With the bandwidth of the antenna being nearly 140MHz and the bandwidth of the SDR only ca. 60MHz, this screenshot still doesn’t show the complete performance of the antenna. The seemingly (sic!) reduced sensitivity at the lower and upper end of the signal/noise is due to the receiver, not the antenna!

Aero makes a good start with powerful signals and free software JAERO which can also run in multi instances to cover all the channels in parallel.

In the upper window you see the SDR GUI, namely free SDRC software. It shows some aero channels with their signal-to-noise radio, or SNR, achieved with the active patch antenna and the RTL-SDR dongle. The two windows at the bottom show the JAERO decoder in action on a 1200bps channel.

You may also set sails for some maritime experience with the std-C Decoder (full version: 55 US-$). It even visualizes e.g., buoys and areas (rectangle, circle and free format) a Open Street Map.

Top: a maritime satellite channel. Bottom: Safety Message for the marked area in the Gulf of Bengal, off the coast of Cuttack/India.

You may also receive the GPS C/A code signal on 1.575420GHz, and IRIDIUM on which John Bloom wrote the pageturner “Eccenctric Orbits – The Iridium Story“, which I can only highly recommend as a truly thrilling backgrounder. As low-orbiting satellites, the channel has to be handed over to another satellite after about nine minutes.

The RTL-SDR Active Patch Antenna is a great, little tool providing high SNRs at a small form factor of 17.5 x 17.5 cm. Its low noise amplifier (powered via bias tee from the SDR stick) together with the SAW filter to suppress any signals outside its passband from 1.525 to 1.660GHz shows unsurpassed performance at this price tag. It is a must, and absolutely a no-brainer. Did you miss a large suction cup to mount it on your window? Wait a minute – it is also included in the turnkey package …

WSPR & Propagation [MH370] – an Experiment

Completely unintentionally, my last blog on WSPR and MH370 had led to more of a social psychology experiment than a technical science discussion. I expressed my doubts whether it is possible to recognize aircraft scatter from the historical WSPR data by “unusual signal changes” without essential knowledge of further circumstances.
As a reminder: WSPR works with weak transmission power at modest antennas in a rhythm of 110.6 seconds. Apparently this average value is noted and made available as SNR at the receivers.

I objected that practically all other influences on the signal on its way from the transmitter to the receiver (“channel”, with refractions both at the dynamically in three dimension, plus density, changing ionosphere and at the ground) exceed those effects by far, as they are to be expected by airplane scatter. I proved this with 3 x 10’000 level data and 30+ Doppler tracks.

The main proponent of the theory, that the proof is possible against all those odds, reacted with a juicy complaint to the German amateur radio association DARC, in which he argued exclusively personally, but not technically-scientifically. A behavior even more bizarre than trying to prove his actual thesis. The DARC immediately jumped over the stick held out to it, and published few hours later – apparently without or against better knowledge – a sweetish-mendacious “press release“, in which a so far not by technical-scientific papers noticed employee praised that as only beatifying truth.

[Auf Wunsch einiger deutschsprachiger Leser erfolgt in einem weiteren Blog eine Erläuterung dazu.]

WSPR vs. high-resolution data

For all those, however, who are interested in technical contexts, this blog answers a still open question from my last blog:

  • What is the smoothing/generalizing influence of the evaluation of mean values over 110 seconds – which is how the WSPR logbook is supposed to work – on the mapping of the actual signal changes?

Let’s simply test it
For this purpose I have analyzed on September 22nd, 2021 with the professional SDR Winradio Sigma between 07:00 and 12:00 UTC the broadcasting station CRI Kashi, which transmits continuously on 17’490 kHz with 500 kW towards Europe – 5’079 km, two hops. My antenna is a professional active vertical dipole antenna with 2 x 5 m long legs, namely MD-300DX.

With the software SDRC 17’930 level values were noted in dBm/Hz, every second. The FFT analysis was performed with a high-sensitivity resolution of 0.0122 Hz, resulting in a process gain of 53.1 dB compared to the data from WSPR, measured in a 2’500 Hz wide channel. Assuming the carrier power of the transmitter to be 250 kW and the gain of the transmitting antenna HR4/4/.5 to be typically 21 dBi, this results in an additional gain of 47 dB compared to a WSPR transmitter of 5 W on a dipole, which is already strong by its standards. Thus, the total gain of this experiment is 100 dB compared to a WSPR signal. If we assume that signals with SNRs between -20 and -30 dB can still be evaluated, the gain is still a robust 70 to 80 dB. Thus, if aircraft scatter were to be detected on a WSPR signal, it would be even more striking with this factor.

The spectrogram of the five hours’ recording see below, followed by an explanation of the annotations (as with all screenshots: double-click to get the original resolution):

Kashi’s carrier over 5 hours, shown within a window of ±50Hz and a resolution bandwidth of 0.0122Hz at an dynamic range of 90 dB. Explanation see the following text.

The spectrogram reveals a couple of different strong influences to level and frequency of the carrier. Most prominent is the Doppler shift by a moving ionosphere, plus the split-up into o- and x-rays due to the magnetionic character of the ionosphere. You may simulate it with PropLab 3.1, but only in 3D mode. Aircraft Doppler is very weak. It has been verified as such by a different spectrogram with better time resolution, not shown here. You see also some Doppler from meteorite’s plasma in the vicinity of the carrier.

The level of the carrier can be seen from the following screenshot at a time resolution of 1 second, enriched with some statistical data:

Levels over 5 hours. Mean = -44.02 dBm, Standard Deviation 7.872, Range 58.81 dBm. Max/min: -21.97 dBm/-80.78 dBm

The next screenshot shows the whole 17’930 datapoints, split up into consecutive groups of 110 each. This should simulate the the 110.6 seconds which the WSPR logbook boils down to one SNR value plus on “drift” value. To read this contour map:

Vertically you see 163 columns. Each column contains the levels 1 … 110, and 110 x 163 = 17’930 total level values. For the first time, you can see here the dynamic within a column of 110 values each.

Contour diagram, showing all 17’930 level data, grouped to 163 blocks of 110 data points each.

So far, we retained the level information of all 17’930 data points. What happens if WSPR boils them down to chunks of 110 seconds only? This question answers the next screenshot:

What is lost by boiling down the 17’930 level values at 1 second’s distance to 163 chunks of the mean of 110 values? This screenshot shows the answer.

If it still isn’t understood that information which simply are not palpable in the 110-seconds’ chunk cannot be “interpreted” as this or that, a zoom-in must convince you:

Same as above, but zoomed into. WSPR logbook will keep only the Chunks. So all information has to be derived from just the red line! Imagine that you don’t have any more information – no “Raw”, no “Spectrogram”.

Looking at the both screenshots above: are you still sure to see any faint details (refer to spectrogram on top of this blog) like any Aircraft Doppler just from the chunks? You have also seen that the “drift”, shown in the WSPR logbook, may have manifold sources, ionospheric Doppler prevailing.

Stanag 4285 & PSKSounder – a better mode

There, of course, is a way out of this dilemma: since many years free PSKSounder provides an excellent tool to extract many more information from STANAG 4285 signals, see the following screenshot:

PSKSounder shows relative “time of flight” of a Stanag 4285 signal. Here with FUV, French Navy in Jibuti. You see that the structure of the spectrogram of the signal at the right has it source in two strong and different paths of the signal. Their times of arrival differ by about one millisecond. This procedure is very sensitive and is also used to reliably reveal meteorites and – aircraft!

Finally two things: The path between two stations does not always have to be exactly reversible – that is, if two stations are equipped exactly the same, it is very likely that a different signal will be detected in each case. And if the black box of MH370 should indeed be found in the area supposedly designated by WSPR, it is due to many things, but certainly last of all to WSPR.

After which methods it might be tried nevertheless, one can read already now in Grete De Francesco’s “The Power of the Charlatan”, Yale University Press, New Haven/USA, 1939.

« Older Entries