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Stormchaser

Meteor Detection with RTL-SDR

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Got this one just half an hour ago, sporadic small pings (some very very faint) right now, but they seem to be there...

image.thumb.png.a91e99853acd76098ff65c1ac49a13ba.png

The scale has been zoomed one time, to make the events a bit clearer (and bigger).

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Posted (edited)

:headbang2: . But I'm truly amazed given your location! It would be interesting to establish whether this is from any antenna backfire or the normal forward lobes (even more amazing!). I know little of long distance radio propagation, but I also wonder if it also down to some particular conditions that currently favour it, and therefore might not be reliable. DXers can obviously provide some insight here.

Are you going to run for a period now?

Ian

Edited by The Admiral
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I'm very surprised too, and also very excited about this! 

I think that it could be a mix of rear lobes presence (as discussed multiple times on the forum) + some kind of good propagation because until yesterday I could not get any echo. There is also the fact that now I'm using SpecLab, and this is giving me echoes while the others didn't show any, especially the small ones.

However yes, I am going to leave my old laptop on, and see the general behavior of the system. Unfortunately, I cannot use the Raspberry Pi anymore, since I could not manage to find a Linux version of SDR#. Because in that case, I would have happily and easily set-up everything on that platform and kept it running 24/7. Still thinking of buying a better antenna, but let's wait for after the Lyrids.

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38 minutes ago, Stormchaser said:

Unfortunately, I cannot use the Raspberry Pi anymore,

Will Spectrum Lab run satisfactorily on a RPi? I've always thought, possibly wrongly, that the FFT process demanded quite a bit of processing power, not to mention a 192kHz soundcard.

I've set mine running at the moment to see what is coming through.

Ian

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To give you an idea of what you will see, some pings with direct signal and a few EME returns.
This was yesterday morning for about two hours, had a lot more pings than these but no really long bursts.

Direct signal at 1000Hz plus some EME at just over 100Hz higher.
The line at 2000Hz is a birdy.

100238.png.68b71423c50d65d963bda948ec319783.png

Several pings
103308.png.c505e6c490e411bef1fd3c8bd633a24d.png

Two more pings.

101608.png.3cf2b89cb2d55fe558bee0dff960b3ea.png

and just one more

102338.png.56dea0cc71c2bdd6a8596cb0c40493db.png

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My guess is that they are predominantly as a result of rear lobes.

The front lobes illuminate the sky at an altitude of 90km well over your southern horizon.  It's possible anomalous propagation could result in back scatter reaching you from the frontal lobes, but there are two generally accepted modes that would provide that path: Tropospheric ducting or Sporadic E.  Neither modes are open right now between Scotland to southern France.

In fact, I'm not sure tropo would even allow for such propagation because the incoming signal originates in the ionosphere, above the troposphere and may not be able to break into any super-refracting duct from above (the process that keeps the signal leaking from a duct may prevent an external signal breaking into a duct).

On a positive note, I find the number of detections recorded at my site drops dramatically in the presence of disturbed weather, such as we have just now.  This suggests that when weather conditions are more favourable (a calmer troposhere), your detection rate could increase.

It will be very interesting to see how your detections develop as we proceed through April to the Lyrids.

If you can run one of the published algorithms on Spectrum Lab on the laptop, you can build a record af background rates, which could be useful if you are able to get the Pi based detector running in the future.

Richard 

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I am of your same opinion @BiggarDigger, even if there was some fortuitous coincidence that I was getting the scatter from the frontal lobes (very low possibilities here), they would have been transient, and definitely not a constant. These have to be the byproduct of the radar rear lobes. Your observation of the effect of the weather on signal propagation is spot on, and there is also the fact that we are receiving across the parallels, rather than along them, and it is a factor to consider.

I remember, when I was doing dx back in the day, how easy was to talk with Russia or Japan from Italy, and how difficult was to do the same with Norway. The problem here is the calmer troposphere... as I am sure that everyone knows, Scotland will be Scotland in that regard ?

For now, I will keep just taking screenshots continuously (unfortunately work doesn't give me lots of time until at least the end of the month) but I have saved every link you gave me, so I will test those as soon as I can.

 

1 hour ago, The Admiral said:

Will Spectrum Lab run satisfactorily on a RPi? I've always thought, possibly wrongly, that the FFT process demanded quite a bit of processing power, not to mention a 192kHz soundcard.

1

Still haven't tried to tell you the truth, but I plan to. However, I am still having problems in making it recognize the AirSpy, while it works pretty well with the normal dongle. However, I would have liked to use it in pair with SDR#, so for now still work to do.

@wxsatuser Thank you very very much for all the screenshots, and for the time in finding and posting them! They will be great as a reference for what I will be able (hopefully) to see in the coming days/weeks.

 

P.s. while I was writing... this beauty came up!

image.thumb.png.c57ac8fababc29144e316c8b7235a70f.png

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6 minutes ago, Stormchaser said:

P.s. while I was writing... this beauty came up!

image.thumb.png.c57ac8fababc29144e316c8b7235a70f.png

Now, that is definitely a meteor!

Well done!

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1 hour ago, Stormchaser said:

P.s. while I was writing... this beauty came up!

That's nice! Now I didn't see that one at all!

Ian

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Posted (edited)

Firstly, thanks again to all the community, @BiggarDigger @wxsatuser @The Admiral for their precious advice and experience in the field!

Now, a much deserved update, after two months and more of tests with both the RaspberryPi 3+ and my old Windows PC.

I spent all of April in trying to receive something more than only the bigger meteors, which at the time were almost all that my setup would receive. Thus, being sparse and not frequent at all, I wasn't sure that my system was working properly. Unfortunately, no one with a good enough apparatus was near my location on the SpyServer AirSpy network, so no chances of making good comparisons, since I could not use the ones in southern England because from there is definitely easier to catch the GRAVES signals.

Fortunately, however, a local radio amateur had an old 2m antenna that he didn't need anymore, and he lent it me for a bit during the first two weeks of May... well, that one changed everything! All of a sudden I was able to receive even the fainter meteors!! I don't have to tell you how great was that day!

So, after I came back from a work trip, I bought myself this, a handmade antenna which is proving fantastic.

image.png.c626809fe3c5cb3f4f050a624fda38ac.png

Its specifications are the following (shortened):

 

Free Space Forward Gain:     14.3 dBi
Front to Back Ratio:            32 dB
3 dB Horizontal Beamwidth:     37°
3 dB Vertical Beamwidth:     40.2°
Number of elements:     9
Element Diameter:     8 mm Aluminum tube
Dipole Diameter:     8 mm Hard Copper tube
Longest element:     1040 mm
Boom Length:     4.67 m
Boom Size:     30 x 30 mm + 20 x 20 mm

Due to it being way bigger than the other, I had to move it, and since I had to do that... why don't move it in a better position? I acquired a heavy umbrella base, put a good 3 metres pine treated wooden pole on it, and put the antenna on the top, and moved it in my garden to have a better and clearer view of the horizon.

Tried the new setup for anothe couple of weeks, switching between the PC and the RasPi3+, and I noticed that the last one often missed something, like every now and then it wasn't receiving anything while instead it should have shown some activity. I identified a problem with the Raspbian drivers of the AirSpy dongle, which (doing the opposite of the normal RTLSDR dongle) seem to disconnect it and reconnect it at random times, and I still haven't identified the cause. For now then, everything is working on the Win PC, on which I'm now trying a set of rules in SpectrumLab (feeded by SDR Sharp) to get nice automatic screenshots.

These are from yesterday/last night's activity, I'd assume a normal night since we are far away from meteor swarms now. But well... it's possible to get the GRAVES radar even from here, in the far up north of Scotland!!

image.png.7a56cbb7bebedb51c1b3ddb51214a2ab.png

  image.png.e5d9c7d6474074585ab6afc7d66c6a01.png
   
   

image.png

image.png

Edited by Stormchaser
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Congratulations! Looking good so far, be good to see what you get during shower activity.

If it is due to reflection of a backfire beam from the Graves antenna, it will be interesting to see if you still see the beam switching. I see no reason why not, but interesting to see nonetheless. Of course, you'd need a nice long duration trail to see that readily, best during shower activity.

Ian

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Thank you very much!

Yes, that will be interesting to see indeed. For now I'm trying to monitor the various ISS passes, to try to understand from where I'm getting the signal (that is, if from the rear lobe or portions of the frontal one) based on the position of the Space Station.

No luck in that as of now, but I managed to script SpectrumLab to take pictures of the meteor echoes above a certain value automatically , so at least now everything runs as I imagined.
Some nice echoes however, even if we are not in a meteor shower, and good statistics of at least 4 to 10 meteors per hour more or less.

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Without checking out the detail, I wonder if the ISS comes sufficiently far north even to be able to get rear lobe reflection, unless it is high angle. If you do pick up the ISS the beam switching would be clearly evident.

Ian

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Well, the northernmost transits that the ISS makes over the region can be seen straight overhead from southern England, so the Space Station should be able to transit (in some instances) in the area interested by the rear lobes of the GRAVES... now, to find those instances is the challenge, and to see if those instances themselves exist in the first place.

As you said, it would be a nice way to capture the beam switching away from the main showers.

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Apologies, I'm slightly late to the party - I've been inactive for a while as there's very little deep sky visual observations available from my site at this time of the year and my meteor detector was offline as we performed some maintenance at the property.

Anyway, those look like excellent out-of-shower detections and bode well for the Perseids in August.  Given the geometries and your radio horizon, I can't see how they would be anything other forward scatter from radiation in the (expectant weak) northern facing lobes.   Your new antenna seems to be performing well - I used to run an array of 4 such long boom yagis in the 1990's for EME on 144MHz.  They work very well.

I have tried on several occasions to detect the ISS from these lobes, but I fear the ISS elevation may be too high for me to detect scatter from them.  I  might have detected a single very weak signal from the north facing lobes, but it's far from convincing.  All of my other detections of the ISS are when it is very low to my horizon, transiting the South of France and south of the radar.  Yet given my range to GRAVES, and even more so with your range, we still have strong circumstantial evidence of north facing radiation.

There is an ISS pass at around 09:45 tomorrow morning that reaches 41 degrees elevation from here and may yield a good common scatter medium from Stornoway.  If you detect that transit (or any like it), the case is closed because the ISS is well north of the radar, being over central England at the time.  Have a look on Heavens Above for ISS passes over central and southern England and you may just detect some.

Richard

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No worries, here is the same, with endless days and not even the nautical twilight to darken the nights. Waiting for the slightly dimmer evenings at the beginning of July to try and see some noctilucents, but other than that, even the surface of the Sun is not that interesting without spots.

Luckily, there are many other things to follow, like this project! A very nice and big echo registered yesterday evening, it's always fascinating to just be able to see something like this from your home!

image.png.c7eb635064deb66a962b38200a17e4d8.png
 

Thank you for your input about the antenna, the guy I bought it from has done similar works with EME and he recommended it to me. He also said that he could build me a bigger one, but I don't have enough space in my garden for that 😆
It is proving very performing however, like you said, so for me it's good enough.


Regarding the ISS, checked with HA and my live video stream for the early transit this morning, but no echoes coming from the waterfall. I'll try again for the other two passes this morning, but its orbit is shifting westward, so there will be a pause after this period of observations.
 

I remember however that I had found (looking on google) a pdf with a particular study on the rear lobes of the GRAVES radar, and there was in there something akin to a mathematical proof that the lobes were indeed where we are hypothesizing them to be, since all the echoes kind prove what everyone is saying in this section of the board. Unfortunately, I cannot seem to find it again (I should have saved it)...

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An update from the ISS portion of the project, around 12:11pm today I got this track on the waterfall:

image.png.cde3d526c0c2afe9aa341b0768d5614e.png


It's very very familiar with what I've seen online with other artificial satellites radar detections, so I went on Heavens Above and checked my transits, and this is the one which likely generated the track:

image.png.5a2f09cbd0b28707c107aa17441eed42.png

Now, the time on the waterfall indicates the first signals at around 12:11:00, and the final ones about 45 seconds later. From my position (checking also via Stellarium) the ISS was between +11 and +9 degrees above my horizon, above the northern portion of the Bay of Biscay, going over land over the city of Royan, on the Gironde estuary.

Still unsure about the if this is truly the ISS, but I reckon that this far away an object so big would be one of the few to get such a track. Am I wrong in thinking this?

Anyway, tomorrow there will be two more tracks which I'm deeming favorable, one at 08:08 on the Channel and one around 11:20 (which is the one having the best chances in my opinion).
It would be interesting to crosscheck all these over time, and then create on a map an appropriate diagram of the hypotesized rear lobes, using these sightings as a concrete proof.

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Posted (edited)

Super! It looks very much like the ISS to me, one often gets signals when it's over Biscay. On it's approach towards Graves the frequency falls from a high positive shift to high negative shift as it recedes from Graves. You will be observing it during this transition phase. If the ISS is above your horizon then I'd have every reason to believe it is the ISS reflecting from the forward lobes.

With Dijon as the focus, Heavens Above gives a better idea of relationships to the track. Note of course that Dijon is BST+1.

PassGTrackLargeGraphic.jpeg.bc14c255b8e711bb8bda2f171ca6d6d7.jpeg

Ian

Edited by The Admiral
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Yes, that looks very much like the ISS scattering off the western facing frontal lobe.

If you can see a pass over central England, that will be really interesting.

 

I made a fascinating observation this evening.  I detected what I would characterise as an incoming large piece of space debris.  It had the classic head echo caused by the radial velocity Doppler shift, followed by a long tail generated by ionised gas ionosphere.  This initially looks like a big meteor, but had a decidedly lower Doppler shift on the head indicating much slower incoming radial velocity.

Compare this trace with Stormchaser's detection of a meteor at 21:30 yesterday.

event20190626_193020_968.jpg.5ce8d4181429af6161d1cac33e150219.jpg

The phased switching of GRAVES is visible within the head echo, but the frequency shift is only around 200Hz over about 3 seconds, very roughly the same as I see for satellites and markedly slower than for meteor strikes.

Based on the intensity of both the head echo and intensity & duration of the tail it appears that it had a fair amount of mass.  Spectrum lab recorded that trace at a peak of 46.7db above noise, some 25db stronger than average detections.  Assuming that the ionised tail indicates an altitude in the ionosphere, it appears to have come in somewhere over Southern England, the English Channel or Northern France.  It may have been a slightly scary yet very interesting sight had it been dark.

Richard

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12 hours ago, The Admiral said:

Super! It looks very much like the ISS to me, one often gets signals when it's over Biscay. On it's approach towards Graves the frequency falls from a high positive shift to high negative shift as it recedes from Graves. You will be observing it during this transition phase. If the ISS is above your horizon then I'd have every reason to believe it is the ISS reflecting from the forward lobes.

With Dijon as the focus, Heavens Above gives a better idea of relationships to the track. Note of course that Dijon is BST+1.

Thank you for the reference with the CEST timezone for Dijon and the details on the frequency behavior, it definitely looks like what you said. The ISS was above my horizon, albeit very low in the daytime sky, but there should be no doubts about that.

I'm monitoring this morning, but for now the two higher transits (one on SE England and one on the Channel) were not seen by my station. Waiting for the third one which should approximately follow the orbit that gave me yesterday's signal echo, just a bit more towards the north, but approaching the GRAVES main lobe in the same way. Crossed fingers!

 

11 hours ago, BiggarDigger said:

Yes, that looks very much like the ISS scattering off the western facing frontal lobe. If you can see a pass over central England, that will be really interesting.

I made a fascinating observation this evening.  I detected what I would characterise as an incoming large piece of space debris.  It had the classic head echo caused by the radial velocity Doppler shift, followed by a long tail generated by ionised gas ionosphere. This initially looks like a big meteor, but had a decidedly lower Doppler shift on the head indicating much slower incoming radial velocity.

 

Still waiting for those transits, but I'm monitoring the waterfall all the same. I lowered a bit the detection treshold so even if the pass is faint it should be able to capture it.

Speaking of captures, that was a fantastic echo! Very big and much more detailed than what I managed to capture the other day. The frequency shift is clear as a day, and you're right, if that was a night time even it would have been very interesting to see, possibly even approaching fireballs brightness if the mass was around what we are talking about.

I noticed that you have seconds in your detection text, together with a buch of nice info. Would it be possible to take a look at your conditional actions to see what needs to be done to obtain that, or if there is an online reference that I've not managed to find, could you please point it to me?
Thank you!

P.s. Got another big one last nigth, always fascinating!

image.png.dd7e833dbc3a7b41bc78b4ea730c7ccc.png

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This afternoon's update about the ISS.
image.png.22ecdccfd21a68544f99d85faa198ff6.png

I managed to get this transit too, from around 11:21:55 to 11:22:15 BST approximately. The signal was fainter than yesterday, in fact the algorithm didn't manage to recognize it as a meteor and didn't capture it, but I clearly saw the oblique line on the screen, along with the frequency shift.

The area remains the same, I think that with this we are possibly at the northern limits of the main GRAVES Radar area. Will continue to check in the next days, but now I'm pretty sure that this is the ISS. Still no echoes from the Channel or southern England transits, will have to wait for pure northern France (like Normandy) ones to see if it's possible to get something from those locations.

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7 hours ago, Stormchaser said:

Thank you for the reference with the CEST timezone for Dijon and the details on the frequency behavior, it definitely looks like what you said. The ISS was above my horizon, albeit very low in the daytime sky, but there should be no doubts about that.

I'm monitoring this morning, but for now the two higher transits (one on SE England and one on the Channel) were not seen by my station. Waiting for the third one which should approximately follow the orbit that gave me yesterday's signal echo, just a bit more towards the north, but approaching the GRAVES main lobe in the same way. Crossed fingers!

 

Still waiting for those transits, but I'm monitoring the waterfall all the same. I lowered a bit the detection treshold so even if the pass is faint it should be able to capture it.

Speaking of captures, that was a fantastic echo! Very big and much more detailed than what I managed to capture the other day. The frequency shift is clear as a day, and you're right, if that was a night time even it would have been very interesting to see, possibly even approaching fireballs brightness if the mass was around what we are talking about.

I noticed that you have seconds in your detection text, together with a buch of nice info. Would it be possible to take a look at your conditional actions to see what needs to be done to obtain that, or if there is an online reference that I've not managed to find, could you please point it to me?
Thank you!

P.s. Got another big one last nigth, always fascinating!

image.png.dd7e833dbc3a7b41bc78b4ea730c7ccc.png

I'm working mobile and will be away until sometime on Saturday now, so may not be able to add much detail, but I use a slightly modified (tuned for my setup and site) version of the detection script presented by IanL here:

 

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Thank you very much @BiggarDigger!
That post was a goldmine of information, I've already found what I needed, so thank you again!

ISS again this morning, today with a more westward track, but I got an echo.
image.png.4a7b57155a36072e87684679fbae6f4a.png

image.png.f300c2826b2a3b821ea3f698f2dbbe4c.png


As you can see, the track is very faint, but it is visible from approximately 10:32:40 to 10:33:00 BST, just at the edge of my 10 degrees visibility circle from Stornoway.

Combining all my three observations (red ticks for start/end echo times) into a single map from Dijon perspective, we get this approx. shape, which is mostly into the GRAVES radar main lobe, but also (especially with today's transit) above it.
image.png.a80d7d240d002deabf3ebc645335405e.png

Further transits are definitely required, but I think that it's already possible to get an idea from this.

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Hallo Stormchaser on Stornoway 

Don't know why I hadn't seen your posting of June 28th before - but now I have 🙂 This is a really interesting study you are doing particularly in mapping out the regions of the sky that return scattering from GRAVES.   It adds to the Narvarro paper that  wxsatuser referred me to in a recent posting in another thread.  Those rear/side lobes are mainly unknown and the fact that they are from a reflection from the ground with local buildings giving clutter makes them even more difficult (impossible?) to predict.  If you have any more evidence of ISS or other satellites I would be most interested.  Also, what do you use for satellite location reporting?

Edited by Geminids

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