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What's the minimum to start meteor detecting?

Stub Mandrel

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The Admiral

The Admiral

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11 minutes ago, Stub Mandrel said:

That's pretty much what I saw, only it was nearly horizontal ?

I think it must be working.

Well done Neil! I think you've cracked it.

I wouldn't worry about your length of co-ax, should be OK with sat grade. Yes, poking a wire into the central pin is really not the way to go ?. Not sure if the standard one from Westlakes would have done, as it's for 5mm cable.

The blips are variable in shape, more often very short, though during showers you can get ones lasting many seconds. In which case of course you get a vertical stripe. With luck you should be able to also see an initial strike, at the beginning, which would be a very short duration horizontal line spanning quite a few kHz, on a vertical waterfall.

Right, now onto SL I guess :wink2:.

Ian

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Stub Mandrel

Stub Mandrel

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Seem to be getting one everyfive minutes or so, mostly faint. You can see this one got slightly higher in frequency as it went.

image.thumb.png.b17e1d35f4d674d2bdf429e198c898d2.png

Faint but promising:

 

image.thumb.png.b8d7b428650054fd6569dff7fe52ce28.png

Quite lot of 'tinies' that give little traces and make a brief whistle.

image.thumb.png.5fabff9d9707c88d4ce4ccd256df0f72.png

Just had abig one but too slow on the print screen...

 

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The Admiral

The Admiral

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55 minutes ago, Stub Mandrel said:

I swapped out the short supplied USB lead and just used my extension, the signal on all channesl was much better. Is it a real effect or just time of day? Stil getting more convincing trace here. Just got a second one.

To be honest, I'd be surprised if a USB cable would make a significant difference, after all, it's only carrying audio. But what do I know? I use a short USB extension cable with mine, and added a ferrite rf trap around it in the belief it would help prevent rf noise entering the dongle, but I don't know if it has made any real difference.

Steve and I have had some strong, lengthy traces during the Perseids in the past, so it would be useful if you could get SL going in time for that. It's quite stunning to experience and record bright traces lasting 10 seconds or more!

Ian

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Stub Mandrel

Stub Mandrel

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Iimage.thumb.png.18510c8dcad09d595ced9a50a624461d.png

This morning as the ISS passed over the south of the UK I tried to catch it. I got a very broad fuzz as a slight hump that started way above the Graves frequency, and gradually drifted below it in the RF display. As the ISS was near closest approach the hump passed through the AF displya as ain increase in noise for several seconds. I have just captured a similar event, but the ISS is near Australia, I suspect this is some other large spacecraft or satellite? It has to be going very fast to get such a massive doppler shift!

 

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The Admiral

The Admiral

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I'm not altogether sure that is the ISS Neil. It is the sort of spurious trace I've seen, the origins of which I'm not sure. The Graves radar switches segmentally to cover the 180° transmission zone, the net effect of which is that the ISS trace is segmented too. See Tomatobro's post above.

The Doppler shift for the ISS is large though, something like 6kHz IIRC, +3kHz at the start of the approach and -3kHz as it recedes into the distance.

Ian

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Stub Mandrel

Stub Mandrel

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I wonder what it is?

It shifted about 1Mhz as it went from right to left, was still on the left when I started up alter and then after about fifteen minutes tarted to drift back to the right.

Perhaps its some source of interference?

I am seriously struggling with SpectrumLab

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The Admiral

The Admiral

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14 minutes ago, Stub Mandrel said:

Perhaps its some source of interference?

I think so. You do see some very odd traces coming and going.

What's your problem with SL exactly? It's a while since I dabbled with it, but you never know, and there are a number on here who are familiar with it. As I've said previously, there is a comprehensive manual but it is dense reading and needs to be interpreted carefully.

Ian

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Stub Mandrel

Stub Mandrel

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Well I got the dongle to work with it, but the waterfall display only seems to have about five steps across it...

I can't get the virtual cable recommended by @steppenwolf to work. I have been sent links to some setup files to try.

At the moment I am just playing, I've found loads of FMradio stations and some weird things. If you google the frequency you can find out what they are - I'm listening to pager noises!

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The Admiral

The Admiral

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13 hours ago, Stub Mandrel said:

I can't get the virtual cable recommended by @steppenwolf to work.

I didn't need to use one, so can't help. I forget now why one would be necessary, but I vaguely remember reading about it.

Ian

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Stub Mandrel

Stub Mandrel

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I used @badger111's scripts and got radio

I am having great confusion with the controls, Spectrum lab has so many and unlike HDSDR the tips don't always make sense without a lot of background knowledge.

Also, HDSDR works happily alongside other apps, but Spectrum Lab stutters continuously if any apps are doing anything - loading a web page, SL stutters and a complex page takes minutes to refresh.

I need to do a lot of experiment and it's not easy on my laptop ?

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The Admiral

The Admiral

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1 hour ago, Stub Mandrel said:

I got the ISS, here it's passed Graves and is heading away SE. It's very faint but it proves the system!

Hmm, it might be, but I'm not so sure it is. I wouldn't have thought it would be at constant frequency, which is perhaps a little too high. The reflected frequency changes from above to below the Graves transmission frequency, and only tends asymptotically to a constant frequency when the ISS is on the horizons. If this was the ISS it would need to be on the approach horizon. Does that tally with the pass times? Checking on 'Heavens Above' I found this for ~10.36 BST. Probably within range. So, assuming that your time scale on the waterfall is UTC, then jury's still out!

ISS.jpg.a66b2d698249c49f868ca57aa08c431a.jpg

But I don't think you need the ISS to prove your system, as it does appear to receive meteor scatters! For interest, here's a chance encounter some years ago with the ISS when my system recorded a meteor strike.

1582422711_MAY-1111_19_56.thumb.jpg.4eead277070e689555e1ecddc8cec3d4.jpg

Also, I think that SL is very demanding of system resources as it's having to do FFTs on the fly. I use my PC which is an i7 machine with lots of RAM, so I tend not to suffer. Even so, the waterfall does stutter occasionally.

This might be of interest.

Radar Echoes from Space DK5EC.pdf

Ian

Edit. Looking at that document I see that the Doppler shift with the ISS is ±6kHz, and not ±3kHz that I originally stated! That of course has significant implications because your receiver bandwidth is going to be much less.

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