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Non-DIY meteor detection

jambouk

By jambouk
in Radio Astronomy and Spectroscopy

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jambouk

jambouk

Posted
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Lots of info out there about making your own antenna, but some of us would rather buy one pre-made; would either of these do the trick:

http://www.ebay.co.uk/itm/2el-144MHz-2m-Quad-Style-Yagi-Shorter-than-HB9CV-just-14cms-long-HUGE-GAIN-/290871701262?pt=UK_Mobile_Phones_Communication_Radio_Antennas&hash=item43b94def0e

http://www.ebay.co.uk/itm/3el-144MHz-2m-Yagi-Shorter-than-HB9CV-and-Moxon-but-more-GAIN-SOTA-Portable-/290812885021?pt=UK_Mobile_Phones_Communication_Radio_Antennas&hash=item43b5cc781d

Are there other options out there with just three elements to keep the "field of view" wide? Are they relatively easy to wire up?

Thanks for any replies.

James

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Al.Grant

Al.Grant

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Hi James,

That second link (3el Yagi) is the same one I'm currently using.  Although I've only borrowed mine it is the same one from the same company.

Not sure if the brand new one comes with any connectors, but even without they are easy enough to wire up, just a couple of crimp connectors and BNC/sma adapter and trust me I am useless at electrics and wiring!

I used a decent quality RG58 cable and some connectors from Maplin.  One thing to look at is what connection type your receiver/dongle uses.

There are 3 or 4 different types. Funcube Pro+ uses sma connectors others have  tv aerial type sockets and I think there are a couple of others.  

I took my dongle into Maplin and made sure I had the correct one.  I ended up using a BNC to SMA adapter (about £3.50).

Setting it up was the easiest part ... then comes the software.  The S@N scripts were fine to get started but once you find yourself tweaking  :BangHead:  

Al

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jambouk

jambouk

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My local astronomical society is doing a radio project and the committee have made a few antennas to hand out. I've now got one and just put it all together tonight in the shed for a mess around and managed to detect what I think are meteors. Screen shot below. My laptop charger introduces a load of interference which I need to sort out, and I need to find the best place for the antenna, probably inside the loft as long as it can still detect activity. Clearly lots of learn as I don't understand this radio physics in the slightest. But it will be good to get it properly running and start collecting data for the project. (I've got the antenna pointing Se at an elevation of about 10 degrees; the funcube thing is plugged into the laptop via a 5m active USB lead, and the funcube the other end goes to the antenna via a 2m coaxial cable I've cobbled togther with a BNC (?) connection the other end I got off ebay.)

James

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John101

John101

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James,

Not sure how to get back to you via e-mail, so will post here as others may have interest.

I found those individual antenna and PC snap on choke cores at a ham radio fest several years back and have no product information as such.  I am sure the cores are ferrite (verses iron, because of weight and size) and probably number 43 material.

Back in the day (I retired in 1997) we purchased our stock cores from Amidon Inc (www.amidoncorp.com) they offer a free PDF with both iron and ferrite core size verses frequency and winding formula.

Google ‘common mode choke’ will return a wealth of info to include elaborate winding methods.

John

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Al.Grant

Al.Grant

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James,

I have my FCD Pro+ in my PC and a laptop plugged in and running sat next to it and I don't see anything like that huge block of interference you are getting.

Ferrite cores sound like a good idea, I've seen them mentioned elsewhere but not tried them, but as they are so cheap I may add one and see if there is any difference.  

There are lots listed on fleabay and also available at Maplin  http://www.maplin.co.uk/p/ferrite-clip-on-hem3012-n89ab   For a £2-£3 there isn't much to lose in giving them a try.

I have my antenna set up outside and mounted on a side roof about 15 ft off the ground.
I used this website to check the bearing from my location to the Graves radar (Dijon) http://www.sunearthtools.com/tools/distance.php  - for me it's between 145 - 150 degrees.

One useful thing you can easily add to Spectrum Lab is an hourly meteor counter.

If you click on one of the spare buttons on the left side and in the top box for the variable string enter   "Meteor/Hr:"+str(COUNT_HR)    including quotation marks.

Then leave the rest at the defaults and close the box this will count up how many detections you've had during the past hour.  

It automatically resets on the hour, but is useful for seeing the sort of activity you are getting.

How many detectors are your astro society setting up ?  It would be interesting to see how results compare for a number of detectors around a similar geographic location, especially if using the same equipment/antenna etc.

I'm not too far South of Nottingham so would also be good to compare levels with those seen by your members.

I'm automatically feeding my data into the RMOB website here:  http://www.rmob.org/livedata/main.php   - if you zoom in on the map, the marker in the centre of the UK is me!

Al

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jambouk

jambouk

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I set the antenna up in the loft, and left the funcube in the loft and ran a usb lead to my PC downstairs - no meaningful signal.

I'm going to check all the connections, and knock up a long co-ax cable and run that down from the loft and have the funcube dongle nearer (or directly in) the pc. The laptop seemed to cope with the long usb lead so not sure why the desktop doesn't.

Jd

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jambouk

jambouk

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My BNC connections on the co-ax were poor so now got it all sorted. It is all running well on my laptop. And no charger interference upstairs compared to downstairs, but it is a different charger.

I can't get the stuff to run well on my desktop, it is just too noisy and it seems the only information the display shows on my desktop if vibrations in my office. Again, need to investigate that at some stage.

With regards the project the society is doing, I'm not too sure about numbers or locations, I just blindly signed up to it. If you want to know more, drop me a message and I'll forward you the email address of the guy who knows all about it.

I couldn't get that command to do an hourly rate either; I remove the text about button 7 from the top line and replaced it with the text you supplied with ", but it just doesn't work. Something else to sort out in time!

James

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jambouk

jambouk

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Intermittantly I get this kind of picture, with something (or more than one thing) drifting through my detector. Is it a plane, satellite, local artefact? Why are there parallel lines like there are two of them? And why do they appear in different directions?

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SteveNickolls

SteveNickolls

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Intermittantly I get this kind of picture, with something (or more than one thing) drifting through my detector. Is it a plane, satellite, local artefact? Why are there parallel lines like there are two of them? And why do they appear in different directions?

Hi James, I am reading your posts with interest and hope you get set up shortly as you want things to be. I wonder if the diagonal traces your occasionally getting are satellite trails? I also wonder if you are near to the East Midlands airport and picking up arrivals and departures there? I found this interesting read-http://dk5ec.de/Graves-Echo-english.pdf which may offer some light on the subject.

Best wishes,

Steve

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jambouk

jambouk

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Steve

Thanks for the link; that is helpful to see similar artefacts to the ones I am observing. The parallel lines do look like planes, and I am now going to use this website (http://www.flightradar24.com/52.89,-1.26/9) to see if they tally with known aircraft passing; yes I am in the flight path of east midlands, I think my house falls under the stacking path.

I've also seen the curved artefact line too, which your link suggests is the ISS; again I will look out for ISS passes on heavenabove and see if that fits with my observations.

Currently the set up is detecting probably a meteor every two or three minutes. I've seen some software which plots the frequency against time of day, which obviously fits with the earths rotation into the orbit of stellar debris.

James

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SteveNickolls

SteveNickolls

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Hi James,

I also recorded the above detection at the same time this morning although Spectrum Labs reported it as several shorter 'meteors' but I would say it was at least originally one meteor from looking at it (while I'm messing with Spectrum Labs I'm sticking with the starter configuration and it doesn't show the detail that your configuration does). You can see on your screen shot that the overall trace changes in frequency with time. Its possible the meteor, being larger than the usual size could have split up on entry causing the effect shown or maybe fast winds affected the ionisation trail high in the atmosphere or thirdly diffraction of the trail (or any combination). This pdf is a very interesting read- http://www.britastro.org/radio/projects/Detection_of_meteors_by_RADAR.pdf

Cheers,

Steve

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Al.Grant

Al.Grant

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Aircraft update:

I've just detected a Boeing 767-336(ER) at 36000ft, travelling at 448 knots, on track 331 degrees. So yes, my dual diagonal lines are aircraft.

James,

I've just been looking at FlightRadar24 for aircraft movements in the direction of my antenna and also using Orbitron for satellite passes.

Now I'm wondering if I'm looking for aircraft in the wrong place!

The beam from Graves is directed South from Dijon.  What we detect here in the UK is 'backscatter' from events over Southern France/Med.

GRAVES%20beam%20geometry.jpg

So any aircraft local to us (or anywhere in the UK) will not have passed through the Graves beam to give us a reflection.   I'd also think that if they were local then this close to East Midlands airport I'd think we'd pick up far more aircraft if they were local.

....  Or maybe I'm missing something !

Of course this also means we are not detecting meteors visible in the UK.  

As far as I understand to do that means using the BRAMS beacons in Belgium on the lower freq of around 50Mhs. This would need a different antenna.

I've seen that this can only be picked up in the South of the UK, but this PDF about BRAMS  shows it can be detected in Bristol.

Although further South, Loughborough/Nottingham is actually closer.  Maybe something I'll look at in the future as it would be great to match up radio and visual detections. Probably worth a try if I can borrow an antenna for a while to try it out.   An HF wire is far larger than the 143mhz Yagi, but would work fine hidden in the loft. 

Al

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jambouk

jambouk

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I don't understand it at all, but I am 99% sure the artefacts I'm observing at related to aircraft in my vicinity; if they are travelling towards house from the south, I first detect artefact when they are over Melton.

My data trace is running right to left. If an aircraft is travelling towards my antenna (pointing south east) from the south, there first appear two weak parallel lines which increase in frequency; from the start of the weak line, about 60 seconds later a much stronger signal is detected, also with increasing frequency, then about 60 seconds after that there are weak lines again... If an aircraft is travelling towards my antenna from the north, the pattern of lines is the same, but they have falling frequency.

James

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Al.Grant

Al.Grant

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Hi James,

Well what you are saying and the screenshots certainly makes sense.  But have to admit that it leaves me a bit confused about aircraft detections.  

The ones from the North are totally the wrong direction for Graves and if you are using a Yagi pointing to the SE then that's even more confusing, as Yagi antennas are directional (although I suspect there is a rear lobe of some description) ......... No idea!    :huh:

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