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Radio Astronomy, Help Needed


TomP

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Hi All,

Alongside traditional visible astronomy, I've been interested quite some time in radio astronomy especially the chance to build something for cheap on such a brilliant conclusion.  However, finding it simple after researching a basic dish telescope, I've also discovered Meteor radio scopes, I would like to build one of each in the near future.

After reading some of the posts on here with great prospect, I want to know if someone can direct on how to build a Meteor radio scope in simple form or some rough diagrams for aerials etc... I plan on using it in my back garden and keeping it in my shed. I could have it attached to the shed, but problems with a neighbor makes it difficult. 

I appreciate everyone's time and response to this post and look forward to hearing from everyone!!

Best

Tom.

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Instead of building a movable dish (which is a right pain given the size needed), you could consider a phased array design, which would be essentially flat (so less obstructive). Some more electronics needed, but electronics is more easily tuned and often cheaper than big bulky mechanisms

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That's a good point, where could I find one?? We have an old sky dish at home but easy to buy new cheap on eBay, I don't mind the dish so much it's just the aerial for meteor but I could work around it no problem.

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Hi Tom

Radio based meteor detectors are fairly easy to build and get working, but you won't be able to use your old sky dish.  

You'll need something like a directional Yagi antenna, some sort of radio receiver a PC/laptop, some software (mostly freeware stuff) and a bunch of cable. I set one up about 3 months ago, mostly based on the articles in June & July's Sky at Night mag and a bucket full of help from people online.  It's been running pretty much full time since it went live. 

You can find an overview of my system here DIY Radio Meteor Detector 1 and here DIY Radio Meteor Detector 2 there are some links out to other pdf documents that give full details on how these systems work.

At the bottom of the 2nd link there is an image capture and associated audio for one of the bigger hits.

My system works by picking up radio back scatter from the Graves Space Surveillance radar nr Dijon in France.  This operates on a freq of 143.050Mhz, so it's easy (and quite cheap) to find a 2m ham Yagi antenna.  

The image below is my antenna and it's not overly big and quite discreet, I don't think any of my neighbours have even noticed it yet!

My neighbours old sky dish and TV aerial are in the pic so it gives some idea of size.

Mounted where it is, it's also quick and easy to take down if needed but I leave it up and the system running 24/7 where possible.

20140908_075427-e1412763278852-225x300.j

This page has screenshots of current meteor detections:  http://www.ukstargazer.org/meteor-detection/

This shows my current rate detections for December (the image should update with a page refresh).  

Most are tiny pings, some are much bigger.

Grant_122014.jpg

Sadly this system doesn't pick up meteors over the UK, but ones over the South of France/Med.  If you want to try detecting meteors closer to home then you'll need to look at the Brams transmitters in Belgium, these operate at around 50Mhz and need a much bigger antenna.

I've looked at uses for my old sky dish and although there are some things that can be done they all look to be a bit more complicated as far as the receive equipment goes and as far as I can tell need a bit more electronics experience than I have!

If this is the sort of system you're looking to make and have any questions then I'll be happy to try and help where I can.  

Cheers

    Al

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Al, you are a star My friend!!! I've found this really useful beyond words and the two links to your page, makes life much easier!!!

I wanted to ask you though on what height will I need the aerial?? I also need to get my hands on those two Sky at Night mags too!!!

Best & thanks

Tom

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Al, you are a star My friend!!! I've found this really useful beyond words and the two links to your page, makes life much easier!!!

I wanted to ask you though on what height will I need the aerial?? I also need to get my hands on those two Sky at Night mags too!!!

Best & thanks

Tom

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Al, you are a star My friend!!! I've found this really useful beyond words and the two links to your page, makes life much easier!!!

I wanted to ask you though on what height will I need the aerial?? I also need to get my hands on those two Sky at Night mags too!!!

Best & thanks

Tom

Hi Tom,

No problem, glad it helps.

For the antenna mounting height I suppose the higher the better!  But that said mine is currently no more than 15ft above ground level and it's been fine. I wanted it mounted in a place easy enough to get to without getting up on the roof.  Before mounting and when I was testing the system, I had it down at about 8ft high and it worked without any problems.    You need to mount it pointing towards the S.E.   If there are houses in that direction it doesn't seem to matter as long as they're not too close ( like right next to the antenna).  Supposed to be best if you can mounting it pointing about 10degs upwards.  Mine isn't and it's all OK!

Al 

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Thanks Al, that direction at mine is pretty open, bungalows behind ours then retail park and endless fields, I'll have to take a pic, I have thought about my bedroom window?? or I could put the aerial on a pole short, then place it on top of the shed for use and bring it down afterwards.

It's interesting though, as on my tablet I have a ISS tracker, watching it come over one evening I could still see it in the distance and while looking at the gps map it was over Paris!!

Best

Tom.

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Hi Tom,

If you're after building your own aerial the instructions are in the June edition of the S@N magazine. The aerial dimensions are tailored to pick up the GRAVES signal. You can get back issues of S@N magazine from here- http://www.skyatnightmagazine.com/magazine/past-issues The July issue details using the FUNcube pro+ dongle and Spectrum Labs software. I went the build it yourself route which was fun and easy to do. The Mk I is still up on the shed after 4 months with no issues despite the rain and the winds. Best of luck whichever way you decide to go! BTW There's a wealth of information on meteors and detection on the Internet and in the SGL 'New to Meteor Detection' thread. Fascinating subject.

Cheers,

Steve

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If you're really keen and you wanted to improve the sensitivity and at the same time some good filtering to help remove problem strong signals then this Filter/LNA would be an exellent way of doing both ..

http://constructions.f6fkn.com/pga103vhf/index.html

It uses a fairly new and very nice and extremely simple 0.5dB NF 1dB compression at 100mW output 50R pre-amp device from Minicircuits. You could power the unit via the coax if you wanted too as well with a slight change.

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Thanks Steve, I was given links via a private message of the pdf files for the Sky at Night articles, fascinating ready for sure. I've also been shown with great thanks to Al some aerials, it would be brill to make one at the same time. Sadly, as previously mentioned we have a troublesome neighbor, so the pole would be 9ft while portable at the same time. I've also been given alternatives for the Dongle but I think I will keep to the original despite expense on a budget, it is holding me back slightly.

I think it was you Steve, there was mention of someone on a topic that used a aerial small?? the outlook from my bedroom East/South is clear also

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Hi Tom,

Glad you have the articles. Given your neighbour's disposition it might be best to have a manufactured aerial fitted on your chimney (after first testing it works) as it will be smaller and less intrusive than a home made wooden one-just a thought. I'm fortunate to have a relative living next door who doesn't mind my experiments. A roof mounted one would also be more tamper proof methinks!

Let us know how you get on.

Cheers,

Steve

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Hi Tom,

No problem, glad it helps.

For the antenna mounting height I suppose the higher the better!  But that said mine is currently no more than 15ft above ground level and it's been fine. I wanted it mounted in a place easy enough to get to without getting up on the roof.  Before mounting and when I was testing the system, I had it down at about 8ft high and it worked without any problems.    You need to mount it pointing towards the S.E.   If there are houses in that direction it doesn't seem to matter as long as they're not too close ( like right next to the antenna).  Supposed to be best if you can mounting it pointing about 10degs upwards.  Mine isn't and it's all OK!

Al 

Clear take off is most likely more important than height but the higher the better.

I spent years working meteorscatter on 2metres and it was hard work considering my location.

In a valley surrounded by chalk does'nt help. :grin:

With a lot of effort I worked as far as North Africa, the Black Sea coast of Romania, western Russia, Finland and

most other countries with in 800 to 2000kms.

BTW

I always had about 5 degrees of elevation on my antennas.

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:) I'll have to put some pics up of my location and direction of E/S it is really clear, I tell you what I'll screen cap the map now to give a rough diagram for both yourself and Al, one chap on here mentioned that someone was using a small aerial instead?? I really want to get into this in the New Year, just the £150 for the funcube that's slightly off putting!!!

I also picked up this book today too off amazon - http://www.amazon.co.uk/Unseen-Cosmos-Universe-Francis-Graham-Smith/dp/0199660581/ref=sr_1_3?ie=UTF8&qid=1417811209&sr=8-3&keywords=radio+astronomy

While I forgot to share with everyone the radio telescope at Knockin in Shropshire, which is part of Jodrell Bank in Cheshire as I visited it a year or so ok, I'll load some pics up in a min alongside the screen cap of my location :)

Best

Tom.

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  • 2 weeks later...

Al, you are a star My friend!!! I've found this really useful beyond words and the two links to your page, makes life much easier!!!

I wanted to ask you though on what height will I need the aerial?? I also need to get my hands on those two Sky at Night mags too!!!

Best & thanks

Tom

I'm a newbie, but from what I've been reading on this forum, Al's comments are highly regarded. My own experience in radio detection of meteors amounts to only a few days, but here is what I do, for what it is worth. I built my own 4-element "Yagi" aerial using K7MEM's aerial designer website http://www.k7mem.com/Electronic_Notebook/antennas/yagi_vhf_quick.html and put it together using plastic plumbing bits and copper pipe. It is mounted in the loft-space and partly "shoots" through the end wall of the house (which is why I chose a 4-element design rather than the customary 3-element), pointing about 130 degrees from mag. north. There's a house next door as well. Even so, I've clocked up quite a few events when tuned to the Graves radar with the Geminid shower.

If you don't feel up to making your own aerial, then I've come across Innovantennas (http://www.innovantennas.com/our-antennas.html)) which might suit your needs. Look for the 144MHz Yagis. Can't vouch for them myself, but worth at look to see what is out there.

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oh, that S@N article has got the frequency wrong, it's not 145.05MHz, it's 143.05MHz.

Only wrong at the top of the article though. It is repeated correctly several times further down. Not sure what wavelength the Yagi is cut for though. (Not that you would notice any difference, as receiving antenna at least)

Robin

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Having built one of the S@N aerials the only modification I would make if I built a second would be to add a small length of wood beneath the reflector element conduit. I have noticed the larger reflector element (it is over a metre long) has a tendency to flex in strong winds and has twisted out the plastic conduit once. A small length of supporting varnished wood would allow a few extra screws to be used along the conduit length. :smiley:

Cheers,

Steve

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