poor-man-s-radio-telescope.pdf

http://www.instructables.com/id/Poor-Man-s-Radio-Telescope/

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Poor Man's Radio Telescopeby z0rb on March 9, 2007

Table of Contents

Poor Man's Radio Telescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro: Poor Man's Radio Telescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1: An examination of the feed assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 2: An Examination of the Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 3: A test run of the Sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 4: I still see radio sunshine on a cloudy day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 5: And so... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

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Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5


Author:z0rbI like to tinker and I like to learn, and if one can support the other then thats great.

Intro: Poor Man's Radio TelescopeA way to peer into the radiosky using little more then junk found on the side of the road.Remembering back to my 10th birthday. I recall receiving a book on outer space. I believe it was published by National Geographic. This was by far my most prized bookin my somewhat limited collection of the time.

In it there was a rough outline of a radio telescope. This diagram so intrigued me that for years in the back of my mind I dreamed of being able to play with one.

Indeed years have past, careers, children, and everyday life was by far the most important of responsibilities. Then it happened. I spotted a 10 foot satellite dish insomeone's trash.. I quickly made off with it and all its components.

The mount was in pretty bad shape. It appears to have some serious wind damage, and the pedals of the dish are in less then what I would consider acceptable shape.

None the less I slapped it all together. In the picture you can see my stinky trashcan mount. It was good for a quick test but boy did it stink.

Image Notes1. Stinky Trashcan Mount2. Dog crap3. Electronics4. Junk Dish

Step 1: An examination of the feed assemblyHere we see the feed horn and low noise amplifier. All the dish components were hauled to the curb except the actual receiver unit. The bolts holding the wave guide andthe amp onto the feed horn had to be purchased. Getting this feed horn back into working order took a little bit of time. It seems that the feed horn assembly was home toa community of wasps. I never realized this before but wasps build there nests to last. It took a good bit of probing and a little 409 to clean it up nice.

This is basically the meat of the system. It takes the focused energy of the dish and downconverts it into a usable signal and then amplifys it.

How is all this powered you might ask? The voltage actually travels down the coax cable that is delivering the signal to the next stage.

The polorizing servo is basically left alone, but for those of you that are curious it's a little motor that turns the antenna inside the feedhorn for better reception.


Image Notes1. Feedhorn and Antenna2. More dog crap3. Downconverter and lownoise amplifier4. Polorizing servo

Step 2: An Examination of the ElectronicsHere we see the power supply and a satellite finder meter.

The power supply is home made, 15 volts regulated. I actually picked up the greater quantity of this at a junk store for 3 dollars.Its not as clean as I want it to be but I'mworking on it.

The little fat coil hooked up on the right of the power supply is a choke I placed in the voltage path so the signals coming from teh dish do not seep back into the powersupply.

The satellite finder meter I just received in the mail a few days ago. It receives from 950-2250Mhz. This is the second most important part of the arrangment. This takesthe total power of all the signals that are coming from the dish and converts them into a meter reading. This is known as a Total Power Receiver .

I hooked all this equipment up together and was ready to start.

I passed about 12 volts through it and would get a decent meter readings whenever I swiped my hand in front of the feedhorn assembly. I was convinced that it worked.

Image Notes1. Satellite meter/ Total Power Receiver2. Homemade junk power supply3. NOT dog crap but a dried out leaf.4. RF choke to starve off unwanted signals


Step 3: A test run of the SunI tried pointing the dish at the sun. As you can see in the picture to the right the meter was pegged. It only did this when the dish was pointing at the sun. I deduced that,"Yes indeed, it was picking up the sun." Note the dB knob turned all the way down. It seems the sun packs a mean punch!

Image Notes1. Full scale meter reading when pointed at the sun.2. Knob turned all the way down so as not to butn anything out3. Screw on coax connectors are not as simple and easy as one might think.

Step 4: I still see radio sunshine on a cloudy dayNext a meter reading when some clouds passed in front of the sun. Still a decent amount of signal but definitely not like the unobscured sun reading. Note that I turnedthe knob up a bit to actually see the signal. The meter shot back up once the clouds were gone.

Image Notes1. Sensitivity knob increaed to pull a reading from teh meter.2. Meter less then half scale.

Step 5: And so...this isn't an awesome, peer into the unknown type of radio telescope. Right now it only sees the sun. I plan on trying it on the moon and some star systems a little lateron.

Believe me there is MUCH room for improvement on this system. But it was good enough to teach me some basics and to strike my curiosity a little further.


Image Notes1. Illuminating the Unknown2. The Unknown3. Illuminating the Unknown

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Comments31 comments Add Comment

wanna be macgyver says: Dec 5, 2010. 6:48 PM REPLYHi zOrb,

Thankyou for uploading this project. My father-in-law installs dishes and decoders. He's going to love doing this project with me.Thankyous to the people who have added comments for this project

Regards

specopps117 says: Oct 19, 2009. 11:50 PM REPLYis there a way to conect this to s screen to see the shapes of the radio transmitations of extra terrestrial phenomena?Ouch...to see the shapes of radio tranmission of other worldly objects....

muunkky says: Sep 10, 2009. 3:22 PM REPLYYou can use this setup for more than seeing the sun. Just plug the raw feed into an oscilloscope and jack up the 21cm bandwidth and you've basically gotyourself a high powered radio telescope. Not sure how the LNB is affecting your signal, might want to take that off to get raw analogue goodness.

z0rb says: Sep 10, 2009. 4:26 PM REPLYIt would be great if I had a scope that could go up to 21cm :)


muunkky says: Sep 10, 2009. 5:54 PM REPLYHaha, good point. An analogue UHF video receiver should do the trick though.

z0rb says: Sep 11, 2009. 5:53 AM REPLYSounds like butchering an old TV might do teh trick.

muunkky says: Sep 11, 2009. 9:33 AM REPLYIt depends on the Low Noise Downconverter (LNB) on the dish. The raw feed from the 21 cm line (1420 MHz) will be downconverted toprobably around 1400 kHz which could be picked up on an AM radio I believe, but you need to check the specs.It may block everything below 4 GHz which means you'll never see the 21 cm bandwidth (*sob*). If this is the case and you really want thathydrogen line, you're better off removing the LNB and installing your own feedhorn, band-pass, and low noise amplifier and downconverter forthe 21 cm.You can get all these parts at http://www.radioastronomysupplies.com/radio_astronomy_supplies.php

Chwlo says: Aug 10, 2009. 9:01 PM REPLYz0rb can you take several dish network dishes and align them to make a more powerful and or longer range radio sat. If so can you point me in the rightdirection for this project. I can get plenty of them for nothing. I thought if I could space them out say over a hundred sq yards and align them I could pick upmuch more distant noise. Yes no hmmm.

z0rb says: Aug 11, 2009. 4:37 AM REPLYSounds to me like you are talking about an inferometer. The concept is possible since this is how most klarger radio observatories work, however I amnot sure where to get the equipment to effectivly phase all these dishes together. Below are a few links for further reading. Also you might want to postthis question in a a forum with people in the know :)Good luck.

http://www.radio-astronomy.org/

http://www.umich.edu/~lowbrows/reflections/2007/jabshier.1.html

SolamenteDoug says: Sep 7, 2007. 8:37 AM REPLYMy science project through most of high school involved a homemade radio telescope. It was a 2-meter helical antenna with a modified police scanner, ampand multimeter. It was sensitive enough to pick up the Sun and Jupiter as well. It was less a scientific instrument and more an experiment itself. I'd like to getback into scope making when I get a yard. Keep up the good work!

thepelton says: Jul 20, 2009. 11:00 AM REPLYIt would be interesting to map the sky, and find out where the "hottest" parts are. I suspect that the center of the galaxy would probably put out moreradio waves that other places.

z0rb says: Jul 20, 2009. 11:08 AM REPLYFrom what I hear Taurus A is pretty loud in the radio spectrum. Unfortunately I am not in a neighborhood anymore that would tolerate suchconstruction in my back yard :)

thepelton says: Jul 22, 2009. 9:27 AM REPLYJupiter I heard is also quite noisy.

z0rb says: Jul 22, 2009. 10:47 AM REPLYIndeed it is, but Jupiter it loudest in the decametric wavelengths 18-24 Mhz. That requires a slightly different atenna. You can find more aboutthat here

http://radiojove.gsfc.nasa.gov/It's fairly inexpensive to get a setup going.

If you are interested in some other solar monitoring I have been doing you can view that here

http://z0rb.livejournal.com/2008/04/13/Enjoy

rod_sutter says: Nov 25, 2008. 10:41 AM REPLYI need a little help, im building a lbt can you give me more detail instruction on how to power the satellite finder with the 12 volt converter, and how can I hookup my laptop to the satellite finder to record the signals that come from the object were looking at.


z0rb says: Nov 26, 2008. 5:48 PM REPLYWell both the satellite finder and the LNB (Low Noise Block) are powered from the same source.The satellite finder looks for a voltage (typically between 12-18 volts) coming in the receiver side of the meter. The link below spells it out a little. Youapply the positive side of the voltage to the center connector and the negative voltage to the connectors jacket. The little coily thing near the positiveterminal of the voltage source is a coil of wire to stop the RF (Radio Frequency) from getting into the power supply. Pretty much any RF choke will do. Myquestion to you is. What kind of power supply are you using? What kind of satellite meter are you using? It would also help to know what kind of dish andfeed horn you are using.

http://i219.photobucket.com/albums/cc216/MightyZ0rb/meter.jpgThis is a little more difficult. It also depends on what type of satellite meter you have. If it is like the one above, then there are two possible routes you cantake.

The first involves opening the meter up and fastening leads to the wires that go to the actual meter portion of the sat finder. These leads would then behooked up to a data logging voltmeter. I use a radio shack one found at the link below.

http://www.radioshack.com/product/index.jsp?productId=2103962The second method is not nearly as accurate but it would be a cheap way to get started. The particular satellite finder above has a little piezo elementthat chirps when a satellite is found. The knob on the front of the meter can vary the intensity of this. If you were to use a spectral analysis program.Found here (its free)http://www.qsl.net/padan/spectran.html

And tape your PCs microphone to the back of the meter it will show you when you detect something.

This is just my 10,000 foot view of your situation. Without knowing exactly the components your working with its difficult to advise the best way toapproach this.

However I hope this helps, and if you wish to pick my brain further, shoot me an email via my website.

Xellers says: Sep 18, 2008. 6:51 PM REPLYIf I don't have a satellite dish, and all I want to do is "see the sun", then how would I be able to build an antenna? Would I be able to make one? Please help.

z0rb says: Sep 19, 2008. 4:46 AM REPLYThere are a variety of ways to do this. I would imagine that this will be dependant on what you have available and how you want to see the sun. Prettymuch any radio receiver will be able to "see the sun" th etrick is to know what you are receiving and how to receive it. What equipment do you have atyour disposal, and are you wanting to track the sun as it goes across the sky or have an antenna just pick up the sun and not follow it. Let me know andI'll fill you in on what I know.

Xellers says: Sep 19, 2008. 12:41 PM REPLYI just found a small dish today; only a few feet in diameter.All I want to do is to be able to point it at something like the sun, and to be able to detect that.The dish had a coaxial cable connection.I am looking at using this: http://www.satpro.tv/index.asp?PageAction=VIEWPROD&ProdID=192to interpret the signal.It would be easy for me to construct the power supply that you described, so all that I need to know is how I should connect everything. From theexplanations within your instructable, I was unable to figure that out.

Please help.TY :-)

z0rb says: Sep 22, 2008. 1:36 PM REPLYThe sat meter that you have is nice. IT should work just fine. The more stable the power supply the better. Basically the center conductor of thecoax will carry your +12-18 volts. That goes on the side of the meter that is designed for the receiver. The other side merely gets hooked up tothe feedhorn of the dish. The small dishes work on the Ku band which is up around 12Ghz. The bigger C band dishes work on 4Ghz. For youmeter it does not matter since the feedhorn in either case will down convert the signals from 950-1450 Mhz Hope this helps.

Xellers says: Sep 23, 2008. 4:04 PM REPLYSo basically, I should set it up like this:


Xellers says: Sep 23, 2008. 4:06 PM REPLYAnd by "outside of cable", I mean the channel that comes out as a ring on the coaxial cable.

z0rb says: Sep 23, 2008. 4:37 PM REPLYThe looks correct to me

maker12 says: Dec 22, 2007. 5:52 AM REPLY"I SAW THE SUN" the telscope is singing that LoL

SHIFT! says: Aug 5, 2007. 11:33 PM REPLYHey Hey Hey! It's Krusty The Klown!

maker12 says: Dec 22, 2007. 5:43 AM REPLYit is LOL

gamma_fear says: Sep 2, 2007. 3:24 AM REPLYI was looking at this and a thought popped into my head (finally!). i have a couple of satellite dishes on my roof if i replaced the built in receiver with a usbWiFi device with a usb extension cord (bad WiFi reception from my house) and some really cool servos to change its direction, would the dish reflect WiFisignals or would i have to add some sort of mesh?

MattTheGeek says: Aug 1, 2007. 3:10 PM REPLYwould a dish network work for this project or do i need a bigger satellite dish?

z0rb says: Aug 1, 2007. 3:19 PM REPLYFor something like the sun you really don't even need a dish at all, but it does help. A dish network dish will work just fine. In fact it's one of the projectscurrently on my workbench. Just remember the difference between the dish in this instructable and a dish network device is the band being used. The bigdish runs on C Band which is around 4Ghz and a dish network device runs on Ku band which is 12Ghz. In respect to the sun there really isn't muchdifference between the two.

Here is a link to a great document on using a dish network dish.Little Bitty Telescope

Enjoy and have fun

HamO says: Mar 14, 2007. 10:57 AM REPLYGreat start... What are your plans for a receiver, what frequencies are you interested in? Keep us posted. Thanks for sharing.

z0rb says: Mar 14, 2007. 11:22 AM REPLYWell, this project was actually done a few years ago. Since then I have moved to another location. Currently I am workin gon a version of the Itty BittyRadio Telescope. This is in the rfequency range of 12Ghz. as far as I know ther ear eonly a few things i nthe sky around that band. As for a receiver Ihave a few ideas I am still kicking around.

poor-man-s-radio-telescope.pdf

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