USRP (Universal Software Radio Peripheral) and Aircraft Transmissions

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matt_wi

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I'm trying to build a aircraft scanner using the USRP system and am having trouble getting it to work. I am able to receive an FM radio signal without a hitch, but when I bump up the frequency to try to get up to the 130MHz range all I get is static. I'm only about a mile from a major airport (CLE). Is it my antenna (I'm using some rabbit ears) or is there something else that might be messing me up? Any help would be greatly appreciated. I'm not an antenna guy so I'm not sure what I need to do.

Thanks!
 

datainmotion

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Super - another acronym to remember. :roll:

Please pardon my ignorance, but looking at a manufacturers site, I don't see anything about AM above 50 MHz?
 
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matt_wi

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Airband transmission use AM at higher frequencies. Most likely this is legacy, but I'm not sure. Regardless, that's what they use :)
 

K4DHR

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For something that looks like the insides of the PCR-100 I used to own, that guy sure is proud of it. $700 doesn't even get you any of the required modules needed to receive/transmit with the thing. Yikes!
 
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N_Jay

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For something that looks like the insides of the PCR-100 I used to own, that guy sure is proud of it. $700 doesn't even get you any of the required modules needed to receive/transmit with the thing. Yikes!

The cost of electronics like this has MUCH more to do with how many are made then what is in it.
 

matt_wi

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I'm using GNU radio. And the only reason I am using this is because my class requires me to use it. believe me, I would much rather just buy a scanner. I need to actually build one though.
 
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N_Jay

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I'm using GNU radio. And the only reason I am using this is because my class requires me to use it. believe me, I would much rather just buy a scanner. I need to actually build one though.


What is the class?
 

matt_wi

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The Radio Frequency amplification and possibly pre-filtering components placed ahead of the USRP system.

Oh got it. I am not using anything really other than the USRP (Ettus Research LLC) and the BasicRX daughter board. The whole point of a software defined radio is that there everything is done in software. I'm afraid that I may still need an amplifies though.
 
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N_Jay

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Oh got it. I am not using anything really other than the USRP (Ettus Research LLC) and the BasicRX daughter board. The whole point of a software defined radio is that there everything is done in software. I'm afraid that I may still need an amplifies though.

"Perfect" SDR is not here yet (or ever).

Do you have access to any RF test equipment to measure the performance of the setup?

What type of class are you taking?
 

matt_wi

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"Perfect" SDR is not here yet (or ever).

Do you have access to any RF test equipment to measure the performance of the setup?

What type of class are you taking?

Your bowl of acronym soup is expanding quickly :)

I really don't have any access to any RF test equipment. Unfortunately the class is pretty limited :-(

It is a class called mobile computing. Loads of fun :)
 
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N_Jay

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Your bowl of acronym soup is expanding quickly :)
Welcome to the world of radio. :wink:

I really don't have any access to any RF test equipment. Unfortunately the class is pretty limited :-(
How do they expect anyone to build a radio without test equipment, and why would a class on Mobile Computing make you use that board?

It is a class called mobile computing. Loads of fun :)
Let me guess; taught be an IT or CS professor.:roll:
 

KI6ABZ

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I'm assuming you know to use AM and not FM. The 108-137 Aircraft band uses AM, even though it's next to the FM broadcast band.

Have you set up a regular scanner to test and see if you're getting any signals? If you're close to an airport (say, less than 5 miles), you should be able to get a pretty clear ATIS signal as a test (it's a 24 hour recorded message that gives weather updates and airport conditions.)

If you don't have a scanner, I'd suggest picking up something, just so you can test properly. Even a cheap, older unit off of EBay should be enough to pick up local airport traffic.

Also, you should use an outdoor antenna. The simplest thing to do is just go down to your local Radio Shack and pick up an outdoor scanner antenna. I use a 20-032, 20-011, and 20-176 for various things. You don't really *need* anything fancy, though. An antenna is really just a piece of wire, when it comes down to it, and you can get a signal with a coat hangar, if it's the right length.

The center of the air band is about 122 MHz, so a 24" antenna is just about right for your needs. (The simplest antenna is a 1/4 wave. It doesn't require a balun or transformer, like a longer antenna would.)
 
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