TIL : A little more about Software Defined Radio

in STEMGeeks3 months ago

Someone actually made something I thought about over 10 years ago

Sometimes the YouTube algorithms hit it out of the park. This morning I saw a video with a super click bait title "The Coolest Radio You've Probably Never Heard Of". Well, it worked on me, so I watched it.

In this video, he talks about Software Defined Radio (SDR). If you are unfamiliar with radios and frequency bands, then this will be way over your head.

Radio frequency (RF) refers to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz, as well as the alternating currents carrying the radio signals. This is the frequency band that is used for communications transmission and broadcasting. Although RF really stands for the rate of oscillation of the waves, it is synonymous to the term "radio," or simply wireless communication.
~ techopedia

In short, different wireless communication use different wave lengths (frequencies) . These frequencies are set by a governing board, so manufacturers know what to set their devices to in order not to broadcast over the entire spectrum of waves and block other communication out.

radio_frequency_bands.png

It also means that you would need different devices in order to communicate on each of these frequency groups.

2_way_radios.jpg

But, if you only wanted to listen to these different radio waves, you can use a single device. Scanners have been around probably as long as police have been using radios to track criminals.

scooper_3330_radio_scanner.jpg

But, even scanners are limited to what they can pick up and the more control you want over handing the frequencies, means more cost. Since a radio wave can be turned into an digital file, that means computers can help with decoding a radio wave. (see. Online Police Scanners) And that is wear Software Defined Radio steps in. It takes the digital or analog radio waves and converts them to a digital format that a software program (like AirSpy ) can use to parse out for the user to manipulate. In the video I posted, he was able to reduce static and then fine tune a frequency

radio_frequency_ytube.png

And this can be done with a small USB dongle and an antenna that we used to use on TVs back in the day. We call them rabbit ears. Only ours weren't screw in, so if you broke one side by messing with it too much, you would have to replace the entire thing, which wasn't too big of an issue, because they were cheap. I like these new ones better.

usb_radion_antenna.jpg

As you can see, the kit comes with 2 sets of antenna to give you different lengths in order to tune into different bands. As the video creator mentions, you could just to a basic length, but it won't be as clear of a tune, so fine tuning is there if you want to make sure you get the best reception.

So, with a little bit of careful setup, you can turn your computer into a radio scanner.

On a side note, last year I was at All Things Open and someone demonstrated using a USB dongle to pick up the radio singles sent from airplane that lists the plane information. This is called Aircraft Communications Addressing and Reporting System (ACARS). This software should probably pick up this as well, as others have been able to do it.

Also, there is software to listen to HAM radio's online and some HAM radios already have SDR built-in.

sun_sdr2_radio.jpg

~ Expert Electronics

Now, as someone who thinks about Shit Hit The Fan (SHTF) and The End Of The World As We Know It (TEOTWAWKI). I ponder all sorts of things. I know that if the system were to crash, communication would be a priority thing. But, I also know, that if you are broadcasting out into the ether, you are also making yourself a target. For a good while, the best thing would be to listen and hear what is going on. And, I would also know that you probably would want something that wouldn't take up a ton of space or electricity to do your wave snooping. Since there are always people thinking the same things I am, that means someone probably also went through the work to do it first.

Which leads you to


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Let the positive energy sing!

More Power to the Minnows!!


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These frequencies are set by a governing board, so manufacturers know what to set their devices to in order not to broadcast over the entire spectrum of waves and block other communication out.

Really? I did not know there are regulations like this on frequencies set by the radio transmitters...wow.

This was a very nice clickbait because it made you have to share these results with us. I must say I have a lot to know about radio waves, and transmission since it back dates to those times when police used them in the field.

But if you think another person may be thinking of snooping in on some information, then you are right because as I read it, I was already imagining doing this....lol

Thank you for this

I did not know there are regulations like this on frequencies set by the radio transmitters.

I probably didn't word that exactly correct, but in the US, the FCC sets what types of communication goes on in specified frequency ranges or bands.

The Federal Communications Commission is an independent agency of the United States government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security.

Just try to setup a pirate radio station in the US and they'll triangulate you and shut you down. The 1990 movie Pump up the Volume highlighted this. Not to spoil it, but he even put his radio station on wheels and they still tracked him.

If it is floating in the air, anyone can snoop on it,whether they can decrypt it, is another thing.

Thanks for reading and commenting.

Lol

I guess it is all for the best that we have all of these regulations. If not, we would have lots of Chaos with transmissions here and there.

Thank you for responding. I appreciate

SDR is a really cool topic! The math behind is a bit tricky, but there are so many tools already available so users hardly get in touch with the low-level stuff. I bought a cheap USB DVB-T stick to play with it and could track nearby planes from a RaspberryPi or listen to FM radio stations.

I let other people handle the tricky math. I prefer to think of the uses for the software.

Thanks for reading and commenting.

Hey @deanlogic, thanks for this one. I enjoyed the read. The solar-powered Raspberry Pi is a great find.

You're welcome.

Thanks. I would like an AIS transmitter, the commercial AIS transmitters costs really a lot, while the receivers are cheap - and there are DIY-plans and open source software out there for the receiver thing, but for the transmitter ... very little. I thought that since "software defined radio" exists nowadays, this was "just" a software problem, but I was scolded by a professional radio engineer when suggesting so.

Thanks to this article, I now understand SDR a bit better, so I see clearly now that this is just a thing on the receiver side, and cannot be used on the transmitting side :-)

Yup, transmitting and receiving are two different things.

Thank you for reading and commenting.