Do you need a license to buy a receiver to listen in?
Nope that’s what the web interface is for.
But an rtlsdr is pretty cheap if you want to go that route. I do satellite tracking with satnogs and it’s fun.
I think I am technologically ignorant when it comes to radio so… I still have questions.
How does the web interface collect the transmissions? Are all the transmissions made digitally accessible with the interface? Why (other than cost) would I want to use a web interface rather than a traditional receiver?
How does the web interface collect the transmissions?
The person or organization hosting the website has an antenna somewhere attached to a Software Defined Radio, or SDR. I honestly don’t know how these work at the silicon level, but radio antenna feed line goes in one side, some JFM happens, and USB and/or PCIe computer data comes out the other end. Instead of tuning into such and such frequency with such and such modulation, it sends the raw RF data to the computer to let it process it digitally, with algorithms and GFLOPS and RAM and shit.
Which means, you get to tell it “process the data as if you’re a single-sideband radio listening on 14.070MHz Upper Sideband” and you can listen into amateur radio slow scan television. It’s basically like you get to remote control someone else’s radio receiver.
Are all the transmissions made digitally accessible with the interface?
No. See the above “A person has an antenna somewhere.” You can hear what that antenna hears. This will be limited to line of sight for VHF and up, and even HF will be limited by propagation conditions and the nature of the antenna. The hardware they’ve hooked to their computer may also have its own limitations. Also, their antenna is imperfect because there is no such thing. This is the world’s shittiest Wi-Fi antenna (only partially because it fell over).
Why (other than cost) would I want to use a web interface rather than a traditional receiver?
Not all radio transmissions can be heard from everywhere. I can’t hear anything above 12 meters out of eastern Europe from here, not in the worst solar cycle since humans learned the sun has cycles. I can hear it loud and clear from some Frenchman who put his SDR online.
No, only the British are dumb enough to require a license for a receiver.
You can go buy whatever radio you want and listen to hams tell each other where they’re from and lie about how well they’re hearing each other. Which is most of what they do on shortwave. 1. Ham radio is a game to most of them, the game is “exchange callsigns with people from as many places as you can.” 2. There is a law (CFR 97.113(5)) that prohibits “Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.” I read that as it’s illegal to have a weekly Wednesday at 5 PM EDT chat with your buddy in Tuscon on 20 meters because the cell phone network can also accomplish that. So are scheduled ragchew nets legal?
If you’re going to play around with an HF receiver, ignore the hams and listen out for numbers stations, they’re way fucking cooler than us licensed radio dorks.
Don’t transmit without a license. If we can hear you, we can find you. Radio isn’t like the internet, radio travels in straight (ish) lines. You’re literally shining a light into the sky, we can tell where it’s coming from. Hams won’t do anything to you. No, that’s what the FCC is for.
No
For local reception, receivers with RTL2832U chips are a cheap option. They are also called RTL-SDR. I have simply been using a long wire as a “random wire antenna”. Some of the older dongles also need an upconverter to be able to tune into low HF frequencies:
An upconverter for the RTL-SDR translates low HF frequencies ‘up’ into ones that are receivable by the RTL-SDR. This is a different method to the direct sampling mode used in the V3 dongles to achieve HF reception.
Quoted source: https://www.rtl-sdr.com/a-homebrew-one-transistor-upconverter-for-the-rtl-sdr/
I like my rtlsdr. It’s great and super cheap.
rtl433 on github is a joy to collect data and send somewhere
Thanks for sharing. It seems like there’s a lot of supported options. Many of them, I have no idea what are, but cars and doorbells are easy enough to understand, at least. Do you have any examples of interesting, less obvious use cases of your own, or of others’?
sure. well i am cheap. my neighbours arent. they have fancy stations like Bresser Weather. so why not share data like a proper pirate? i bought several rtl sticks by now. one i use in a pi/nuc/etc to just run https://github.com/merbanan/rtl_433 which has the excellent possibility to send the captured data over mqtt. so one line in terminal gives me weather data.
you could also grab flightpositions with the stick…if you share those you get even more data: https://www.rtl-sdr.com/rtl433-plugin-for-sdrsharp-updated/
still too boring? gnuradio could helpp find interesting frequencies and you might wanna google what they are for. you can also grab an send sensordata from busstationdisplay, temperaturecontrol of houses, tire pressure of passing cars etc. you could use that data in homeassistant/nodered or whatever to trigger alerts…like that police car is close by, shutdown shutdown… and so on. new cars are so chatty.
Also it isnt crazy hard to actually get the basic ham license. Try the hamstudy app and find the local radio club that offers testing.
I’ll give it a shot thanks!
