[gr33nq]

Something I've had a longstanding desire to learn about is radio frequencies. I'm a very visual person, but I have yet to find any resource that explains it in a way that really makes sense to me. Especially when you start getting into modulation and whatnot. I'm fortunate to be able to use a variety of wireless technologies at work (licensed 80GHz, 18GHz and 950MHz frequencies), but I admittedly only have basic working knowledge and don't clearly comprehend what's happening at the lower physical level.

Does anyone have a good recommendation on any material that really made wireless technology understandable for you?

[superkuh]

There's no all in one stop for understanding radio but these 5 resources helped me a lot.

The RF Get Down courses. This is by far the best material online to learn RF and how modulation works: https://www.youtube.com/@rfgetdown/videos

3blue1brown's video tutorial on the fourier transform: https://www.youtube.com/watch?v=spUNpyF58BY

AT&T Archives: Similiarities of Wave Behavior http://www.youtube.com/watch?v=DovunOxlY1k

Quadrature Signals: Complex, But Not Complicated by Richard Lyons, https://dspguru.com/files/QuadSignals.pdf https://dspguru.com/dsp/tutorials/quadrature-signals/

Antenna Theory's website and forums, https://www.antenna-theory.com/antennas/main.php

I also highly recommend getting a $20 rtl-sdr USB software defined radio dongle. They're great toys for learning RF, what modulation is, and exploring the spectrum.

[threeio]

A 20$ RTL-SDR will give you a very broad view of the spectrum and an idea of how one area can be quiet, the other filled with signals and the oddities of atmospheric noise, etc. Super fun and there are 100,000 YouTube videos on how to get it working.

https://www.amazon.com/NooElec-NESDR-Mini-Compatible-Package...

[NikkiA]

I would argue that a $0 web-sdr bookmark will teach you exactly the same things without you forever wondering if it's your antennae that's the problem.

[actionfromafar]

You sort of back-handedly made a case for using your own antenna to better understand radio. :-)

[NikkiA]

Oh, there is absolutely a case for trying your own antennae, and experimenting with various antenna topologies, to understand radio.

The issue is if it's the first thing a newbie should be doing while also trying to work out if their USB dongle works at all :D

[ale42]

Very true... only issue is that you wont receive any local signals if there's no local web-SDR in your area.

[furyg3]

Where do you find these? Is there an online library?

[NikkiA]

websdr.org has a huge list. You can find a few more via google.

[yabbs]

One place to start peeling the onion is amature radio. In the US, see: https://www.arrl.org/

Introduction to spectrum, freq allocation (bands) and modes.

[nickysielicki]

https://youtu.be/DovunOxlY1k

https://youtu.be/-F7KYLO4Bkg

https://youtu.be/ScOd3ExKFM8

https://youtu.be/I9m2w4DgeVk

[rramadass]

Hardware to play with:

1) HackRF : https://greatscottgadgets.com/sdr/

2) RF Explorer : https://j3.rf-explorer.com/

You also need to study Physics (Electromagnetics) and Electronics (Communication Electronics). Checkout both popular textbooks and general audience books.

For a absolute beginner a good place to start is The Essential Guide to RF and Wireless by Carl Weisman.

[_whiteCaps_]

You might like:

* https://www.sigidwiki.com/wiki/Signal_Identification_Guide

* https://www.receiverbook.de/?type=openwebrx&band=

[i_am_a_peasant]

awesome, I found an open websdr at the olympia tower in munich :)

[supertrope]

It depends how far down you want to look. At the bottom is Maxwell's equations.

[pierat]

I thought that too, but things get weird when you try to separate 'electron-magnetism' and photonics.

If you try to understand WHY a metal outer electron shell will shed a photon, you'll come up empty handed. And with electricity, the electrons move around from one side to the other. Except, do they? What exactly happens at an antenna interface?

And why do we call it the EM spectrum, when the actual carriers are photons?

It's the quantum-EM interactions that I think would make Maxwell's explanation why the equations work as they do make more sense. But even simple stuff in RF makes people evoke ideas of 'black magic'.

[pid-1]

Download GNU Radio and implement modulation blocks by yourself. You can use it to simulate systems, without buying any hardware. You can write blocks in Python or C++.

I don't recommend getting real hardware. Cheap software define radios will only work in uninteresting frequencies like AM / FM. You need way, way more expensive equipment to work with Wifi / 4G systems.

[haswell]

> Cheap software define radios will only work in uninteresting frequencies like AM / FM

There’s quite a bit interesting stuff to listen to on cheap hardware.

With a $20 dongle:

- Local police/fire

- Marine bands

- Watch airplanes transmitting ADSB

- Follow trunked radios in the area (more police depts are doing this)

- Receive NOAA weather images

- Pagers operate here, but legally this gets dicy

Beyond this, addons like the Ham it Up upconverter can bring you Ham bands for a little more money and a lot more entertainment.

And there’s a lot of other misc stuff to explore.

Working with 4G systems is a whole other ball of wax anyway, and also gets into legally challenging territory.

If the goal is to learn more about radio and find some interesting stuff going on in your area, a cheap dongle provides a lot of value and fun.

I definitely can’t agree that this requires expensive equipment.