RTLSDR is a small cheap USB radio receiver. You can use it to see, listen to and decode radio signals, for instance those sent from your Flipper Zero or HackRF Portapack or other radio transmitting devices, such as aeroplanes, handhelds, marine, military, shortwave radio, number stations and much more. Here is a quick introduction for the beginners into SDR.

Get an RTLSDR here: https://www.rtlsdr.com/

Software mentioned in the video:
SDR Console: https://www.sdrradio.com/console
SDR++: https://www.sdrpp.org/
SDR#: https://airspy.com/download/
HDSDR: https://www.hdsdr.de/
SDR Angel: https://www.sdrangel.org/
OpenWebRX+: https://luarvique.github.io/ppa/
dump1090: https://github.com/gvanem/Dump1090
rtl_433: https://github.com/merbanan/rtl_433

0:00 Introduction
0:46 The history behind RTLSDR
1:53 What is an SDR receiver?
3:10 General Purpose SDR Software
3:54 What is radio?
5:30 What is HF?
6:57 Ham Radio
7:13 Choosing the correct modulation
8:43 SDR angel
9:43 Other decoding software
10:13 Audio piping
10:47 OpenWebRX+ and Raspberry Pi
11:23 Tip 1: Use the appropriate antenna
12:02 Tip 2: Be mindful of noisy environments
12:33 Tip 3: Be careful with transmitters
12:53 Tip 4: Be mindful of the gain setting
13:19 Tip 5: Be mindful of antenna polarisation
13:47 Outro