Everyday multiple NOAA weather satellites pass above you. Each NOAA weather satellite broadcasts an Automatic Picture Transmission (APT) signal, which contains a live weather image of your area. The RTL-SDR dongle combined with a good antenna, SDRSharp and a decoding program can be used to download and display these live images several times a day.
This tutorial will show you how to set up a NOAA weather satellite receiving station, which will allow you to gather several live weather satellite images each day. Most parts of this tutorial are also applicable to other software radios, such as the Funcube dongle and HackRF and Airspy, but the RTL-SDR is the cheapest option. Hardware radio scanners can also work, provided the radio has a large IF bandwidth (30 kHz +) and a discriminator tap.
Note that if you have success with this tutorial, you may also be interested in decoding Meteor M N2 weather satellites which provide much higher resolution images. Also, an alternative tutorial for decoding NOAA satellites that uses rtl_fm can be found here.
YouTube user GaitUutLiern shows an example of receiving NOAA satellite weather images with a RTL-SDR, SDRSharp, a decoding program called WXtoImg and a QFH antenna.
Large ships and passenger boats are required to broadcast an identification signal containing position, course, speed, destination, and vessel dimension information to help prevent sea collisions. This system is known as the “Automatic Identification System” or AIS for short. There are dedicated AIS receivers intended to be used on boats, or by hobbyists, but they can be expensive. A radio scanner, or the cheap RTL-SDR software defined radio (or a more advanced SDR such an Airspy) can be used to receive these signals, and with the help of decoding software, ship positions can be plotted on a map.
This tutorial will show you how to set up an AIS receiver with the RTL-SDR. Most parts of this tutorial are also applicable to other software radios, such as the Funcube dongle, Airspy and HackRF, or even regular hardware scanners if a discriminator tap is used, but the RTL-SDR is the cheapest option.
Safety Warning: This probably should not be used a navigational aid on a boat as the field reliability of the RTL-SDR or other software radios is not proven. This guide is intended for land based scanner hobbyists.
Note, tracking ships with AIS is very similar to tracking aircraft with ADS-B, which is another project that may interest you.
Examples of AIS received with RTL-SDR
An AIS radar example is shown by YouTube user Vinicius Lenci who uses an RTL-SDR, SDRSharp and ShipPlotter. This video also shows what a strong AIS signal sounds like.
Digital Radio Monodial (DRM) radio is a type of digital shortwave radio signal that is used by international shortwave radio broadcasters. It provides superior audio quality compared to AM signals by using digital audio encoding. With an upconverter, good antenna, and decoding software the RTL-SDR software defined radio can receive and decode DRM signals. This tutorial is also applicable to other software defined radios that can receive HF with or without an upconverter, such as the HackRF, Airspy, Softrock and Funcube dongle.
Examples of DRM Decoding
YouTube user Superphish shows DRM reception with his Ham-it-up upconverter, and rtl-sdr.
The RTL-SDR software defined radio combined with SDRSharp and a program called “digital speech decoder” (DSD) can be used as a radio scanner to easily and cheaply listen to unencrypted digital radio voice conversations.
Digital radio voice communications are becoming more commonly used in the radio spectrum. This is due to the various improvements offered over traditional analogue voice radio systems. Unfortunately for radio scanner hobbyists, digital radio is difficult to receive, as special radio scanners which can be expensive are required to decode the digital signal. Additionally, digital radio systems can be encrypted making it impossible for communications to be decoded by a hobbyist. However, most users of digital radio do not bother to encrypt their systems as it can introduce lag, monetary expense and extra battery drain in portable radios.
The most common digital speech codec is APCO P25, which DSD is able to decode. DSD is also capable of decoding other common digital codecs such as DMR/MOTOTRBO, NXDN, D-STAR and ProVoice.
Super cheap software defined radios such as the RTL-SDR can be used to decode these digital voice communication signals instead of expensive radio scanners. While this tutorial is aimed at the RTL-SDR, other software radios such as the Funcube dongle, Airspy, HackRF and BladeRF will also work. Hardware radios with discriminator taps connected to a PC may also work.
Examples of DSD Decoding Digital Voice with RTL-SDR as a Radio Scanner
YouTube user Geoff Wolf shows a video where he uses RTL-SDR as a police scanner to listen to public safety P25 digital radio using DSD, SDRSharp and virtual audio cable.