RTL_433 is a command line Linux tool to decode ISM band gizmos like remote temperature and humidity sensors with an SDR. These signals are transmitted around 433 MHz and are not encrypted but they are digital. RTL_433 handles both the reception and decoding of these signals. No other apps are required for use other than a web browser for a GUI display. RTL_433 was developed by Benjamin Larsson and the source code is available at https://github.com/merbanan/rtl_433
The focus of this guide is establishing basic functionality under Linux Mint 19.3 with an RTL-SDR Version 3 dongle. Operation under other distributions and SDR's will be similar yet beyond the scope of this guide to cover them all. I'll assume you've already installed the drivers and have a working SDR dongle. If not, see my guide RTL-SDR Quick Start Guide for Linux.
Install needed libraries. The system will indicate if they're already installed and nothing will be over-written.
sudo apt-get install libtool libusb-1.0-0-dev librtlsdr-dev rtl-sdr build-essential cmake pkg-config
Get the source code.
git clone https://github.com/merbanan/rtl_433.git
Build & install rtl_433.
cd rtl_433/
mkdir build
cd build
cmake ..
make
make install
Open a terminal and do one of the following:
rtl_433 (default mode with auto gain)
rtl_433 -C customary (displays temp in F)
rtl_433 -C customary -F http (as above plus enables web server)
Open a browser and enter localhost:8433 It will take you to the developers website https://triq.org/rxui/#localhost:8433 to format and display the data. Yes, they're legit. :)
I did some experimenting with gain and bandwidth settings and found the defaults to be just as good. Results will vary based on how many sensors are in your neighborhood, interference, etc. The output power is pretty low on these devices so range is maybe 100' at best. A 1/4 wave ground-plane or telescoping antenna about 6.5" long works well. I created a bash script to quickly start the app without needing to remember switches.
For more documentation and related projects see the https://triq.org/ site.
-Ken
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