Tagged: rtl_433

Monitoring 3D Printer Filament Moisture with an RTL-SDR and rtl_433

Over on Hackaday we've seen a post about Scott M. Baker's 3D printer filament drying farm that is monitored by a 433 MHz ISM band sensor and an RTL-SDR running rtl_433. If you're familiar with 3D printing then you'll know that it is critical to keep the plastic filament free from absorbing moisture, otherwise it can cause all sorts of issues when it comes time to print something.

To keep them away from humid air Scott uses "PrintDry" plastic vacuum canisters. Unfortunately he found that the vacuum sealing system wasn't perfect, and that some canisters would lose their vacuum after a few days. In order to ensure that the canisters were properly sealed he decided to add some active monitoring with pressure and humidity sensors and a wireless transmitter.

His monitoring system consists of a cheap 315 MHz ISM band transmitter, ATTINY85  microcontroller and pressure + humidity sensor. To receive and monitor the data he uses an RTL-SDR that runs the rtl_433 software, which is a program that is capable of decoding many different types of wireless ISM band sensors.

DIY Wireless Temp/Humid/Pressure sensors for measuring vacuum sealed 3d printed filament containers

Video Tutorial About Decoding 433 MHz ISM Devices with rtl_433

Over on his YouTube channel Tech Minds has recently uploaded a video that demonstrates and shows how to use the rtl_433 software with an RTL-SDR to decode 433 MHz ISM band low power devices. Typically these devices include things like home wireless temperature and weather sensors, tire pressure sensors, remote controls, and other various sensors.

In the video he sets up an RTL-SDR and magmount antenna by his window and is able to receive data from several of his neighbors weather stations, and some car key remotes. He shows how to run the software on both Linux and on Windows.

How To Decode 433Mhz Low Power Devices Using RTL433 And A RTL-SDR Receiver

Fixing USB Reset Problems for 24/7 rtl_433 Monitoring

Rtl_433 is an RTL-SDR compatible command line based tool for monitoring various 433 MHz ISM band devices, such as temperature sensors, weather monitors, TPMS, energy meters etc. A full list of support devices can be found on the rtl_433 Github.

Over on his blog “raspberrypiandstuff” mentions that he’s been using rtl_433 and an RTL-SDR on a remote headless Raspberry Pi to receive and monitor temperature and humidity from his weather station. From the data he’s able to produce some nice graphs that show changes over time.

However, one problem that he ran into was that the USB controller on the Raspberry Pi would sometimes hang. The only solution he’d previously found to fixing it was to physically disconnect and then reconnect the RTL-SDR. But now “raspberrypiandstuff” writes that he’s found a new solution which is to use a small C-program called usbreset.c. Combined with a bash script that detects which device the RTL-SDR is on the bus, this tool helps to automatically reset the USB on the Pi if it fails to keep the RTL-SDR logging 24/7 without physical intervention.

This may be a solution to look into if you’re experiencing similar issues with 24/7 monitoring on the Raspberry Pi. If you’re also interesting in rtl_433 monitoring, “raspberrypiandstuff” also has a post on creating a simple GUI for rtl_433.

Analyzing 433 MHz Transmitters with the RTL-SDR

Over on his blog, Yashin has written a post showing how to analyze 433 MHz transmitters using several methods. Devices that transmit using low power 433 MHz are common and often include devices such as weather monitors, power monitors and alarm sensors.

To show his analysis methods Yashin used an ASK modulated FS1000A 433 MHz transmitter connected to an Arduino Teensy microcontroller. He first uses GQRX and baudline together with an RTL-SDR in Kali Linux to test that the transmitter is working and to visually inspect the RF spectrum. Then he shows how to use GNU Radio to receive the 433 MHz transmitter and how to record an audio file. The final tool he shows how to use is rtl_433 which will automatically decode the data into binary strings using the analysis option.

ASK 433 MHz Transmitter
ASK 433 MHz Transmitter

Using an RTL-SDR and RTL_433 to Decode Various Devices

Over on his blog, Gough Lui has posted about his experiences with decoding various ASK/OOK devices on the unlicenced 433 MHz ISM band using an RTL-SDR and the command line program rtl_433.

Gough shows how he was able to receive and decode the data from an Aldi weather station device and a wireless doorbell transmitter. He also was able to modify the rtl_433 code slightly to produce a CSV log file of the temperatures that were received and decoded from the weather station.

rtl_433 output of the weather station
rtl_433 output of the weather station