Tagged: gnu radio

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

Decoding a Weather Temperature Sensor with the RTL-SDR and GNU Radio

Over on YouTube user MrCircuitMatt has uploaded two videos on how he was able to decode a temperature weather sensor using an RTL-SDR and GNU Radio. His videos go through the GNU Radio technical steps as well as the signal encoding theory he used to decode the temperature.

Using RTL-SDR to read temperature from outdoor sensor, part 1

Using RTL-SDR to read temperature from outdoor sensor, part 2

Reverse Engineering a RF Controlled Ceiling Fan with the RTL-SDR

Using an RTL-SDR Clayton Smith was able to reverse engineer his remote controlled ceiling fan. To do this he first used his BladeRF to determine that the remote control was transmitting a signal at 303.747 MHz. He then used a simple GNU Radio flow graph with the RTL-SDR to plot the amplitude of the signal over time which suggested that the signal was using on-off keying. From the plot he was then able to visually determine the bit pattern sent from each button on the ceiling fan remote.

Next he used his bladeRF and another GNU Radio flowgraph to replicate and transmit the the bit pattern which was able to control the ceiling fan from the PC.

Clayton notes that all this reverse engineering was done in half an hour, demonstrating the power of software defined radio.

Ceiling Fan Bit Pattern Recovered with an RTL-SDR and GNU Radio
Ceiling Fan Bit Pattern Recovered with an RTL-SDR and GNU Radio

Controlling a Remote Control Car with the HackRF

On YouTube user 王康 has been working with his HackRF One to create a computer keyboard controlled interface for his remote control car. The HackRF is a ~$300 software defined radio similar to the RTL-SDR, but with transmit capabilities.

To control the car he wrote a GNU Radio program to generate a control signal that is transmitted by the HackRF and a GUI to listen to keyboard presses on the PC.

HackRF One with gr-remotecar

Transmitting DVB-T with the BladeRF and Receiving it on a RTL-SDR

The BladeRF is a software defined radio that has transmit and receive capability. Over on his blog, Clayton Smith has recently posted about his experiments which involve using the BladeRF to transmit DVB-T digital TV on one laptop to another laptop running an RTL-SDR in DVB-T mode. This is one of the few applications where the RTL-SDR is used as a DVB-T receiver as it was originally intended. Clayton used GNU Radio, a DVB-T package for GNU Radio and some python scripts to create the BladeRF transmitter.

The newer Linux kernels have DVB-T support for the RTL2832U chip, so the latest version of Ubuntu 13.10 will be able to recognize the RTL-SDR stick as a DVB-T receiver easily. Clayton used VLC in Ubuntu 13.10 to receive the DVB-T signal transmitted by the BladeRF which was tested on the 70cm, 33cm and 23cm bands.

DVB-T Received by the RTL-SDR
Webcam DVB-T TX by a BladeRF and RX by the RTL-SDR

Video Tutorial: Hak5 on Decoding RDS with GNU Radio and GR-RDS

Hak5 has recently posted another video continuing their easy to follow series on GNU Radio and the RTL-SDR. In this video they talk about Radio Data System (RDS) and explain how it is a digital signal that is embedded in broadcast FM signals. They then download GR-RDS, a GNU Radio based RDS decoder program and use it to decode a local RDS signal.

Decoding Digital Subcarriers with a $20 SDR, Hak5 1602

Video Tutorial: Hak5 GNU Radio FM Radio Receiver

The popular YouTube technology show Hak5 has recently been posting videos related to software defined radio and more specifically RTL-SDR. Two of their recent videos are about an easy to follow GNU Radio tutorial for complete beginners. In the first tutorial they show how to add an RTL2832U source in GNU Radio and output it to a FFT Sink. In the second tutorial they go further and show how to build an FM Receiver.

Building Software Radios With A Little Bit Of Python, Hak5 1526

Going Deeper Into GNURadio Companion, Hak5 1601

Demo of Osmocoms ‘Phosphor’ Spectrum Visualizer

Over on YouTube, user superkuh2 has posted a video showing off osmocoms gr-fosphor GNU Radio block which shows a real time spectrum visualization using the GPU. He combines gr-fosphor with multimode for visualizing the ISM and pager bands with his RTL-SDR.

osmocom's fosphor with patchvonbraun's multimode looking at ISM + FLEX pager bands with rtlsdr