Category: RTL-SDR

Decoding HOT, EOT & DPU Train Data

On YouTube user Curt Rowlett has uploaded a video showing how he was able to decode HOT, EOT & DPU signals from trains using an RTL-SDR. Head of Train (HOT) and End of Train (EOT) signals are used on trains to transmit telemetry data such as brake line pressure and monitor accidental separation of the train. Distributed Power Unit (DPU) signals are control signals that are used to control remote DPU’s on long trains. DPU’s are locomotives which are placed in the middle or rear of a train to help more evenly distribute pushing and pulling power over the entire train.

Curt used the SoftEOT and SoftDPU software programs to monitor and decode these signals. This software can be downloaded from the softEOT Yahoo! Group after requesting and being accepted into membership.

HOT signals can be found on 452.9375 MHz, EOT signals on 457.9375 MHz and DPU signals on 457.9250 MHz.

Decoding HOT, EOT & DPU Train Data

Ham it up Upconverter 3D Printed Case YouTube Giveaway

Over on YouTube Eric William has posted a video about his competition where he is giving away two 3D printed ham-it-up upconverter cases. The ham-it-up is an upconverter that can be used with the RTL-SDR to allow it to receive HF (0-30 MHz) frequencies. To enter the competition you simply need to go to Erics web forum and post about what you use SDR for in the competition thread. The competition is open only for North American viewers and ends on May 19 2014.

Decoding 2x AIS Channels with SDR Console, AISMon and OpenCPN

YouTube user k2nccvids has posted a video showing him decoding and plotting both AIS channels simultaneously on a Windows PC with free software. To do this he uses SDR Console and two AISMon instances. SDR Console is a general purpose SDR GUI that supports the RTL-SDR. One of it’s major advantages over other SDR software is that it can tune to multiple signals in the same swath of tuned bandwidth simultaneously and output their audio to different virtual audio cables.

k2nccvids used two AISMon instances, each one connected to a separate virtual audio cable outputting AIS audio from SDR Console. He set AISMon to output decoded UDP packets on two different ports. Then he created two UDP listeners in OpenCPN for plotting, one for each port.

RTL-SDR Wide Spectrum Analyzer

Over on YouTube claudio giuliani has posted a video of his RTL-SDR Wide Spectrum Analyzer software. The software is written in the basic for gambas language and uses an RTL-SDR software defined radio to plot a wide chunk of the frequency spectrum by sweeping over it. It looks to be similar to the RTL-SDR Scanner software. Currently it is only available for Linux.

RTL-SDR Wide Scanner
RTL-SDR Wide Scanner
RTL_SDR Wide spectrum analyzer

RTL-SDR DSD Call Log Recorder

Programmer Tyler Watt has been working on software that automatically logs each call from an RTL-SDR running DSD (Digital Speech Decoder) and then stores it in a time stamped database as an mp3 file. There is also a web front end for the database which allows public users to search and play recorded calls.

Recently Tyler updated his code by rewriting it in PHP and making it multiplatform.

The old version of his web front end in action for his local P25 calls can be viewed here, and the newer one can be found here.

Reverse Engineering Radio Controlled Power Outlets with Help from the RTL-SDR

Radio controlled electricity power outlets are outlets that can be turned on or off using a wireless radio controlled remote. Over on the blog leetupload.com the author has written an article showing how he was able to reverse engineer the wireless power outlets radio protocol.

The author used an RTL-SDR and SDR# to listen to the outlets wireless AM transmissions at 434 MHz. He then recorded the signal audio and then used audacity to view the waveform. By analyzing the audio output he discovered that the signal was a Non-Return-To-Zero (NRZ), pulse width modulated (PWM), Amplitude Shift Keying / On Off Keying (ASK/OOK) signal.

Later he was also able to use the RFCat USB dongle to transmit an on off signal from his computer. RFCat is an USB dongle that is capable of transmitting on 433 MHz.

RTL-SDR Software Radio used to Reverse Engineer the Wireless Power Outlet
RTL-SDR RTL2832U Software Radio Audio output Analyzed in Audacity for Reverse Engineering a Wireless Power Outlet
Remote Control Outlet Replay With RFCat

Source Hackaday

Coaxial Cable Loss

Akos from the SDR for Mariners blog has posted an article that highlights the effects of coaxial cable attenuation. Long runs of coaxial cable between the antenna and RTL-SDR can significantly attenuate signals. This means that strong signals at the antenna will become weak signals at the receiver. The solution to this is to either reduce the cable length or to use higher quality cable. A preamp like an LNA may also help to overcome long runs of coaxial cable. Akos’ article discusses these issues.

Results from Akos' test on different lengths of coax cabling
Results from Akos’ test on different lengths of coax cabling

Chinese and Russian Custom RTL-SDR Kits

There are now some custom RTL-SDR kits available from Chinese and Russian manufacturers. These kits are essentially the standard RTL-SDR laid out on a custom PCB with extra upconverter (or direct sampling) circuitry on board.

This is a 100 KHz to 1 GHz RTL-SDR kit (~$23 USD), and this is another 100 KHz to 1 GHz pre made custom RTL-SDR in a nice box (~$40 USD) (alternative Chinese seller). The Chinese sellers page shows some examples of the performance on Youku (Chinese YouTube)

Custom RTL-SDR with 100 KHz to 1 GHz range in box
Custom RTL-SDR with 100 KHz to 1 GHz range in box
Custom RTL-SDR Kit with 100 KHz to 1 GHz range
Custom RTL-SDR Kit with 100 KHz to 1 GHz range