Orbcomm Reception with the RTL-SDR

YouTube user Drvarnick has uploaded a video showing how he receives Orbcomm satellite data with the RTL-SDR. To do this he uses a a homemade 1/4 wave antenna, SDR# and the Orbcomm-Plotter software by COAA.

COAA describes Orbcomm satellites as

a satellite communication system (www.orbcomm.com) providing two-way data and positioning service to small, portable user terminals in the VHF frequency bands. You can use a simple VHF radio receiver (scanner) tuned to the band between 137 and 138 MHz to pick up the strong signals from these satellites. With OrbcommPlotter you can decode the telemetry and find out the positions of the satellites, their operational status and their uplink and downlink channels. Unlike most satellite signals, there are so many Orbcomm satellites that there is likely to be one within range of almost any spot on Earth at any time of the day or night.

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Receiving ISS Data Comms with the RTL-SDR

YouTube user mutezone has uploaded a video showing some data communication packets from the International Space Station (ISS) being received with the RTL-SDR. To receive the packets he used SDRSharp, and piped the audio using a virtual audio cable to the Qtmm AFSK1200 Decoder.

I tried to get the ISS (International Space Station) data comms on 145.825 MHz while the satellite was in orbit close to my location & it worked, even though it can go off frequency due to atmospherics & such. On this day, I caught it when it orbited twice around my location in the space of almost three hours. The data comms was decoded on the 2nd attempt. The antenna I used was an omni placed outdoors, & also using a TV + radio signal booster.
For anyone interested in getting the ISS, you have to wait until it orbits close to your location, & I fully recommend a decent aerial that should be placed externally. You can check the ISS tracker websites to see live updates of when & where it will orbit. Here is a link to one website…

http://www.isstracker.com

List of frequencies link…

http://www.issfanclub.com/frequencies

Receiving ISS Data comms on RTL-SDR in UK, 6th June 2013

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Talk: My journey into FM-RDS by Oona Räisänen

Back in November we posted about Oona’s work with decoding radio controlled bus stop display signs using her RTL-SDR. Oona has given a talk at the Chaos Communication Congress about her work on decoding FM-RDS and the bus stop displays. The talk is now available on YouTube.

How I discovered mysterious hidden signals on a public radio channel and eventually found out their meaning through hardware hacking, reverse engineering and little cryptanalysis.

A story about my experiences with FM-RDS (Radio Data System), a digital subcarrier embedded in FM broadcast transmissions, and also cryptanalysis of the weakly encrypted TMC traffic messages contained therein. I originally found about the existence of such transmissions in a roundabout way, by using a spectrum analyzer program to examine intermodulation distortion in my radio’s Line Out audio. As it turned out, the inaudibly quiet distortion, probably caused by the radio’s stereo demuxer circuitry, contained all the information needed to decode all RDS data present in the transmission. I will demonstrate the journey I took and give a short introduction to how the data is actually encoded. Live acquisition of local RDS data depending on signal conditions in the premises.

As a bonus, I’m introducing yet another little-known FM subcarrier called DARC, and my recent reverse engineering of the bus stop display radio protocol used in Helsinki.

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Talk: Monitoring the Spectrum: Building Your Own Distributed RF Scanner Array

Andrew Reiter a researcher at Veracode has given a talk at the Chaos Communication Congress about building a distributed RF scanner array using cheap RTL-SDR dongles. This talk has been uploaded to YouTube.

Software-Defined Radio (SDR) has increased in popularity in recent years due to the decrease in hardware costs and increase in processing power. One example of such a class of devices is the RTL-SDR USB dongles based on the Realtek RTL2832U demodulator. This talk will discuss my experience in building a distributed RF scanner array for monitoring and spectrum mapping using such cheap SDR devices. The goal is to help the audience understand the what, why, and how of building their own RF monitoring array so that they will be able to do it themselves. In this era of increasingly being “watched”, we must be prepared to do our own “watching”.

Software-Defined Radio (SDR) has increased in popularity in recent years due to the decrease in hardware costs and increase in processing power.One example of such a class of devices is the RTL-SDR USB dongles based on the Realtek RTL2832U demodulator. This work investigates building and running an RF scanner array for monitoring and spectrum mapping using cheap SDR devices. The array allows for both RF sampling and power analysis to be split over multiple systems in order to increase capture and spectrum analysis capabilities. The system allows for “strong signal capture” as well as, simply, signal modeling with “strong signal alerting”. Also discussed will be using the array versus USRPs and the issue of antennae for all of the devices. I will explain the mistakes I made in building the array and what I did to attempt toovercome such pitfalls. The code for running the array will be introduced and released for public consumption. In addition, while we target the RTL-SDR devices, we will discuss the feasibility of including non-traditional SDR hardware in the array, including non-Realtek tuner cards and inclusion of HackRF devices.

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Talk: Tracking of Low Earth Orbit Satellites with the RTL-SDR

Back in July we posted about Travis Goodspeed’s project on setting up a satellite dish that automatically tracks satellites in low earth orbit, where he uses an RTL-SDR for the radio. Travis gave a talk on this project at the Chaos Communication Congress conference, and the video has now been uploaded to YouTube.

Satellites in Low Earth Orbit have tons of nifty signals, but they move quickly though the sky and are difficult to track with fine accuracy. This lecture describes a remotely operable satellite tracking system that the author built from a Navy-surplus Inmarsat dish in Southern Appalachia.

The entire system is controlled through a Postgres database, fed by various daemons spread across multiple machines. So when I click on a satellite on my laptop or cellphone, it runs “UPDATE target SET name=’Voyager 1′;” and the motor daemon then begins to track the new target while the prediction daemon maintains accurate estimates of its position in the sky. Additional daemons take spectral prints or software-defined radio recordings of the targeted object for later review.

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Improved Digital Voice P25 Decoding with DSD+

Update: This post is now very old. The latest version of DSD+ can now to found at www.dsdplus.com.

Over on Reddit we've seen mention of an upgraded Digital Speech Decoder (DSD) program, named DSD+. The original DSD is a program that can be used in conjuction with a SDR receiving program such as SDR#, and an audio piping program like VBCable to decode digital speech, such as P25 and DMR/MOTOTRBO.

DSD+ claims to have improved decoding and audio quality capabilities. An audio sample from a weak P25 sample can be found here for DSD+, and for comparison here for the old DSD.

DSD+ can be downloaded from this megaupload link.

To run DSD+. you will need to place an MP3 encoder file lame_enc.dll into the same folder as the dsd.exe executable. This file is not included with DSD+ due to licencing. For Windows, lame_enc.dll can be downloaded from http://lame1.buanzo.com.ar/#lamewindl (Mega Mirror). Download the ZIP option, and then copy the dll file into the same folder as DSD+.

If you don't know how to use DSD, see our tutorial on using DSD here, and if desired simply use DSD+ instead of the original DSD. (Note cygwin is not required for DSD+)

DSD+ Output
DSD+ Output
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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
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Elster R2S Smart Meter GNU Radio Decoder

Smart meters are meters that monitor electricity usage and wirelessly transmit their data to the electricity company. They are a part of the “smart grid”, and allow for better electricity control and usage reporting.

Clayton Smith was able to reverse engineer the data signal from the Elster R2S meters which are used in the Ottawa area on the 902-928 MHz band. The Elster meters use frequency hopping channels, and Clayton was able to receive 6 out of the 25 channels in his area, which should be sufficient, as most of the data packets are repeated on different channels.

He has released his GNU Radio program which will work the the RTL-SDR. Currently, it is capable of displaying meter readings and hourly electricity usage to a terminal.

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