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.
On Eric Williams YouTube channel Eric has posted a video showing how he records audio from his RTL-SDR using SDR# and Audacity. Although SDR# can record audio itself, the advantage to using Audacity is that you can set up Voice Activation (VOX), which will only record audio when someone is speaking or when a digital signal is active. This allows you to listen to a summary of communications at a later time.
SDR# is the most commonly used Software Defined Radio receiver GUI that is used with the RTL-SDR. Natively, it runs on Windows, but since it is written in C#, it can also run on Mac OSX and Linux with Mono. Installing SDR# on OSX using Mono is a little more complicated compared to simply running it on Windows however.
To help with this, Jan Szumiec has written a simple guide on installing SDR# using Mono on OSX. The guide includes the steps of installing Mono, the Xamarin Studio Mono IDE, the rtl-sdr libraries and then compiling the SDR Sharp sources and symlinking the Mono runtime to the native libraries.
Update: This is no longer possible as the SDR# code is not available anymore.
Acarsdec is a recently released open source, multi-channel realtime ACARS decoder for Linux. It supports direct input from an RTL-SDR dongle, and with the RTL-SDR can listen to four ACARS channels simultaneously. It’s official feature list includes
– up to four channels decoded simultaneously
– multithreaded
– error detection AND correction
– input from sound file , also sound card or software defined radio (SDR) via a rtl dongle
Recently an RTL-SDR.com reader wrote in to let us know about a fork of SDR# written by “Gubo682” which has some added features. Note you will need to be a member of the SDR# Yahoo group to access the download page linked above. The added features and changes to SDR# are
Frequency Manager
– Names show up in spectrum
– Scan button for simple scanning through current group
– Selected group remembered after restart
– Adding new entry: group defaults to current group
– Simple DMR support (see Tips)
– SHIFT click (or SHIFT ENTER) will select according relais input frequency for 2m/70cmSpectrum Display
– When dragging spectrum left/right, holding SHIFT will keep frequency constantWaterfall Display
– With the new HF [Radio Freqeuency]/AF [Audio Frequency] button waterfall can be switched to AF. Cursor will be annotated with AF frequency.
– Splitter position (hopefully) restored properly after restartRecording
– AF recording pauses if squelch closedDX Cluster Plugin
– Displays DX cluster stations in the spectrum
– Displays currently on-air SW radio stations in spectrum (data from http://www.eibispace.de/)
In addition there is also now a notch filter with adjustable bandwidth which can be applied by right clicking in the new AF (Audio Frequency) mode of the waterfall.
To use with the RTL-SDR, you will need to download the SDRSharp_gubo68_4d.zip file, run install.bat and then manually un-comment the line
You can follow the development of this modified SDR# on the SDRSharp Yahoo group, and specifically in this Yahoo Groups thread.
TD-LTE is a mobile phone standard acronym for Time Division Long Term Evolution. It is one of two variants of LTE technology, with the other being FD-LTE (Frequency Division LTE).
Over in China where TD-LTE is commonly used, Jiao Xianjun discovered that the current LTE-Cell-Scanner Linux program did not support TD-LTE, so he made a fork which does support TD-LTE. LTE-Cell-Scanner is a program which can decode LTE cell tower data which contains information like the cell ID, transmit frequency and transmit strength. With his modified LTE-Cell-Scanner, some MATLAB scripts he wrote and an RTL-SDR, Jiao was able to decode the cell information from 10 TD-LTE signals and 2 FD-LTE signals. He has uploaded a video showing this too.
Recently we posted about PU2VLW’s project where he was able to decode and listen to D-STAR voice using an RTL-SDR and SDR# running on Windows connected via physical audio cable to a second Linux machine running DSD 1.7.
Now a RTL-SDR.com reader by the name of “Skywatcher” has written in to tell us how he was able to compile DSD 1.7 on a Windows PC using Cygwin. This allows him to decode D-STAR audio on a single Windows PC. Skywatcher kindly sent us the steps he used to compile DSD 1.7 on Windows.
1. Download the zip archive for dsd-1.7.0 from here: https://github.com/szechyjs/dsd and then unzip the archive, so that you get the folder dsd-master, which includes all the source files.
2. Download the zip archive for mbelib-1.2.5 from here: https://github.com/szechyjs/mbelib and then unzip the archive, so that you get the folder mbelib-master, which includes all the source files.
3. Download and install the Cygwin environment. It is important to use the 32 bit version. It will not work with the 64 bit version. In the installation process, you also have to make sure that you choose gcc (the compiler) for installation.
4. Within the Cygwin command window, use gcc, to compile every .c file within the folders mbelib-master and dsd-master (subfolders can be ignored), so that you will get an .o file (object file) for each source file.
5. Copy all the resulting .o files from mbelib-master to dsd-master and use gcc again to link all the object files, so that you will get the final executable dsd.exe. This final step also has to include the sndfile library from Cygwin being mentioned in the call of gcc, otherwise it will not work.
6. In order to start dsd.exe, it is necessary to copy cygwin1.dll to the same folder, where your built dsd.exe is. It is very important that the version number of the dll is being lower than 1.7.26, otherwise dsd.exe will crash. If this is not the case for your dll, you have to find an alternative version from the internet. Additionally, it may be necessary to copy more dlls, needed by the sndfile library, next to your dsd.exe. This may depend on your environment variables of your system.
7. For decoding D-Star, you should call DSD like following: dsd -i /dev/dsp -o /dev/dsp -fd
8. For best results, make sure that all your SDR# and VAC sample rates are set to 48kHz and that you have disabled “Filter Audio” in SDR#. Also, the audio volume of SDR# should not be set to high.
With DSD 1.7 running on Windows, Skywatcher was able to get these results shown in the video links below.
https://www.youtube.com/watch?v=5qpwnTDvI-Q
https://www.youtube.com/watch?v=30GcI4LDjdg&feature=youtu.be
EDIT: Reader Kotelnikov007 from the comments section has been kind enough to upload a pre-compiled windows version. https://mega.co.nz/#!Ft9WFbgQ!sOhsUeMC83Xi5Wxjr4eEPoc0WuM0cJOM2bq9DnE4dWE
EDIT 2 (30/12/2016): The above link seems dead. Reader Adrian wrote in to submit his compilation which is available at https://mega.nz/#!jJZRALrb!
Adrian also writes
– The list of the required DLLs to make it work are these:
https://twitter.com/CodingFree/status/813788401610739712
– It is needed to load sndfile library (already prebuilt in Cygwin).
– It needs MBE, but also the ITPP libraries.
PW2VLW’s shows on his blog how to adapt an Icom IC-706 hardware radio to be able to use an RTL-SDR as a cheap panadapter (Note site is in Portuguese, so use Google Translate). A panadapter is device that allows you to visually see the RF spectrum and waterfall being received by the ham radio.
He shows instructions on how to perform the required modification to get the IF output of the ICOM, and also shows how to interface the PC with the ICOM so that it may be controlled directly via HDSDR.
