Adam the manufacturer of the LNA4HF has recently uploaded a video showing how to easily build an upconverter from the LNA4HF. The LNA4HF is a low noise amplifier intended for use with SDRs like the RTL-SDR. The video shows how to connect up two components, the Mixer and Oscillator which are required to create the upconverter.
Akos from the SDR for Mariners blog has put out another post this time comparing various antennas cut for 121 MHz with the RTL-SDR. He tests monopole, dipole, two radial and rubber ducky antennas on their signal to noise ratio performance on an ATIS signal in SDRSharp.
It is important to note that different antennas will have different gain directionality, so your own experimentation may still be required for your own RF environment.
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.
