Tagged: rtl-sdr

Comprehensive Video Guide to Trunking and Digital Voice with the RTL-SDR

Over on YouTube user AVT Marketing has uploaded a five part video series that very clearly and slowly shows how to use an RTL-SDR to set up trunking and digital voice monitoring. In the videos he uses SDR#, Unitrunker, DSD+ and VBCable for the monitoring.

The first video in the series shows a brief overview of the digital trunking voice set up, and explains a bit about digital voice communications. The second video shows how to install an RTL-SDR, and walks you through downloading Unitrunker and DSD+. The third video is a tutorial about SDR# and also explains how trunking radio systems works. The fourth video shows how to install Unitrunker, DSD+, VBCable, and how to configure each program. Finally the fifth and last video in the series shows the final steps in using Unitrunker and DSD+.

This looks like a very good video series, especially for those that like to see every step in the process played out in full.

Cheap Digital Trunked Scanning Using SDR for the Absolute Beginner

Nigun Downconverter PCB Completed

We last posted about Nigun back in January 2017, and at that point the schematic design had just been completed. Nigun is a downconverter which can be used to allow the RTL-SDR and other SDRs to receive frequencies above their typical maximum tuning range, which for the RTL-SDR is about 1.8 GHz. A downconverter works by taking those high frequencies and converting them down into a frequency which the SDR can actually tune to.

Recently “raziele”, the designer of Nigun has completed the PCB design and he aims to order the first batch of units during June. The main specifications of Nigun are pasted below:

  • Dynamic LO – LO will be determined by the user and programmed by the MCU
  • Almost no filtering – will leave this challenge outside of this project scope
  • Power up and programming via micro-usb connector. Should be able to power up from a USB power-pack (but probably not from a computer port)
  • Highest RF frequency will be 3GHz
  • Product also features a VCO for signal-generation purposes. VCO support should be 200-2700MHz

Previously Outernet had been working on a downconverter design for their 1.5 GHz satellite service, but they decided that it was not economical. So it is good to see an alternative downconverter in the works. More details about Nigun are available on the GitHub page.

The Nigun Downconverter PCB Design
The Nigun Downconverter PCB Design

DAB/DAB+ Decoder Software “Welle.io” Now Available on Android

Back in March of this year we posted about “Welle.io”, a DAB/DAB+ decoder that supports the RTL-SDR and other SDRs like the Airspy. It was available for Windows, Linux and Raspberry Pi 2/3.

Albrecht Lohöfener, the author of Welle.io has recently written in to announce that Welle.io is now available for Android as well. The app appears to be free, but is currently marked as beta, so there may still be a few bugs.

The only other app that we’ve seen which is capable of decoding DAB/DAB+ on Android is Wavesink. Wavesink costs $14.90 USD on the Google Play store, but there is a free trial version available with runtime limitations and no DAB+ support.

Albrecht notes that the app is fairly computationally intensive and will require an Android device with at least 4 cores and a clock speed of 1.3 GHz to run the app. He also mentions that they are also looking for any interested developers and translators to help with development of the app.

Welle.io on Android
Welle.io on Android
welle.io on Android (DAB+/DAB software radio, RTL-SDR , RTL2832U)

RTL-SDR.com Presentation Slides from Hamvention

During this years 2017 Hamvention convention I was invented by TAPR to present three talks about the RTL-SDR. Several people who watched the talks have requested the slides, so they are uploaded here in PDF format.

The World Of Low Cost Software Defined Radio – Presented at the TAPR Banquet. An introduction to the RTL-SDR and many of the interesting applications that it has been used for.

An Introduction to RTL-SDR – Presented at the TAPR Digital Forum. A brief introduction to the RTL-SDR and a selection of some of the most popular applications.

Introduction to Cheap SDRs for Radio Monitoring – Presented at the Digital Modes Now and In the Future Forum. A brief introduction to the RTL-SDR and a selection of some interesting digital modes that can be monitored.

The talks may be on YouTube in the future. If and when they are they will be posted here too.

A big thanks to all that came to the talks, and all the people who I met at Hamvention. It was a great event and really nice to meet everyone interested in RTL-SDRs and SDRs in general.

Radio For Everyone: An Easy ADS-B Antenna, ADS-B Advice, and Long Term Results

Over on his blog Akos has uploaded several new posts all relating to ADS-B reception. His first post shows how to build a very simple yet effective “Coketenna” ADS-B antenna which can be built with an empty coke can and some coax cable. This antenna is essentially a 1/4 wave ground plane antenna with the ground plane being a coke can cut in half and mounted upside down. The whip sticking up is simply the coax inner wire. In his post Akos shows exactly how to construct one.

Cantenna and Coketenna
Cantenna and Coketenna

In his second post Akos offers some advice on mounting and positioning ADS-B antennas, discusses the ‘range myth’, talks a bit about LNA’s and filters and shows the differences between a stock RTL-SDR dongle, and one optimized for ADS-B reception like a FlightAware Protstick.

In his third post Akos shows his results from long term ADS-B reception comparisons between a generic RTL-SDR dongle, an RTL-SDR.com V3 dongle with 1090 MHz LNA powered by bias tee, a FlightAware Prostick and a FlightAware Prostick Plus. The V3 dongle with bias tee powered LNA is used as the benchmark receiver and the results show that it received the most signals. The next best was the Prostick Plus, followed by the Prostick and finally the generic dongle.

ADS-B Comparisons between 4 different RTL-SDR setups.
ADS-B Comparisons between 4 different RTL-SDR setups.

QIRX SDR: A New MultiMode RTL-SDR Program with Built-In DAB+ Decoder

Recently Clem from softsyst.com wrote in and let us know about their new SDR software called ‘QIRX SDR’. This is a multimode receiver currently capable of receiving AM/NFM/WFM and also DAB Plus. It supports the RTL-SDR via an rtl_tcp connection, so it can be used on a local machine, or a remote networked one. The main differentiating features that QIRX has against other multimode receivers like SDR#, HDSDR and SDR-Console etc is:

  • Dual Receiver, within the bandwidth of the frontend. This is most useful e.g. for watching two stations simultaneously in busy airband regions.
  • DAB+ Demodulator, to our knowledge the first one written in C#, allowing for recordings in very good quality (some samples provided for download).

The full list of features are quoted below:

QIRX is an Open Source Software Defined Radio, written in C#, downloadable on this site as a Visual Studio 2013 Solution, offering the following features:

  • TCP/IP Based: QIRX accepts 8-bit I/Q-Data either from TCP/IP sources or from pre-recorded files containing the I/Q-data. It is designed to cooperate with RTL-SDR dongles and the widely available rtl-tcp.exe as I/Q-data server. Both QIRX and rtl-tcp may run on the same machine or on separate ones. The rtl-tcp.exe might be started automatically without additional user actions, also when used remote via a LAN.
  • Dual Receiver: Within the selected bandwidth, e.g. 2.56MHz QIRX is able to operate two independent receivers simultaneously.
  • Squelch: For each receiver, QIRX provides a digital squelch, enabling to monitor the selected stations – when not transmitting – without annoying background noise.
  • Simplest Operating Principle: QIRX – using its AM, NFM or WFM demodulators – is purely FFT-based, with a NF lowpass filter only. This might change in a future version.
  • Scanner: QIRX provides for Receiver 1 a simple scanner, being able to scan large frequency areas. This is still in an experimental state.
  • HF and NF Spectrum: For each receiver, QIRX provides a spectrum viewer being able to show the HF and the NF spectrum. No waterfall spectrum yet. For DAB+, it shows the constellation.
  • DAB+ Receiver: QIRX provides a comfortable DAB+ receiver ( Transmission Mode I ). It is -to the best of our knowledge- the first C# based SDR providing this facility. Some standard libraries like the Viterbi decoder are used as C/C++ packages, accessed via P/Invoke.
  • File Recorder: For all demodulators, the audio output can be saved to .wav files, independently for each of the both receivers. For DAB+ this allows for high-quality audio recordings.

    Additionally, the I/Q raw data can be saved to a file. It is possible to replay recorded I/Q-data files.

QIRX SDR: A new multimode receiver with DAB+ decoding
QIRX SDR: A new multimode receiver with DAB+ decoding

A 3D Printed Case for the DIY Outernet Kit

Thanks to Manuel (aka Tysonpower) for writing in and sharing his 3D printed ‘Universal Outernet Case’. Outernet is a satellite file casting service that uses an RTL-SDR based solution for reception. With an Outernet set up you can receive things like daily news, weather updates, books, Wikipedia pages and more all for free. About 20 MB of data can be transmitted in one day.

The DIY Outernet kit consists of an RTL-SDR ‘SDRx’ board, patch antenna and C.H.I.P single board computer. The patch antenna needs to point roughly in the direction of the Inmarsat/Alphsat satellite in your area. This can be a problem because the Outernet patch antenna doesn’t come with a stand or mounting solution.

Manuel solved this problem with his 3D printed Outernet enclosure. The enclosure houses the patch antenna, SDRx and C.H.I.P, and also doubles as a stand for pointing the patch antenna. Inside he’s also fitted a small 30mm fan to keep everything cool while inside the enclosure as the C.H.I.P is known to have overheating problems.

The 3D printed Outernet enclosure.
The 3D printed Outernet enclosure.

Over on YouTube Manuel has uploaded a video explaining how the enclosure is made with 3D printing, demonstrates the assembly steps and finally shows the final product. The video is narrated in German, but it has English subtitles available. The design files required for 3D printing the case are also available on thingiverse.

[EN subs] Outernet Case aus dem 3D Drucker (Universal elv. Winkel) - für DIY Kit

Decoding ADS-B in MATLAB Video Tutorial

Over on YouTube the official MATLAB channel has uploaded a new video that is a tutorial on setting up ADS-B decoding in MATLAB. MATLAB is a technical computing language that is frequently used by many scientists and engineers around the world. They write:

Use the software-defined radio capabilities that are part of Communications System Toolbox™ to capture and decode ADS-B messages. ADS-B is a relatively simple standard used by commercial aircraft to transmit flight data such as aircraft ID, position, velocity, and altitude to air traffic control centers. ADS-B messages are 56 or 112 bits long, the data rate is 1 Mbit/sec, and the messages are amplitude modulated signals, transmitted at a carrier frequency of 1090 MHz

The video goes over what ADS-B is, how to receive it, and then goes on to explain a bit of the MATLAB code. This is a good introduction for people wanting to use an RTL-SDR in MATLAB, or for anyone wanting to learn about ADS-B.

Real-time Airplane Tracking with ADS-B Signals and RTL-SDR Radios