Tagged: digital audio broadcast

Techminds: Testing out the new Plugins Feature on SDRuno V1.4 RC1

Earlier in the month SDRplay released SDRuno V1.4 RC1. This is a beta version that amongst other changes now has the capability to run "plugins". Plugins allow developers to easily create modules that extend the functionality of the SDRUno software. For example right now there is a plugin included with V1.4 RC1 that allows users to listen to DAB audio. Up until recently plugin functionality has only been available in Airspy's SDR# software, so it's good to see SDRuno finally including this feature too.

Over on the Techminds YouTube channel Matthew has uploaded a short video where he tests out the new plugins feature. First he tests out the DAB decoder, noting that the CoreAAC codec needs to be installed first separately. Later he tests the second plugin which is an audio recorder that allows users to record audio to MP3.

SDRPlay SDRuno Plugins Feature - NEW!

TechMinds: Demonstrating the QT-DAB Digital Audio Broadcast Decoder

Over on YouTube TechMinds has uploaded a video where he explores the QT-DAB software (formerly known as SDR-J), which is a program capable of decoding Digital Audio Broadcast (DAB) signals. QT-DAB is compatible with several SDRs including the RTL-SDR, HackRF, Airspy and SDRplay units. 

DAB stands for Digital Audio Broadcast and is a digital broadcast radio signal that is available in many countries outside of the USA. The digital signal encodes several radio stations, and it is considered a modern alternative or future replacement for standard analog broadcast FM.

In the video TechMinds explains how to download, install and use the software on a Windows machine. He goes on to demonstrate some DAB decoding in action with various SDRs and then shows how to connect QT-DAB to a remote RTL-SDR via rtl_tcp.

DAB Radio Decoder For SDR (RTL_SDR - HACKRF - AIRSPY)

Tysonpower Reviews A Cheap 15€ DAB/DAB+ USB Receiver Dongle that Generates an MP3 Stream

Thank you to Tysonpower who wanted to share his review of a cheap 15€ DAB/DAB+ receiver USB dongle that he found on eBay.de (we also found the same device on eBay.com for US$23.99).  The device is not an SDR, but it receives BAND III DAB/DAB+ at 160-240 MHz and generates an MP3 stream which can be played back on any MP3 capable device such as a PC, single board computer or car head unit.

His review notes that the dongle works well. When you plug it in the device shows up as a storage device. You then simply press a button to automatically search for DAB+ channels, and then choose one of the mp3 stream files that will show up to play live DAB+ audio on your device. In his video he also gives a quick tear down, showing that it uses a FCI FC8080 demodulator and a MVSilicon 32-bit Micro with audio FFT accelerator.

While RTL-SDR dongles can also be used to receive DAB+ cheaply with software like SDR-J and welle.io, this may be a simpler method since it can be used on any device that can play MP3s.

Note that Tysonpowers video is narrated in German, with English subtitles. He also has a short blog post with images from the tear down.

[EN subs] DAB+ für nur 15€ Nachrüsten! - Digitalradio für alle MP3 fähigen Geräte mit USB

QIRX SDR Now Shows Received DAB Transmitters on A Map

QIRX SDR is an RTL-SDR compatible program that focuses on DAB+ decoding and listening. In a recent update programmer Clem notes that the newest feature is a map powered by OpenStreetMap that can display a the location of received DAB stations. He writes

The main new feature is the integration of Openstreetmap to display the locations of DAB transmitters (please see attached picture of a raw recording from England), together with the own position of the receiver.

In case the transmitter ident code (TII) is detected and the transmitter is contained in the database, it is displayed on the map as an icon, colored according to the TII signal strength.

The "Own Position" is indicated as a red or green dot, either (without GNSS sensor) placed by dragging the red circle with the mouse to its correct position, or by attaching a GNSS (GPS or GLONASS) sensor.

When recording raw I/Q data, the GNSS positions are written into a second file, parallel with the .raw file. On replaying, the current recorded geolocation is displayed synchronously to the recorded transmitters on the map. This might be useful in a mobile environment. The distances are displayed in the TII table.

The transmitter database comes from two sources:

  • UK: Public OFCOM database,
  • Rest of Europe: DABLIST (www.fmlist.org), as provided by the UKW/TV Arbeitskreis e.V. (www.ukwtv.de).

Currently, both databases are merged into a single, local Excel file, serving as the data source to the software.

QIRX SDR Screenshot with OpenStreetMap and Received DAB Transmitter Locations Showing
QIRX SDR Screenshot with OpenStreetMap and Received DAB Transmitter Locations Showing

Creating a DAB+ Radio Station with a LimeSDR

Thank you to Godrey L for submitting his article/tutorial that shows us how to broadcast a DAB/DAB+ radio station using a LimeSDR and ODR-mmbTools. The LimeSDR Mini is a US$159 12-bit TX/RX capable SDR that can tune between 10 MHz – 3.5 GHz, with a maximum bandwidth of up to 30.72 MHz. ODR-mmbTools is an open source DAB transmission chain which is compatible with USRP and LimeSDR SDRs.

DAB stands for Digital Audio Broadcast and is a digital broadcast radio signal that is available in many countries outside of the USA. The digital signal encodes several radio stations, and it is considered a modern alternative/replacement for standard analog broadcast FM.

The tutorial is split into four parts. The first part simply explains what SDRs are and in particular discusses the LimeSDR and how it can be used with ODR-mmbTools. Part two discusses what hardware you need, and explains what each component of the ODR-mmbTools software does. Part three gets into the actual setup of the software on Linux. Part four finishes with actually transmitting the signal and decoding it with an RTL-SDR and the Welle.io DAB decoder.

The end result is a DAB radio station with three stations being broadcast.

LimeSDR Transmitting 3 DAB stations, and receiving it with an RTL-SDR and Welle.io.
LimeSDR Transmitting 3 DAB stations, and receiving it with an RTL-SDR and Welle.io.

QIRX SDR Beta 2.0.1.0 Released: Improvements to DAB Scanner, Recorder and Spectra Display

QIRX SDR is a multimode SDR program compatible with the RTL-SDR. One of its defining features is that it has a built in DAB+ decoder. Recently beta version 2.01 of QIRX SDR was released which has some scanner, recording and spectra display improvements. We note that the beta version appears to be a DAB decoder only, with no multi-mode features. The new features and improvements include:

Scanner:

  • Configurable w/r to the Muxes to be scanned and/or included in the usual set of Muxes being used.
  • New algo, considerably faster
  • "Scan forever" feature, interesting for DX-ers wishing to observe Muxes over a longer time, particularly together with TII logging.
  • Selectable waiting time after recognition of a Mux, for TII logging.

Recorders:

  • TII Recorder: File structure improved, now directly importable into Excel, with TAB as separator.
  • Audio Recorder (DAB+ only): Format selectable between WAV (as usual) and pure AAC (with ADTS headers). The latter allows for high-quality recordings compressed by at least a factor of 10 compared to WAV. The popular Foobar2000 app is able to play these files. Not seekable yet though, because embedding in a suitable container is not yet implemented.

Spectra:

  • CIR with different scales (Samples, Distance, Time)
  • Indication of the correlation peaks used for the "FFT Window" determination in the CIR spectrum.
QIRX SDR Beta 2.0.1.0
QIRX SDR Beta 2.0.1.0
 

Part III of Calibrating your RTL-SDR with QIRX SDR Now Uploaded

Earlier in the month we posted about Clem's three part series on how his QIRX SDR software can be used to accurately calibrate an RTL-SDR using DAB signals. Back then only parts I and II had been released. Now part III has been released, and in the article he explains why it is beneficial to calibrate the frequency error, and also the sampling rate when attempting to decode DAB signals..

Clem begins by explaining how DAB signals work and why it is important to have accurate frequency calibration when receiving DAB. Later he goes on to explain the effect of sampling rate errors due to frequency inaccuracy on received DAB signals. He shows the effect of gradually increasing the sample rate error on the ability of the algorithms to decode DAB signals.

Comparing constellations with sampling rate error correction turned on and off.
Comparing constellations with sampling rate error correction turned on and off.

Using QIRX SDR and DAB Signals to Calibrate RTL-SDR Dongles

Over on his site, Clem the author of the QIRX SDR software package has written up a three part series where he explains an ultra-fast and very accurate method for calibrating the frequency offset of RTL-SDR receivers by using DAB signals. If you are unfamiliar with DAB, it stands for 'Digital Audio Broadcast' and is a type of digital radio station available in multiple countries in the world, especially in Europe. However it is not used in the USA. Clem writes:

I wrote a three-part tutorial about an ultra-fast, generally available (where you have DAB reception) and very accurate method to calibrate RTL-SDR receivers. It is called "Tutorial: Calibrate your RTL-SDR in 15 Seconds", http://softsyst.com/QIRXCalibrate?sequenceNo=0. It is using the frequency of a DAB transmitter as the reference signal, and is coming in three parts:

· Part I: Method and Measurement, describes the method (example) and compares it to two other, well-known methods.

· Part II: Checks, Frequencies, Sampling Rates: Tells how to make plausibility checks on the obtained calibration result, goes into the foundation of different measuring methods, and explains why calibrating a receiver is generally beneficial, not only for DAB purposes (where at least the frequency correction is mandatory).

· Part III: Improving DAB, Tells why it is advantageous for DAB reception not only correcting the frequency, but also the sampling rate (which is often omitted).

Part I and Part II of these are already on our website, Part III will come soon.

QIRX Being used to Calibrate an RTL-SDR dongle on DAB signals
QIRX Being used to Calibrate an RTL-SDR dongle on DAB signals