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
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.
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.
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:
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.
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.
CIR with different scales (Samples, Distance, Time)
Indication of the correlation peaks used for the "FFT Window" determination in the CIR spectrum.
Welle.io is a Windows/Linux/MacOS/Android/Raspberry Pi compatible DAB and DAB+ broadcast radio decoder which supports RTL-SDR dongles, as well as the Airspy and any dongle supported by SoapySDR. It is a touch screen friendly software which is excellent for use on tablets, phones and perhaps on vehicle radio touch screens.
Thank you to Albrecht Lohofener, the author of welle.io for writing in and sharing his news about the release on welle.io version 2.
welle.io 2.0 Beta 1 released
I’m happy to announce the version welle.io 2.0 Beta 1. Since the first rtl-sdr.com post roughly two years ago (Mar 2017) welle.io became the leading open source DAB/DAB+ SDR. Many people are using welle.io in their daily life and gave a lot of feedback.
With all this feedback we started developing the version 2.0. Apparently, the biggest change is the complete redesign of the user interface (GUI). It changed from a dark design to a bright design and handles easily different screen resolutions and orientations.
Many users asked for a favorite list, automatic playing of last station and a mute button. Now these features are ready to test with the 2.0 Beta 1!
Another new feature is the settings menu where users can set the hardware receiver with all the necessary settings. This is more user friendly than the command line parameters.
For people with a deep technical interest we improved the expert mode a lot. In addition to the spectrum users can also view the impulse response, null symbol and constellation diagram, even at the same time! An experimental I/Q RAW file recorder as well as a debug output window is available for systems without a text console.
In the back-end we improved the multi-path behavior and started a source code refactoring to allow the code to be easily maintained. Great thanks to the people from the Opendigitalradio association (http://www.opendigitalradio.org/) which are actively contributing to this project.
Now it is possible to build a complete DAB/DAB+ system (transmitter and receiver) with open source!
As a result from this collaboration welle-cli is available. The main use case is to monitor DAB/DAB+ transmitters networks over the internet. Thus it has a HTTP API and includes a basic Web page which shows the features.
The PantronX Titus II is a yet-to-be-released portable Android tablet based SDR that we've been following since 2016. The device will feature a 100 kHz - 2 GHz tuning range, and software that focuses on HF digital DRM decoding, as well as DAB on VHF.
As you might be aware, we have joined up with Fraunhofer to include their MMPlayer app standard on Titus–what a difference a professional decoder, for both analog, DRM(+), and DAB(+), makes! MMPlayer is full featured even including reliable one way file downloads with DRM.
We are attempting also to license HD to include on the app for North America, making a truly worldwide receiver. Some deficiencies in our version of Android have caused issues as well as MMPlayer. All of which have caused delays leading to some serious business decisions – as you can imagine. You are correct that broadcasters have made large orders that will be fulfilled first. There are units in the field testing and such and continuing resolution of the software issues.
One of the issues that folks seem to have a hard time understanding is that we can not just build a few hundred or even thousands of units. Our minimum run is 10,000pcs! To do that everything has to be 100% – including the software. We simply will not ship units that are not 100%. Titus works, MMPlayer works – its that last 5% that takes the most time to resolve. These facts preclude any incremental production attempts. All that being said, we are very hopeful that the first production run is ready by last quarter of this year.
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.
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.