Qt-DAB is software for Linux, Windows, MacOS and Raspberry Pi for listening to terrestrial Digital Audio Broadcasting (DAB and DAB+).

Of course, as for previous versions, for the current version, Qt-DAB-7.1.1, predefined executables - for Linux an AppImage, for Windows an installer - are (or will be) available.

• What is new in Qt-DAB-7.1.2
• Eliminating buttons and replacing some
• Handling packet services
• Windows and scopes
• Devices and device support
• Scan control
• Displaying TII data
• EPG Handling and time tables
• Journaline data
• Installation on Windows
• Installation on Linux
• Software for device support
• Building an executable: a few notes
• Copyright and acknowledgements

It turns out that using (sometimes left, sometimes right) mouseclicks in the GUI to achieve things is not very intuitive. 7.1.2 basically fixes this. The main window of the GUI has some additional buttons.

In the fourth quarter of 2023 the major version number for Qt-DAB became "6", the GUI had undergone some major changes since the "5" version, and the basic idea was to increment major version numbers only when the GUI changed significantly.

While on the surface the GUI in 7.1.1 does not differ that much with the one in 6.9.10, there are fundamental differences in the main window while the configuration and control window differs completely with that of 6.9. So, it was time to increment the major version number.

The Beta version of 7.0 showed unfortunately a persistent error, fixing that required significant modifications, and, while doing that, a number of important changes was made, so it felt better to update to 7.1.1.

The major visible change in the main window is how services are shown. The ensemble display is completely redesigned and now runs is in one of three "modes".

Handling of data services is changed; when selecting a packet service, it will run as background task, so it is possible to listen to an audio service and have a couple of packet services run in the background.

To control running one or more services in the background, it is obviously possible to select and run an audio service, since that runs in the foreground.

The ensemble display is in one of a three modes:

• ensemble mode, where services of the (current) channel(s) are shown,
• favorite mode, where only the favorites are shown, and
• file mode, where the services from a file are shown.

ensemble mode - the most common mode - a list is compiled of services encountered, and - depending on the settings - the services of the currently selected channel - or all encountered sudio ervices are shown.

Ensemble mode has two submodes, one - when "audio only" is set on the configuration window - in which all audio services of all visited channels are shown and the names stored in a database, or - when "audio only" is not selected - one in which the services - both audio and data - are shown of the currently selected channel.

On (normal) program termination, the list ("database") is stored in a file with the name ".qt-dab-serviceList.mxl", stored in the user's home directory 1n program startup, the list is read-in again.

For experimenting ith e.g. scanning, the configuration and control window contains an entry labeled load selection that - when set - shows (on the next program invocation) a dialog with options to read on the NEXT program invocation either an existing ensemble file, create a new one, clear the current ensemble file, or just stop with selecting. In the last two cases, the setting on the configuration window is "undone".

As in previous versions, ensemble mode, a service in the list can be "promoted" to favorite, by clicking on the left column.

The window contains at the bottow - below the channel selector - a button with which a switch can be made between ensemble mode and favorite mode.

In favorite mode, the list of favorites is shown. Selecting this mode makes channel selection, scanning and eti-generation rather useless and in Qt-DAB-7.XX these options are then blocked.

In file mode, i.e. after reading a file, the services are shown, and

• obviously - may be selected. Again, scanning etc is not very usefull, so some options are blocked.

On starting the program with a device the ensemble mode is set, when starting with a file as input, the mode is set to file mode.

It is always nice if settings to start or stop activities related to the processing are "within reach", i.e. directly reachable from the main window. A number of such settings were put on the configuration and control window, for some of them the functionality is moved back to the main window

• selecting an audio channel in previous versions was on a combobox on the configuration window; since it is a real "control" item rather than a "configuration" item, its functionality is moved to the main window, and implemented by clicking on the speaker symbol (clicking with the right hand mouse button on the speaker now controls the muting);
• as meantioned earlier, the "dump" button on the configuration window was removed. Dump functionality is obtained by clicking with the right hand mouse button on the ensemble name. Furthermore, while by default input dumping created ".uff" files, if selected (or the input device soes not support writing an ".uff" file), dumping is in ".wav" files.
• similarly, the button on the configuration window to control the visibility od the device control window is removed. Clicking with the (again) right hand mouse button on the blue icon gives the same functionality;
• I wanted the button for "eti" on the main window, after all, clicking on it starts or stops an activity. The "scan" button functionality is now implemented by clicking with the right hand mouse button on the channel selector (The rationale being that scanning is closely related to channel selection), and eti control is by the button that used to be for scan control.

The buttons for selection between Portaudio and QtAudio as well as for "skin" selection are removed, their functionality is not considered very useful.

DAB (DAB+) supports next to audio services also packet services. The EPG/SPI service (if available) is an example: Qt-DAB starts automatically a backend interpreting the EPG/SPI data in a separate thread as background task, invisible to the user.

While the default setting in the configuration window in Qt-DAB is to show only audio services, the "audio only" setting can be "unset", and the audio services and - if available - the data services are shown.

Selecting a packet service is the same as selecting an audio service, just clicking on it starts processing. However, running a packet service is usually rather boring, since there is not much to be seen or heard, that is why Qt-DAB akways starts a packet service as background task.

Starting a packet service is simply by clicking on the name, same as for audio services. To avoid confusion, if the "audio only" selector is "unset", only the services of the currently selected channel are shown, including the data services.

Obviously, when switching to another channel, the service interpretation stops.

Most package services contain some form of TPEG data, which is usually encoded; Qt_DAB is unable to interpret the TPEG data and Qt-DAB restricts itself to compile the TPEG frames and send the data as UDP packet to an IP port (default 8888, but can be set in the configuration window).

The sourcetree contains in the directory helpers/tdc-client a simple reader for just reading udp packets (with no further interpretation at all).

Manually stopping a background service is possible, a separate facility was created to stop such a service. For that purpose, a small window can be made visible showing all running backends (starting an audio service in the background shows the window, its visibility iscontrolled by clicking on the number of services as shown in the configuration and control window)

The number "5", displayed in the process counter, tells that there are 5 backends running.

(Note that the NPO and other Dutch broadcasters do not provide EPG/SPI or other packet services, so the example is using a recording).

The figure shows that 5 services are running, the "Mode" indicator set to 1 tells the task is running in the background.

The picture shows an audio service, Dlf which carriers a secondary service, DlfTXT. Secondary services are also running in the background.

Touching the name of the service running in the background stops that service.

Note that it is also possible to run audio services found in the currently selected channel in the background. The audio - for DAB mp2 format, for DAB+ aac format - is written into a file that carries name of the service combined with the date.

Click with the right hand mouse button on the name of an audio service in the services list, and the decoding is started.

Manually stopping the service is by clicking again on the servicename.

In the latest releases of 6.10 the dump button was already moved from the configuration window to the main window (the button implemented by a click on the right hand button on the mouse on the ensemblename). Furthermore, when dumpimg, a small window is shown that remminds the user that dumping is going on.

In Qt-DAB-7.0 the reset button also moved to the main window (it was felt rather clumsy to first have to activate the configuration and control window before being able to press the reset button).

The reset button is located in the top line of the right half of the main window.

The list of audio devices was traditionally shown as combobox, it was felt better to be able to access the list from the main window. Clicking with the mouse of the speaker symbol shows (or hides) the list, a list that appears in a separate window. Clicking with the right hand mouse button controls the muting.

The other icons on the top line behave as in previous versions, i.e. the yellow one controls the visibility of the Qt-DAB-files directory (folder), and the small blue one controls the visibility of the device list. On the second line the "book style" icon controls the visibility of the technical window, and the icon with label EPG, is shown in case an EPG/SPI service is detected in the currently selected channel (Note that the EPG/SPI service is NOT shown in the services list.)

Touching the EPG icon make a small window visible, the timetable list. The list shows the entries in the ensemblelist, coloured green is timetable data for the service could be detected, red otherwide.

Touching in this list on a green entry, shows yet another window, with time table data.

(Note: our NPO is not that advanced that it provides EPG/SPI data, so the development and testing uses file input).

As in previous versions, touching the ensemble name on the top left, controls the visibility of the content table, i.e. a window that shows the details of all services in the current ensemble.

The technical window shows - as the name suggests - technical details of the selected audio service. New is that - if available - the icon of the selected service is shown.

The spectrum widget is not modfied

In the view shown in the picture above, the spectrum of the incoming DAB signal is shown. To the right of this spectrum, one sees the signal constellation, i.e. the mapping from the complex signals onto their real and imaginary components. If the selector labeled "ncp" is set, the centerpoints of the 4 lobs is shown.

Below this constellation widget, some quality indicators of the DAB signal are shown. From top to bottom

• the channel and the frequency of the channel
• the computed correction on the frequency of the incoming signal, applied to the signal;
• the remaining freq error (in Hz) after applying the correction;
• the SNR, i.e. the Signal-Noise Ratio in dB;
• the time offset, the (relative) resulting error in sampling;
• the clock offset, telling the offset in the samplerate in Hz;
• the IQ unbalance, i.e. the (average) difference in strength between the I and the Q part of the DAB signal.

At the bottom of the window from left to right

• a sync indicator, green indicates that the software is synchronized with the incoming sample stream;
• a FIC indicator, telling the (average) successrate of decoding the FIC part of the DAB frames (i.e. the data that specifies the payload);
• a BER, Bit Error Rate, telling (on average) how many input bits were wrong (and were corrected), per 1000 input bits (lower is better) when processing the FIC;
• a MER, Modulation Error Rate, indicating the quality of the input signal (higher is better);

The ideal form of the spectrum and the signal constellation as shown in the picture above is not often seen with real inputs.

The correlation scope shows the correlation between the incoming signal and predefined data, i.e. the data as they should be. Correlation is used to identify the precise input sample in the input stream where the (relevant) data of the frame starts. The picture shows more than one peaks, i.e. the signal from more than one transmitter is received. The software chooses either the largest peak, or - if selected - the first peak one larger than a threshold. The picture shows an estimate of the TII numbers near the peaks, it shows that "(4, 21) Alphen aan den Rijn/Celinex toren" gives the strongest signal.

A DAB signal is received as a sequence of samples, and can be thought to be built up from frames (DAB frames) where each frame consists of 199608 consecutive samples. The amplitude of the first app. 2500 samples is (almost) zero, the NULL period. The NULL scope shows the samples in the transition from the NULL part to the first samples with data of a DAB frame. It shows that samples 504 and up in the first data block are used.

In reality the NULL period is - in most cases - not completely without signal, each second NULL period may contain an encoding of the TII (Transmitter Identification Information) data. The TII scope shows a condensed form of the spectrum of the data in the relevant NULL period, the TII data is encoded as a 4 out of 8 code. Indeed, four larger (and four smaller) peaks can be seen in the picture. In this picture the pattern shown is 0x1e.

The DAB definition provides tables to map the recognized patterm to two 2 digit numbers, the numbers are used to identify the transmitter in a database, available in Qt-DAB.

The picture shows the channel response on the amplitude, and the red line, i.e. the channel effects on the phase of the samples. The picture clearly shows two larger and a few smaller peaks.

The last scope shows some of the output of the ofdm decoding process, the resulting bits have values between -127 to 127.

The configuration and control window is completely redesigned. Some selectors, buttons and checkboxes are removed, as mentioned the functionality is moved to (mainly using right hand mouse clicks) the main window.

Settings for the http and tpreg port, as well as the setting for the home position can now be set on the configuration window.

In the previous version, a selector mapview was added, that selector is now placed in a line with other http related settings.

Since the software - on startup - always loads a database, i.e. if one can be found in the user's how directory that one, otherwise a default version, there was no need for selector for loading a database.

New are selectors labeled load selection and update check. If the load selection selector is set, on program startup the user is asked for a filename to load a selection. If

• no name is specified, the default is loaded,
• a name is given and a file with that name exists, its content is loaded,
• a name is given and no file with that name exists (yet), an empty file with that name is created.

Also new is a checkbox, bottom line right end, that - when set - instructs the software to check on program startup on the availability of a new version of Qt-DAB.

In the current set up, Qt-DAB supports 6 types of (physical) input devices, some network input, and file input:

• DABsticks (RTL2838U or similar), with separate libraries for the V3 and V4 versions of the stick in the precompiled Windows versions;
• All SDRplay SDR models (RSP I, RSP 1A and 1B, RSP II, RSP Duo, RSP Dx and RSPDxR2), with separate entries for the v2 and v3 library. New is extended support for the SDRPlay RspDuo. Tuner selection (and tuner 2 is connected to a port with biasT support) is now operational;
• a special entry exists for the SDRplay RSPDuo, one for running both tuners simultaneously;
• HACKRF One;
• Airspy, including Airspy mini (be aware that AirspyHF is not able to provide the samplerate required for DAB);
• LimeSDR;
• Adalm Pluto;
• untested UHD (due to lack of equipment)

Apart from the untested UHD device, support for these 6 device types is commonly included in the precompiled versions. It was noted by users running Qt-DAB on Windows that, when using the support library for the V4 version of the RTLSDR (aka DABsticks) devices with a V3 device connected, the software seemed rather deaf. To accommodate that, there are in the Windows peecompiled version two device entries, one supporting the V3 versions of the DAB sticks, the other for the V4 versions.

For the Windows version(s), the device libraries for almost all configured devices are provided in the installer. The exceptions are the SDRplay and Pluto devices.

• For SDRplay devices the user has to install the drivers from the SDRplay site,
• for Pluto support one should see the instructions in "https://github.com/analogdevicesinc/plutosdr-m2k-drivers-win".

For Linux users, Ubuntu provides the required libraries for Pluto in a repository (i.e. libii0 and libad9361, for e.g. Fedora the support seems to stop at F33.

Qt-DAB also supports input using a network:

• an rtl_tcp server connected to an RTLSDR device.
• a spyServer (both 8 bit and a 16 bit version), i.e. from AIRSpy devices and RTLSDR devices.
• (NEW) is support for using the SDRconnect program as "input device".

Be aware that Qt-DAB processes the input with 2048000 Samples/second. When connected over a network to the SDRconnect server, it x sends - with a samplerate of 2000000 (which is converted to the required rate of 2048000), 4 bytes per sample over the network. My wifi cannot handle that.

The same applies to using the other servers. The rtl_tcp server sends 2 byte samples, i.e. a payload of 4096000 bytes per second; the 16 bit spyServer sends 4 byte samples (with an even higher rate), all leading to a transmission rate that a regular WiFi cannot handle.

Qt-DAB furthermore supports

• Soapy (Linux only, not included in the AppImage), a renewed Soapy interface driver is even able to handle other samplerates than the required 2048000 (limited to the range 2000000 .. 4000000).

In 6.10 soapy is renewed and now shows a deviceselector when more than a single soapy-supported device is seen.

Furthermore, soapy now supports xml (i.e. ".uff") files to be written, although not in native format.

Qt-DAB obviously supports:

• reading (and writing) ".sdr" type files from the input, where ".sdr" type is a form of ".wav" file with IQ samples with fixed inputrate of 2048000 samples per secnd. Qt-DAB generates such files. As an extension to classical RIFF files that are limited to 4 Gb, Qt-DAB is able to handle (i.e. generate and read) ".wav" files with a size larger than 4 Gb, their type is BW64.

The device window gives information on the "type" of the file i.e. RIFF or BW64. When reading input from an ".sdr" file that was generated by Qt-DAB both the name of the SDR device as well as the channel frequency of the reception is displayed as shown in the pictures above.

• reading prerecorded dump rtlsdr type "raw" (8 bits) files. The RTLSDR device handlers show a button "dump" for dumping the raw input into a ".raw" file.

• reading (and writing) so-called "xml" files, i.e. a file format preserving the precise structure of the input samples. All device handlers show on their device window a button to control dumping the unmodified input into an xml file (e.g. for the Airspy this means with a samplerate of 25000000 or 3000000). Note that there is no 4Gb limit for xml type files.

A separate window - visible under control of the scan button on the main window - provides full control on scanning. Qt-DAB provides different scanning modes: scan to data, single scan and scan continuously.

New is the spinbox, at the left side with the default value 20. The value of this spinbox tells that if a channel is encountered with SOME DAB data, the software will be tuned to that channel for the number of seconds specified to collect DAB data. As said, the default value is 20 (seconds), increments are 20 (seconds).

• With single scan, i.e. a (single) scan over the channels of the band, a listing is produced of (the contents of) all ensembled encountered. In the scan window the channels where data was found, and the transmitters found for these channels, are given, as shown in the above picture.
• With scan to data scanning starts and continues until a channel is detected that carries DAB data (or scanning is stopped by touching the stop button).
• With scan continuously, i.e. scanning until stopped by the user, a single line is shown for each ensemble encountered, and - as the name suggests - scanning goes on until stopped by the user.

To allow skipping given channels when scanning, Qt-DAB supports the notion of a scantable, a table in which channels can be marked for skipping. Next to a default scantable - which is stored in the users ".ini" file, scantables can be created as separate files and read-in when required.

The show button controls the visibility of the scantable, scantables can be loaded and stored in either the ".ini" file (use the "...default" buttons, or can be kept as xml file on a user defined place (the other load/store buttons).

The table at the bottom of the window is just for convenience, on scanning it displays the channel name being scanned currently, the ensemble name encountered and the number of services detected in the ensemble. Only for scan single the transmitters that were identified are shown as well.

As mentioned, transmitters (usually) transmit some identifying data, the TII (Transmitter Identification Information) data. Qt-DAB uses a database (gratefully made available by "www.fmList.org") to map the decoded TII data to name and location of the transmitter.

In recent versions, a copy of that database is part of the precompiled versions which is automatically loaded if no database can be found in the user's home directory.

A fresh copy of that database can be installed in the user's home directory by a small utility, a db-loader, precompiled for Windows and Linux-x64. The db-loader installs the database, file ".txdata.ti" in the user's home directory, that is where Qt-DAB expects a database - with that name - to be found. The configuration and control window contains a button to load the database from the user's home directory into the program.

Alternatively (and for other computing environments) one can download a reasonably up to date copy of the database from the directory helpers in the Qt-DAB repository. Unpack the zipped file "tiiFile.zip" and name it ".txdata.tii" in the home directory.

As was shown earlier, one usually receives signals from more than one transmitter. While the line at the bottom on the right half of the Qt-DAB's main window always shows the strongest transmitter, Qt-DAB can also show data of all identified transmitters on a small separate window (if selected), the dxDisplay.

The picture shows that the ensemble, transmitted in channel 12C is "NPO", and it shows for each of the identified transmitters some data. The first column shows a mark for the strongest transmitter, the pattern is shown as well as the TII values (the mainId, and the subId) of the identified transmitters. Furthermore, the azimuth from and the distance to my home location, the power of the transmitter, the altitude (we are in a low-laying part of the country), and the height of the transmitting antenna.

The compass shows the direction of the signal from the strongest transmitter.

Qt-DAB has as said - on the main window - a button labeled http, when touched, a webserver is started with on it a map centered around the home position, that - when running - shows the position(s) of the transmitter(s) received. (Note that since recently, Qt-DAB contains a default home location - somewhere in Amsterdam - that - together with default database - allows the software to handle TII data and show the result of decoding on a map). It is advised to update the user's home location, the configuration and control window contains a button coordinates that when touched, shows a small menu where latitude and longitude can be filled in).

The picture shows the channels I receive with a simple whip next to my "lazy chair". Of course, using a more advanced antenna. more transmitters show, as seen on the picture below (courtesy of Herman Wijnants)

The webbrowser listens to port 8080. By default, the "standard" browser on the system is activated. The configuration and control window contains selector changing the port as well as turning the automatic activation off.

NEW is the possibility of saving the data of the transmitters that are shown on the map into a file and show the transmitters (or a selection) on a map off-line. The configuration window contains a selector that - when set - tells the software to save the map contents into a file.

For that purpose, a small utility is available. The utility allows reading in a generated map file, and displaying it, per country, per channel, per ensemble or completely.

While not here in the Netherlands, in many other countries an ensemble contains an EPG or SPI service. Such a service contains data for service logo's and uduslly for time tables. If such a service is detected within a handful of seconds after the start of the channel, Qt-DAB will attempt to start the service as background task. If the EPG/SPI service was identified late, the service can be started manually and will also run as background task.

Data decoded by this service will be stored in a separate directory that is itself stored in the user's Qt-DAB-files directory.

If sufficient data is read in that directory, the software might find a service logo and a time table for the selected service. The logo - if found - is shown on the main window (picture above) next to the service name. The time table - if found - is made visible by touching the small icon on the main window labeled "EPG". (This selector is chosen since it is certain that if the icon is visible, there is at least an EPG/SPI service)

The timetable catalog shows for which channels their is SOME timetable data.

If no data for the time table is found, the time table will say so

The timeTable window contains a next and prev button to scan through different dates. Older pages are not removed by default, selecting a page and touching the "remove" button will remove the currently selected page.

While (again) not in the region where I live, in some countries (Germany) DAB services are sometimes augmented with Journaline data. This data is - at least in the examples I have - transmitted in a subservice as shown in the picture Qt-DAB uses the NewsService Journaline (R) Decoder software from Fraunhofer IIS Erlangen in a slightly modified form (all rights gratefully acknowledged).

(Categorie names with an asterisks attatched show that new data is available)

For Windows an installer can be found in the releases section of this repository

• https://github.com/JvanKatwijk/qt-dab/releases.

Currently, there might be two versions, one with the name ending in -scalar, the other one with the name ending in -avx. As mesntioned earlier, the suffix tells whether or not avx2 instructions are used in some of the computations or not. Older CPU's do not support these instructions.

The installer will install the executable as well as required libraries, although for both SDRplay devices (when used) or for the Adam Pluto (when used), one has to install libraries from the provider of the device (see below).

For Linux-x64 systems, an appImage can be found in the releases section of this repository

• https://github.com/JvanKatwijk/qt-dab/releases.

As for Windows, two versions might be available, one with and one without use of avx2 instructions.

The appImage contains next to the executable Qt-DAB program, the required interface libraries but not the support libraries for the configured devices. If you want to use a physical device - e.g. a DABstick, an SDRplay, or an AIRspy you need to install the driver libraries for the device as well.

For using an SDRplay device one should download the - proprietary - driver software from the SDRplay site. Note that while Qt-DAB has a device entry for the "old" 2.13 library, that library does not support the newer SDRPlay device model such as the SDRPlay 1B, the SDRplayDx and the SDRPlay Dx-II. Use the 3.XX library instead. The libraries can be found on the website of SDRplay

• www.sdrplay.com

For using an AIRspy or a Hackrf device the Windows Installers contain support libraries. For Linux, the Ubuntu (and bullseye repository for the RPI) the repository contains appropriate software.

For using an RTLSDR device the Windows Installers contain support libraries. For Linux, the Ubuntu (and bullseye) repositories do provide a package. However, using that package one needs the kernel module to be blacklisted, see e.g.

• https://www.reddit.com/r/RTLSDR/wiki/blacklist_dvb_usb_rtl28xxu/

Personally, I prefer to build a version of the library myself, installation is easy, see:

• "https://osmocom.org/projects/rtl-sdr/wiki".

For using the LimeSDR device the Windows Installers contain support libraries. For Linux I went back to the sources and compiled the support library myself, see:

• "https://wiki.myriadrf.org/Lime_Suite".

For installing the support software for the Adalm Pluto for both Windows and Linux I followed the instructions on

• "https://wiki.analog.com/university/tools/pluto/users"

Note that Ubuntu releases provide libraries for supporting the Pluto.

As mentioned, Windows an installer, for Linux an AppImage is available. Since the sources are available, it is certainly possible to build and executable. I am doing the development on a Fedora box, but I am building the AppImage on an Ubuntu 22 VM. For Windows, I have installed Mingw64/MSYS and build the Windows version on it.

It is strongly advised to use qmake/make for the compilation process, the qt-dab-6.9.pro file contains (much) more configuration options than the CMakeLists.txt file that is used when using cmake.

Note that the scheme presented below is applied when building the AppImage on Ubuntu 22, and the Windows version using MSYS/Mingw64.

For other distributions (or later Ubuntu versions), names of library packages may be different. Note that in all cases, the development versions (i.e. the versions with the include (".h") files) are required.

For creating an executable on and for Windows the easiest approach is to install msys/mingw and follow the process as sketched. Using an MS toolchain on Windows was for me (I tried it once) not successfull and, since I develop compile and cross compile on a Fedora Linux box, my interest in developing ON windows is less than zero.

• ℹ️ In the repository, the sources for the current Qt-DAB version (6.10) are in the directory "qt-dab/ sources". All sources and include files are found in this directory". The ".pro" file is - as is the CMakeLists.txt file - in the "qt-dab" directory. The qt-dab repository contains a file "structure.md" in which the structure is explained.

Running with the ".pro" file as in the repository, the resulting Qt-DAB executable is stored in a directory "/linux-bin" when compiled for Linux and in a directory "/d/systems/qt-dab/linux-bin" when compiling for windows (using mingw64). You probably want to modify it.

For building the AppImage on Ubuntu 22, I load the required libraries as given below:

• sudo apt-get update
• sudo apt-get install git
• sudo apt-get install cmake
• sudo apt-get install qmake6
• sudo apt-get install build-essential
• sudo apt-get install g++
• sudo apt-get install pkg-config
• sudo apt-get install libfftw3-dev
• sudo apt-get install portaudio19-dev
• sudo apt-get install zlib1g-dev
• sudo apt-get install libusb-1.0-0-dev
• sudo apt-get install mesa-common-dev
• sudo apt-get install qt6-base-dev
• sudo apt-get install qt6-multimedia-dev
• sudo apt-get install libcurl4-openssl-dev
• sudo apt-get install libfdk-aac-dev (read the note below)

• ℹ️ An issue is getting the required qwt library. On my Fedora box, a qwt-6.2 version for Qt6 is available, Ubuntu does not provide the Qt6 version for qwt. I had to install it myself as shown below

• Download qwt-6.30 from "https://sourceforge.net/projects/qwt/files/qwt/6.3.0/";
• follow the instructions (i.e. unzip, cd to the unzipped folder) and adapt the config file to your likings;
• building is then simple (takes some time though): "qmake6 qwt.pro", "make";
• install the library ("sudo make install") and inform the loader "sudo ldconfig";
• Note that the default for installation is "/usr/local/qwt/6.3.0", adjust the PATH settings accordingly.

• ℹ️ While the libfdk-aac-dev package in both Fedora and Ubuntu 24 seems to work fine, I had some problems with the package from the repository in Ubuntu 22. For the AppImage, built on Ubuntu 22, a library version was created from the sources to be found as github repository:

• "https://github.com/mstorsjo/fdk-aac"

The sources contain a CMakeLists.txt file, building and installing is straightforward.

Alternatively, one could configure for libfaad, change the configuration to

• CONFIG += faad
• #CONFIG += fdk-aac

and install the libfaad package

• sudo apt-get install libfaad-dev

• ℹ️ If "soapy" is configured, libsamplerate (both the library and the include files) should be installed on the development system. Of course the various Soapy libraries as well.

While there are dozens of configuration options, take note of the following ones:

• ℹ️ A new viterbi decoder is part of the sources, one may choose between this "new" one and the "older" version derived from the spiral project.

  CONFIG += viterbi-scalar #CONFIG += viterbi-sse #CONFIG += viterbi-avx2 #CONFIG += spiral-sse #CONFIG += spiral-no-sse

If unsure, choose either "viterbi-scalar" or "spiral-no-sse"

While the cou load is somewhat higher when using a scalar version, the implementation does not use any special CPU specific instructions. Default is there using a scalar version of the viterbi decoder, which works just fine.

• ℹ️ Qt-DAB can be compiled with floating numbers as "floats" or as "doubles"

  CONFIG += single

  CONFIG += double.

In the latter case, all computations in the "front end" are done with double precision arithmetic.

• ℹ️ Devices like SDRplay, AIRspy, RTLSDR dongle, LimeSDR, HackRf and Adalm Pluto can be included in the configuration even if no support library is installed. (Note that including Soapy requires Soapy libraries to be installed, so this does not apply for Soapy). Qt-DAB is designed such that on selecting a device in runtime, the required functions from the device library are linked in.

• ℹ️ The Soapy library used in Ubuntu 22 (used for tessting the AppImage) is incompatible with Soapy libraries installed on other versions of Ubuntu and other Linux distributions, therefore Soapy is NOT configured for inclusion in the AppImage.

• ℹ️ Uncomment the line DEFINES += __THREADED_BACKEND if you intend to have more than one backend running simultaneously. E.g. activating the automatic search for an EPG service starts a separate service if such a service is found. With this setting each backend will run in its own thread.

Run qmake (variants of the name are qmake6, qt6-qmake, etc), which generates a Makefile and then run make. Compiling may take some time. Use make -j XX for speeding up the build process, with XX the amount of parallel threads used. Of course, qmake will complain if not all required libraries can be found. If all libraries were found, this step should result in an executable.

Use the database downloader (for Windows and Linux available as precompiled item) to download a fresh copy of the database. Or download a copy of the database from the repository.

A copy of the database is part of the repository. The directory helpers contains a file "tiiFile.zip", unpack the zipped file and store the result in your homedirectory (folder).

If Qt-DAB does not see the database, it will just function without mapping TII data onto names and locations.

A user compiled Qt-DAB-6.9, on and for an RPI, and met the following issues:

Once I had downloaded the qt-dab-master from the code page, installed all the libraries listed in the Readme on the code page, and then installed the new qwt 6.30 as instructed, I had a problem getting the .pro file to recognise the new qwt version. This was because on the pi it installs to /usr/include.

So I changed the .pro file as follows:

 Line 433
 INCLUDEPATH += /usr/include
 !mac {
 INCLUDEPATH += /usr/include/qwt-6.3.0/lib
 #correct this for the correct path to the qwt6 library on your system
 #LIBS += -lqwt
 equals (QT_MAJOR_VERSION, 6) {
 LIBS += -lqwt-qt6
 }else{ LIBS += -lqwt-qt5

However I still could not get the qwt recognised so further changes were needed, this time to the Modules folder.

To do this, I went to the qt-dab-6.9 folder in the qt-dab-master, and then opened the folder cmake. Then Modules. Found the relevant FindQwt file and made the following changes:

find_path(QWT_INCLUDE_DIRS
NAMES qwt_global.h
HINTS
${CMAKE_INSTALL_PREFIX}/include/qwt
${CMAKE_INSTALL_PREFIX}/include/qwt-qt6
PATHS
/usr/local/include/qwt-qt6
/usr/local/include/qwt
/usr/include/qwt6
/usr/include/qwt6-qt6
/usr/include/qt6/qwt
/opt/local/include/qwt
/usr/include/qwt-6.3.0
/sw/include/qwt
/usr/local/lib/qwt.framework/Headers
/usr/local/lib/qwt-qt5/lib/framework/Headers
/usr/include/qwt-6.3.0/include
)
if (APPLE)
set(CMAKE_FIND_LIBRARY_SUFFIXES " " " .dylib" ".so" ".a ")
endif (APPLE)

find_library (QWT_LIBRARIES
NAMES qwt6 qwt6-qt6 qwt-qt6 qwt
HINTS
${CMAKE_INSTALL_PREFIX}/lib
${CMAKE_INSTALL_PREFIX}/lib64
PATHS
/usr/local/lib
/usr/lib
/opt/local/lib
/sw/lib
/usr/local/lib/qwt.framework
/usr/local/lib/qwt-qt6/lib/framework
/usr/include/qwt-6.3.0/lib
)

With these settings Qt-DAB could be compiled

While it is known that the DAB transmissions are now all in Band III, there might be situations where it is desirable to use other frequencies. Qt-DAB provides (Unix/Linux builds only) the opportunity to specify one's own band. Specify in a file a list of channels, e.g.

one	227360
two	220352
three	1294000
four	252650

and pass the file on program start-up with the -A command line switch. The channel name is just any identifier, the channel frequency is given in kHz. Your SDR device obviously has to support the frequencies for these channels.

Copyright (C)  2016 .. 2025
Jan van Katwijk (J.vanKatwijk@gmail.com)
Lazy Chair Computing

Copyright of libraries used - Qt, qwt, fftw, portaudio,
libusb-1, libfaad, libfdk-aac, - is gratefully acknowledged.

In developing Qt-DAB many people have contributed, special thanks
to 
* Herman Wijnants,
* Andreas Mikula,
* and Jarod Middelman
for continuous feedback and suggestions, and

* Rolf Zerr (aka old-dab),
* Stefan Poeschel,
for important code contributions.

Qt-DAB is distributed under the GPL V2 library, in the hope that
it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.  See the GNU General Public License for
more details.