GUI-Based, flexible screen layout, powered by the Windows Presentation Foundation (WPF).
Usable on large as well on small screens, by collapsable and expandable sub-windows.
Dockable windows (in V4) for optimum exploitation of a larger screen. Map, three receivers and most DAB windows and spectra can use this feature.
Number inputs on the main screen are done very fast by using the mouse wheel.
Aircraft and DAB TII Database Updates by a few mouse clicks from within the app.
Persistence on the hard-disk of all relevant parameters, accompanied by the saving of the complete GUI layout.
Easy Installation by just clicking on the downloaded .msi file.
Issue Tracker by providing a public "issues-only" repository on GitHub.
Multi-Frontend, TCP/IP- or file-input based, locally and remotely, allowing the simultaneous reception of up to three hardware devices of the same or different types, like RTL-SDR dongles, sdrplay or Airspy devices.
Raw-file recording and replay (8- or 16-bit) of arbitrary sized files (many GBytes), with exact timing information, seekable, Fast Forward up to a factor of 8. All GUI-based.
Versatile RF spctra, line plot and/or waterfall, with wide zoom ranges for time and amplitude.
Configurable Bandpass Filters, analog (for RTL-SDR dongles) and digital.
DAB, AM, FM, SSB and ADS-B Signals can be demodulated. WFM Stereo and RDS decoder.
Audio spectrum for all demodulators, MPX spectrum for WFM.
DAB Standard Features, like mux and service selectors, scanner with DX-features, Slideshow, Audio Recording of WAV or AAC files.
DAB Technical Information, like service quality, synchronization information, enabling experienced users to control their DAB reception.
DAB spectra, like Channel Impulse Response (CIR), Constellation and more, being displayed in collapsable (V3) or undockable (V4) windows.
ADS-B Filters, as a great help to declutter the map in densely populated airspaces (V4).
DAB Decoder. First C#-based DAB decoder.
TII Decoder. First SDR to decode the DAB Transmitter Ident Information (TII) of all transmitters contributing to a multiplex.
DAB Service logos. First SDR to show the logo of a service, if provided.
DAB Bit Error Rate (BER). First SDR to measure FIC, MSC and Reed-Solomon bit error rates.
Map Integration, showing on a geographical map the Aircraft detected by the ADS-B decoder or the DAB transmitters found by the TII detector.
GNSS Integration. Synchronized logging of the receivers geographical location together with the I/Q data when recording and/or replay raw data files.
Receiver Calibration. First app to integrate an ultra-fast method for the frequency calibration of cheap receivers usually showing many ppm's of frequency error, by using DAB.
Constellation visualization. First app to implement a linear (in contrast to circular) display of the DAB bit constellation, for a reliable Signal to Noise Ratio (SNR) calculation. Others have followed.
Airband Features not found in any other SDR, like the Channel Input or the Flip Switch for a quick exchange between the active and standby channel. Correct handling of the 8.33kHz separation.
In Version 4 the DAB sensitivity has been much improved in order to deliver audio also on the weakest signals.
It would be great if you considered to use the QIRX SDR. In case the unprobable happens and you find an error, please use the Error-Reporting system on GitHub, or send me an email about it. Here you can find the history of the software. In case you think something might be wrong, please let me know! All comments are welcome!
QIRX like most SDRs processes so-called I/Q Data. In case you are not yet familiar with this important concept, you may find a nice introduction on the site I/Q Data for Dummies.
The following hardware is supported by QIRX:
QIRX (V3, V4) is able to work flexibly in various configurationsv, purely local (i.e. the hardware connected to the local PC), purely remote (i.e. the hardware connected to one or more remote PCs), ore mixed local-remote.
The picture shows a nearly ideal spectrum of a DAB+ ensemble.
Coarse timing and frequency checks are only performed after a complete synchronization loss.
The following pictures will show the two different views of the constellation, all obtained from the same demodulated spectrum.
Linear Constellation: Advantages
In QIRX, the sampling rate error is permanently corrected. The fact that the deviation of the bit positions from the horizontal is proportional to the carrier index results in the fact that the bits remain scattered around a straight line. This fact is exploited in the correction algorithm which re-positions all bits around their horizontal angle line.
Even more, the Modulation Error Rate MER is the Standard Deviation of the bit positions around the horizontal line, of course after correction of the sampling rate error. This holds with a relatively small error, see the Report about Signal Quality. For more information and possible benefits of the sampling rate error correction you might wish to read the third part of our "Calibration" tutorial.