drm-receiver-0.99

Since the drm decoder in the sw receiver has got a lot of updates, it seemed time to adapt the drm decoder in the
drm receiver. The decoder is now a complete copy of the drm decoder in the sw receiver.
A fresh AppImage and windows installer are created

drmreceiver-0.9

DRM is digital radio on short and medium waves. Other than e.g. DAB it does not need a bandwidth of 1.5 MHz, DRM transmissions fit (well, most of them) with their 10 KHz width within existing Brodcast bands.
DRM works fine with nice signals, it is sensitive to fading and other signal distortions.

The "payload" isi usually transferred as QAM16 or QAM64 data. The picture shows the decosign of a transmission of Radio Romenia International.
The "scope" with the yellow arrows shows the correction to be applied on the pilots in the frames,
i.e. the equalization, needed for the decoding of the signal. Each yellow arrow tells the correction to be applied
on the amplitude of the a pilot (i.e. a carrier with a predefined signal) , the other one the correction on the phase.
The small black square to the right shows the constellation of the signal: in QAM16 a value may take one of 16 positions, both amplitude and phase are important here. (The picture here is from the recording of a nice recorded signal).

The audio encoding here is AAC (a variant for DRM), alternatively the data could have been decoded in xHE-AAC.
When building the software, there is a choice between using the "faad" library or the "fdk-aac" library, the second oone is
able to decode xHE-AAC encoded data. However, the version of fdk-aac on U20, where I build the AppImage is (probably)
to old and not capable of decoding xHE-AAC. So the AppImage was built with the faad library, while the windows installer is built with an fdk-aac library.

In my environment, I receive two stations broadcasting in DRM, Radio Romenia Internation with transmissions in English and German, and Kuwait, with an transmission Arab language.

I am always interested in getting recordings in whatever language, such recordings help in improving the implementation

drm-receiver 0.8

drm 0.95 has some support for xHE-AAC encoded services

The current version (including the precompiled versions) has a modified interface for the "dabsticks".
As known, dabsticks usually function on frequencies above 28 Mhz, with a clever trick (not mine) that is lowered to app 15 MHz.
The currebnt version has an aditional seletor, one for direct sampling. Direct sampling for low frequencies requires a small
modification to the stick itself (see e.g. rtlsdr.com for details).
A drawback is that with direct sampling the data stream consists of only I samples, rather than the complex IQ samples.
Since drm decoding requires full IQ samples, the direct sampling extension is equipped with a filter to transform the I samples
into analytical IQ samples, i.e. only for "positive" frequencies

Note that since my - pretty old - dabstick broke into two pieces, the extension was not tested

drm-receiver 0.9

DRM receiver
AppImage working with faad, windows installed version working with fdk-aac, and is able to handle xHE-AAC

Supported devices
a. sdrplay
b. hackrf
c. dabsticks with an RT820 tuner chip

drm-receiver 0.85

For windows an installer is available, for Linux-64 an AppImage
Note that there is a slight difference between the two, the AppImage uses the faad library for AAC decoding, the Windows version the fdk-aac lib

drm-receiver

A decoder putely for drm. A redesigned and partially reimplemented version of the drm decoder of the sw software

For Windows an installer is available, Linux users have to create an executable