domenica 1 luglio 2018 / DAB

Searching for a DAB/DAB+ decoder I found this useful software running on Windows 10, Linux, macOS, Android. The picture above show a DAB signal ( OFDM modulation: Orthogonal Frequency Division Multiplexing ) with a bandwidth of 1,536 MHz, 1536 carriers at 1 kHz spacing and a symbol rate of 800 Hz. is an open source software with support for rtl-sdr (RTL2832U) and airspy. I tested the software with an AirSpy sdr receiver. After the program launch, detected automatically the sdr and start to scan the frequencies for any possibile DAB transmission.
The scanning frequency was very quickly and after few minutes I found 2 DAB carriers ( 30 stations ).

The second picture show the program window with many useful informations about the DAB signal: a stations list ( in this case 30 stations - channels 12A and 12C ), station name, signal strenght, error code, program type, Kbps, DAB audio mode, an image of the current audio program ( normally a cover of the on air song… ) and other technical informations:

- Sdr device
- Channel and frequency
- Frequency corrections
- Frames error
- RS Error
- AAC error
- Frame Synchronization

The three rectangles are an indicator for the signal quality and decoding, from left to right:

1. Signal sysnchronization: red = out of sync / green: sync
2. FIC CRC Fast Information Channel Checksum: red = NO CRC / green = CRC OK
3. Frame errors: red = Error / green: No error

Another interesting feature is the "waveform visualizer" window useful to have an "eye quality" view of the signal.

More info here :

Please visit the GitHub repository:

giovedì 21 giugno 2018

VFT - T207 detector tool

This VFT signal was recorded in july 2016.

After some necessary "cuts" I isolated the FSk signal.

As showed on the pictures above I found the bits sequence on air...

Using the "T207-detector" coded by Antonio Anselmi and Christoph Mayer is was very simple to find out a T207 encoding in FSK bitstreams.

More info:
GNU Octave, scientific programming language

73 de Ik1yde