Automatic Recognition and Decoding

go2DECODE’s signal detection and production is a multi-level process. go2DECODE buffers the incoming signal continuously. Buffering allows loss-less demodulation in time respect. go2DECODE checks the signal for the predefined modem types in the steps:

• detection
• recognition
• demodulation and decoding.

Signal characteristics (e. g. centre frequency and symbol rate) are determined and displayed. Decoded text will be displayed as plain text or as a formatted XML-stream.

Because of this multi-level process a modulation classification, a modem recognition and a complete production can be realised with go2DECODE. Thus even incomplete processing steps lead to partial results. Quality criterion's of all results are calculated and displayed.

For best results, code aided and soft-decision decoders are implemented in some decoders.

Processing of Voice Signals

A powerful voice detection module is integrated. The voice processing algorithms of go2DECODE are insensitive to interferences like wideband interferences caused by a thunderstorm.

The sensitivity level itself can be parameterized. In addition to the decision “voice yes or no” the module determines the values for nominal frequency, voice pitch and modulation type.

The voice transmission can be demodulated and stored in audio files for listening and further processing. All this is done in real-time and tailored to the typical COMINT signal scenario.

Recording of Signals and Bits

Apart from the demodulation and decoding of radio signals, the recording of signals is an important application in everyday use. Signal recording not only yields the material for manual technical analyses of unknown signals but also for archiving the signals of interest. go2DECODE enables to record both IF as well as AF upon demodulation.

The recordings are started and stopped either via automatic triggers or manually by the operator. The triggers supported by go2DECODE are;

• configurable squelch
• signal detection
• modem recognition
• voice detection

go2DECODE can record the demodulated bit stream to a txt-file or to a special go2DECODE file format that includes additional meta data like the quality of each bit.

Manual Signal Analysis

Precise measurements can be obtained with the displays provided by go2DECODE.

All the important tools needed to determine the signal characteristics are available:

• Spectrum display
• Spectrum/Sonagram (Spectrogram) display
• Autocorrelation display
• Constellation display
• Time display
• Analysis display (for the simultaneous interpretation of magnitude, frequency and phase of a signal to get a first impression of the used modulation)
• Hell display
• Bit display

Hell and bit display show information about the used coding. In each display cross-hair or harmonic cursors are offered.

This powerful tool kit can be used to get the required parameters to setup new demodulators for decoders(modems).