The increasing density of signals, the growing complexity and the use of modified standard modems are posing ever-increasing challenges. To keep a handle on these challenges of signal monitoring and interception, it is necessary to automate the processing of signals of interest and to concentrate on the analysis and decoding of new, unidentified emissions. Generating more results, the use of our go2MONITOR solution reduces the routine workload, processing known signals job-based and automatically. Therefore the highly educated specialists can focus on the analysis and determination of technical parameters and settings of new, unidentified signals and unknown modems.

go2DECODE provides all functions and comprehensive analysis tools to recognize modems, to analyze signals, adapt demodulator parameters, develop new decoders, set up new protocols and create monitoring tasks in order to include these into the knowledge base for future automatic processing.

This way the analysts’ knowledge and experience gets incorporated into all monitoring solutions based on go2SIGNALS products for future automatic processing.

Automatic Recognition and Decoding

Working in changing signal scenarios needs a decoder with automatic modem recognition to lossless process every signal of interest. Therefore, go2DECODE checks the input signal for the predefined modem types in the steps:

• detection
• automatic 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. go2DECODE buffers the incoming signal continuously. Buffering allows lossless demodulation and decoding in time respect.

Because of this multi-level process a modulation classification, 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 demodulators are implemented in the decoders if supported by the transmission protocol.

Manual Signal Analysis

Precise measurements can be obtained with the signal analysis 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. Each display can be parametrized freely and offers many different cursors functionalities (like cross-hair or harmonic cursors). This powerful tool kit can also be used to get the required signal parameters to set-up new demodulators for own decoders(modems).

Decoder Description Language (DDL)

As an outstanding feature go2DECODE enables the user to edit and extend the existing decoder library. Using its integrated decoder development features, its easy to develop new or modify existing decoders and use them together with the integrated universal demodulators.

The evolutionary growing Decoder Description Language (DDL) is the particularly suitable tool kit for this task. More than 100 commands e.g. for pre-processing, searching, reading, transformation, error correction and output formatting can easily be learned and used like a standard programming language.

The set of commands is designed not only for plain detecting and synchronising tasks but also for complex channel decoding methods. The decoders supplied have been created on the same basis; with the source code available users can adapt them easily or use them as models for their own solutions.

The decoders can be deployed to other go2SIGNALS installations (e.g. go2MONITOR) and to other radio monitoring systems using the same technology. Based on DDL technology, it is also easy possible to integrate decoders written in C, C++ or other programming languages

Triggered 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 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
• speech detection

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

Processing of Speech Signals

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

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

The speech 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.

Optional Tools

DANA (Digital Analogue Audio Interface)

DANA is the ultimate data source management tool for easy selection of various signal sources. Two signal sources are selectable:

• Analogue signals from the sound card
• Wav (IQ, real) and RAW files.

Single files or a play list can be played back. Varirous helpful settings are available for sampling rate conversion, filtering, DC removal, mirroring, selection of the time source, center frequency tuning, sound card configuration, automatic buffer flushing at the end of the file, loop mode and FM pre-demodulation.

PMO (Production Memory Observer)

The PMO tool can be used to manage the output of the decoder. AF recordings , IF recordings, Binary results and Production results are displayed in a structured list and lets the user select the specific data in a comfortable way. The tools of the context menu, which will be pop up on right mouse click, can be configured to have a quick export short cut to:

• Play audio recording
• Display decoder output
• Play IF-recordings (maybe with DANA)
• Display Binary data with a hex viewer
• Call a post processing tool
• ...

SOMO (part of the professional version)

SOftware based generation of MOdulated signals. SOMO is an advanced signal generator for operator training, simulation and testing.

• Wide range of modulation generators (ASK, FSK, PSK, QAM, OFDM, multi-channel, analogue, ...)
• Complex signal scenarios with several signals generated in parallel
• Burst signals with burst shaping
• Multi-channel signals with up to 64 channels
• Configurable modulation parameters
• Variable coding standards with editable text or binary pattern for coding
• Generator bandwidth of 20/40 kHz in online mode
• Adjustable noise level
• Running on COTS hardware, output soundcard or audio file
• HF Channel Simulation (multipath fading and noise)

DDL Debugger (part of the professional version)

A professional debugger specialized on DDL decoder development. The debugging functionality serves to verify the executable decoders in details. In an advanced mode, the Decoder Debugger can be operated with further analysing possibilities in an environment with all signal processing components running.

• Testing of isolated decoder sections
• Verifying intermediate results
• Stepping through the source code line by line
• Monitoring variables and intermediated buffers with each step
• Changing variable values at any step
• Defining breakpoints within the programme to stop continuous operation
• Running decoders independent of real time baud rate (i.e. faster or slower)

go2DECODE Technical Specifications

Features

Analysis

Decoder Development (optional)

SOMO Signal Generator (optional)

go2DECODE configurations and included functions
 

The performance of our software products depends on the hardware used.  
Technical parameters can differ under real operational conditions. Specifications subject to change.

Available from software version 19.2 (July 2019).

Decoders and Demodulators

1. MIL and PMR decoders may need an End-User-Certificate (depending on the country of the user)
2. Automatic sideband detection can be achieved via two modems set to inverse sidebands
3. A time gap between message bursts and acknowledge burst must be detectable
4. Separation of slow selcall types cannot be guaranteed
5. Slow multitone modems are recommended to operate with fixed nominal frequency

Our set of standard, military, PMR and SAT decoders is subject to continuous development.
Please download go2SIGNALS decoderlist the current list of available decoders.

go2DECODE Training

This training course familiarises the participant with all go2DECODE components and functions and their practical use. It focuses on delivery of basic knowledge of digital modulation and how to use signal analysis tools available. Configuration and parameter setting of demodulators and decoders for automatic detection of new modems will be explored in more depth. Skills will be gained in practical authentic situations using live signal recordings.

This training offers the possibility to handle individual tasks and queries as well as discussing the signal samples provided by the participants.

Training content:

• Field of application for go2DECODE
• Introduction to the user interface
• Fundamentals of digital signal modulation
• Use of signal analysis functions
• Creation of new transmission modes for automatic detection and production

Decoder Description Language Training

In this training course, participants are introduced to the fundamentals of the Decoder Description Language (DDL). The essential functions will be explained in detail and the commands of this easy to learn programming language will be explained.

Building on the participant‘s prior knowledge of the principles of channel coding and the fundamentals of bit error correction procedures, existing decoders will be modified and adapted to individual requirements. Following this training course, participants will be able to modify and to create new decoders. This training course addresses to technical employees who are familiar with programming, modification and adaptation of signal decoding software.

Training content:

• Creation and modification of decoders
• Program structure, function and commands and interfaces of the DDL
• Use of the decoder debugging function
• Practical exercise: writing a simple decoder
• Methods for bit error recognition and correction