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

Parameter	Specification
Data acquisition	Digital IF stream (complex baseband I/Q) Soundcard (real or complex) Digital AF (WAV 8, 16, 32 Bit) Others on request
Localization	English or German Others on request
Documentation	PDF User manual / PDF Online-Help
Recommended PC hardware	Notebook or Desktop; CPU: Intel i5, min. 2 GHz Memory: ≥ 2 GByte RAM, HDD: ≥  10 GB Screen Resolution min. 1280 x 1024 Pixel Soundcard for analog IF input, 1 GBit/s Ethernet for digital IF input
OS	Windows 7 SP1 (with Microsoft Windows patch KB2999226) / 10 de/en, 64 bit Linux (CentOS 7.5) 64 bit

 

Features

Software Feature	Remarks
Alphabets	Can be added to the decoder, free configurable (requires go2DECODE Standard or Professional)
Decoders	Our list of standard, military,PMR and SAT decoders is subject to continuous development. You find a current list of available decoders here.
Voice detection, demodulation, recording	Modulation types: AM, FM, USB, LSB Detection:  voice yes/no Nominal frequency Voice Pitch Automatic audio demodulation and recording
Demodulators	AM / A3E Analogue Selcal ASK 2, 4 ASK2PSK8 ASK4PSK8 Chirp Clover II Clover 2000 Clover 2500 Coquelet DPSK 2, 4, 8, 16 A/B F1A FM / F3E F6 / F7B FSK 2 matched FSK 2, 3, 4 disc. FSK 2, 3 auto shift MSK / GMSK J3E (USB, LSB) LINK 11 MDPSK 2, 4, 8, 16 A/B MFSK 2 Morse MPSK 2, 4, 8, 16 A/B MT63 MultiModem MultiTone (FSKn) OFDM OQPSK Pactor II, III, IV PSK 2, 4, 8, 16 A/B PSK data aided (mode controlled by decoder) QAM 16, 32, 64, 128, 256 TFM3 THROB / THROBX
Demodulator features	Automatic frequency, amplitude and symbol rate control Fast equalizer using known training sequences (via DDL) Primary demodulation USB/LSB/AM/FM Automatic burst synchronization
Signal bandwidth	Typical 50 kHz; higher value possible but not guaranteed
Symbolrate	Higher values (up to 500 kBd) possible but not guaranteed
Sensitivity	6 dB (decoding), 10 dB (automatic recognition)
GUI	Easy and intuitive to operate user interface Input spectrogram with live audio Manual and automatic demodulator and decoder control Different analysis displays for manual signal analysis Specialized signal analyzing cursor measurement functions Modem editor with demodulator and decoder settings Decoder editor an compiler (DDL)
Input Audio (DANA)	Up to 10 MHz sampling rate (note: functionality may be limited for sampling rates higher than 2 MHz) Playlist (files) Loop mode Complex IQ / real files Remove DC Filtering Mirror FM demodulation Time source selection (file / system clock) Sample rate converter Center frequency tuning Streaming TCP/IP
Input Files	Digital IF (complex baseband I/Q 32bit) Sampling rate <= 10 MHz (note: functionality may be limited for sampling rates higher than 2 MHz) Playback of standard wav files Digital AF (WAV 8, 16, 32 Bit) Playback of Perseus and WiNRADiO WAV recordings with correct frequency display
Input TCP/IP Streaming	Generic PROCITEC/PLATH format VITA 49 PXGF
Signal recordings	Types: IF / AF Start / Stop Manual by operator Automatic by trigger Trigger types Configurable squelch level Signal detected Transmission method recognized Transmission method unknown Voice/Morse detected File formats: WAV
Compatible receivers	AirSpy CommsAudit CA7851 CommsAudit CA7852 Grintek GRX Lan IZT R3xxx series IZT R4000 (SignalSuite) Microtelecom PERSEUS narda® NRA-3000 RX narda® NRA-6000 RX narda® IDA 2 narda® SignalShark® 3310 PLATH SIR 5110/5115 R&S EB500 R&S EM100 / PR100 RFSPACE NetSDR RFSPACE SDR-14 RTLSDR/Noxon USB-sticks SDRplay RSP1 & RSP2 Signalhound BB60C ThinkRF R5500-408 ThinkRF R5500-427 ThinkRF WSA5000-408 ThinkRF WSA5000-427 WiNRADiO G31DDC WiNRADiO G33DDC WiNRADiO G35DDC WiNRADiO G39DDC Generic VITA 49 receiver support Other generic “Winrad ExtIO” supported receivers Note: not all listed receivers are supported with Linux operation systems
ISO 9001:2015	Company is certified (not only hardware)
License	USB-Dongle  (WIBU-KEY/CodeMeter) License sharing with license server The AMBE+2™ voice coding Technology embodied in this product is protected by intellectual property rights inclu-ding patent rights, copyrights and trade secrets of Digital Voice Systems, Inc.  This voice coding Technology is licen-sed solely for use within this Licensed Product.  The user of this Technology is explicitly prohibited from attempting to extract, remove, decompile, reverse engineer, or disassemble the object code, or in any other way convert the Object Code into a human-readable form. US Patent Nos.  #8,595,002, #8,359,197, #8,315,860, #8,200,497, #7,970,606, #6,912,495 B2, #6,199,037.
Output	Decoding results TXT-File with decoded text XML-File with decoded text and metadata Signal recordings Voice recordings Bitstream *.rec files (bits and quality of each bit) Bitstream *.txt files (bits)
Sonagram Viewer (SoVi)	Standalone application for spectrum/spectrogram display
ResultViewer (PMO)	Display of: Decoder output Demodulated audio files (CW, TETRA etc.) Text output (ALE, HFDL, etc.) Binary files
Signal Generator (SOMO)	For standard test signals Requires go2DECODE-Professional; detailed description see below
Decoder Development	Modification of standard decoders Definition of new decoders Integration of existing decoders requires go2DECODE-standard or professional; detailed description see below
Soundcard Interface (DANA)	Analog input WiNRADiO VSC Virtual-Audio-Cable (VAC) etc.
Third party decoder	Interface to the DDC channel output Interface to the bitstream output Streaming and control interface with DDL
Training	Very short training period Same technology as in large decoding systems

 

Analysis

Analysis	Items
Displays	Spectrum Spectrogram/Sonagram Autocorrelation I/Q Constellation Eye pattern Time domain (oscilloscope) Analysis (magnitude, frequency and phase) Hell Bit
Squaring	Squaring: 0, 1, 2, 3
Windowing	Rectangle Hanning Hamming Kaiser Flat top Blackman
Cursors	Harmonic Crosshair 2 cursor modes
Center frequency	Adjustable
Operation modes	Online / offline

  

Decoder Development (optional)

Decoder Development	Item
Basic functions	Modification of standard decoders Definition of new decoders Integration of existing decoders
Function library	Preprocessing Symbol conversions Descrambling procedures Channel selections Pattern search Burst detection Forward/backward time jumps Deinterleaving Check and correction procedures: CRC, Hamming, Viterbi, BCH, Reed-Solomon Elementary arithmetic and bit manipulations Table handling Various output formats, alphabets, channels Control of demodulation and decoding Setting of demodulator parameters Selected voice codecs Branches and sub-routines (special functions on request) Soft decision
Decoder Editor	Automatic command completion Content related help Syntax highlighting
Compiler	Generation of binary decoder files Detailed code check and error messages
Debugger	Debugging Breakpoints on lines of code Single-step mode for lines of code Display of variable contents in various formats and displays Editing of variable contents Display of all input data packages Display of internal data buffer and current read position Advanced analysis of recognition, demodulation and decoding Breakpoints in several decoders of one modem list Comparison of the decoder behavior in search phase and decoding phase Monitoring the current demodulator state

 

SOMO Signal Generator (optional)

SOMO Signal generator	Item
Modulation generation	Single and multichannel, continuous and short-duration / burst signals Waveform and digital modulation (using ITU emission designators): ASKn PSKn (single and multi channel) QAMn (single and multi channel) ASKnPSKm (single and multi channel) NCPFSKn (Non-Coherent-Phase FSK) FSKn (single and multi channel) MSK (single and multi channel) GMSK (single and multi channel) F7B (FM with 2 or more digital channels) TFM 3/5 (Tamed Frequency Modulation) Morse Sine Rectangle Sawtooth Triangular Analogue modulation: AM, SSB (LSB / USB), FM Variable modulation parameters: Attenuation Center frequency Baud rate Pulse shapes: RC pulse, RC/RRC spectrum, Gauss pulse Short-duration / burst parameters
Coding generation	Binary, Baudot, ASCII, HC ARQ, ITA2 Differential/absolute coding Convolutional encoding / Viterbi CCITT standards V.17 - V.33 Variable bit stream, bit order, parity Scrambling algorithms and recursive sequences
Channel simulation	AWGN Multipath propagation: Watterson (ITU) and enhanced ITS model
Output	Soundcard / Wav Files / network stream

 

go2DECODE configurations and included functions
 

X = included o = as option available	Software go2DECODE Light	Software go2DECODE Standard	Software go2DECODE Professional
Automatic processing	x	x	x
Signal analysis		x	x
Edit of demodulator/decoder		x	x
Decoder Debugger			x
Signal generator (SOMO)			x
Recording / replay	x	x	x
Standard set of decoders	x	x	x
Set of military decoders ¹	o	o	o
Set of PMR decoders ²	o	o	o

 

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