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+49 7231 155 61-0


Manual technical signal analysis – Decoder development

go2DECODE is the analysis tool to determine technical parameters of unknown or new transmission methods, to adapt or develop decoders in order to incorporate them into an existing go2MONITORING solution. Therefore go2DECODE provides various displays and measurement functions as well as a complete decoder development environment including an easy-to-learn programming language.


Automatic signal production
  • Automatic signal detection, protocol recognition, demodulation and content decoding (content, text, audio, binaries etc.).
  • Automatic voice signal detection, modulation detection and demodulation
  • Signal triggered (squelch, recognized protocol, unknown signal) recording of AF and IF
  • Signal buffering with automatic internal replay for lossless recognition and decoding (production from the first bit)
Extensive list of communication protocols
  • More than 200 HF, VHF and UHF modes as standard, military and PMR package directly available. Permanently increased with new modern modes.
  • User-expandable decoder library with integrated decoder development tools and easy to use Decoder Description Language (DDL)
  • Many full automatic modes. Autonomous detection of used transmission modes and alphabets
  • Large set of freely parametrizable universal demodulators using high quality filters, soft decision and decoder output control
Manual signal analysis
  • Large list of manual signal analysis displays, freely parametrizable for modulation type detection, symbol rate measurement etc.
  • Different cursor functions with special measurement features (cross-hair, harmonic, selection, centered, ...)
  • Many integrated special signal analysis functions like signal squaring, bitstream synchronization, …
  • Optimization of demodulation and decoding process by processing analysis
Open signal and result interfaces
  • Signal decoding from digital or analogous receivers via streaming, audio, files or internal signal buffer
  • Universal receiver control with open ExtIO support, many receiver models from different manufacturers are supported
  • Full compatible with other go2SIGNALS products to exchange decoders, records and results for further automatic production or bitstream analysis


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)

Tech Specs

go2DECODE Technical Specifications



Data acquisition

Digital IF stream (complex baseband I/Q)
Soundcard (real or complex)
Digital AF (WAV 8, 16, 32 Bit)
Others on request


English or German
Others on request


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


Windows 7 SP1 (with Microsoft Windows patch KB2999226) / 10 de/en, 64 bit
Linux (CentOS 7.5) 64 bit



Software Feature



Can be added to the decoder, free configurable
(requires go2DECODE Standard or Professional)


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


AM / A3E

Analogue Selcal

ASK 2, 4




Clover II

Clover 2000

Clover 2500


DPSK 2, 4, 8, 16 A/B


FM / F3E

F6 / F7B

FSK 2 matched

FSK 2, 3, 4 disc.

FSK 2, 3 auto shift




MDPSK 2, 4, 8, 16 A/B



MPSK 2, 4, 8, 16 A/B



MultiTone (FSKn)



Pactor II, III, IV

PSK 2, 4, 8, 16 A/B

PSK data aided (mode controlled by decoder)

QAM 16, 32, 64, 128, 256



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


Higher values (up to 500 kBd) possible but not guaranteed


6 dB (decoding), 10 dB (automatic recognition)


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



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



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


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



RTLSDR/Noxon USB-sticks

SDRplay RSP1 & RSP2

Signalhound BB60C

ThinkRF R5500-408

ThinkRF R5500-427

ThinkRF WSA5000-408

ThinkRF WSA5000-427





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)


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.


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


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


Very short training period

Same technology as in large decoding systems






I/Q Constellation
Eye pattern
Time domain (oscilloscope)
Analysis (magnitude, frequency and phase)


Squaring: 0, 1, 2, 3


Flat top


2 cursor modes

Center frequency


Operation modes

Online / offline


Decoder Development (optional)

Decoder Development


Basic functions

Modification of standard decoders
Definition of new decoders
Integration of existing decoders

Function library

Symbol conversions
Descrambling procedures
Channel selections
Pattern search
Burst detection
Forward/backward time jumps
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


Generation of binary decoder files
Detailed code check and error messages



  • 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


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


Multipath propagation: Watterson (ITU) and enhanced ITS model


Soundcard / Wav Files / network stream


go2DECODE configurations and included functions

X = included
o = as option available

Software go2DECODE

Software go2DECODE Standard

Software go2DECODE Professional

Automatic processing




Signal analysis




Edit of demodulator/decoder




Decoder Debugger




Signal generator (SOMO)




Recording / replay




Standard set of decoders




Set of military decoders ¹




Set of PMR decoders ²





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


Signal overview and decoding

go2DECODE combines manual and automatic signal recognition and decoding in one tool. Demodulation and decoding is traceable by various signal displays and adaptable by variable parameter settings.

  • Input signal overview

  • Modem parameter settings

  • Display parameter setting

  • Modem list, producing modem is marked

  • Decoded content

Signal overview and decoding
go2DECODE combines manual and automatic signal recognition and decoding in one tool. Demodulation and decoding is traceable by various signal displays and adaptable by variable parameter settings.

  • Spectrogram with variable time resolution

  • Harmonic cursors

  • Spectrum with variable frequency resolution

Signal analysis – Spectrogram and spectrum
Manual signal analysis features make it a complete signal analysis tool. FFT analysis with various parameter settings and cursor functions are available.

  • Constellation display

  • Spectrogram and spectrum

  • Spectrum over squared input signal

Signal analysis – Constellation display / squared spectrum
High level analysis functionalities like constellation display, squared signal spectrum, etc. make it a powerful tool.

  • Bit display

  • Hell display

  • Signal autocorrelation

Signal analysis – Signal correlation and bit framing
Different signal correlation and bit framing measurement can be used to detect protocol type and framing behavior.

  • Time analysis with amplitude, phase and frequency

  • Eye pattern

Signal analysis – Time analysis and eye pattern
go2DECODE includes time analysis features with amplitude, phase and frequency graph and value histograms. Demodulation tracing analysis (e.g. eye pattern) with variety functions is also available.

  • Automatic modem recognition search results

  • Production results

Automatic modem recognition and production
Automatic signal and protocol recognition and decoding makes it easy to handle with unknown or changing signals. More than 200 modes are directly available; the operator can enhance the number including its own modes.

  • Parametrizable Demodulator

Freely parametrizable universal demodulator
Own modes can be generated by parameter setting of the universal demodulator and writing own decoder or integrate existing ones.

  • Decoder editor

  • Compiler output

Full integrated decoder development tools
go2DECODE is an open decoder tool. Own decoders can be implemented to expand the list of available modes by using the full integrated decoder development tools, including a special decoder description language, editor, compiler and debugger.

  • Modulator list

  • Modulator parameter settings

  • Display parameter settings

  • Generated signal scenario

SOMO Software modulator
SOMO is an additional, included software tool for signal scenario generation, used for testing and training. It includes a variety of different modulators, all in a wide range parametrizable.