# go2signals Signal Analyzer

Signal Analyzer offers manual and automated modulation off-line analysis in a user-friendly way. It provides analysts and operators with a quick display of all modulation-specific information on a few predefined screens. The user does not have to work step by step through the various analysis functions and set up the mathematical operators to analyze the signal.

The result of the "signal analysis" can be used to identify/document signals or to set up new demodulators and decoders for go2DECODE/go2MONITOR.

### Key Facts

- Analysis windows that offer direct support for all necessary analysis methods
- Use the expertise of our analysis specialists in combination with your knowledge
- Easy to use, perfect for both beginners and experts
- Simple signal selection (frequency and time range), similar to "cropping" an image
- Analysis screens for Time, Periodicity, PSK, FSK, Multi-CH PSK/QAM OFDM
- Waterfall, Spectrum, Histogram, Auto-correlation, Constellation, Scatter etc.
- COTS hardware (computers, receivers)

# Features

### Time

The Time Analysis module provides various time domain diagrams for manual analysis of basic emission characteristics, e.g. the modulation type of an emission.

The Time Analysis shows three diagrams that can contain:

- Amplitude
- Phase
- Frequency
- Amplitude (I+Q)
- Real (in phase)
- Imaginary (quadrature)
- Power (squared magnitude, lin.)
- Level (log. power)

### Periodicity

Periodicity Analysis enables the detection of repetitive components, such as regularly sent synchronization sequences.

The analysis is performed depending on the selected metric and an auto-correlation is displayed.

Repeating sequences become visible in a circulation display.

### Classifier

The Classiﬁcation Analysis module runs an automatic signal classification of a selected part of a signal.

All relevant signal parameters are displayed in a table if the classification was successful, otherwise only

generic parameters are displayed.

### PSK

PSK Analysis can be used for manual analysis of PSK modulated signals.

Several diagrams are displayed, which can be used to determine the following values:

- Carrier frequency
- Symbol rate
- Version of the PSK modulation and order

### FSK

FSK Analysis can be used for manual analysis of FSK modulated signals.

Several diagrams are displayed which can be used to determine the following values:

- modulation order, the number of tones
- Symbol rate
- Frequency-Oﬀset aka center frequency
- Shift, (the frequency spacing of the outer tones).

### MCH-PSK / QAM

This module provides plots and measurements for the analysis of PSK/QAM multicarrier signals.

The following assumptions apply to a signal to be analyzed:

- Carriers are equidistant in frequency
- The symbol rate on all carriers is the same
- The analyzed signal is coherent, i.e., it is taken from a single burst or continuous emission
- Sufficient signal is available for processing, i.e., at least a few hundred symbols are recommended.
- Automatic estimation of the parameters uses the statistical properties of the signal. The analysis works best with strong (high SNR), undistorted signals. Idle or repetitive symbol sequences can lead to confusing analysis results

The following parameters can be determined with the analysis:

- Carrier spacing
- Carrier frequency, i.e. center of the first (left) carrier
- Symbol rate
- Used constellation for each carrier

### OFDM (Optional)

OFDM signals are a special case of multicarrier modulated PSK/QAM signals.

The abbreviation stands for Orthogonal Frequency Division Multiplexing. In this modulation method, symbols that are deﬁned as I/Q values (complex numbers) are distributed over several carriers. This modulation method places symbols that are deﬁned as I/Q values (complex numbers) on multiple carriers.

The modulation and demodulation are usually performed by applying the Inverse Discrete Fourier Transform (IDFT) in the modulator and the Discrete Fourier Transform in the demodulator (DFT).

The analysis performs an automatic estimation of the basic modulation parameters of a modulated OFDM signal.

These parameters can be checked by the user and modified if necessary. Selected parameter values can be overwritten, allowing manually controlled demodulation. The results are shown on several displays.

### Demodulation

This module provides demodulation functions for various modulation types. The purpose of the module is to visualize the demodulation quality to enable the user to optimize the demodulation parameters

The graphical eye pattern diagram and the I/Q plot give a very good impression of the demodulation quality.

The variety of demodulation parameters requires precise configuration for best results.

Although the demodulated bits are displayed, bit analysis and decoding are not part of this module.

### OQPSK

This module provides tools for manual analysis of Offset-QPSK (OQPSK) modulated emissions, similar to the PSK-analysis (see module PSK Signal Analysis). OQPSK is a special case of QPSK (aka PSK-4A), where the Q-branch is shifted (offset) by half a symbol duration relative to the I-branch - before transmission.

The offset reduces the variation of the envelope - compared to a usual QPSK waveform. Moreover the transitions through zero are completely removed. The power spectrum of OQPSK is same as for a usual QPSK.

Initially modulating 2 bits in one symbol, the offset’ed signal modulates 1 bit per half symbol duration, alternating I- and Q-branch per bit.

Metrics are calculated and plotted to enable users to measure the following modulation parameters:

- carrier frequency fc
- symbol rate Rs

### Signal Analyzer

- Easy to use
- Works with I/Q data recordings (.wav files)
- Possibility to modify metadata, if contained in the file
- FM and AM demodulator to remove primary modulation
- Demodulation capability