SIGVIEW FAQ – Common Questions Answered - SIGVIEW Signal & Spectrum Analyzer

A: Yes. SIGVIEW has a full command-line automation interface: if SIGVIEW is already running, calling SIGVIEW.exe <command> <parameters> from any external application or batch file passes the command to the running instance rather than launching a new one. Available commands include loading workspaces, starting/stopping DAQ, saving signal windows to files, resetting windows, and more — see Command-line Functions for the full reference. Additionally, Instrument Properties allow triggering an external executable when a measured value crosses a threshold, and Julia scripting can implement arbitrarily complex automation logic inside SIGVIEW itself.

A: Yes. SIGVIEW licenses are not hardware-locked. Install SIGVIEW on the new computer using the standard installer from the Download page and enter your existing registration key. If you no longer have your key, contact us with your original order details and we will resend it.

A: The lowest frequency of FFT result depends on the sample rate of the signal and the length of a signal segment used for FFT calculation. It will always be equal to SampleRate/SegmentSize. This is not a SIGVIEW limitation, but a mathematical rule for DFT and FFT. For example, if your signal is sampled at 22050Hz, and you perform FFT on its first 512 samples, the lowest frequency will be 22050/512=43.066Hz. If you perform FFT on a 1 second segment from the same signal, the lowest frequency will be 22050/22050=1Hz.

A: The spectral resolution of FFT result depends on the sample rate of the signal and the length of a signal segment used for FFT calculation. It will always be equal to SampleRate/SegmentSize. This is not a SIGVIEW limitation, but a mathematical rule for DFT and FFT. For example, if your signal is sampled at 22050Hz, and you perform FFT on its first 512 samples, the difference between two adjacent FFT points will be 22050/512=43.066Hz. If you perform FFT on 1 sec segment from the same signal, the resolution will be 22050/22050=1Hz.

A: All spectral analysis tools in SIGVIEW are integrated under FFT option. By default, this option will calculate and display standard Magnitude (Amplitude) FFT plot. If you open Properties dialog for the FFT window, you will be able to change all calculation parameters and to define what will exactly be the result of the calculation: Magnitude, Power spectrum, PSD,... You can change default settings by using Signal tools/Spectral analysis defaults menu option.

A: By default, SIGVIEW will calculate spectrum values with optimal parameters - you don't have to bother with complicated things. Just load your signal, press FFT button and then choose Signal tools/Instruments and markers/Maximum position menu option, and an instrument with wanted result will appear along with the marker in the FFT graphics.

A: Yes, you can create overlay graphics by using context menus of each signal window, or by using Control window's context menu (select target signals first).

A: Yes, you can open Axes settings for a FFT window (Edit/Axes settings menu option) and select "Logarithmic X-Axis" and/or "Logarithmic Y-Axis" option. There are also corresponding context-menu options available after mouse right-click on the window.

A: Yes, you can set spectrum values to be in dB (logarithmic axis) in Spectral analysis defaults or in properties for each FFT window.

A: You can compare signals in time domain by showing them as overlays in one coordinate system (context menus or from Control window) or by subtracting them to determine the difference (Signal tools/Signal calculator). To compare signals in frequency domain, you can calculate their FFTs and compare them, or you can use some of cross spectral functions available through Signal calculator. For example, coherence function will show you similarities between signals for each frequency component on 0...1 scale.

A: Markers in SIGVIEW are closely related with Instruments. Most Instrument can place corresponding marker in a signal. For example, if you use Maximum instrument to show you the maximal signal value, marker will be displayed on the signal graph maximal value location. You can turn marker on/off or set its parameters by editing instrument properties. If you want simply to set marker on some specific location in the signal, please use "Marker at..." instrument or "Place marker here" option from the signal's context menu.

Since spectral analysis is used in many different fields, acoustics, vibration analysis, electronics, etc. , there are also many interpretations and units used for Y-axis values. SIGVIEW should be useful for spectral analysis in all of these application fields and therefore are the units simply omitted. Each user can define own units by using Axes settings for the FFT window.

A: Yes, you can select corresponding option on spectral analysis defaults or on Properties dialog for each FFT window.

A: SIGVIEW does not directly offers printing services, because there are simply much better applications for this purpose. You can simply use "Edit/Copy picture to clipboard" menu option to transfer the bitmap of the active window to the clipboard. After you do that, you can open any other graphics-capable application (MS Word, Excel, Visio, MS Paint) and paste the picture there. That way you can integrate SIGVIEW graphics with the rest of your text or you can edit graphics and print everything when you are finished.

A: Use the Calibration feature, accessible via "Data acquisition / Sound card calibration" from the main menu. A six-step process lets you record a signal of known amplitude and map the raw input level to a physical unit (e.g., m/s², Pa, V). The resulting calibration file is then assigned in the Data Acquisition dialog. Once calibrated, SIGVIEW will display the physical unit label on signal axes and automatically propagate it into derived spectrum results. For unit conversion between physical quantities (e.g., m/s² to g), the same calibration mechanism applies — define the scaling factor accordingly.

A: All three are selectable output types in the Spectral Analysis Defaults dialog ("Show result as" section):

For random/broadband signals, PSD is almost always the right choice. For discrete tonal signals, Magnitude or Power Spectrum is more intuitive.

A: SIGVIEW offers three averaging modes, configured in the Spectral Analysis Defaults dialog:

The "Average complex spectra" checkbox determines whether averaging is applied before or after computing magnitude/PSD — complex averaging removes incoherent components, which is useful for FRF measurements.

A: Window functions are selected in the Spectral Analysis Defaults dialog under "Apply window". The choice depends on your signal type:

A: SIGVIEW loads the complete signal into RAM, so available memory is the practical limit. For very long recordings, practical options are: (1) use "File / Extract from-to" to work on a specific time segment; (2) use the Time-FFT / Spectrogram view to visually navigate the entire file and identify segments of interest before extracting; (3) use a Julia script with a Signal Source Window to read and process the file in chunks, producing summary results without loading the full file. All signals are stored internally as 4-byte floats — use this to estimate the required RAM (samples × 4 bytes).

A: Julia scripting is available via the "Scripts" main menu. There are three script window types, described in Basic principles:

SIGVIEW monitors the script file and re-executes it automatically each time you save it in the editor. Missing Julia packages can be installed via "Scripts / Julia console" or automatically on first use. To speed up startup, a precompiled system image can be created via "Scripts / Create system image with common packages". Julia can also call Python libraries through PyCall — see Using Python Modules from Julia Scripts for details.

A: The most common problem is that you did not enter the data exactly as stated in the registration email. All three strings: registration name, email address and registration key must be identical as in the registration email. If this does not solve the problem, just contact us and we will find the solution.

A: Spectral leakage occurs when the analyzed signal is not exactly periodic within the FFT window length. This is normal behavior for any real-world signal analyzed with a rectangular window. Fix: apply a window function (Hann is the standard recommendation) in the Spectral Analysis Defaults dialog. If leakage persists after windowing, check for a DC offset — enable the "Subtract mean" option in the same dialog, or remove the DC component first using the Signal Calculator (subtract the Mean instrument value from the signal).

A: A DC spike indicates a non-zero signal mean. The fastest fix is enabling "Subtract mean" in the Spectral Analysis Defaults dialog — this subtracts the mean from each FFT frame before calculation. Alternatively, use the Signal Calculator to subtract the Mean instrument value from the signal permanently, or apply a high-pass IIR filter with a low cutoff frequency via "Signal tools / IIR filter".

A: Frame drops are typically caused by insufficient CPU time for the analysis chain. Try the following: (1) reduce the number of simultaneously open analysis windows chained to the DAQ input; (2) increase the DAQ block size in the Data Acquisition device settings dialog; (3) reduce FFT size or disable segment averaging. If the issue persists, consider using "Data acquisition / Log data in file" to record first and analyze offline, which removes the real-time processing constraint entirely. See Logging Signal Data to File.