This chapter provides guidance on managing physical units within SIGVIEW and how the software handles these units during analysis.


Amplitudes ("Y-Axis" units)


To ensure SIGVIEW properly handles the amplitude values of your signal or spectrum, it’s crucial to specify the correct amplitude units of your input signal. Since most common input formats (e.g., WAV files, sound cards, and many DAQ devices) don’t include unit information, SIGVIEW must convert the raw integer or floating-point values into physical units. The following scenarios outline how to handle amplitude units:


  1. If you know the units of your input signal, but SIGVIEW doesn’t display them: It’s likely because the input format doesn’t include unit information. For example, standard WAV file does not contain unit information at all. In this case, you can manually enter the unit in the Axes Settings dialog. Once entered, the unit will be displayed on the Y-Axis and will be used to automatically determine the units for various analysis windows derived from your signal (e.g., spectrum, Time-FFT, etc.).
  2. SIGVIEW displays the amplitude units as provided by your DAQ device or file, but those are not the units you need or expect:. For example, most professional DAQ devices will provide voltage values, and SIGVIEW will display the signal accordingly. But, you know that your sensor, which is attached to a DAQ device, actually measures acceleration and delivers "100mV/g", based on its specification. Of course, you would like SIGVIEW to display and work with "g" units instead with voltages. In that case, you would create a Calibration File, converting V to g according to the sensor specification. Once this calibration is applied, SIGVIEW will display and use the correct amplitude units, and these units will also apply to various analysis windows. For signal files, you can use the Scale/Normalize function to achieve the same goal. As in the first case, the amplitude unit of the input signal will be used to deduct units of various analysis windows originating from your signal (spectrum, Time-FFT etc.). In the case of signal file, you would use Scale/Normalize
  3. If you’re unsure about the units SIGVIEW is displaying or how to convert them to the desired units, consult the documentation for your file source, DAQ device or sensor to identify the provided signal units. Alternatively, you can use an external calibrated signal source to correlate the physical units with the values shown in SIGVIEW, as described in the Calibration chapter. Once you understand the correct units, you can follow the steps in the previous scenarios.


If you change the amplitude unit in a signal after some analysis windows have been created, they may not apply the new unit value immediately. Therefore, it is recommended to specify the correct amplitude value before starting to create analysis windows based on that input signal.


Units will be calculated for Signal Calculator results only for very simple expressions. For more complex ones, you will have to enter the unit manually by using Axes Settings dialog.


Time/Frequency Units ("X-Axis" units)


  • For time-domain input signals, SIGVIEW assumes the units are in seconds, and will display "sec" on the X-axis. You can change this unit in the Axes Settings dialog if necessary. The time unit of the input signal will also be used to determine the units for analysis windows, such as Time-FFT.
  • Spectrum windows automatically generate and display units, typically in Hz (or "Order" for order tracking windows). Even if the source signal uses different X-Axis units (not seconds), spectra will still display in Hz. In such cases, Hz should be interpreted as the "number of oscillations per unit of the base signal’s X-Axis unit". You can switch between Hz/kHz/MHz unit in the properties of the spectrum window or in default spectral analysis settings.